Added binding support for canvas "draw-function"

canvasView.go

@@ -1,5 +1,7 @@
 package rui
 
+import "reflect"
+
 // DrawFunction is the constant for "draw-function" property tag.
 //
 // Used by `CanvasView`.
@@ -55,7 +57,7 @@ func (canvasView *canvasViewData) removeFunc(tag PropertyName) []PropertyName {
 	if tag == DrawFunction {
 		if canvasView.getRaw(DrawFunction) != nil {
 			canvasView.setRaw(DrawFunction, nil)
-			canvasView.Redraw()
+			//canvasView.Redraw()
 			return []PropertyName{DrawFunction}
 		}
 		return []PropertyName{}
@@ -66,9 +68,14 @@ func (canvasView *canvasViewData) removeFunc(tag PropertyName) []PropertyName {
 
 func (canvasView *canvasViewData) setFunc(tag PropertyName, value any) []PropertyName {
 	if tag == DrawFunction {
-		if fn, ok := value.(func(Canvas)); ok {
-			canvasView.setRaw(DrawFunction, fn)
-		} else {
+		switch value := value.(type) {
+		case func(Canvas):
+			canvasView.setRaw(DrawFunction, value)
+
+		case string:
+			canvasView.setRaw(DrawFunction, value)
+
+		default:
 			notCompatibleType(tag, value)
 			return nil
 		}
@@ -94,8 +101,30 @@ func (canvasView *canvasViewData) Redraw() {
 	canvas := newCanvas(canvasView)
 	canvas.ClearRect(0, 0, canvasView.frame.Width, canvasView.frame.Height)
 	if value := canvasView.getRaw(DrawFunction); value != nil {
-		if drawer, ok := value.(func(Canvas)); ok {
+		switch drawer := value.(type) {
+		case func(Canvas):
 			drawer(canvas)
+
+		case string:
+			bind := canvasView.binding()
+			if bind == nil {
+				ErrorLogF(`There is no a binding object for call "%s"`, drawer)
+				break
+			}
+
+			val := reflect.ValueOf(bind)
+			method := val.MethodByName(drawer)
+			if !method.IsValid() {
+				ErrorLogF(`The "%s" method is not valid`, drawer)
+				break
+			}
+
+			methodType := method.Type()
+			if methodType.NumIn() == 1 && equalType(methodType.In(0), reflect.TypeOf(canvas)) {
+				method.Call([]reflect.Value{reflect.ValueOf(canvas)})
+			} else {
+				ErrorLogF(`Unsupported prototype of "%s" method`, drawer)
+			}
 		}
 	}
 	canvas.finishDraw()

image.go

@@ -4,34 +4,44 @@ import (
 	"strconv"
 )
 
+// ImageLoadingStatus defines type of status of the image loading
+type ImageLoadingStatus int
+
 // Constants which represent return values of the LoadingStatus function of an [Image] view
 const (
 	// ImageLoading is the image loading status: in the process of loading
-	ImageLoading = 0
+	ImageLoading ImageLoadingStatus = 0
 	// ImageReady is the image loading status: the image is loaded successfully
-	ImageReady = 1
+	ImageReady ImageLoadingStatus = 1
 	// ImageLoadingError is the image loading status: an error occurred while loading
-	ImageLoadingError = 2
+	ImageLoadingError ImageLoadingStatus = 2
 )
 
 // Image defines the image that is used for drawing operations on the Canvas.
 type Image interface {
 	// URL returns the url of the image
 	URL() string
-	// LoadingStatus returns the status of the image loading: ImageLoading (0), ImageReady (1), ImageLoadingError (2)
-	LoadingStatus() int
+
+	// LoadingStatus returns the status of the image loading:
+	//  - ImageLoading (0) - in the process of loading;
+	//  - ImageReady (1) - the image is loaded successfully;
+	//  - ImageLoadingError (2) - an error occurred while loading.
+	LoadingStatus() ImageLoadingStatus
+
 	// LoadingError: if LoadingStatus() == ImageLoadingError then returns the error text, "" otherwise
 	LoadingError() string
 	setLoadingError(err string)
+
 	// Width returns the width of the image in pixels. While LoadingStatus() != ImageReady returns 0
 	Width() float64
+
 	// Height returns the height of the image in pixels. While LoadingStatus() != ImageReady returns 0
 	Height() float64
 }
 
 type imageData struct {
 	url           string
-	loadingStatus int
+	loadingStatus ImageLoadingStatus
 	loadingError  string
 	width, height float64
 	listener      func(Image)
@@ -45,7 +55,7 @@ func (image *imageData) URL() string {
 	return image.url
 }
 
-func (image *imageData) LoadingStatus() int {
+func (image *imageData) LoadingStatus() ImageLoadingStatus {
 	return image.loadingStatus
 }