rui/mouseEvents.go

package rui

import (
	"strconv"
	"strings"
)

const (
	// ClickEvent is the constant for "click-event" property tag
	// The "click-event" event occurs when the user clicks on the View.
	// The main listener format: func(View, MouseEvent).
	// The additional listener formats: func(MouseEvent), func(View), and func().
	ClickEvent = "click-event"

	// DoubleClickEvent is the constant for "double-click-event" property tag
	// The "double-click-event" event occurs when the user double clicks on the View.
	// The main listener format: func(View, MouseEvent).
	// The additional listener formats: func(MouseEvent), func(View), and func().
	DoubleClickEvent = "double-click-event"

	// MouseDown is the constant for "mouse-down" property tag.
	// The "mouse-down" event is fired at a View when a pointing device button is pressed
	// while the pointer is inside the view.
	// The main listener format: func(View, MouseEvent).
	// The additional listener formats: func(MouseEvent), func(View), and func().
	MouseDown = "mouse-down"

	// MouseUp is the constant for "mouse-up" property tag.
	// The "mouse-up" event is fired at a View when a button on a pointing device (such as a mouse
	// or trackpad) is released while the pointer is located inside it.
	// "mouse-up" events are the counterpoint to "mouse-down" events.
	// The main listener format: func(View, MouseEvent).
	// The additional listener formats: func(MouseEvent), func(View), and func().
	MouseUp = "mouse-up"

	// MouseMove is the constant for "mouse-move" property tag.
	// The "mouse-move" event is fired at a view when a pointing device (usually a mouse) is moved
	// while the cursor's hotspot is inside it.
	// The main listener format: func(View, MouseEvent).
	// The additional listener formats: func(MouseEvent), func(View), and func().
	MouseMove = "mouse-move"

	// MouseOut is the constant for "mouse-out" property tag.
	// The "mouse-out" event is fired at a View when a pointing device (usually a mouse) is used to move
	// the cursor so that it is no longer contained within the view or one of its children.
	// "mouse-out" is also delivered to a view if the cursor enters a child view,
	// because the child view obscures the visible area of the view.
	// The main listener format: func(View, MouseEvent).
	// The additional listener formats: func(MouseEvent), func(View), and func().
	MouseOut = "mouse-out"

	// MouseOver is the constant for "mouse-over" property tag.
	// The "mouse-over" event is fired at a View when a pointing device (such as a mouse or trackpad)
	// is used to move the cursor onto the view or one of its child views.
	// The main listener formats: func(View, MouseEvent).
	MouseOver = "mouse-over"

	// ContextMenuEvent is the constant for "context-menu-event" property tag
	// The "context-menu-event" event occurs when the user calls the context menu by the right mouse clicking.
	// The main listener format: func(View, MouseEvent).
	ContextMenuEvent = "context-menu-event"

	// PrimaryMouseButton is a number of the main pressed button, usually the left button or the un-initialized state
	PrimaryMouseButton = 0
	// AuxiliaryMouseButton is a number of the auxiliary pressed button, usually the wheel button
	// or the middle button (if present)
	AuxiliaryMouseButton = 1
	// SecondaryMouseButton is a number of the secondary pressed button, usually the right button
	SecondaryMouseButton = 2
	// MouseButton4 is a number of the fourth button, typically the Browser Back button
	MouseButton4 = 3
	// MouseButton5 is a number of the fifth button, typically the Browser Forward button
	MouseButton5 = 4

	// PrimaryMouseMask is the mask of the primary button (usually the left button)
	PrimaryMouseMask = 1
	// SecondaryMouseMask is the mask of the secondary button (usually the right button)
	SecondaryMouseMask = 2
	// AuxiliaryMouseMask  is the mask of the auxiliary button (usually the mouse wheel button or middle button)
	AuxiliaryMouseMask = 4
	// MouseMask4 is the mask of the 4th button (typically the "Browser Back" button)
	MouseMask4 = 8
	//MouseMask5 is the mask of the  5th button (typically the "Browser Forward" button)
	MouseMask5 = 16
)

type MouseEvent struct {
	// TimeStamp is the time at which the event was created (in milliseconds).
	// This value is time since epoch—but in reality, browsers' definitions vary.
	TimeStamp uint64

	// Button indicates which button was pressed on the mouse to trigger the event:
	// PrimaryMouseButton (0), AuxiliaryMouseButton (1), SecondaryMouseButton (2),
	// MouseButton4 (3), and MouseButton5 (4)
	Button int

	// Buttons indicates which buttons are pressed on the mouse (or other input device)
	// when a mouse event is triggered. Each button that can be pressed is represented by a given mask:
	// PrimaryMouseMask (1), SecondaryMouseMask (2), AuxiliaryMouseMask (4), MouseMask4 (8), and MouseMask5 (16)
	Buttons int

	// X provides the horizontal coordinate within the view's viewport.
	X float64
	// Y provides the vertical coordinate within the view's viewport.
	Y float64

	// ClientX provides the horizontal coordinate within the application's viewport at which the event occurred.
	ClientX float64
	// ClientY provides the vertical coordinate within the application's viewport at which the event occurred.
	ClientY float64

	// ScreenX provides the horizontal coordinate (offset) of the mouse pointer in global (screen) coordinates.
	ScreenX float64
	// ScreenY provides the vertical coordinate (offset) of the mouse pointer in global (screen) coordinates.
	ScreenY float64

	// CtrlKey == true if the control key was down when the event was fired. false otherwise.
	CtrlKey bool
	// ShiftKey == true if the shift key was down when the event was fired. false otherwise.
	ShiftKey bool
	// AltKey == true if the alt key was down when the event was fired. false otherwise.
	AltKey bool
	// MetaKey == true if the meta key was down when the event was fired. false otherwise.
	MetaKey bool
}

func valueToMouseListeners(value interface{}) ([]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 View, event MouseEvent) {
			value(event)
		}
		return []func(View, MouseEvent){fn}, true

	case func(View):
		fn := func(view View, event MouseEvent) {
			value(view)
		}
		return []func(View, MouseEvent){fn}, true

	case func():
		fn := func(view View, event 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 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, event 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 View, event MouseEvent) {
				v()
			}
		}
		return listeners, true

	case []interface{}:
		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 View, event MouseEvent) {
					v(event)
				}

			case func(View):
				listeners[i] = func(view View, event MouseEvent) {
					v(view)
				}

			case func():
				listeners[i] = func(view View, event 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"},
	MouseDown:        {jsEvent: "onmousedown", jsFunc: "mouseDownEvent"},
	MouseUp:          {jsEvent: "onmouseup", jsFunc: "mouseUpEvent"},
	MouseMove:        {jsEvent: "onmousemove", jsFunc: "mouseMoveEvent"},
	MouseOut:         {jsEvent: "onmouseout", jsFunc: "mouseOutEvent"},
	MouseOver:        {jsEvent: "onmouseover", jsFunc: "mouseOverEvent"},
	ContextMenuEvent: {jsEvent: "oncontextmenu", jsFunc: "contextMenuEvent"},
}

func (view *viewData) setMouseListener(tag string, value interface{}) bool {
	listeners, ok := valueToMouseListeners(value)
	if !ok {
		notCompatibleType(tag, value)
		return false
	}

	if listeners == nil {
		view.removeMouseListener(tag)
	} else if js, ok := mouseEvents[tag]; ok {
		view.properties[tag] = listeners
		if view.created {
			updateProperty(view.htmlID(), js.jsEvent, js.jsFunc+"(this, event)", view.Session())
		}
	} else {
		return false
	}
	return true
}

func (view *viewData) removeMouseListener(tag string) {
	delete(view.properties, tag)
	if view.created {
		if js, ok := mouseEvents[tag]; ok {
			updateProperty(view.htmlID(), js.jsEvent, "", view.Session())
		}
	}
}

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 {
			if listeners, ok := value.([]func(View, MouseEvent)); ok && len(listeners) > 0 {
				buffer.WriteString(js.jsEvent + `="` + js.jsFunc + `(this, event)" `)
			}
		}
	}
}

func getTimeStamp(data DataObject) uint64 {
	if value, ok := data.PropertyValue("timeStamp"); ok {
		if index := strings.Index(value, "."); index > 0 {
			value = value[:index]
		}
		if n, err := strconv.ParseUint(value, 10, 64); err == nil {
			return n
		}
	}
	return 0
}

func (event *MouseEvent) init(data DataObject) {

	event.TimeStamp = getTimeStamp(data)
	event.Button = dataIntProperty(data, "button")
	event.Buttons = dataIntProperty(data, "buttons")
	event.X = dataFloatProperty(data, "x")
	event.Y = dataFloatProperty(data, "y")
	event.ClientX = dataFloatProperty(data, "clientX")
	event.ClientY = dataFloatProperty(data, "clientY")
	event.ScreenX = dataFloatProperty(data, "screenX")
	event.ScreenY = dataFloatProperty(data, "screenY")
	event.CtrlKey = dataBoolProperty(data, "ctrlKey")
	event.ShiftKey = dataBoolProperty(data, "shiftKey")
	event.AltKey = dataBoolProperty(data, "altKey")
	event.MetaKey = dataBoolProperty(data, "metaKey")
}

func handleMouseEvents(view View, tag string, data DataObject) {
	listeners := getMouseListeners(view, "", tag)
	if len(listeners) == 0 {
		return
	}

	var event MouseEvent
	event.init(data)

	for _, listener := range listeners {
		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)
}

// 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)
}

// 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)
}

// 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)
}

// 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)
}

// 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)
}

// 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)
}

// 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)
}