Added drag-and-drop support

app_scripts.js

@@ -2125,3 +2125,103 @@ function createPath2D(svg) {
 		return new Path2D();
 	}
 }
+
+function stringToBase64(str) {
+	const bytes = new TextEncoder().encode(str);
+	const binString = String.fromCodePoint(...bytes);
+	return btoa(binString);
+}
+
+function base64ToString(base64) {
+	const binString = atob(base64);
+  	const bytes = Uint8Array.from(binString, (m) => m.codePointAt(0));
+	const result = new TextDecoder().decode(bytes);
+	return result;
+}
+
+function dragAndDropEvent(element, event, tag) {
+	event.stopPropagation();
+	//event.preventDefault()
+
+	let message = tag + "{session=" + sessionID + ",id=" + element.id + mouseEventData(element, event);
+	if (event.dataTransfer) {
+		if (event.target) {
+			message += ",target=" + event.target.id;
+		}
+		let dataText = ""
+		for (const item of event.dataTransfer.items) {
+			const data = event.dataTransfer.getData(item.type);
+			if (data) {
+				if (dataText != "") {
+					dataText += ";";
+				}
+				dataText += stringToBase64(item.type) + ":" + stringToBase64(data);
+			}
+		}
+		if (dataText != "") {
+			message += ',data="' + dataText + '"';
+		}
+	}
+	message += "}";
+	sendMessage(message);
+}
+
+function dragStartEvent(element, event) {
+	const data = element.getAttribute("data-drag");
+	if (data) {
+		const elements = data.split(";");
+		for (const line of elements) {
+			const pair = line.split(":");
+			if (pair.length == 2) {
+				event.dataTransfer.setData(base64ToString(pair[0]), base64ToString(pair[1]));
+			}
+		}
+	}
+
+	const image = element.getAttribute("data-drag-image");
+	if (image) {
+		let x = element.getAttribute("data-drag-image-x");
+		if (!x) {
+			x = 0;
+		}
+
+		let y = element.getAttribute("data-drag-image-y");
+		if (!y) {
+			y = 0;
+		}
+
+		let img = new Image();
+  		img.src = image;
+		event.dataTransfer.setDragImage(img, x, y);
+	}
+
+	// TODO drag effect
+
+	dragAndDropEvent(element, event, "drag-start-event");
+}
+
+function dragEndEvent(element, event) {
+	dragAndDropEvent(element, event, "drag-end-event")
+}
+
+function dragEnterEvent(element, event) {
+	dragAndDropEvent(element, event, "drag-enter-event")
+}
+
+function dragLeaveEvent(element, event) {
+	dragAndDropEvent(element, event, "drag-leave-event")
+}
+
+function dragOverEvent(element, event) {
+	event.preventDefault();
+	if (element.getAttribute("data-drag-over") == "1") {
+		dragAndDropEvent(element, event, "drag-over-event")
+	} else {
+		event.stopPropagation();
+	}
+}
+
+function dropEvent(element, event) {
+	event.preventDefault();
+	dragAndDropEvent(element, event, "drop-event")
+}

dragAndDrop.go

@@ -0,0 +1,260 @@
+package rui
+
+import (
+	"encoding/base64"
+	"maps"
+	"strings"
+)
+
+const (
+	// DragData is the constant for "drag-data" property tag.
+	//
+	// Used by View:
+	//
+	// Supported types: map[string]string.
+	DragData PropertyName = "drag-data"
+
+	// DragImage is the constant for "drag-image" property tag.
+	//
+	// Used by View:
+	// An url of image to use for the drag feedback image.
+	//
+	// Supported type: string.
+	DragImage PropertyName = "drag-image"
+
+	// DragImageXOffset is the constant for "drag-image-x-offset" property tag.
+	//
+	// Used by View:
+	// The horizontal offset in pixels within the drag feedback image.
+	//
+	// Supported types: float, int, string.
+	DragImageXOffset PropertyName = "drag-image-x-offset"
+
+	// DragImageYOffset is the constant for "drag-image-y-offset" property tag.
+	//
+	// Used by View.
+	// The vertical offset in pixels within the drag feedback image.
+	//
+	// Supported types: float, int, string.
+	DragImageYOffset PropertyName = "drag-image-y-offset"
+
+	// DragStartEvent is the constant for "drag-start-event" property tag.
+	//
+	// Used by View.
+	// Fired when the user starts dragging an element or text selection.
+	//
+	// General listener format:
+	//
+	DragStartEvent PropertyName = "drag-start-event"
+
+	// DragEndEvent is the constant for "drag-end-event" property tag.
+	//
+	// Used by View.
+	// Fired when a drag operation ends (by releasing a mouse button or hitting the escape key).
+	//
+	// General listener format:
+	//
+	DragEndEvent PropertyName = "drag-end-event"
+
+	// DragEnterEvent is the constant for "drag-enter-event" property tag.
+	//
+	// Used by View.
+	// Fired when a dragged element or text selection enters a valid drop target.
+	//
+	// General listener format:
+	//
+	DragEnterEvent PropertyName = "drag-enter-event"
+
+	// DragLeaveEvent is the constant for "drag-leave-event" property tag.
+	//
+	// Used by View.
+	// Fired when a dragged element or text selection leaves a valid drop target.
+	//
+	// General listener format:
+	//
+	DragLeaveEvent PropertyName = "drag-leave-event"
+
+	// DragOverEvent is the constant for "drag-over-event" property tag.
+	//
+	// Used by View.
+	// Fired when an element or text selection is being dragged over a valid drop target (every few hundred milliseconds).
+	//
+	// General listener format:
+	//
+	DragOverEvent PropertyName = "drag-over-event"
+
+	// DropEvent is the constant for "drop-event" property tag.
+	//
+	// Used by View.
+	// Fired when an element or text selection is dropped on a valid drop target.
+	//
+	// General listener format:
+	//
+	DropEvent PropertyName = "drop-event"
+)
+
+// MouseEvent represent a mouse event
+type DragAndDropEvent struct {
+	MouseEvent
+	Data   map[string]string
+	Target View
+}
+
+func (event *DragAndDropEvent) init(session Session, data DataObject) {
+	event.MouseEvent.init(data)
+
+	event.Data = map[string]string{}
+	if value, ok := data.PropertyValue("data"); ok {
+		data := strings.Split(value, ";")
+		for _, line := range data {
+			pair := strings.Split(line, ":")
+			if len(pair) == 2 {
+				mime, err := base64.StdEncoding.DecodeString(pair[0])
+				if err != nil {
+					ErrorLog(err.Error())
+				} else {
+					val, err := base64.StdEncoding.DecodeString(pair[1])
+					if err == nil {
+						event.Data[string(mime)] = string(val)
+					} else {
+						ErrorLog(err.Error())
+					}
+				}
+			}
+		}
+	}
+
+	if targetId, ok := data.PropertyValue("target"); ok {
+		event.Target = session.viewByHTMLID(targetId)
+	}
+}
+
+func handleDragAndDropEvents(view View, tag PropertyName, data DataObject) {
+	listeners := getOneArgEventListeners[View, DragAndDropEvent](view, nil, tag)
+	if len(listeners) > 0 {
+		var event DragAndDropEvent
+		event.init(view.Session(), data)
+
+		for _, listener := range listeners {
+			listener(view, event)
+		}
+	}
+}
+
+func base64DragData(view View) string {
+	if value := view.getRaw(DragData); value != nil {
+		if data, ok := value.(map[string]string); ok && len(data) > 0 {
+			buf := allocStringBuilder()
+			defer freeStringBuilder(buf)
+
+			for mime, value := range data {
+				if buf.Len() > 0 {
+					buf.WriteRune(';')
+				}
+				buf.WriteString(base64.StdEncoding.EncodeToString([]byte(mime)))
+				buf.WriteRune(':')
+				buf.WriteString(base64.StdEncoding.EncodeToString([]byte(value)))
+			}
+
+			return buf.String()
+		}
+	}
+	return ""
+}
+
+func dragAndDropHtml(view View, buffer *strings.Builder) {
+
+	if len(getOneArgEventListeners[View, DragAndDropEvent](view, nil, DropEvent)) > 0 {
+		buffer.WriteString(`ondragover="dragOverEvent(this, event)" ondrop="dropEvent(this, event)" `)
+		if len(getOneArgEventListeners[View, DragAndDropEvent](view, nil, DragOverEvent)) > 0 {
+			buffer.WriteString(`data-drag-over="1" `)
+		}
+	}
+
+	if dragData := base64DragData(view); dragData != "" {
+		buffer.WriteString(`draggable="true" data-drag="`)
+		buffer.WriteString(dragData)
+		buffer.WriteString(`" ondragstart="dragStartEvent(this, event)" `)
+	} else if len(getOneArgEventListeners[View, DragAndDropEvent](view, nil, DragStartEvent)) > 0 {
+		buffer.WriteString(` ondragstart="dragStartEvent(this, event)" `)
+	}
+
+	viewEventsHtml[DragAndDropEvent](view, []PropertyName{DragEndEvent, DragEnterEvent, DragLeaveEvent}, buffer)
+
+	session := view.Session()
+	if img, ok := stringProperty(view, DragImage, session); ok && img != "" {
+		img = strings.Trim(img, " \t")
+		if img[0] == '@' {
+			if img, ok = session.ImageConstant(img[1:]); ok {
+				buffer.WriteString(` data-drag-image="`)
+				buffer.WriteString(img)
+				buffer.WriteString(`" `)
+			}
+		} else {
+			buffer.WriteString(` data-drag-image="`)
+			buffer.WriteString(img)
+			buffer.WriteString(`" `)
+		}
+	}
+
+	if f, ok := floatTextProperty(view, DragImageXOffset, session, 0); ok {
+		buffer.WriteString(` data-drag-image-x="`)
+		buffer.WriteString(f)
+		buffer.WriteString(`" `)
+	}
+
+	if f, ok := floatTextProperty(view, DragImageYOffset, session, 0); ok {
+		buffer.WriteString(` data-drag-image-y="`)
+		buffer.WriteString(f)
+		buffer.WriteString(`" `)
+	}
+}
+
+// GetDragStartEventListeners returns the "drag-start-event" listener list. If there are no listeners then the empty list is returned.
+// If the second argument (subviewID) is not specified or it is "" then a value from the first argument (view) is returned.
+func GetDragStartEventListeners(view View, subviewID ...string) []func(View, DragAndDropEvent) {
+	return getOneArgEventListeners[View, DragAndDropEvent](view, subviewID, DragStartEvent)
+}
+
+// GetDragEndEventListeners returns the "drag-end-event" listener list. If there are no listeners then the empty list is returned.
+// If the second argument (subviewID) is not specified or it is "" then a value from the first argument (view) is returned.
+func GetDragEndEventListeners(view View, subviewID ...string) []func(View, DragAndDropEvent) {
+	return getOneArgEventListeners[View, DragAndDropEvent](view, subviewID, DragEndEvent)
+}
+
+// GetDragEnterEventListeners returns the "drag-enter-event" listener list. If there are no listeners then the empty list is returned.
+// If the second argument (subviewID) is not specified or it is "" then a value from the first argument (view) is returned.
+func GetDragEnterEventListeners(view View, subviewID ...string) []func(View, DragAndDropEvent) {
+	return getOneArgEventListeners[View, DragAndDropEvent](view, subviewID, DragEnterEvent)
+}
+
+// GetDragLeaveEventListeners returns the "drag-leave-event" listener list. If there are no listeners then the empty list is returned.
+// If the second argument (subviewID) is not specified or it is "" then a value from the first argument (view) is returned.
+func GetDragLeaveEventListeners(view View, subviewID ...string) []func(View, DragAndDropEvent) {
+	return getOneArgEventListeners[View, DragAndDropEvent](view, subviewID, DragLeaveEvent)
+}
+
+// GetDragOverEventListeners returns the "drag-over-event" listener list. If there are no listeners then the empty list is returned.
+// If the second argument (subviewID) is not specified or it is "" then a value from the first argument (view) is returned.
+func GetDragOverEventListeners(view View, subviewID ...string) []func(View, DragAndDropEvent) {
+	return getOneArgEventListeners[View, DragAndDropEvent](view, subviewID, DragOverEvent)
+}
+
+// GetDropEventListeners returns the "drag-start-event" listener list. If there are no listeners then the empty list is returned.
+// If the second argument (subviewID) is not specified or it is "" then a value from the first argument (view) is returned.
+func GetDropEventListeners(view View, subviewID ...string) []func(View, DragAndDropEvent) {
+	return getOneArgEventListeners[View, DragAndDropEvent](view, subviewID, DropEvent)
+}
+
+func GetDragData(view View, subviewID ...string) map[string]string {
+	result := map[string]string{}
+	if view = getSubview(view, subviewID); view != nil {
+		if value := view.getRaw(DragData); value != nil {
+			if data, ok := value.(map[string]string); ok {
+				maps.Copy(result, data)
+			}
+		}
+	}
+
+	return result
+}

events.go

@@ -33,6 +33,9 @@ var eventJsFunc = map[PropertyName]struct{ jsEvent, jsFunc string }{
 	AnimationEndEvent:       {jsEvent: "onanimationend", jsFunc: "animationEndEvent"},
 	AnimationIterationEvent: {jsEvent: "onanimationiteration", jsFunc: "animationIterationEvent"},
 	AnimationCancelEvent:    {jsEvent: "onanimationcancel", jsFunc: "animationCancelEvent"},
+	DragEndEvent:            {jsEvent: "ondragend", jsFunc: "dragEndEvent"},
+	DragEnterEvent:          {jsEvent: "ondragenter", jsFunc: "dragEnterEvent"},
+	DragLeaveEvent:          {jsEvent: "ondragleave", jsFunc: "dragLeaveEvent"},
 }
 
 func valueToNoArgEventListeners[V any](value any) ([]func(V), bool) {

propertySet.go

@@ -2,6 +2,7 @@ package rui
 
 import (
 	"math"
+	"slices"
 	"strconv"
 	"strings"
 )
@@ -22,6 +23,7 @@ var colorProperties = []PropertyName{
 	AccentColor,
 }
 
+/*
 	func isPropertyInList(tag PropertyName, list []PropertyName) bool {
 		for _, prop := range list {
 			if prop == tag {
@@ -30,7 +32,7 @@ func isPropertyInList(tag PropertyName, list []PropertyName) bool {
 		}
 		return false
 	}
-
+*/
 var angleProperties = []PropertyName{
 	From,
 }
@@ -91,6 +93,8 @@ var floatProperties = map[PropertyName]struct{ min, max float64 }{
 	VideoWidth:        {min: 0, max: 10000},
 	VideoHeight:       {min: 0, max: 10000},
 	PushDuration:      {min: 0, max: math.MaxFloat64},
+	DragImageXOffset:  {min: -math.MaxFloat64, max: math.MaxFloat64},
+	DragImageYOffset:  {min: -math.MaxFloat64, max: math.MaxFloat64},
 }
 
 var sizeProperties = map[PropertyName]string{
@@ -849,19 +853,19 @@ func propertiesSet(properties Properties, tag PropertyName, value any) []Propert
 		return setFloatProperty(properties, tag, value, limits.min, limits.max)
 	}
 
-	if isPropertyInList(tag, colorProperties) {
+	if slices.Contains(colorProperties, tag) {
 		return setColorProperty(properties, tag, value)
 	}
 
-	if isPropertyInList(tag, angleProperties) {
+	if slices.Contains(angleProperties, tag) {
 		return setAngleProperty(properties, tag, value)
 	}
 
-	if isPropertyInList(tag, boolProperties) {
+	if slices.Contains(boolProperties, tag) {
 		return setBoolProperty(properties, tag, value)
 	}
 
-	if isPropertyInList(tag, intProperties) {
+	if slices.Contains(intProperties, tag) {
 		return setIntProperty(properties, tag, value)
 	}
 
@@ -874,18 +878,6 @@ func propertiesSet(properties Properties, tag PropertyName, value any) []Propert
 	return nil
 }
 
-/*
-func (properties *propertyList) Set(tag PropertyName, value any) bool {
-	tag = properties.normalize(tag)
-	if value == nil {
-		properties.remove(properties, tag)
-		return true
-	}
-
-	return properties.set(properties, tag, value) != nil
-}
-*/
-
 func (data *dataProperty) Set(tag PropertyName, value any) bool {
 	if value == nil {
 		data.Remove(tag)

view.go

@@ -2,6 +2,7 @@ package rui
 
 import (
 	"fmt"
+	"maps"
 	"strconv"
 	"strings"
 )
@@ -399,6 +400,85 @@ func (view *viewData) setFunc(tag PropertyName, value any) []PropertyName {
 
 	case ResizeEvent, ScrollEvent:
 		return setOneArgEventListener[View, Frame](view, tag, value)
+
+	case DragData:
+		switch value := value.(type) {
+		case map[string]string:
+			if len(value) == 0 {
+				view.setRaw(DragData, nil)
+			} else {
+				view.setRaw(DragData, maps.Clone(value))
+			}
+
+		case string:
+			if value == "" {
+				view.setRaw(DragData, nil)
+			} else {
+				data := map[string]string{}
+				for _, line := range strings.Split(value, ";") {
+					index := strings.IndexRune(line, ':')
+					if index < 0 {
+						invalidPropertyValue(DragData, value)
+						return nil
+					}
+					mime := line[:index]
+					val := line[index+1:]
+					if len(mime) > 0 || len(val) > 0 {
+						data[mime] = val
+					}
+				}
+
+				if len(data) == 0 {
+					view.setRaw(DragData, nil)
+				} else {
+					view.setRaw(DragData, data)
+				}
+			}
+
+		case DataObject:
+			data := map[string]string{}
+			count := value.PropertyCount()
+			for i := range count {
+				node := value.Property(i)
+				if node.Type() == TextNode {
+					data[node.Tag()] = node.Text()
+				} else {
+					invalidPropertyValue(DragData, value)
+					return nil
+				}
+			}
+			if len(data) == 0 {
+				view.setRaw(DragData, nil)
+			} else {
+				view.setRaw(DragData, data)
+			}
+
+		case DataNode:
+			switch value.Type() {
+			case TextNode:
+				return view.setFunc(DragData, value.Text())
+
+			case ObjectNode:
+				return view.setFunc(DragData, value.Object())
+			}
+			invalidPropertyValue(DragData, value)
+			return nil
+
+		case DataValue:
+			if value.IsObject() {
+				return view.setFunc(DragData, value.Object())
+			}
+			return view.setFunc(DragData, value.Value())
+
+		default:
+			notCompatibleType(DragData, value)
+		}
+
+		return []PropertyName{DragData}
+
+	case DragStartEvent, DragEndEvent, DragEnterEvent, DragLeaveEvent, DragOverEvent, DropEvent:
+		return setOneArgEventListener[View, DragAndDropEvent](view, tag, value)
+
 	}
 
 	return viewStyleSet(view, tag, value)
@@ -724,10 +804,81 @@ func (view *viewData) propertyChanged(tag PropertyName) {
 		PointerDown, PointerUp, PointerMove, PointerOut, PointerOver, PointerCancel,
 		TouchStart, TouchEnd, TouchMove, TouchCancel,
 		TransitionRunEvent, TransitionStartEvent, TransitionEndEvent, TransitionCancelEvent,
-		AnimationStartEvent, AnimationEndEvent, AnimationIterationEvent, AnimationCancelEvent:
+		AnimationStartEvent, AnimationEndEvent, AnimationIterationEvent, AnimationCancelEvent,
+		DragEndEvent, DragEnterEvent, DragLeaveEvent:
 
 		updateEventListenerHtml(view, tag)
 
+	case DragStartEvent:
+		if view.getRaw(DragStartEvent) != nil || view.getRaw(DragData) != nil {
+			session.updateProperty(htmlID, "ondragstart", "dragStartEvent(this, event)")
+		} else {
+			session.removeProperty(view.htmlID(), "ondragstart")
+		}
+
+	case DropEvent:
+		if view.getRaw(DropEvent) != nil {
+			session.updateProperty(htmlID, "ondrop", "dropEvent(this, event)")
+			session.updateProperty(htmlID, "ondragover", "dragOverEvent(this, event)")
+			if view.getRaw(DragOverEvent) != nil {
+				session.updateProperty(htmlID, "data-drag-over", "1")
+			} else {
+				session.removeProperty(view.htmlID(), "data-drag-over")
+			}
+		} else {
+			session.removeProperty(view.htmlID(), "ondrop")
+			session.removeProperty(view.htmlID(), "ondragover")
+		}
+
+	case DragOverEvent:
+		if view.getRaw(DragOverEvent) != nil {
+			session.updateProperty(htmlID, "data-drag-over", "1")
+		} else {
+			session.removeProperty(view.htmlID(), "data-drag-over")
+		}
+
+	case DragData:
+		if data := base64DragData(view); data != "" {
+			session.updateProperty(htmlID, "draggable", "true")
+			session.updateProperty(htmlID, "data-drag", data)
+			session.updateProperty(htmlID, "ondragstart", "dragStartEvent(this, event)")
+		} else {
+			session.removeProperty(view.htmlID(), "draggable")
+			session.removeProperty(view.htmlID(), "data-drag")
+			if view.getRaw(DragStartEvent) == nil {
+				session.removeProperty(view.htmlID(), "ondragstart")
+			}
+		}
+
+	case DragImage:
+		if img, ok := stringProperty(view, DragImage, view.session); ok && img != "" {
+			img = strings.Trim(img, " \t")
+			if img[0] == '@' {
+				img, ok = view.session.ImageConstant(img[1:])
+				if !ok {
+					session.removeProperty(view.htmlID(), "data-drag-image")
+					return
+				}
+			}
+			session.updateProperty(htmlID, "data-drag-image", img)
+		} else {
+			session.removeProperty(view.htmlID(), "data-drag-image")
+		}
+
+	case DragImageXOffset:
+		if f, ok := floatTextProperty(view, DragImageXOffset, session, 0); ok {
+			session.updateProperty(htmlID, "data-drag-image-x", f)
+		} else {
+			session.removeProperty(view.htmlID(), "data-drag-image-x")
+		}
+
+	case DragImageYOffset:
+		if f, ok := floatTextProperty(view, DragImageYOffset, session, 0); ok {
+			session.updateProperty(htmlID, "data-drag-image-y", f)
+		} else {
+			session.removeProperty(view.htmlID(), "data-drag-image-y")
+		}
+
 	case DataList:
 		updateInnerHTML(view.htmlID(), view.Session())
 
@@ -891,18 +1042,12 @@ func viewHTML(view View, buffer *strings.Builder, htmlTag string) {
 	keyEventsHtml(view, buffer)
 
 	viewEventsHtml[MouseEvent](view, []PropertyName{ClickEvent, DoubleClickEvent, MouseDown, MouseUp, MouseMove, MouseOut, MouseOver, ContextMenuEvent}, buffer)
-	//mouseEventsHtml(view, buffer, hasTooltip)
-
 	viewEventsHtml[PointerEvent](view, []PropertyName{PointerDown, PointerUp, PointerMove, PointerOut, PointerOver, PointerCancel}, buffer)
-	//pointerEventsHtml(view, buffer)
-
 	viewEventsHtml[TouchEvent](view, []PropertyName{TouchStart, TouchEnd, TouchMove, TouchCancel}, buffer)
-	//touchEventsHtml(view, buffer)
-
 	viewEventsHtml[string](view, []PropertyName{TransitionRunEvent, TransitionStartEvent, TransitionEndEvent, TransitionCancelEvent,
 		AnimationStartEvent, AnimationEndEvent, AnimationIterationEvent, AnimationCancelEvent}, buffer)
-	//transitionEventsHtml(view, buffer)
-	//animationEventsHtml(view, buffer)
+
+	dragAndDropHtml(view, buffer)
 
 	buffer.WriteRune('>')
 	view.htmlSubviews(view, buffer)
@@ -952,6 +1097,12 @@ func (view *viewData) handleCommand(self View, command PropertyName, data DataOb
 	case TouchStart, TouchEnd, TouchMove, TouchCancel:
 		handleTouchEvents(self, command, data)
 
+	case DragStartEvent:
+		handleDragAndDropEvents(self, command, data)
+
+	case DragEndEvent, DragEnterEvent, DragLeaveEvent, DragOverEvent, DropEvent:
+		handleDragAndDropEvents(self, command, data)
+
 	case FocusEvent:
 		view.hasFocus = true
 		for _, listener := range getNoArgEventListeners[View](view, nil, command) {