Refactoring and optimisation

animationEvents.go

@@ -51,131 +51,6 @@ const (
 	AnimationIterationEvent = "animation-iteration-event"
 )
 
-func valueToAnimationListeners(value any) ([]func(View, string), bool) {
-	if value == nil {
-		return nil, true
-	}
-
-	switch value := value.(type) {
-	case func(View, string):
-		return []func(View, string){value}, true
-
-	case func(string):
-		fn := func(_ View, event string) {
-			value(event)
-		}
-		return []func(View, string){fn}, true
-
-	case func(View):
-		fn := func(view View, _ string) {
-			value(view)
-		}
-		return []func(View, string){fn}, true
-
-	case func():
-		fn := func(View, string) {
-			value()
-		}
-		return []func(View, string){fn}, true
-
-	case []func(View, string):
-		if len(value) == 0 {
-			return nil, true
-		}
-		for _, fn := range value {
-			if fn == nil {
-				return nil, false
-			}
-		}
-		return value, true
-
-	case []func(string):
-		count := len(value)
-		if count == 0 {
-			return nil, true
-		}
-		listeners := make([]func(View, string), count)
-		for i, v := range value {
-			if v == nil {
-				return nil, false
-			}
-			listeners[i] = func(_ View, event string) {
-				v(event)
-			}
-		}
-		return listeners, true
-
-	case []func(View):
-		count := len(value)
-		if count == 0 {
-			return nil, true
-		}
-		listeners := make([]func(View, string), count)
-		for i, v := range value {
-			if v == nil {
-				return nil, false
-			}
-			listeners[i] = func(view View, _ string) {
-				v(view)
-			}
-		}
-		return listeners, true
-
-	case []func():
-		count := len(value)
-		if count == 0 {
-			return nil, true
-		}
-		listeners := make([]func(View, string), count)
-		for i, v := range value {
-			if v == nil {
-				return nil, false
-			}
-			listeners[i] = func(View, string) {
-				v()
-			}
-		}
-		return listeners, true
-
-	case []any:
-		count := len(value)
-		if count == 0 {
-			return nil, true
-		}
-		listeners := make([]func(View, string), count)
-		for i, v := range value {
-			if v == nil {
-				return nil, false
-			}
-			switch v := v.(type) {
-			case func(View, string):
-				listeners[i] = v
-
-			case func(string):
-				listeners[i] = func(_ View, event string) {
-					v(event)
-				}
-
-			case func(View):
-				listeners[i] = func(view View, _ string) {
-					v(view)
-				}
-
-			case func():
-				listeners[i] = func(View, string) {
-					v()
-				}
-
-			default:
-				return nil, false
-			}
-		}
-		return listeners, true
-	}
-
-	return nil, false
-}
-
 var transitionEvents = map[string]struct{ jsEvent, jsFunc string }{
 	TransitionRunEvent:    {jsEvent: "ontransitionrun", jsFunc: "transitionRunEvent"},
 	TransitionStartEvent:  {jsEvent: "ontransitionstart", jsFunc: "transitionStartEvent"},
@@ -184,7 +59,7 @@ var transitionEvents = map[string]struct{ jsEvent, jsFunc string }{
 }
 
 func (view *viewData) setTransitionListener(tag string, value any) bool {
-	listeners, ok := valueToAnimationListeners(value)
+	listeners, ok := valueToEventListeners[View, string](value)
 	if !ok {
 		notCompatibleType(tag, value)
 		return false
@@ -212,20 +87,6 @@ func (view *viewData) removeTransitionListener(tag string) {
 	}
 }
 
-func getAnimationListeners(view View, subviewID string, tag string) []func(View, string) {
-	if subviewID != "" {
-		view = ViewByID(view, subviewID)
-	}
-	if view != nil {
-		if value := view.Get(tag); value != nil {
-			if result, ok := value.([]func(View, string)); ok {
-				return result
-			}
-		}
-	}
-	return []func(View, string){}
-}
-
 func transitionEventsHtml(view View, buffer *strings.Builder) {
 	for tag, js := range transitionEvents {
 		if value := view.getRaw(tag); value != nil {
@@ -250,7 +111,7 @@ func (view *viewData) handleTransitionEvents(tag string, data DataObject) {
 			}
 		}
 
-		for _, listener := range getAnimationListeners(view, "", tag) {
+		for _, listener := range getEventListeners[View, string](view, "", tag) {
 			listener(view, property)
 		}
 	}
@@ -264,7 +125,7 @@ var animationEvents = map[string]struct{ jsEvent, jsFunc string }{
 }
 
 func (view *viewData) setAnimationListener(tag string, value any) bool {
-	listeners, ok := valueToAnimationListeners(value)
+	listeners, ok := valueToEventListeners[View, string](value)
 	if !ok {
 		notCompatibleType(tag, value)
 		return false
@@ -303,7 +164,7 @@ func animationEventsHtml(view View, buffer *strings.Builder) {
 }
 
 func (view *viewData) handleAnimationEvents(tag string, data DataObject) {
-	if listeners := getAnimationListeners(view, "", tag); len(listeners) > 0 {
+	if listeners := getEventListeners[View, string](view, "", tag); len(listeners) > 0 {
 		id := ""
 		if name, ok := data.PropertyValue("name"); ok {
 			for _, animation := range GetAnimation(view, "") {
@@ -322,54 +183,54 @@ func (view *viewData) handleAnimationEvents(tag string, data DataObject) {
 // If there are no listeners then the empty list is returned.
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetTransitionRunListeners(view View, subviewID string) []func(View, string) {
-	return getAnimationListeners(view, subviewID, TransitionRunEvent)
+	return getEventListeners[View, string](view, subviewID, TransitionRunEvent)
 }
 
 // GetTransitionStartListeners returns the "transition-start-event" listener list.
 // If there are no listeners then the empty list is returned.
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetTransitionStartListeners(view View, subviewID string) []func(View, string) {
-	return getAnimationListeners(view, subviewID, TransitionStartEvent)
+	return getEventListeners[View, string](view, subviewID, TransitionStartEvent)
 }
 
 // GetTransitionEndListeners returns the "transition-end-event" listener list.
 // If there are no listeners then the empty list is returned.
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetTransitionEndListeners(view View, subviewID string) []func(View, string) {
-	return getAnimationListeners(view, subviewID, TransitionEndEvent)
+	return getEventListeners[View, string](view, subviewID, TransitionEndEvent)
 }
 
 // GetTransitionCancelListeners returns the "transition-cancel-event" listener list.
 // If there are no listeners then the empty list is returned.
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetTransitionCancelListeners(view View, subviewID string) []func(View, string) {
-	return getAnimationListeners(view, subviewID, TransitionCancelEvent)
+	return getEventListeners[View, string](view, subviewID, TransitionCancelEvent)
 }
 
 // GetAnimationStartListeners returns the "animation-start-event" listener list.
 // If there are no listeners then the empty list is returned.
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetAnimationStartListeners(view View, subviewID string) []func(View, string) {
-	return getAnimationListeners(view, subviewID, AnimationStartEvent)
+	return getEventListeners[View, string](view, subviewID, AnimationStartEvent)
 }
 
 // GetAnimationEndListeners returns the "animation-end-event" listener list.
 // If there are no listeners then the empty list is returned.
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetAnimationEndListeners(view View, subviewID string) []func(View, string) {
-	return getAnimationListeners(view, subviewID, AnimationEndEvent)
+	return getEventListeners[View, string](view, subviewID, AnimationEndEvent)
 }
 
 // GetAnimationCancelListeners returns the "animation-cancel-event" listener list.
 // If there are no listeners then the empty list is returned.
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetAnimationCancelListeners(view View, subviewID string) []func(View, string) {
-	return getAnimationListeners(view, subviewID, AnimationCancelEvent)
+	return getEventListeners[View, string](view, subviewID, AnimationCancelEvent)
 }
 
 // GetAnimationIterationListeners returns the "animation-iteration-event" listener list.
 // If there are no listeners then the empty list is returned.
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetAnimationIterationListeners(view View, subviewID string) []func(View, string) {
-	return getAnimationListeners(view, subviewID, AnimationIterationEvent)
+	return getEventListeners[View, string](view, subviewID, AnimationIterationEvent)
 }

colorPicker.go

@@ -87,57 +87,14 @@ func (picker *colorPickerData) set(tag string, value any) bool {
 
 	switch tag {
 	case ColorChangedEvent:
-		switch value := value.(type) {
+		listeners, ok := valueToEventListeners[ColorPicker, Color](value)
-		case func(ColorPicker, Color):
+		if !ok {
-			picker.colorChangedListeners = []func(ColorPicker, Color){value}
+			notCompatibleType(tag, value)
-
-		case func(Color):
-			fn := func(_ ColorPicker, date Color) {
-				value(date)
-			}
-			picker.colorChangedListeners = []func(ColorPicker, Color){fn}
-
-		case []func(ColorPicker, Color):
-			picker.colorChangedListeners = value
-
-		case []func(Color):
-			listeners := make([]func(ColorPicker, Color), len(value))
-			for i, val := range value {
-				if val == nil {
-					notCompatibleType(tag, val)
 			return false
-				}
+		} else if listeners == nil {
-
+			listeners = []func(ColorPicker, Color){}
-				listeners[i] = func(_ ColorPicker, date Color) {
-					val(date)
-				}
 		}
 		picker.colorChangedListeners = listeners
-
-		case []any:
-			listeners := make([]func(ColorPicker, Color), len(value))
-			for i, val := range value {
-				if val == nil {
-					notCompatibleType(tag, val)
-					return false
-				}
-
-				switch val := val.(type) {
-				case func(ColorPicker, Color):
-					listeners[i] = val
-
-				case func(Color):
-					listeners[i] = func(_ ColorPicker, date Color) {
-						val(date)
-					}
-
-				default:
-					notCompatibleType(tag, val)
-					return false
-				}
-			}
-			picker.colorChangedListeners = listeners
-		}
 		picker.propertyChangedEvent(tag)
 		return true
 
@@ -249,15 +206,5 @@ func GetColorPickerValue(view View, subviewID string) Color {
 // If there are no listeners then the empty list is returned
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetColorChangedListeners(view View, subviewID string) []func(ColorPicker, Color) {
-	if subviewID != "" {
+	return getEventListeners[ColorPicker, Color](view, subviewID, ColorChangedEvent)
-		view = ViewByID(view, subviewID)
-	}
-	if view != nil {
-		if value := view.Get(ColorChangedEvent); value != nil {
-			if listeners, ok := value.([]func(ColorPicker, Color)); ok {
-				return listeners
-			}
-		}
-	}
-	return []func(ColorPicker, Color){}
 }

datePicker.go

@@ -235,57 +235,14 @@ func (picker *datePickerData) set(tag string, value any) bool {
 		}
 
 	case DateChangedEvent:
-		switch value := value.(type) {
+		listeners, ok := valueToEventListeners[DatePicker, time.Time](value)
-		case func(DatePicker, time.Time):
+		if !ok {
-			picker.dateChangedListeners = []func(DatePicker, time.Time){value}
+			notCompatibleType(tag, value)
-
-		case func(time.Time):
-			fn := func(_ DatePicker, date time.Time) {
-				value(date)
-			}
-			picker.dateChangedListeners = []func(DatePicker, time.Time){fn}
-
-		case []func(DatePicker, time.Time):
-			picker.dateChangedListeners = value
-
-		case []func(time.Time):
-			listeners := make([]func(DatePicker, time.Time), len(value))
-			for i, val := range value {
-				if val == nil {
-					notCompatibleType(tag, val)
 			return false
-				}
+		} else if listeners == nil {
-
+			listeners = []func(DatePicker, time.Time){}
-				listeners[i] = func(_ DatePicker, date time.Time) {
-					val(date)
-				}
 		}
 		picker.dateChangedListeners = listeners
-
-		case []any:
-			listeners := make([]func(DatePicker, time.Time), len(value))
-			for i, val := range value {
-				if val == nil {
-					notCompatibleType(tag, val)
-					return false
-				}
-
-				switch val := val.(type) {
-				case func(DatePicker, time.Time):
-					listeners[i] = val
-
-				case func(time.Time):
-					listeners[i] = func(_ DatePicker, date time.Time) {
-						val(date)
-					}
-
-				default:
-					notCompatibleType(tag, val)
-					return false
-				}
-			}
-			picker.dateChangedListeners = listeners
-		}
 		picker.propertyChangedEvent(tag)
 		return true
 
@@ -463,15 +420,5 @@ func GetDatePickerValue(view View, subviewID string) time.Time {
 // If there are no listeners then the empty list is returned
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetDateChangedListeners(view View, subviewID string) []func(DatePicker, time.Time) {
-	if subviewID != "" {
+	return getEventListeners[DatePicker, time.Time](view, subviewID, DateChangedEvent)
-		view = ViewByID(view, subviewID)
-	}
-	if view != nil {
-		if value := view.Get(DateChangedEvent); value != nil {
-			if listeners, ok := value.([]func(DatePicker, time.Time)); ok {
-				return listeners
-			}
-		}
-	}
-	return []func(DatePicker, time.Time){}
 }

dropDownList.go

@@ -113,7 +113,16 @@ func (list *dropDownListData) set(tag string, value any) bool {
 		return list.setDisabledItems(value)
 
 	case DropDownEvent:
-		return list.setDropDownListener(value)
+		listeners, ok := valueToEventListeners[DropDownList, int](value)
+		if !ok {
+			notCompatibleType(tag, value)
+			return false
+		} else if listeners == nil {
+			listeners = []func(DropDownList, int){}
+		}
+		list.dropDownListener = listeners
+		list.propertyChangedEvent(tag)
+		return true
 
 	case Current:
 		oldCurrent := GetCurrent(list, "")
@@ -291,64 +300,6 @@ func (list *dropDownListData) setDisabledItems(value any) bool {
 
 }
 
-func (list *dropDownListData) setDropDownListener(value any) bool {
-	switch value := value.(type) {
-	case func(DropDownList, int):
-		list.dropDownListener = []func(DropDownList, int){value}
-
-	case func(int):
-		list.dropDownListener = []func(DropDownList, int){func(_ DropDownList, index int) {
-			value(index)
-		}}
-
-	case []func(DropDownList, int):
-		list.dropDownListener = value
-
-	case []func(int):
-		listeners := make([]func(DropDownList, int), len(value))
-		for i, val := range value {
-			if val == nil {
-				notCompatibleType(DropDownEvent, value)
-				return false
-			}
-			listeners[i] = func(_ DropDownList, index int) {
-				val(index)
-			}
-		}
-		list.dropDownListener = listeners
-
-	case []any:
-		listeners := make([]func(DropDownList, int), len(value))
-		for i, val := range value {
-			if val == nil {
-				notCompatibleType(DropDownEvent, value)
-				return false
-			}
-			switch val := val.(type) {
-			case func(DropDownList, int):
-				listeners[i] = val
-
-			case func(int):
-				listeners[i] = func(_ DropDownList, index int) {
-					val(index)
-				}
-
-			default:
-				notCompatibleType(DropDownEvent, value)
-				return false
-			}
-		}
-		list.dropDownListener = listeners
-
-	default:
-		notCompatibleType(DropDownEvent, value)
-		return false
-	}
-
-	list.propertyChangedEvent(DropDownEvent)
-	return true
-}
-
 func (list *dropDownListData) Get(tag string) any {
 	return list.get(strings.ToLower(tag))
 }

editView.go

@@ -333,75 +333,29 @@ func (edit *editViewData) set(tag string, value any) bool {
 		return false
 
 	case EditTextChangedEvent:
-		ok := edit.setChangeListeners(value)
+		listeners, ok := valueToEventListeners[EditView, string](value)
 		if !ok {
 			notCompatibleType(tag, value)
+			return false
+		} else if listeners == nil {
+			listeners = []func(EditView, string){}
 		}
+		edit.textChangeListeners = listeners
 		edit.propertyChangedEvent(tag)
-		return ok
+		return true
 	}
 
 	return edit.viewData.set(tag, value)
 }
 
-func (edit *editViewData) setChangeListeners(value any) bool {
-	switch value := value.(type) {
-	case func(EditView, string):
-		edit.textChangeListeners = []func(EditView, string){value}
-
-	case func(string):
-		fn := func(_ EditView, text string) {
-			value(text)
-		}
-		edit.textChangeListeners = []func(EditView, string){fn}
-
-	case []func(EditView, string):
-		edit.textChangeListeners = value
-
-	case []func(string):
-		listeners := make([]func(EditView, string), len(value))
-		for i, v := range value {
-			if v == nil {
-				return false
-			}
-			listeners[i] = func(_ EditView, text string) {
-				v(text)
-			}
-		}
-		edit.textChangeListeners = listeners
-
-	case []any:
-		listeners := make([]func(EditView, string), len(value))
-		for i, v := range value {
-			if v == nil {
-				return false
-			}
-			switch v := v.(type) {
-			case func(EditView, string):
-				listeners[i] = v
-
-			case func(string):
-				listeners[i] = func(_ EditView, text string) {
-					v(text)
-				}
-
-			default:
-				return false
-			}
-		}
-		edit.textChangeListeners = listeners
-
-	default:
-		return false
-	}
-	return true
-}
-
 func (edit *editViewData) Get(tag string) any {
 	return edit.get(edit.normalizeTag(tag))
 }
 
 func (edit *editViewData) get(tag string) any {
+	if tag == EditTextChangedEvent {
+		return edit.textChangeListeners
+	}
 	return edit.viewData.get(tag)
 }
 
@@ -635,17 +589,7 @@ func IsSpellcheck(view View, subviewID string) bool {
 // If there are no listeners then the empty list is returned
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetTextChangedListeners(view View, subviewID string) []func(EditView, string) {
-	if subviewID != "" {
+	return getEventListeners[EditView, string](view, subviewID, EditTextChangedEvent)
-		view = ViewByID(view, subviewID)
-	}
-	if view != nil {
-		if value := view.Get(EditTextChangedEvent); value != nil {
-			if result, ok := value.([]func(EditView, string)); ok {
-				return result
-			}
-		}
-	}
-	return []func(EditView, string){}
 }
 
 // GetEditViewType returns a value of the Type property of EditView.

filePicker.go

@@ -151,57 +151,14 @@ func (picker *filePickerData) set(tag string, value any) bool {
 
 	switch tag {
 	case FileSelectedEvent:
-		switch value := value.(type) {
+		listeners, ok := valueToEventListeners[FilePicker, []FileInfo](value)
-		case func(FilePicker, []FileInfo):
+		if !ok {
-			picker.fileSelectedListeners = []func(FilePicker, []FileInfo){value}
+			notCompatibleType(tag, value)
-
-		case func([]FileInfo):
-			fn := func(_ FilePicker, files []FileInfo) {
-				value(files)
-			}
-			picker.fileSelectedListeners = []func(FilePicker, []FileInfo){fn}
-
-		case []func(FilePicker, []FileInfo):
-			picker.fileSelectedListeners = value
-
-		case []func([]FileInfo):
-			listeners := make([]func(FilePicker, []FileInfo), len(value))
-			for i, val := range value {
-				if val == nil {
-					notCompatibleType(tag, val)
 			return false
-				}
+		} else if listeners == nil {
-
+			listeners = []func(FilePicker, []FileInfo){}
-				listeners[i] = func(_ FilePicker, files []FileInfo) {
-					val(files)
-				}
 		}
 		picker.fileSelectedListeners = listeners
-
-		case []any:
-			listeners := make([]func(FilePicker, []FileInfo), len(value))
-			for i, val := range value {
-				if val == nil {
-					notCompatibleType(tag, val)
-					return false
-				}
-
-				switch val := val.(type) {
-				case func(FilePicker, []FileInfo):
-					listeners[i] = val
-
-				case func([]FileInfo):
-					listeners[i] = func(_ FilePicker, files []FileInfo) {
-						val(files)
-					}
-
-				default:
-					notCompatibleType(tag, val)
-					return false
-				}
-			}
-			picker.fileSelectedListeners = listeners
-		}
 		picker.propertyChangedEvent(tag)
 		return true
 
@@ -436,15 +393,5 @@ func GetFilePickerAccept(view View, subviewID string) []string {
 // If there are no listeners then the empty list is returned.
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetFileSelectedListeners(view View, subviewID string) []func(FilePicker, []FileInfo) {
-	if subviewID != "" {
+	return getEventListeners[FilePicker, []FileInfo](view, subviewID, FileSelectedEvent)
-		view = ViewByID(view, subviewID)
-	}
-	if view != nil {
-		if value := view.Get(FileSelectedEvent); value != nil {
-			if result, ok := value.([]func(FilePicker, []FileInfo)); ok {
-				return result
-			}
-		}
-	}
-	return []func(FilePicker, []FileInfo){}
 }

focusEvents.go

@@ -20,22 +20,22 @@ const (
 	LostFocusEvent = "lost-focus-event"
 )
 
-func valueToFocusListeners(value any) ([]func(View), bool) {
+func valueToNoParamListeners[V View](value any) ([]func(V), bool) {
 	if value == nil {
 		return nil, true
 	}
 
 	switch value := value.(type) {
-	case func(View):
+	case func(V):
-		return []func(View){value}, true
+		return []func(V){value}, true
 
 	case func():
-		fn := func(View) {
+		fn := func(V) {
 			value()
 		}
-		return []func(View){fn}, true
+		return []func(V){fn}, true
 
-	case []func(View):
+	case []func(V):
 		if len(value) == 0 {
 			return nil, true
 		}
@@ -51,12 +51,12 @@ func valueToFocusListeners(value any) ([]func(View), bool) {
 		if count == 0 {
 			return nil, true
 		}
-		listeners := make([]func(View), count)
+		listeners := make([]func(V), count)
 		for i, v := range value {
 			if v == nil {
 				return nil, false
 			}
-			listeners[i] = func(View) {
+			listeners[i] = func(V) {
 				v()
 			}
 		}
@@ -67,17 +67,17 @@ func valueToFocusListeners(value any) ([]func(View), bool) {
 		if count == 0 {
 			return nil, true
 		}
-		listeners := make([]func(View), count)
+		listeners := make([]func(V), count)
 		for i, v := range value {
 			if v == nil {
 				return nil, false
 			}
 			switch v := v.(type) {
-			case func(View):
+			case func(V):
 				listeners[i] = v
 
 			case func():
-				listeners[i] = func(View) {
+				listeners[i] = func(V) {
 					v()
 				}
 
@@ -97,7 +97,7 @@ var focusEvents = map[string]struct{ jsEvent, jsFunc string }{
 }
 
 func (view *viewData) setFocusListener(tag string, value any) bool {
-	listeners, ok := valueToFocusListeners(value)
+	listeners, ok := valueToNoParamListeners[View](value)
 	if !ok {
 		notCompatibleType(tag, value)
 		return false

imageView.go

@@ -118,77 +118,6 @@ func (imageView *imageViewData) Set(tag string, value any) bool {
 	return imageView.set(imageView.normalizeTag(tag), value)
 }
 
-func valueToImageListeners(value any) ([]func(ImageView), bool) {
-	if value == nil {
-		return nil, true
-	}
-
-	switch value := value.(type) {
-	case func(ImageView):
-		return []func(ImageView){value}, true
-
-	case func():
-		fn := func(ImageView) {
-			value()
-		}
-		return []func(ImageView){fn}, true
-
-	case []func(ImageView):
-		if len(value) == 0 {
-			return nil, true
-		}
-		for _, fn := range value {
-			if fn == nil {
-				return nil, false
-			}
-		}
-		return value, true
-
-	case []func():
-		count := len(value)
-		if count == 0 {
-			return nil, true
-		}
-		listeners := make([]func(ImageView), count)
-		for i, v := range value {
-			if v == nil {
-				return nil, false
-			}
-			listeners[i] = func(ImageView) {
-				v()
-			}
-		}
-		return listeners, true
-
-	case []any:
-		count := len(value)
-		if count == 0 {
-			return nil, true
-		}
-		listeners := make([]func(ImageView), count)
-		for i, v := range value {
-			if v == nil {
-				return nil, false
-			}
-			switch v := v.(type) {
-			case func(ImageView):
-				listeners[i] = v
-
-			case func():
-				listeners[i] = func(ImageView) {
-					v()
-				}
-
-			default:
-				return nil, false
-			}
-		}
-		return listeners, true
-	}
-
-	return nil, false
-}
-
 func (imageView *imageViewData) set(tag string, value any) bool {
 	if value == nil {
 		imageView.remove(tag)
@@ -228,8 +157,12 @@ func (imageView *imageViewData) set(tag string, value any) bool {
 		notCompatibleType(tag, value)
 
 	case LoadedEvent, ErrorEvent:
-		if listeners, ok := valueToImageListeners(value); ok {
+		if listeners, ok := valueToNoParamListeners[ImageView](value); ok {
+			if listeners == nil {
+				delete(imageView.properties, tag)
+			} else {
 				imageView.properties[tag] = listeners
+			}
 			return true
 		}
 

keyEvents.go

@@ -50,34 +50,52 @@ type KeyEvent struct {
 	MetaKey bool
 }
 
-func valueToKeyListeners(value any) ([]func(View, KeyEvent), bool) {
+func (event *KeyEvent) init(data DataObject) {
+	getBool := func(tag string) bool {
+		if value, ok := data.PropertyValue(tag); ok && value == "1" {
+			return true
+		}
+		return false
+	}
+
+	event.Key, _ = data.PropertyValue("key")
+	event.Code, _ = data.PropertyValue("code")
+	event.TimeStamp = getTimeStamp(data)
+	event.Repeat = getBool("repeat")
+	event.CtrlKey = getBool("ctrlKey")
+	event.ShiftKey = getBool("shiftKey")
+	event.AltKey = getBool("altKey")
+	event.MetaKey = getBool("metaKey")
+}
+
+func valueToEventListeners[V View, E any](value any) ([]func(V, E), bool) {
 	if value == nil {
 		return nil, true
 	}
 
 	switch value := value.(type) {
-	case func(View, KeyEvent):
+	case func(V, E):
-		return []func(View, KeyEvent){value}, true
+		return []func(V, E){value}, true
 
-	case func(KeyEvent):
+	case func(E):
-		fn := func(_ View, event KeyEvent) {
+		fn := func(_ V, event E) {
 			value(event)
 		}
-		return []func(View, KeyEvent){fn}, true
+		return []func(V, E){fn}, true
 
-	case func(View):
+	case func(V):
-		fn := func(view View, _ KeyEvent) {
+		fn := func(view V, _ E) {
 			value(view)
 		}
-		return []func(View, KeyEvent){fn}, true
+		return []func(V, E){fn}, true
 
 	case func():
-		fn := func(View, KeyEvent) {
+		fn := func(V, E) {
 			value()
 		}
-		return []func(View, KeyEvent){fn}, true
+		return []func(V, E){fn}, true
 
-	case []func(View, KeyEvent):
+	case []func(V, E):
 		if len(value) == 0 {
 			return nil, true
 		}
@@ -88,33 +106,33 @@ func valueToKeyListeners(value any) ([]func(View, KeyEvent), bool) {
 		}
 		return value, true
 
-	case []func(KeyEvent):
+	case []func(E):
 		count := len(value)
 		if count == 0 {
 			return nil, true
 		}
-		listeners := make([]func(View, KeyEvent), count)
+		listeners := make([]func(V, E), count)
 		for i, v := range value {
 			if v == nil {
 				return nil, false
 			}
-			listeners[i] = func(_ View, event KeyEvent) {
+			listeners[i] = func(_ V, event E) {
 				v(event)
 			}
 		}
 		return listeners, true
 
-	case []func(View):
+	case []func(V):
 		count := len(value)
 		if count == 0 {
 			return nil, true
 		}
-		listeners := make([]func(View, KeyEvent), count)
+		listeners := make([]func(V, E), count)
 		for i, v := range value {
 			if v == nil {
 				return nil, false
 			}
-			listeners[i] = func(view View, _ KeyEvent) {
+			listeners[i] = func(view V, _ E) {
 				v(view)
 			}
 		}
@@ -125,12 +143,12 @@ func valueToKeyListeners(value any) ([]func(View, KeyEvent), bool) {
 		if count == 0 {
 			return nil, true
 		}
-		listeners := make([]func(View, KeyEvent), count)
+		listeners := make([]func(V, E), count)
 		for i, v := range value {
 			if v == nil {
 				return nil, false
 			}
-			listeners[i] = func(View, KeyEvent) {
+			listeners[i] = func(V, E) {
 				v()
 			}
 		}
@@ -141,27 +159,27 @@ func valueToKeyListeners(value any) ([]func(View, KeyEvent), bool) {
 		if count == 0 {
 			return nil, true
 		}
-		listeners := make([]func(View, KeyEvent), count)
+		listeners := make([]func(V, E), count)
 		for i, v := range value {
 			if v == nil {
 				return nil, false
 			}
 			switch v := v.(type) {
-			case func(View, KeyEvent):
+			case func(V, E):
 				listeners[i] = v
 
-			case func(KeyEvent):
+			case func(E):
-				listeners[i] = func(_ View, event KeyEvent) {
+				listeners[i] = func(_ V, event E) {
 					v(event)
 				}
 
-			case func(View):
+			case func(V):
-				listeners[i] = func(view View, _ KeyEvent) {
+				listeners[i] = func(view V, _ E) {
 					v(view)
 				}
 
 			case func():
-				listeners[i] = func(View, KeyEvent) {
+				listeners[i] = func(V, E) {
 					v()
 				}
 
@@ -181,7 +199,7 @@ var keyEvents = map[string]struct{ jsEvent, jsFunc string }{
 }
 
 func (view *viewData) setKeyListener(tag string, value any) bool {
-	listeners, ok := valueToKeyListeners(value)
+	listeners, ok := valueToEventListeners[View, KeyEvent](value)
 	if !ok {
 		notCompatibleType(tag, value)
 		return false
@@ -209,67 +227,48 @@ func (view *viewData) removeKeyListener(tag string) {
 	}
 }
 
-func getKeyListeners(view View, subviewID string, tag string) []func(View, KeyEvent) {
+func getEventListeners[V View, E any](view View, subviewID string, tag string) []func(V, E) {
 	if subviewID != "" {
 		view = ViewByID(view, subviewID)
 	}
 	if view != nil {
 		if value := view.Get(tag); value != nil {
-			if result, ok := value.([]func(View, KeyEvent)); ok {
+			if result, ok := value.([]func(V, E)); ok {
 				return result
 			}
 		}
 	}
-	return []func(View, KeyEvent){}
+	return []func(V, E){}
 }
 
 func keyEventsHtml(view View, buffer *strings.Builder) {
 	for tag, js := range keyEvents {
-		if listeners := getKeyListeners(view, "", tag); len(listeners) > 0 {
+		if listeners := getEventListeners[View, KeyEvent](view, "", tag); len(listeners) > 0 {
 			buffer.WriteString(js.jsEvent + `="` + js.jsFunc + `(this, event)" `)
 		}
 	}
 }
 
 func handleKeyEvents(view View, tag string, data DataObject) {
-	listeners := getKeyListeners(view, "", tag)
+	listeners := getEventListeners[View, KeyEvent](view, "", tag)
-	if len(listeners) == 0 {
+	if len(listeners) > 0 {
-		return
+		var event KeyEvent
-	}
+		event.init(data)
-
-	getBool := func(tag string) bool {
-		if value, ok := data.PropertyValue(tag); ok && value == "1" {
-			return true
-		}
-		return false
-	}
-
-	key, _ := data.PropertyValue("key")
-	code, _ := data.PropertyValue("code")
-	event := KeyEvent{
-		TimeStamp: getTimeStamp(data),
-		Key:       key,
-		Code:      code,
-		Repeat:    getBool("repeat"),
-		CtrlKey:   getBool("ctrlKey"),
-		ShiftKey:  getBool("shiftKey"),
-		AltKey:    getBool("altKey"),
-		MetaKey:   getBool("metaKey"),
-	}
 
 		for _, listener := range listeners {
 			listener(view, event)
 		}
 	}
+}
 
 // GetKeyDownListeners returns the "key-down-event" listener list. If there are no listeners then the empty list is returned.
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetKeyDownListeners(view View, subviewID string) []func(View, KeyEvent) {
-	return getKeyListeners(view, subviewID, KeyDownEvent)
+	return getEventListeners[View, KeyEvent](view, subviewID, KeyDownEvent)
 }
 
 // GetKeyUpListeners returns the "key-up-event" listener list. If there are no listeners then the empty list is returned.
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetKeyUpListeners(view View, subviewID string) []func(View, KeyEvent) {
-	return getKeyListeners(view, subviewID, KeyUpEvent)
+	return getEventListeners[View, KeyEvent](view, subviewID, KeyUpEvent)
 }

listView.go

@@ -205,29 +205,38 @@ func (listView *listViewData) set(tag string, value any) bool {
 
 	switch tag {
 	case ListItemClickedEvent:
-		listeners := listView.valueToItemListeners(value)
+		listeners, ok := valueToEventListeners[ListView, int](value)
-		if listeners == nil {
+		if !ok {
 			notCompatibleType(tag, value)
 			return false
+		} else if listeners == nil {
+			listeners = []func(ListView, int){}
 		}
 		listView.clickedListeners = listeners
 		listView.propertyChangedEvent(tag)
 		return true
 
 	case ListItemSelectedEvent:
-		listeners := listView.valueToItemListeners(value)
+		listeners, ok := valueToEventListeners[ListView, int](value)
-		if listeners == nil {
+		if !ok {
 			notCompatibleType(tag, value)
 			return false
+		} else if listeners == nil {
+			listeners = []func(ListView, int){}
 		}
 		listView.selectedListeners = listeners
 		listView.propertyChangedEvent(tag)
 		return true
 
 	case ListItemCheckedEvent:
-		if !listView.setItemCheckedEvent(value) {
+		listeners, ok := valueToEventListeners[ListView, []int](value)
+		if !ok {
+			notCompatibleType(tag, value)
 			return false
+		} else if listeners == nil {
+			listeners = []func(ListView, []int){}
 		}
+		listView.checkedListeners = listeners
 		listView.propertyChangedEvent(tag)
 		return true
 
@@ -288,61 +297,6 @@ func (listView *listViewData) set(tag string, value any) bool {
 	return true
 }
 
-func (listView *listViewData) setItemCheckedEvent(value any) bool {
-	switch value := value.(type) {
-	case func(ListView, []int):
-		listView.checkedListeners = []func(ListView, []int){value}
-
-	case func([]int):
-		fn := func(_ ListView, date []int) {
-			value(date)
-		}
-		listView.checkedListeners = []func(ListView, []int){fn}
-
-	case []func(ListView, []int):
-		listView.checkedListeners = value
-
-	case []func([]int):
-		listeners := make([]func(ListView, []int), len(value))
-		for i, val := range value {
-			if val == nil {
-				notCompatibleType(ListItemCheckedEvent, val)
-				return false
-			}
-
-			listeners[i] = func(_ ListView, date []int) {
-				val(date)
-			}
-		}
-		listView.checkedListeners = listeners
-
-	case []any:
-		listeners := make([]func(ListView, []int), len(value))
-		for i, val := range value {
-			if val == nil {
-				notCompatibleType(ListItemCheckedEvent, val)
-				return false
-			}
-
-			switch val := val.(type) {
-			case func(ListView, []int):
-				listeners[i] = val
-
-			case func([]int):
-				listeners[i] = func(_ ListView, checked []int) {
-					val(checked)
-				}
-
-			default:
-				notCompatibleType(ListItemCheckedEvent, val)
-				return false
-			}
-		}
-		listView.checkedListeners = listeners
-	}
-	return true
-}
-
 func (listView *listViewData) Get(tag string) any {
 	return listView.get(listView.normalizeTag(tag))
 }
@@ -460,61 +414,6 @@ func (listView *listViewData) setItems(value any) bool {
 	return true
 }
 
-func (listView *listViewData) valueToItemListeners(value any) []func(ListView, int) {
-	if value == nil {
-		return []func(ListView, int){}
-	}
-
-	switch value := value.(type) {
-	case func(ListView, int):
-		return []func(ListView, int){value}
-
-	case func(int):
-		fn := func(_ ListView, index int) {
-			value(index)
-		}
-		return []func(ListView, int){fn}
-
-	case []func(ListView, int):
-		return value
-
-	case []func(int):
-		listeners := make([]func(ListView, int), len(value))
-		for i, val := range value {
-			if val == nil {
-				return nil
-			}
-			listeners[i] = func(_ ListView, index int) {
-				val(index)
-			}
-		}
-		return listeners
-
-	case []any:
-		listeners := make([]func(ListView, int), len(value))
-		for i, val := range value {
-			if val == nil {
-				return nil
-			}
-			switch val := val.(type) {
-			case func(ListView, int):
-				listeners[i] = val
-
-			case func(int):
-				listeners[i] = func(_ ListView, index int) {
-					val(index)
-				}
-
-			default:
-				return nil
-			}
-		}
-		return listeners
-	}
-
-	return nil
-}
-
 func (listView *listViewData) setChecked(value any) bool {
 	var checked []int
 	if value == nil {

mediaPlayer.go

@@ -205,7 +205,7 @@ func (player *mediaPlayerData) set(tag string, value any) bool {
 	case AbortEvent, CanPlayEvent, CanPlayThroughEvent, CompleteEvent, EmptiedEvent, LoadStartEvent,
 		EndedEvent, LoadedDataEvent, LoadedMetadataEvent, PauseEvent, PlayEvent, PlayingEvent,
 		ProgressEvent, SeekedEvent, SeekingEvent, StalledEvent, SuspendEvent, WaitingEvent:
-		if listeners, ok := valueToPlayerListeners(value); ok {
+		if listeners, ok := valueToNoParamListeners[MediaPlayer](value); ok {
 			if listeners == nil {
 				delete(player.properties, tag)
 			} else {
@@ -218,7 +218,7 @@ func (player *mediaPlayerData) set(tag string, value any) bool {
 		notCompatibleType(tag, value)
 
 	case DurationChangedEvent, RateChangedEvent, TimeUpdateEvent, VolumeChangedEvent:
-		if listeners, ok := valueToPlayerTimeListeners(value); ok {
+		if listeners, ok := valueToEventListeners[MediaPlayer, float64](value); ok {
 			if listeners == nil {
 				delete(player.properties, tag)
 			} else {
@@ -311,202 +311,6 @@ func (player *mediaPlayerData) setSource(value any) bool {
 	return true
 }
 
-func valueToPlayerListeners(value any) ([]func(MediaPlayer), bool) {
-	if value == nil {
-		return nil, true
-	}
-
-	switch value := value.(type) {
-	case func(MediaPlayer):
-		return []func(MediaPlayer){value}, true
-
-	case func():
-		fn := func(MediaPlayer) {
-			value()
-		}
-		return []func(MediaPlayer){fn}, true
-
-	case []func(MediaPlayer):
-		if len(value) == 0 {
-			return nil, true
-		}
-		for _, fn := range value {
-			if fn == nil {
-				return nil, false
-			}
-		}
-		return value, true
-
-	case []func():
-		count := len(value)
-		if count == 0 {
-			return nil, true
-		}
-		listeners := make([]func(MediaPlayer), count)
-		for i, v := range value {
-			if v == nil {
-				return nil, false
-			}
-			listeners[i] = func(MediaPlayer) {
-				v()
-			}
-		}
-		return listeners, true
-
-	case []any:
-		count := len(value)
-		if count == 0 {
-			return nil, true
-		}
-		listeners := make([]func(MediaPlayer), count)
-		for i, v := range value {
-			if v == nil {
-				return nil, false
-			}
-			switch v := v.(type) {
-			case func(MediaPlayer):
-				listeners[i] = v
-
-			case func():
-				listeners[i] = func(MediaPlayer) {
-					v()
-				}
-
-			default:
-				return nil, false
-			}
-		}
-		return listeners, true
-	}
-
-	return nil, false
-}
-
-func valueToPlayerTimeListeners(value any) ([]func(MediaPlayer, float64), bool) {
-	if value == nil {
-		return nil, true
-	}
-
-	switch value := value.(type) {
-	case func(MediaPlayer, float64):
-		return []func(MediaPlayer, float64){value}, true
-
-	case func(float64):
-		fn := func(_ MediaPlayer, time float64) {
-			value(time)
-		}
-		return []func(MediaPlayer, float64){fn}, true
-
-	case func(MediaPlayer):
-		fn := func(player MediaPlayer, _ float64) {
-			value(player)
-		}
-		return []func(MediaPlayer, float64){fn}, true
-
-	case func():
-		fn := func(MediaPlayer, float64) {
-			value()
-		}
-		return []func(MediaPlayer, float64){fn}, true
-
-	case []func(MediaPlayer, float64):
-		if len(value) == 0 {
-			return nil, true
-		}
-		for _, fn := range value {
-			if fn == nil {
-				return nil, false
-			}
-		}
-		return value, true
-
-	case []func(float64):
-		count := len(value)
-		if count == 0 {
-			return nil, true
-		}
-		listeners := make([]func(MediaPlayer, float64), count)
-		for i, v := range value {
-			if v == nil {
-				return nil, false
-			}
-			listeners[i] = func(_ MediaPlayer, time float64) {
-				v(time)
-			}
-		}
-		return listeners, true
-
-	case []func(MediaPlayer):
-		count := len(value)
-		if count == 0 {
-			return nil, true
-		}
-		listeners := make([]func(MediaPlayer, float64), count)
-		for i, v := range value {
-			if v == nil {
-				return nil, false
-			}
-			listeners[i] = func(player MediaPlayer, _ float64) {
-				v(player)
-			}
-		}
-		return listeners, true
-
-	case []func():
-		count := len(value)
-		if count == 0 {
-			return nil, true
-		}
-		listeners := make([]func(MediaPlayer, float64), count)
-		for i, v := range value {
-			if v == nil {
-				return nil, false
-			}
-			listeners[i] = func(MediaPlayer, float64) {
-				v()
-			}
-		}
-		return listeners, true
-
-	case []any:
-		count := len(value)
-		if count == 0 {
-			return nil, true
-		}
-		listeners := make([]func(MediaPlayer, float64), count)
-		for i, v := range value {
-			if v == nil {
-				return nil, false
-			}
-			switch v := v.(type) {
-			case func(MediaPlayer, float64):
-				listeners[i] = v
-
-			case func(float64):
-				listeners[i] = func(_ MediaPlayer, time float64) {
-					v(time)
-				}
-
-			case func(MediaPlayer):
-				listeners[i] = func(player MediaPlayer, _ float64) {
-					v(player)
-				}
-
-			case func():
-				listeners[i] = func(MediaPlayer, float64) {
-					v()
-				}
-
-			default:
-				return nil, false
-			}
-		}
-		return listeners, true
-	}
-
-	return nil, false
-}
-
 func valueToPlayerErrorListeners(value any) ([]func(MediaPlayer, int, string), bool) {
 	if value == nil {
 		return nil, true

mouseEvents.go

@@ -144,131 +144,6 @@ type MouseEvent struct {
 	MetaKey bool
 }
 
-func valueToMouseListeners(value any) ([]func(View, MouseEvent), bool) {
-	if value == nil {
-		return nil, true
-	}
-
-	switch value := value.(type) {
-	case func(View, MouseEvent):
-		return []func(View, MouseEvent){value}, true
-
-	case func(MouseEvent):
-		fn := func(_ View, event MouseEvent) {
-			value(event)
-		}
-		return []func(View, MouseEvent){fn}, true
-
-	case func(View):
-		fn := func(view View, _ MouseEvent) {
-			value(view)
-		}
-		return []func(View, MouseEvent){fn}, true
-
-	case func():
-		fn := func(View, MouseEvent) {
-			value()
-		}
-		return []func(View, MouseEvent){fn}, true
-
-	case []func(View, MouseEvent):
-		if len(value) == 0 {
-			return nil, true
-		}
-		for _, fn := range value {
-			if fn == nil {
-				return nil, false
-			}
-		}
-		return value, true
-
-	case []func(MouseEvent):
-		count := len(value)
-		if count == 0 {
-			return nil, true
-		}
-		listeners := make([]func(View, MouseEvent), count)
-		for i, v := range value {
-			if v == nil {
-				return nil, false
-			}
-			listeners[i] = func(_ View, event MouseEvent) {
-				v(event)
-			}
-		}
-		return listeners, true
-
-	case []func(View):
-		count := len(value)
-		if count == 0 {
-			return nil, true
-		}
-		listeners := make([]func(View, MouseEvent), count)
-		for i, v := range value {
-			if v == nil {
-				return nil, false
-			}
-			listeners[i] = func(view View, _ MouseEvent) {
-				v(view)
-			}
-		}
-		return listeners, true
-
-	case []func():
-		count := len(value)
-		if count == 0 {
-			return nil, true
-		}
-		listeners := make([]func(View, MouseEvent), count)
-		for i, v := range value {
-			if v == nil {
-				return nil, false
-			}
-			listeners[i] = func(View, MouseEvent) {
-				v()
-			}
-		}
-		return listeners, true
-
-	case []any:
-		count := len(value)
-		if count == 0 {
-			return nil, true
-		}
-		listeners := make([]func(View, MouseEvent), count)
-		for i, v := range value {
-			if v == nil {
-				return nil, false
-			}
-			switch v := v.(type) {
-			case func(View, MouseEvent):
-				listeners[i] = v
-
-			case func(MouseEvent):
-				listeners[i] = func(_ View, event MouseEvent) {
-					v(event)
-				}
-
-			case func(View):
-				listeners[i] = func(view View, _ MouseEvent) {
-					v(view)
-				}
-
-			case func():
-				listeners[i] = func(View, MouseEvent) {
-					v()
-				}
-
-			default:
-				return nil, false
-			}
-		}
-		return listeners, true
-	}
-
-	return nil, false
-}
-
 var mouseEvents = map[string]struct{ jsEvent, jsFunc string }{
 	ClickEvent:       {jsEvent: "onclick", jsFunc: "clickEvent"},
 	DoubleClickEvent: {jsEvent: "ondblclick", jsFunc: "doubleClickEvent"},
@@ -281,7 +156,7 @@ var mouseEvents = map[string]struct{ jsEvent, jsFunc string }{
 }
 
 func (view *viewData) setMouseListener(tag string, value any) bool {
-	listeners, ok := valueToMouseListeners(value)
+	listeners, ok := valueToEventListeners[View, MouseEvent](value)
 	if !ok {
 		notCompatibleType(tag, value)
 		return false
@@ -309,20 +184,6 @@ func (view *viewData) removeMouseListener(tag string) {
 	}
 }
 
-func getMouseListeners(view View, subviewID string, tag string) []func(View, MouseEvent) {
-	if subviewID != "" {
-		view = ViewByID(view, subviewID)
-	}
-	if view != nil {
-		if value := view.Get(tag); value != nil {
-			if result, ok := value.([]func(View, MouseEvent)); ok {
-				return result
-			}
-		}
-	}
-	return []func(View, MouseEvent){}
-}
-
 func mouseEventsHtml(view View, buffer *strings.Builder) {
 	for tag, js := range mouseEvents {
 		if value := view.getRaw(tag); value != nil {
@@ -363,11 +224,8 @@ func (event *MouseEvent) init(data DataObject) {
 }
 
 func handleMouseEvents(view View, tag string, data DataObject) {
-	listeners := getMouseListeners(view, "", tag)
+	listeners := getEventListeners[View, MouseEvent](view, "", tag)
-	if len(listeners) == 0 {
+	if len(listeners) > 0 {
-		return
-	}
-
 		var event MouseEvent
 		event.init(data)
 
@@ -375,52 +233,53 @@ func handleMouseEvents(view View, tag string, data DataObject) {
 			listener(view, event)
 		}
 	}
+}
 
 // GetClickListeners returns the "click-event" listener list. If there are no listeners then the empty list is returned.
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetClickListeners(view View, subviewID string) []func(View, MouseEvent) {
-	return getMouseListeners(view, subviewID, ClickEvent)
+	return getEventListeners[View, MouseEvent](view, subviewID, ClickEvent)
 }
 
 // GetDoubleClickListeners returns the "double-click-event" listener list. If there are no listeners then the empty list is returned.
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetDoubleClickListeners(view View, subviewID string) []func(View, MouseEvent) {
-	return getMouseListeners(view, subviewID, DoubleClickEvent)
+	return getEventListeners[View, MouseEvent](view, subviewID, DoubleClickEvent)
 }
 
 // GetContextMenuListeners returns the "context-menu" listener list.
 // If there are no listeners then the empty list is returned.
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetContextMenuListeners(view View, subviewID string) []func(View, MouseEvent) {
-	return getMouseListeners(view, subviewID, ContextMenuEvent)
+	return getEventListeners[View, MouseEvent](view, subviewID, ContextMenuEvent)
 }
 
 // GetMouseDownListeners returns the "mouse-down" listener list. If there are no listeners then the empty list is returned.
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetMouseDownListeners(view View, subviewID string) []func(View, MouseEvent) {
-	return getMouseListeners(view, subviewID, MouseDown)
+	return getEventListeners[View, MouseEvent](view, subviewID, MouseDown)
 }
 
 // GetMouseUpListeners returns the "mouse-up" listener list. If there are no listeners then the empty list is returned.
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetMouseUpListeners(view View, subviewID string) []func(View, MouseEvent) {
-	return getMouseListeners(view, subviewID, MouseUp)
+	return getEventListeners[View, MouseEvent](view, subviewID, MouseUp)
 }
 
 // GetMouseMoveListeners returns the "mouse-move" listener list. If there are no listeners then the empty list is returned.
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetMouseMoveListeners(view View, subviewID string) []func(View, MouseEvent) {
-	return getMouseListeners(view, subviewID, MouseMove)
+	return getEventListeners[View, MouseEvent](view, subviewID, MouseMove)
 }
 
 // GetMouseOverListeners returns the "mouse-over" listener list. If there are no listeners then the empty list is returned.
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetMouseOverListeners(view View, subviewID string) []func(View, MouseEvent) {
-	return getMouseListeners(view, subviewID, MouseOver)
+	return getEventListeners[View, MouseEvent](view, subviewID, MouseOver)
 }
 
 // GetMouseOutListeners returns the "mouse-out" listener list. If there are no listeners then the empty list is returned.
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetMouseOutListeners(view View, subviewID string) []func(View, MouseEvent) {
-	return getMouseListeners(view, subviewID, MouseOut)
+	return getEventListeners[View, MouseEvent](view, subviewID, MouseOut)
 }

numberPicker.go

@@ -99,52 +99,14 @@ func (picker *numberPickerData) set(tag string, value any) bool {
 
 	switch tag {
 	case NumberChangedEvent:
-		switch value := value.(type) {
+		listeners, ok := valueToEventListeners[NumberPicker, float64](value)
-		case func(NumberPicker, float64):
+		if !ok {
-			picker.numberChangedListeners = []func(NumberPicker, float64){value}
+			notCompatibleType(tag, value)
-
-		case func(float64):
-			fn := func(_ NumberPicker, newValue float64) {
-				value(newValue)
-			}
-			picker.numberChangedListeners = []func(NumberPicker, float64){fn}
-
-		case []func(NumberPicker, float64):
-			picker.numberChangedListeners = value
-
-		case []func(float64):
-			listeners := make([]func(NumberPicker, float64), len(value))
-			for i, val := range value {
-				if val == nil {
-					notCompatibleType(tag, val)
 			return false
-				}
+		} else if listeners == nil {
-
+			listeners = []func(NumberPicker, float64){}
-				listeners[i] = func(_ NumberPicker, newValue float64) {
-					val(newValue)
-				}
 		}
 		picker.numberChangedListeners = listeners
-
-		case []any:
-			listeners := make([]func(NumberPicker, float64), len(value))
-			for i, val := range value {
-				if val == nil {
-					notCompatibleType(tag, val)
-					return false
-				}
-
-				switch val := val.(type) {
-				case func(NumberPicker, float64):
-					listeners[i] = val
-
-				default:
-					notCompatibleType(tag, val)
-					return false
-				}
-			}
-			picker.numberChangedListeners = listeners
-		}
 		picker.propertyChangedEvent(tag)
 		return true
 
@@ -386,15 +348,5 @@ func GetNumberPickerValue(view View, subviewID string) float64 {
 // If there are no listeners then the empty list is returned
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetNumberChangedListeners(view View, subviewID string) []func(NumberPicker, float64) {
-	if subviewID != "" {
+	return getEventListeners[NumberPicker, float64](view, subviewID, NumberChangedEvent)
-		view = ViewByID(view, subviewID)
-	}
-	if view != nil {
-		if value := view.Get(NumberChangedEvent); value != nil {
-			if listeners, ok := value.([]func(NumberPicker, float64)); ok {
-				return listeners
-			}
-		}
-	}
-	return []func(NumberPicker, float64){}
 }

pointerEvents.go

@@ -87,131 +87,6 @@ type PointerEvent struct {
 	IsPrimary bool
 }
 
-func valueToPointerListeners(value any) ([]func(View, PointerEvent), bool) {
-	if value == nil {
-		return nil, true
-	}
-
-	switch value := value.(type) {
-	case func(View, PointerEvent):
-		return []func(View, PointerEvent){value}, true
-
-	case func(PointerEvent):
-		fn := func(_ View, event PointerEvent) {
-			value(event)
-		}
-		return []func(View, PointerEvent){fn}, true
-
-	case func(View):
-		fn := func(view View, _ PointerEvent) {
-			value(view)
-		}
-		return []func(View, PointerEvent){fn}, true
-
-	case func():
-		fn := func(View, PointerEvent) {
-			value()
-		}
-		return []func(View, PointerEvent){fn}, true
-
-	case []func(View, PointerEvent):
-		if len(value) == 0 {
-			return nil, true
-		}
-		for _, fn := range value {
-			if fn == nil {
-				return nil, false
-			}
-		}
-		return value, true
-
-	case []func(PointerEvent):
-		count := len(value)
-		if count == 0 {
-			return nil, true
-		}
-		listeners := make([]func(View, PointerEvent), count)
-		for i, v := range value {
-			if v == nil {
-				return nil, false
-			}
-			listeners[i] = func(_ View, event PointerEvent) {
-				v(event)
-			}
-		}
-		return listeners, true
-
-	case []func(View):
-		count := len(value)
-		if count == 0 {
-			return nil, true
-		}
-		listeners := make([]func(View, PointerEvent), count)
-		for i, v := range value {
-			if v == nil {
-				return nil, false
-			}
-			listeners[i] = func(view View, _ PointerEvent) {
-				v(view)
-			}
-		}
-		return listeners, true
-
-	case []func():
-		count := len(value)
-		if count == 0 {
-			return nil, true
-		}
-		listeners := make([]func(View, PointerEvent), count)
-		for i, v := range value {
-			if v == nil {
-				return nil, false
-			}
-			listeners[i] = func(View, PointerEvent) {
-				v()
-			}
-		}
-		return listeners, true
-
-	case []any:
-		count := len(value)
-		if count == 0 {
-			return nil, true
-		}
-		listeners := make([]func(View, PointerEvent), count)
-		for i, v := range value {
-			if v == nil {
-				return nil, false
-			}
-			switch v := v.(type) {
-			case func(View, PointerEvent):
-				listeners[i] = v
-
-			case func(PointerEvent):
-				listeners[i] = func(_ View, event PointerEvent) {
-					v(event)
-				}
-
-			case func(View):
-				listeners[i] = func(view View, _ PointerEvent) {
-					v(view)
-				}
-
-			case func():
-				listeners[i] = func(View, PointerEvent) {
-					v()
-				}
-
-			default:
-				return nil, false
-			}
-		}
-		return listeners, true
-	}
-
-	return nil, false
-}
-
 var pointerEvents = map[string]struct{ jsEvent, jsFunc string }{
 	PointerDown:   {jsEvent: "onpointerdown", jsFunc: "pointerDownEvent"},
 	PointerUp:     {jsEvent: "onpointerup", jsFunc: "pointerUpEvent"},
@@ -222,7 +97,7 @@ var pointerEvents = map[string]struct{ jsEvent, jsFunc string }{
 }
 
 func (view *viewData) setPointerListener(tag string, value any) bool {
-	listeners, ok := valueToPointerListeners(value)
+	listeners, ok := valueToEventListeners[View, PointerEvent](value)
 	if !ok {
 		notCompatibleType(tag, value)
 		return false
@@ -250,20 +125,6 @@ func (view *viewData) removePointerListener(tag string) {
 	}
 }
 
-func getPointerListeners(view View, subviewID string, tag string) []func(View, PointerEvent) {
-	if subviewID != "" {
-		view = ViewByID(view, subviewID)
-	}
-	if view != nil {
-		if value := view.Get(tag); value != nil {
-			if result, ok := value.([]func(View, PointerEvent)); ok {
-				return result
-			}
-		}
-	}
-	return []func(View, PointerEvent){}
-}
-
 func pointerEventsHtml(view View, buffer *strings.Builder) {
 	for tag, js := range pointerEvents {
 		if value := view.getRaw(tag); value != nil {
@@ -291,7 +152,7 @@ func (event *PointerEvent) init(data DataObject) {
 }
 
 func handlePointerEvents(view View, tag string, data DataObject) {
-	listeners := getPointerListeners(view, "", tag)
+	listeners := getEventListeners[View, PointerEvent](view, "", tag)
 	if len(listeners) == 0 {
 		return
 	}
@@ -307,35 +168,35 @@ func handlePointerEvents(view View, tag string, data DataObject) {
 // GetPointerDownListeners returns the "pointer-down" listener list. If there are no listeners then the empty list is returned.
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetPointerDownListeners(view View, subviewID string) []func(View, PointerEvent) {
-	return getPointerListeners(view, subviewID, PointerDown)
+	return getEventListeners[View, PointerEvent](view, subviewID, PointerDown)
 }
 
 // GetPointerUpListeners returns the "pointer-up" listener list. If there are no listeners then the empty list is returned.
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetPointerUpListeners(view View, subviewID string) []func(View, PointerEvent) {
-	return getPointerListeners(view, subviewID, PointerUp)
+	return getEventListeners[View, PointerEvent](view, subviewID, PointerUp)
 }
 
 // GetPointerMoveListeners returns the "pointer-move" listener list. If there are no listeners then the empty list is returned.
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetPointerMoveListeners(view View, subviewID string) []func(View, PointerEvent) {
-	return getPointerListeners(view, subviewID, PointerMove)
+	return getEventListeners[View, PointerEvent](view, subviewID, PointerMove)
 }
 
 // GetPointerCancelListeners returns the "pointer-cancel" listener list. If there are no listeners then the empty list is returned.
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetPointerCancelListeners(view View, subviewID string) []func(View, PointerEvent) {
-	return getPointerListeners(view, subviewID, PointerCancel)
+	return getEventListeners[View, PointerEvent](view, subviewID, PointerCancel)
 }
 
 // GetPointerOverListeners returns the "pointer-over" listener list. If there are no listeners then the empty list is returned.
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetPointerOverListeners(view View, subviewID string) []func(View, PointerEvent) {
-	return getPointerListeners(view, subviewID, PointerOver)
+	return getEventListeners[View, PointerEvent](view, subviewID, PointerOver)
 }
 
 // GetPointerOutListeners returns the "pointer-out" listener list. If there are no listeners then the empty list is returned.
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetPointerOutListeners(view View, subviewID string) []func(View, PointerEvent) {
-	return getPointerListeners(view, subviewID, PointerOut)
+	return getEventListeners[View, PointerEvent](view, subviewID, PointerOut)
 }

popup.go

@@ -36,6 +36,10 @@ const (
 	// It occurs after the Popup disappears from the screen.
 	// The main listener for this event has the following format: func(Popup)
 	DismissEvent = "dismiss-event"
+
+	// PopupArrow is the constant for the "popup-arrow" property tag.
+	// Using the "popup-arrow" property you can add ...
+	PopupArrow = "popup-arrow"
 )
 
 // PopupButton describes a button that will be placed at the bottom of the window.
@@ -181,11 +185,10 @@ func (popup *popupData) init(view View, params Params) {
 	viewRow := 0
 	if title != nil || closeButton {
 		viewRow = 1
-		titleHeight, _ := sizeConstant(popup.Session(), "ruiPopupTitleHeight")
 		titleView := NewGridLayout(session, Params{
 			Row:               0,
 			Style:             titleStyle,
-			CellWidth:         []SizeUnit{Fr(1), titleHeight},
+			CellWidth:         []any{Fr(1), "@ruiPopupTitleHeight"},
 			CellVerticalAlign: CenterAlign,
 			PaddingLeft:       Px(12),
 		})
@@ -195,8 +198,8 @@ func (popup *popupData) init(view View, params Params) {
 		if closeButton {
 			titleView.Append(NewGridLayout(session, Params{
 				Column:              1,
-				Height:              titleHeight,
+				Height:              "@ruiPopupTitleHeight",
-				Width:               titleHeight,
+				Width:               "@ruiPopupTitleHeight",
 				CellHorizontalAlign: CenterAlign,
 				CellVerticalAlign:   CenterAlign,
 				TextSize:            Px(20),

resizeEvent.go

@@ -22,146 +22,18 @@ func (view *viewData) onItemResize(self View, index string, x, y, width, height
 }
 
 func (view *viewData) setFrameListener(tag string, value any) bool {
-	if value == nil {
+	listeners, ok := valueToEventListeners[FilePicker, []FileInfo](value)
-		delete(view.properties, tag)
+	if !ok {
-		return true
-	}
-
-	switch value := value.(type) {
-	case func(View, Frame):
-		view.properties[tag] = []func(View, Frame){value}
-
-	case []func(View, Frame):
-		if len(value) > 0 {
-			view.properties[tag] = value
-		} else {
-			delete(view.properties, tag)
-			return true
-		}
-
-	case func(Frame):
-		fn := func(_ View, frame Frame) {
-			value(frame)
-		}
-		view.properties[tag] = []func(View, Frame){fn}
-
-	case []func(Frame):
-		count := len(value)
-		if count == 0 {
-			delete(view.properties, tag)
-			return true
-		}
-
-		listeners := make([]func(View, Frame), count)
-		for i, val := range value {
-			if val == nil {
-				notCompatibleType(tag, val)
-				return false
-			}
-
-			listeners[i] = func(_ View, frame Frame) {
-				val(frame)
-			}
-		}
-		view.properties[tag] = listeners
-
-	case func(View):
-		fn := func(view View, _ Frame) {
-			value(view)
-		}
-		view.properties[tag] = []func(View, Frame){fn}
-
-	case []func(View):
-		count := len(value)
-		if count == 0 {
-			delete(view.properties, tag)
-			return true
-		}
-
-		listeners := make([]func(View, Frame), count)
-		for i, val := range value {
-			if val == nil {
-				notCompatibleType(tag, val)
-				return false
-			}
-
-			listeners[i] = func(view View, _ Frame) {
-				val(view)
-			}
-		}
-		view.properties[tag] = listeners
-
-	case func():
-		fn := func(View, Frame) {
-			value()
-		}
-		view.properties[tag] = []func(View, Frame){fn}
-
-	case []func():
-		count := len(value)
-		if count == 0 {
-			delete(view.properties, tag)
-			return true
-		}
-
-		listeners := make([]func(View, Frame), count)
-		for i, val := range value {
-			if val == nil {
-				notCompatibleType(tag, val)
-				return false
-			}
-
-			listeners[i] = func(View, Frame) {
-				val()
-			}
-		}
-		view.properties[tag] = listeners
-
-	case []any:
-		count := len(value)
-		if count == 0 {
-			delete(view.properties, tag)
-			return true
-		}
-
-		listeners := make([]func(View, Frame), count)
-		for i, val := range value {
-			if val == nil {
-				notCompatibleType(tag, val)
-				return false
-			}
-
-			switch val := val.(type) {
-			case func(View, Frame):
-				listeners[i] = val
-
-			case func(Frame):
-				listeners[i] = func(_ View, frame Frame) {
-					val(frame)
-				}
-
-			case func(View):
-				listeners[i] = func(view View, _ Frame) {
-					val(view)
-				}
-
-			case func():
-				listeners[i] = func(View, Frame) {
-					val()
-				}
-
-			default:
-				notCompatibleType(tag, val)
-				return false
-			}
-		}
-		view.properties[tag] = listeners
-
-	default:
 		notCompatibleType(tag, value)
 		return false
 	}
 
+	if listeners == nil {
+		delete(view.properties, tag)
+	} else {
+		view.properties[tag] = listeners
+	}
+	view.propertyChangedEvent(tag)
 	return true
 }
 
@@ -204,15 +76,5 @@ func GetViewFrame(view View, subviewID string) Frame {
 // GetResizeListeners returns the list of "resize-event" listeners. If there are no listeners then the empty list is returned
 // If the second argument (subviewID) is "" then the listeners list of the first argument (view) is returned
 func GetResizeListeners(view View, subviewID string) []func(View, Frame) {
-	if subviewID != "" {
+	return getEventListeners[View, Frame](view, subviewID, ResizeEvent)
-		view = ViewByID(view, subviewID)
-	}
-	if view != nil {
-		if value := view.Get(ResizeEvent); value != nil {
-			if result, ok := value.([]func(View, Frame)); ok {
-				return result
-			}
-		}
-	}
-	return []func(View, Frame){}
 }

scrollEvent.go

@@ -3,7 +3,7 @@ package rui
 import "fmt"
 
 // ScrollEvent is the constant for "scroll-event" property tag.
-// The "resize-event" is fired when the content of the view is scrolled.
+// The "scroll-event" is fired when the content of the view is scrolled.
 // The main listener format:
 //   func(View, Frame).
 // The additional listener formats:
@@ -46,17 +46,7 @@ func GetViewScroll(view View, subviewID string) Frame {
 // GetScrollListeners returns the list of "scroll-event" listeners. If there are no listeners then the empty list is returned
 // If the second argument (subviewID) is "" then the listeners list of the first argument (view) is returned
 func GetScrollListeners(view View, subviewID string) []func(View, Frame) {
-	if subviewID != "" {
+	return getEventListeners[View, Frame](view, subviewID, ResizeEvent)
-		view = ViewByID(view, subviewID)
-	}
-	if view != nil {
-		if value := view.Get(ScrollEvent); value != nil {
-			if result, ok := value.([]func(View, Frame)); ok {
-				return result
-			}
-		}
-	}
-	return []func(View, Frame){}
 }
 
 // ScrollTo scrolls the view's content to the given position.

session.go

@@ -431,7 +431,7 @@ func (session *sessionData) handleViewEvent(command string, data DataObject) {
 		if view := session.viewByHTMLID(viewID); view != nil {
 			view.handleCommand(view, command, data)
 		}
-	} else {
+	} else if command != "clickOutsidePopup" {
 		ErrorLog(`"id" property not found. Event: ` + command)
 	}
 }

stackLayout.go

@@ -109,8 +109,8 @@ func (layout *stackLayoutData) set(tag string, value any) bool {
 
 	switch tag {
 	case TransitionEndEvent:
-		listeners, ok := valueToAnimationListeners(value)
+		listeners, ok := valueToEventListeners[View, string](value)
-		if ok {
+		if ok && listeners != nil {
 			listeners = append(listeners, layout.pushFinished)
 			listeners = append(listeners, layout.popFinished)
 			layout.properties[TransitionEndEvent] = listeners

tableView.go

@@ -384,20 +384,24 @@ func (table *tableViewData) set(tag string, value any) bool {
 		table.cellSelectedListener = listeners
 
 	case TableRowClickedEvent:
-		listeners := table.valueToRowListeners(value)
+		listeners, ok := valueToEventListeners[TableView, int](value)
-		if listeners == nil {
+		if !ok {
 			notCompatibleType(tag, value)
 			return false
+		} else if listeners == nil {
+			listeners = []func(TableView, int){}
 		}
 		table.rowClickedListener = listeners
 
 	case TableRowSelectedEvent:
-		listeners := table.valueToRowListeners(value)
+		listeners, ok := valueToEventListeners[TableView, int](value)
-		if listeners == nil {
+		if !ok {
 			notCompatibleType(tag, value)
 			return false
+		} else if listeners == nil {
+			listeners = []func(TableView, int){}
 		}
-		table.rowSelectedListener = []func(TableView, int){}
+		table.rowSelectedListener = listeners
 
 	case CellStyle:
 		if style, ok := value.(TableCellStyle); ok {
@@ -731,61 +735,6 @@ func (table *tableViewData) valueToCellListeners(value any) []func(TableView, in
 	return nil
 }
 
-func (table *tableViewData) valueToRowListeners(value any) []func(TableView, int) {
-	if value == nil {
-		return []func(TableView, int){}
-	}
-
-	switch value := value.(type) {
-	case func(TableView, int):
-		return []func(TableView, int){value}
-
-	case func(int):
-		fn := func(_ TableView, index int) {
-			value(index)
-		}
-		return []func(TableView, int){fn}
-
-	case []func(TableView, int):
-		return value
-
-	case []func(int):
-		listeners := make([]func(TableView, int), len(value))
-		for i, val := range value {
-			if val == nil {
-				return nil
-			}
-			listeners[i] = func(_ TableView, index int) {
-				val(index)
-			}
-		}
-		return listeners
-
-	case []any:
-		listeners := make([]func(TableView, int), len(value))
-		for i, val := range value {
-			if val == nil {
-				return nil
-			}
-			switch val := val.(type) {
-			case func(TableView, int):
-				listeners[i] = val
-
-			case func(int):
-				listeners[i] = func(_ TableView, index int) {
-					val(index)
-				}
-
-			default:
-				return nil
-			}
-		}
-		return listeners
-	}
-
-	return nil
-}
-
 func (table *tableViewData) htmlTag() string {
 	return "table"
 }

tabsLayout.go

@@ -210,10 +210,12 @@ func (tabsLayout *tabsLayoutData) set(tag string, value any) bool {
 		tabsLayout.tabListener = listeners
 
 	case TabCloseEvent:
-		listeners := tabsLayout.valueToCloseListeners(value)
+		listeners, ok := valueToEventListeners[TabsLayout, int](value)
-		if listeners == nil {
+		if !ok {
 			notCompatibleType(tag, value)
 			return false
+		} else if listeners == nil {
+			listeners = []func(TabsLayout, int){}
 		}
 		tabsLayout.tabCloseListener = listeners
 
@@ -433,61 +435,6 @@ func (tabsLayout *tabsLayoutData) valueToTabListeners(value any) []func(TabsLayo
 	return nil
 }
 
-func (tabsLayout *tabsLayoutData) valueToCloseListeners(value any) []func(TabsLayout, int) {
-	if value == nil {
-		return []func(TabsLayout, int){}
-	}
-
-	switch value := value.(type) {
-	case func(TabsLayout, int):
-		return []func(TabsLayout, int){value}
-
-	case func(int):
-		fn := func(_ TabsLayout, index int) {
-			value(index)
-		}
-		return []func(TabsLayout, int){fn}
-
-	case []func(TabsLayout, int):
-		return value
-
-	case []func(int):
-		listeners := make([]func(TabsLayout, int), len(value))
-		for i, val := range value {
-			if val == nil {
-				return nil
-			}
-			listeners[i] = func(_ TabsLayout, index int) {
-				val(index)
-			}
-		}
-		return listeners
-
-	case []any:
-		listeners := make([]func(TabsLayout, int), len(value))
-		for i, val := range value {
-			if val == nil {
-				return nil
-			}
-			switch val := val.(type) {
-			case func(TabsLayout, int):
-				listeners[i] = val
-
-			case func(int):
-				listeners[i] = func(_ TabsLayout, index int) {
-					val(index)
-				}
-
-			default:
-				return nil
-			}
-		}
-		return listeners
-	}
-
-	return nil
-}
-
 func (tabsLayout *tabsLayoutData) tabsLocation() int {
 	tabs, _ := enumProperty(tabsLayout, Tabs, tabsLayout.session, 0)
 	return tabs

timePicker.go

@@ -223,57 +223,14 @@ func (picker *timePickerData) set(tag string, value any) bool {
 		}
 
 	case TimeChangedEvent:
-		switch value := value.(type) {
+		listeners, ok := valueToEventListeners[TimePicker, time.Time](value)
-		case func(TimePicker, time.Time):
+		if !ok {
-			picker.timeChangedListeners = []func(TimePicker, time.Time){value}
+			notCompatibleType(tag, value)
-
-		case func(time.Time):
-			fn := func(_ TimePicker, time time.Time) {
-				value(time)
-			}
-			picker.timeChangedListeners = []func(TimePicker, time.Time){fn}
-
-		case []func(TimePicker, time.Time):
-			picker.timeChangedListeners = value
-
-		case []func(time.Time):
-			listeners := make([]func(TimePicker, time.Time), len(value))
-			for i, val := range value {
-				if val == nil {
-					notCompatibleType(tag, val)
 			return false
-				}
+		} else if listeners == nil {
-
+			listeners = []func(TimePicker, time.Time){}
-				listeners[i] = func(_ TimePicker, time time.Time) {
-					val(time)
-				}
 		}
 		picker.timeChangedListeners = listeners
-
-		case []any:
-			listeners := make([]func(TimePicker, time.Time), len(value))
-			for i, val := range value {
-				if val == nil {
-					notCompatibleType(tag, val)
-					return false
-				}
-
-				switch val := val.(type) {
-				case func(TimePicker, time.Time):
-					listeners[i] = val
-
-				case func(time.Time):
-					listeners[i] = func(_ TimePicker, time time.Time) {
-						val(time)
-					}
-
-				default:
-					notCompatibleType(tag, val)
-					return false
-				}
-			}
-			picker.timeChangedListeners = listeners
-		}
 		picker.propertyChangedEvent(tag)
 		return true
 
@@ -458,15 +415,5 @@ func GetTimePickerValue(view View, subviewID string) time.Time {
 // If there are no listeners then the empty list is returned
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetTimeChangedListeners(view View, subviewID string) []func(TimePicker, time.Time) {
-	if subviewID != "" {
+	return getEventListeners[TimePicker, time.Time](view, subviewID, TimeChangedEvent)
-		view = ViewByID(view, subviewID)
-	}
-	if view != nil {
-		if value := view.Get(TimeChangedEvent); value != nil {
-			if listeners, ok := value.([]func(TimePicker, time.Time)); ok {
-				return listeners
-			}
-		}
-	}
-	return []func(TimePicker, time.Time){}
 }

touchEvents.go

@@ -90,131 +90,6 @@ type TouchEvent struct {
 	MetaKey bool
 }
 
-func valueToTouchListeners(value any) ([]func(View, TouchEvent), bool) {
-	if value == nil {
-		return nil, true
-	}
-
-	switch value := value.(type) {
-	case func(View, TouchEvent):
-		return []func(View, TouchEvent){value}, true
-
-	case func(TouchEvent):
-		fn := func(_ View, event TouchEvent) {
-			value(event)
-		}
-		return []func(View, TouchEvent){fn}, true
-
-	case func(View):
-		fn := func(view View, _ TouchEvent) {
-			value(view)
-		}
-		return []func(View, TouchEvent){fn}, true
-
-	case func():
-		fn := func(View, TouchEvent) {
-			value()
-		}
-		return []func(View, TouchEvent){fn}, true
-
-	case []func(View, TouchEvent):
-		if len(value) == 0 {
-			return nil, true
-		}
-		for _, fn := range value {
-			if fn == nil {
-				return nil, false
-			}
-		}
-		return value, true
-
-	case []func(TouchEvent):
-		count := len(value)
-		if count == 0 {
-			return nil, true
-		}
-		listeners := make([]func(View, TouchEvent), count)
-		for i, v := range value {
-			if v == nil {
-				return nil, false
-			}
-			listeners[i] = func(_ View, event TouchEvent) {
-				v(event)
-			}
-		}
-		return listeners, true
-
-	case []func(View):
-		count := len(value)
-		if count == 0 {
-			return nil, true
-		}
-		listeners := make([]func(View, TouchEvent), count)
-		for i, v := range value {
-			if v == nil {
-				return nil, false
-			}
-			listeners[i] = func(view View, _ TouchEvent) {
-				v(view)
-			}
-		}
-		return listeners, true
-
-	case []func():
-		count := len(value)
-		if count == 0 {
-			return nil, true
-		}
-		listeners := make([]func(View, TouchEvent), count)
-		for i, v := range value {
-			if v == nil {
-				return nil, false
-			}
-			listeners[i] = func(View, TouchEvent) {
-				v()
-			}
-		}
-		return listeners, true
-
-	case []any:
-		count := len(value)
-		if count == 0 {
-			return nil, true
-		}
-		listeners := make([]func(View, TouchEvent), count)
-		for i, v := range value {
-			if v == nil {
-				return nil, false
-			}
-			switch v := v.(type) {
-			case func(View, TouchEvent):
-				listeners[i] = v
-
-			case func(TouchEvent):
-				listeners[i] = func(_ View, event TouchEvent) {
-					v(event)
-				}
-
-			case func(View):
-				listeners[i] = func(view View, _ TouchEvent) {
-					v(view)
-				}
-
-			case func():
-				listeners[i] = func(View, TouchEvent) {
-					v()
-				}
-
-			default:
-				return nil, false
-			}
-		}
-		return listeners, true
-	}
-
-	return nil, false
-}
-
 var touchEvents = map[string]struct{ jsEvent, jsFunc string }{
 	TouchStart:  {jsEvent: "ontouchstart", jsFunc: "touchStartEvent"},
 	TouchEnd:    {jsEvent: "ontouchend", jsFunc: "touchEndEvent"},
@@ -223,7 +98,7 @@ var touchEvents = map[string]struct{ jsEvent, jsFunc string }{
 }
 
 func (view *viewData) setTouchListener(tag string, value any) bool {
-	listeners, ok := valueToTouchListeners(value)
+	listeners, ok := valueToEventListeners[View, TouchEvent](value)
 	if !ok {
 		notCompatibleType(tag, value)
 		return false
@@ -251,20 +126,6 @@ func (view *viewData) removeTouchListener(tag string) {
 	}
 }
 
-func getTouchListeners(view View, subviewID string, tag string) []func(View, TouchEvent) {
-	if subviewID != "" {
-		view = ViewByID(view, subviewID)
-	}
-	if view != nil {
-		if value := view.Get(tag); value != nil {
-			if result, ok := value.([]func(View, TouchEvent)); ok {
-				return result
-			}
-		}
-	}
-	return []func(View, TouchEvent){}
-}
-
 func touchEventsHtml(view View, buffer *strings.Builder) {
 	for tag, js := range touchEvents {
 		if value := view.getRaw(tag); value != nil {
@@ -309,7 +170,7 @@ func (event *TouchEvent) init(data DataObject) {
 }
 
 func handleTouchEvents(view View, tag string, data DataObject) {
-	listeners := getTouchListeners(view, "", tag)
+	listeners := getEventListeners[View, TouchEvent](view, "", tag)
 	if len(listeners) == 0 {
 		return
 	}
@@ -325,23 +186,23 @@ func handleTouchEvents(view View, tag string, data DataObject) {
 // GetTouchStartListeners returns the "touch-start" listener list. If there are no listeners then the empty list is returned.
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetTouchStartListeners(view View, subviewID string) []func(View, TouchEvent) {
-	return getTouchListeners(view, subviewID, TouchStart)
+	return getEventListeners[View, TouchEvent](view, subviewID, TouchStart)
 }
 
 // GetTouchEndListeners returns the "touch-end" listener list. If there are no listeners then the empty list is returned.
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetTouchEndListeners(view View, subviewID string) []func(View, TouchEvent) {
-	return getTouchListeners(view, subviewID, TouchEnd)
+	return getEventListeners[View, TouchEvent](view, subviewID, TouchEnd)
 }
 
 // GetTouchMoveListeners returns the "touch-move" listener list. If there are no listeners then the empty list is returned.
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetTouchMoveListeners(view View, subviewID string) []func(View, TouchEvent) {
-	return getTouchListeners(view, subviewID, TouchMove)
+	return getEventListeners[View, TouchEvent](view, subviewID, TouchMove)
 }
 
 // GetTouchCancelListeners returns the "touch-cancel" listener list. If there are no listeners then the empty list is returned.
 // If the second argument (subviewID) is "" then a value from the first argument (view) is returned.
 func GetTouchCancelListeners(view View, subviewID string) []func(View, TouchEvent) {
-	return getTouchListeners(view, subviewID, TouchCancel)
+	return getEventListeners[View, TouchEvent](view, subviewID, TouchCancel)
 }