package rui import ( "fmt" "strconv" "strings" ) // Frame - the location and size of a rectangle area type Frame struct { // Left - the left border Left float64 // Top - the top border Top float64 // Width - the width of a rectangle area Width float64 // Height - the height of a rectangle area Height float64 } // Right returns the right border func (frame Frame) Right() float64 { return frame.Left + frame.Width } // Bottom returns the bottom border func (frame Frame) Bottom() float64 { return frame.Top + frame.Height } // View - base view interface type View interface { ViewStyle fmt.Stringer // Session returns the current Session interface Session() Session // Parent returns the parent view Parent() View // Tag returns the tag of View interface Tag() string // ID returns the id of the view ID() string // Focusable returns true if the view receives the focus Focusable() bool // Frame returns the location and size of the view in pixels Frame() Frame // Scroll returns the location size of the scrollable view in pixels Scroll() Frame // SetAnimated sets the value (second argument) of the property with name defined by the first argument. // Return "true" if the value has been set, in the opposite case "false" are returned and // a description of the error is written to the log SetAnimated(tag string, value any, animation Animation) bool // SetChangeListener set the function to track the change of the View property SetChangeListener(tag string, listener func(View, string)) // HasFocus returns 'true' if the view has focus HasFocus() bool handleCommand(self View, command string, data DataObject) bool htmlClass(disabled bool) string htmlTag() string closeHTMLTag() bool htmlID() string parentHTMLID() string setParentID(parentID string) htmlSubviews(self View, buffer *strings.Builder) htmlProperties(self View, buffer *strings.Builder) htmlDisabledProperties(self View, buffer *strings.Builder) cssStyle(self View, builder cssBuilder) addToCSSStyle(addCSS map[string]string) onResize(self View, x, y, width, height float64) onItemResize(self View, index string, x, y, width, height float64) setNoResizeEvent() isNoResizeEvent() bool setScroll(x, y, width, height float64) } // viewData - base implementation of View interface type viewData struct { viewStyle session Session tag string viewID string _htmlID string parentID string systemClass string changeListener map[string]func(View, string) singleTransition map[string]Animation addCSS map[string]string frame Frame scroll Frame noResizeEvent bool created bool hasFocus bool //animation map[string]AnimationEndListener } func newView(session Session) View { view := new(viewData) view.init(session) return view } func setInitParams(view View, params Params) { if params != nil { session := view.Session() if !session.ignoreViewUpdates() { session.setIgnoreViewUpdates(true) defer session.setIgnoreViewUpdates(false) } for _, tag := range params.AllTags() { if value, ok := params[tag]; ok { view.Set(tag, value) } } } } // NewView create new View object and return it func NewView(session Session, params Params) View { view := new(viewData) view.init(session) setInitParams(view, params) return view } func (view *viewData) init(session Session) { view.viewStyle.init() view.tag = "View" view.session = session view.changeListener = map[string]func(View, string){} view.addCSS = map[string]string{} //view.animation = map[string]AnimationEndListener{} view.singleTransition = map[string]Animation{} view.noResizeEvent = false view.created = false } func (view *viewData) Session() Session { return view.session } func (view *viewData) Parent() View { return view.session.viewByHTMLID(view.parentID) } func (view *viewData) parentHTMLID() string { return view.parentID } func (view *viewData) setParentID(parentID string) { view.parentID = parentID } func (view *viewData) Tag() string { return view.tag } func (view *viewData) ID() string { return view.viewID } func (view *viewData) ViewByID(id string) View { if id == view.ID() { if v := view.session.viewByHTMLID(view.htmlID()); v != nil { return v } return view } return nil } func (view *viewData) Focusable() bool { if focus, ok := boolProperty(view, Focusable, view.session); ok { return focus } return false } func (view *viewData) Remove(tag string) { view.remove(strings.ToLower(tag)) } func (view *viewData) remove(tag string) { switch tag { case ID: view.viewID = "" case TabIndex, "tab-index": delete(view.properties, tag) if view.Focusable() { view.session.updateProperty(view.htmlID(), "tabindex", "0") } else { view.session.updateProperty(view.htmlID(), "tabindex", "-1") } case UserData: delete(view.properties, tag) case Style, StyleDisabled: if _, ok := view.properties[tag]; ok { delete(view.properties, tag) view.session.updateProperty(view.htmlID(), "class", view.htmlClass(IsDisabled(view))) } case FocusEvent, LostFocusEvent: view.removeFocusListener(tag) case KeyDownEvent, KeyUpEvent: view.removeKeyListener(tag) case ClickEvent, DoubleClickEvent, MouseDown, MouseUp, MouseMove, MouseOut, MouseOver, ContextMenuEvent: view.removeMouseListener(tag) case PointerDown, PointerUp, PointerMove, PointerOut, PointerOver, PointerCancel: view.removePointerListener(tag) case TouchStart, TouchEnd, TouchMove, TouchCancel: view.removeTouchListener(tag) case TransitionRunEvent, TransitionStartEvent, TransitionEndEvent, TransitionCancelEvent: view.removeTransitionListener(tag) case AnimationStartEvent, AnimationEndEvent, AnimationIterationEvent, AnimationCancelEvent: view.removeAnimationListener(tag) case ResizeEvent, ScrollEvent: delete(view.properties, tag) case Content: if _, ok := view.properties[Content]; ok { delete(view.properties, Content) updateInnerHTML(view.htmlID(), view.session) } default: view.viewStyle.remove(tag) viewPropertyChanged(view, tag) } view.propertyChangedEvent(tag) } func (view *viewData) propertyChangedEvent(tag string) { if listener, ok := view.changeListener[tag]; ok { listener(view, tag) } switch tag { case BorderLeft, BorderRight, BorderTop, BorderBottom, BorderStyle, BorderLeftStyle, BorderRightStyle, BorderTopStyle, BorderBottomStyle, BorderColor, BorderLeftColor, BorderRightColor, BorderTopColor, BorderBottomColor, BorderWidth, BorderLeftWidth, BorderRightWidth, BorderTopWidth, BorderBottomWidth: tag = Border case CellBorderStyle, CellBorderColor, CellBorderWidth, CellBorderLeft, CellBorderLeftStyle, CellBorderLeftColor, CellBorderLeftWidth, CellBorderRight, CellBorderRightStyle, CellBorderRightColor, CellBorderRightWidth, CellBorderTop, CellBorderTopStyle, CellBorderTopColor, CellBorderTopWidth, CellBorderBottom, CellBorderBottomStyle, CellBorderBottomColor, CellBorderBottomWidth: tag = CellBorder case OutlineColor, OutlineStyle, OutlineWidth: tag = Outline case RadiusX, RadiusY, RadiusTopLeft, RadiusTopLeftX, RadiusTopLeftY, RadiusTopRight, RadiusTopRightX, RadiusTopRightY, RadiusBottomLeft, RadiusBottomLeftX, RadiusBottomLeftY, RadiusBottomRight, RadiusBottomRightX, RadiusBottomRightY: tag = Radius case MarginTop, MarginRight, MarginBottom, MarginLeft, "top-margin", "right-margin", "bottom-margin", "left-margin": tag = Margin case PaddingTop, PaddingRight, PaddingBottom, PaddingLeft, "top-padding", "right-padding", "bottom-padding", "left-padding": tag = Padding case CellPaddingTop, CellPaddingRight, CellPaddingBottom, CellPaddingLeft: tag = CellPadding case ColumnSeparatorStyle, ColumnSeparatorWidth, ColumnSeparatorColor: tag = ColumnSeparator default: return } if listener, ok := view.changeListener[tag]; ok { listener(view, tag) } } func (view *viewData) Set(tag string, value any) bool { return view.set(strings.ToLower(tag), value) } func (view *viewData) set(tag string, value any) bool { if value == nil { view.remove(tag) return true } result := func(res bool) bool { if res { view.propertyChangedEvent(tag) } return res } switch tag { case ID: text, ok := value.(string) if !ok { notCompatibleType(ID, value) return false } view.viewID = text case TabIndex, "tab-index": if !view.setIntProperty(tag, value) { return false } if value, ok := intProperty(view, TabIndex, view.Session(), 0); ok { view.session.updateProperty(view.htmlID(), "tabindex", strconv.Itoa(value)) } else if view.Focusable() { view.session.updateProperty(view.htmlID(), "tabindex", "0") } else { view.session.updateProperty(view.htmlID(), "tabindex", "-1") } case UserData: view.properties[tag] = value case Style, StyleDisabled: text, ok := value.(string) if !ok { notCompatibleType(ID, value) return false } view.properties[tag] = text if view.created { view.session.updateProperty(view.htmlID(), "class", view.htmlClass(IsDisabled(view))) } case FocusEvent, LostFocusEvent: return result(view.setFocusListener(tag, value)) case KeyDownEvent, KeyUpEvent: return result(view.setKeyListener(tag, value)) case ClickEvent, DoubleClickEvent, MouseDown, MouseUp, MouseMove, MouseOut, MouseOver, ContextMenuEvent: return result(view.setMouseListener(tag, value)) case PointerDown, PointerUp, PointerMove, PointerOut, PointerOver, PointerCancel: return result(view.setPointerListener(tag, value)) case TouchStart, TouchEnd, TouchMove, TouchCancel: return result(view.setTouchListener(tag, value)) case TransitionRunEvent, TransitionStartEvent, TransitionEndEvent, TransitionCancelEvent: return result(view.setTransitionListener(tag, value)) case AnimationStartEvent, AnimationEndEvent, AnimationIterationEvent, AnimationCancelEvent: return result(view.setAnimationListener(tag, value)) case ResizeEvent, ScrollEvent: return result(view.setFrameListener(tag, value)) default: if !view.viewStyle.set(tag, value) { return false } if view.created { viewPropertyChanged(view, tag) } } view.propertyChangedEvent(tag) return true } func viewPropertyChanged(view *viewData, tag string) { if view.updateTransformProperty(tag) { return } htmlID := view.htmlID() session := view.session switch tag { case Disabled: updateInnerHTML(view.parentHTMLID(), session) return case Visibility: switch GetVisibility(view) { case Invisible: session.updateCSSProperty(htmlID, Visibility, "hidden") session.updateCSSProperty(htmlID, "display", "") case Gone: session.updateCSSProperty(htmlID, Visibility, "hidden") session.updateCSSProperty(htmlID, "display", "none") default: session.updateCSSProperty(htmlID, Visibility, "visible") session.updateCSSProperty(htmlID, "display", "") } return case Background: session.updateCSSProperty(htmlID, Background, view.backgroundCSS(session)) return case Border: if getBorder(view, Border) == nil { if session.startUpdateScript(htmlID) { defer session.finishUpdateScript(htmlID) } session.updateCSSProperty(htmlID, BorderWidth, "") session.updateCSSProperty(htmlID, BorderColor, "") session.updateCSSProperty(htmlID, BorderStyle, "none") return } fallthrough case BorderLeft, BorderRight, BorderTop, BorderBottom: if border := getBorder(view, Border); border != nil { if session.startUpdateScript(htmlID) { defer session.finishUpdateScript(htmlID) } session.updateCSSProperty(htmlID, BorderWidth, border.cssWidthValue(session)) session.updateCSSProperty(htmlID, BorderColor, border.cssColorValue(session)) session.updateCSSProperty(htmlID, BorderStyle, border.cssStyleValue(session)) } return case BorderStyle, BorderLeftStyle, BorderRightStyle, BorderTopStyle, BorderBottomStyle: if border := getBorder(view, Border); border != nil { session.updateCSSProperty(htmlID, BorderStyle, border.cssStyleValue(session)) } return case BorderColor, BorderLeftColor, BorderRightColor, BorderTopColor, BorderBottomColor: if border := getBorder(view, Border); border != nil { session.updateCSSProperty(htmlID, BorderColor, border.cssColorValue(session)) } return case BorderWidth, BorderLeftWidth, BorderRightWidth, BorderTopWidth, BorderBottomWidth: if border := getBorder(view, Border); border != nil { session.updateCSSProperty(htmlID, BorderWidth, border.cssWidthValue(session)) } return case Outline, OutlineColor, OutlineStyle, OutlineWidth: session.updateCSSProperty(htmlID, Outline, GetOutline(view).cssString(session)) return case Shadow: session.updateCSSProperty(htmlID, "box-shadow", shadowCSS(view, Shadow, session)) return case TextShadow: session.updateCSSProperty(htmlID, "text-shadow", shadowCSS(view, TextShadow, session)) return case Radius, RadiusX, RadiusY, RadiusTopLeft, RadiusTopLeftX, RadiusTopLeftY, RadiusTopRight, RadiusTopRightX, RadiusTopRightY, RadiusBottomLeft, RadiusBottomLeftX, RadiusBottomLeftY, RadiusBottomRight, RadiusBottomRightX, RadiusBottomRightY: radius := GetRadius(view) session.updateCSSProperty(htmlID, "border-radius", radius.cssString(session)) return case Margin, MarginTop, MarginRight, MarginBottom, MarginLeft, "top-margin", "right-margin", "bottom-margin", "left-margin": margin := GetMargin(view) session.updateCSSProperty(htmlID, Margin, margin.cssString(session)) return case Padding, PaddingTop, PaddingRight, PaddingBottom, PaddingLeft, "top-padding", "right-padding", "bottom-padding", "left-padding": padding := GetPadding(view) session.updateCSSProperty(htmlID, Padding, padding.cssString(session)) return case AvoidBreak: if avoid, ok := boolProperty(view, AvoidBreak, session); ok { if avoid { session.updateCSSProperty(htmlID, "break-inside", "avoid") } else { session.updateCSSProperty(htmlID, "break-inside", "auto") } } return case Clip: if clip := getClipShape(view, Clip, session); clip != nil && clip.valid(session) { session.updateCSSProperty(htmlID, `clip-path`, clip.cssStyle(session)) } else { session.updateCSSProperty(htmlID, `clip-path`, "none") } return case ShapeOutside: if clip := getClipShape(view, ShapeOutside, session); clip != nil && clip.valid(session) { session.updateCSSProperty(htmlID, ShapeOutside, clip.cssStyle(session)) } else { session.updateCSSProperty(htmlID, ShapeOutside, "none") } return case Filter: text := "" if value := view.getRaw(tag); value != nil { if filter, ok := value.(ViewFilter); ok { text = filter.cssStyle(session) } } session.updateCSSProperty(htmlID, tag, text) return case BackdropFilter: text := "" if value := view.getRaw(tag); value != nil { if filter, ok := value.(ViewFilter); ok { text = filter.cssStyle(session) } } if session.startUpdateScript(htmlID) { defer session.finishUpdateScript(htmlID) } session.updateCSSProperty(htmlID, "-webkit-backdrop-filter", text) session.updateCSSProperty(htmlID, tag, text) return case FontName: if font, ok := stringProperty(view, FontName, session); ok { session.updateCSSProperty(htmlID, "font-family", font) } else { session.updateCSSProperty(htmlID, "font-family", "") } return case Italic: if state, ok := boolProperty(view, tag, session); ok { if state { session.updateCSSProperty(htmlID, "font-style", "italic") } else { session.updateCSSProperty(htmlID, "font-style", "normal") } } else { session.updateCSSProperty(htmlID, "font-style", "") } return case SmallCaps: if state, ok := boolProperty(view, tag, session); ok { if state { session.updateCSSProperty(htmlID, "font-variant", "small-caps") } else { session.updateCSSProperty(htmlID, "font-variant", "normal") } } else { session.updateCSSProperty(htmlID, "font-variant", "") } return case Strikethrough, Overline, Underline: session.updateCSSProperty(htmlID, "text-decoration", view.cssTextDecoration(session)) for _, tag2 := range []string{TextLineColor, TextLineStyle, TextLineThickness} { viewPropertyChanged(view, tag2) } return case Transition: view.updateTransitionCSS() return case AnimationTag: session.updateCSSProperty(htmlID, AnimationTag, view.animationCSS(session)) return case AnimationPaused: paused, ok := boolProperty(view, AnimationPaused, session) if !ok { session.updateCSSProperty(htmlID, `animation-play-state`, ``) } else if paused { session.updateCSSProperty(htmlID, `animation-play-state`, `paused`) } else { session.updateCSSProperty(htmlID, `animation-play-state`, `running`) } return case ZIndex, Order, TabSize: if i, ok := intProperty(view, tag, session, 0); ok { session.updateCSSProperty(htmlID, tag, strconv.Itoa(i)) } return case Row, Column: if parentID := view.parentHTMLID(); parentID != "" { updateInnerHTML(parentID, session) } return case UserSelect: if session.startUpdateScript(htmlID) { defer session.finishUpdateScript(htmlID) } if userSelect, ok := boolProperty(view, UserSelect, session); ok { if userSelect { session.updateCSSProperty(htmlID, "-webkit-user-select", "auto") session.updateCSSProperty(htmlID, "user-select", "auto") } else { session.updateCSSProperty(htmlID, "-webkit-user-select", "none") session.updateCSSProperty(htmlID, "user-select", "none") } } else { session.updateCSSProperty(htmlID, "-webkit-user-select", "") session.updateCSSProperty(htmlID, "user-select", "") } return case ColumnSpanAll: if spanAll, ok := boolProperty(view, ColumnSpanAll, session); ok && spanAll { session.updateCSSProperty(htmlID, `column-span`, `all`) } else { session.updateCSSProperty(htmlID, `column-span`, `none`) } return case Tooltip: if tooltip := GetTooltip(view); tooltip == "" { session.removeProperty(htmlID, "data-tooltip") } else { session.updateProperty(htmlID, "data-tooltip", tooltip) session.updateProperty(htmlID, "onmouseenter", "mouseEnterEvent(this, event)") session.updateProperty(htmlID, "onmouseleave", "mouseLeaveEvent(this, event)") } return } if cssTag, ok := sizeProperties[tag]; ok { size, _ := sizeProperty(view, tag, session) session.updateCSSProperty(htmlID, cssTag, size.cssString("", session)) return } colorTags := map[string]string{ BackgroundColor: BackgroundColor, TextColor: "color", TextLineColor: "text-decoration-color", CaretColor: CaretColor, AccentColor: AccentColor, } if cssTag, ok := colorTags[tag]; ok { if color, ok := colorProperty(view, tag, session); ok { session.updateCSSProperty(htmlID, cssTag, color.cssString()) } else { session.updateCSSProperty(htmlID, cssTag, "") } return } if valuesData, ok := enumProperties[tag]; ok && valuesData.cssTag != "" { n, _ := enumProperty(view, tag, session, 0) session.updateCSSProperty(htmlID, valuesData.cssTag, valuesData.cssValues[n]) return } for _, floatTag := range []string{Opacity, ScaleX, ScaleY, ScaleZ, RotateX, RotateY, RotateZ} { if tag == floatTag { if f, ok := floatTextProperty(view, floatTag, session, 0); ok { session.updateCSSProperty(htmlID, floatTag, f) } return } } } func (view *viewData) Get(tag string) any { return view.get(strings.ToLower(tag)) } func (view *viewData) get(tag string) any { if tag == ID { if view.viewID != "" { return view.viewID } else { return nil } } return view.viewStyle.get(tag) } func (view *viewData) htmlTag() string { if semantics := GetSemantics(view); semantics > DefaultSemantics { values := enumProperties[Semantics].cssValues if semantics < len(values) { return values[semantics] } } return "div" } func (view *viewData) closeHTMLTag() bool { return true } func (view *viewData) htmlID() string { if view._htmlID == "" { view._htmlID = view.session.nextViewID() } return view._htmlID } func (view *viewData) htmlSubviews(self View, buffer *strings.Builder) { } func (view *viewData) addToCSSStyle(addCSS map[string]string) { view.addCSS = addCSS } func (view *viewData) cssStyle(self View, builder cssBuilder) { view.viewStyle.cssViewStyle(builder, view.session) switch GetVisibility(view) { case Invisible: builder.add(`visibility`, `hidden`) case Gone: builder.add(`display`, `none`) } if view.addCSS != nil { for tag, value := range view.addCSS { builder.add(tag, value) } } } func (view *viewData) htmlProperties(self View, buffer *strings.Builder) { view.created = true if view.frame.Left != 0 || view.frame.Top != 0 || view.frame.Width != 0 || view.frame.Height != 0 { buffer.WriteString(fmt.Sprintf(` data-left="%g" data-top="%g" data-width="%g" data-height="%g"`, view.frame.Left, view.frame.Top, view.frame.Width, view.frame.Height)) } } func (view *viewData) htmlDisabledProperties(self View, buffer *strings.Builder) { if IsDisabled(self) { buffer.WriteString(` data-disabled="1"`) } else { buffer.WriteString(` data-disabled="0"`) } } func viewHTML(view View, buffer *strings.Builder) { viewHTMLTag := view.htmlTag() buffer.WriteRune('<') buffer.WriteString(viewHTMLTag) buffer.WriteString(` id="`) buffer.WriteString(view.htmlID()) buffer.WriteRune('"') disabled := IsDisabled(view) if cls := view.htmlClass(disabled); cls != "" { buffer.WriteString(` class="`) buffer.WriteString(cls) buffer.WriteRune('"') } cssBuilder := viewCSSBuilder{buffer: allocStringBuilder()} view.cssStyle(view, &cssBuilder) if style := cssBuilder.finish(); style != "" { buffer.WriteString(` style="`) buffer.WriteString(style) buffer.WriteRune('"') } buffer.WriteRune(' ') view.htmlProperties(view, buffer) buffer.WriteRune(' ') view.htmlDisabledProperties(view, buffer) if view.isNoResizeEvent() { buffer.WriteString(` data-noresize="1" `) } else { buffer.WriteRune(' ') } if !disabled { if value, ok := intProperty(view, TabIndex, view.Session(), -1); ok { buffer.WriteString(`tabindex="`) buffer.WriteString(strconv.Itoa(value)) buffer.WriteString(`" `) } else if view.Focusable() { buffer.WriteString(`tabindex="0" `) } } hasTooltip := false if tooltip := GetTooltip(view); tooltip != "" { buffer.WriteString(`data-tooltip=" `) buffer.WriteString(tooltip) buffer.WriteString(`" `) hasTooltip = true } buffer.WriteString(`onscroll="scrollEvent(this, event)" `) keyEventsHtml(view, buffer) mouseEventsHtml(view, buffer, hasTooltip) pointerEventsHtml(view, buffer) touchEventsHtml(view, buffer) focusEventsHtml(view, buffer) transitionEventsHtml(view, buffer) animationEventsHtml(view, buffer) buffer.WriteRune('>') view.htmlSubviews(view, buffer) if view.closeHTMLTag() { buffer.WriteString(`') } } func (view *viewData) htmlClass(disabled bool) string { cls := "ruiView" disabledStyle := false if disabled { if value, ok := stringProperty(view, StyleDisabled, view.Session()); ok && value != "" { cls += " " + value disabledStyle = true } } if !disabledStyle { if value, ok := stringProperty(view, Style, view.Session()); ok { cls += " " + value } } if view.systemClass != "" { cls = view.systemClass + " " + cls } return cls } func (view *viewData) handleCommand(self View, command string, data DataObject) bool { switch command { case KeyDownEvent, KeyUpEvent: if !IsDisabled(self) { handleKeyEvents(self, command, data) } case ClickEvent, DoubleClickEvent, MouseDown, MouseUp, MouseMove, MouseOut, MouseOver, ContextMenuEvent: handleMouseEvents(self, command, data) case PointerDown, PointerUp, PointerMove, PointerOut, PointerOver, PointerCancel: handlePointerEvents(self, command, data) case TouchStart, TouchEnd, TouchMove, TouchCancel: handleTouchEvents(self, command, data) case FocusEvent: view.hasFocus = true for _, listener := range getFocusListeners(view, nil, command) { listener(self) } case LostFocusEvent: view.hasFocus = false for _, listener := range getFocusListeners(view, nil, command) { listener(self) } case TransitionRunEvent, TransitionStartEvent, TransitionEndEvent, TransitionCancelEvent: view.handleTransitionEvents(command, data) case AnimationStartEvent, AnimationEndEvent, AnimationIterationEvent, AnimationCancelEvent: view.handleAnimationEvents(command, data) case "scroll": view.onScroll(view, dataFloatProperty(data, "x"), dataFloatProperty(data, "y"), dataFloatProperty(data, "width"), dataFloatProperty(data, "height")) case "widthChanged": if value, ok := data.PropertyValue("width"); ok { if width, ok := StringToSizeUnit(value); ok { self.setRaw(Width, width) } } case "heightChanged": if value, ok := data.PropertyValue("height"); ok { if height, ok := StringToSizeUnit(value); ok { self.setRaw(Height, height) } } /* case "resize": floatProperty := func(tag string) float64 { if value, ok := data.PropertyValue(tag); ok { if result, err := strconv.ParseFloat(value, 64); err == nil { return result } } return 0 } self.onResize(self, floatProperty("x"), floatProperty("y"), floatProperty("width"), floatProperty("height")) return true */ default: return false } return true } func (view *viewData) SetChangeListener(tag string, listener func(View, string)) { if listener == nil { delete(view.changeListener, tag) } else { view.changeListener[tag] = listener } } func (view *viewData) HasFocus() bool { return view.hasFocus } func (view *viewData) String() string { return getViewString(view) }