Improve extensibility of the DiagramWidget

cmd/diagramdemo/main.go

@@ -9,6 +9,7 @@ import (
 
 	"fyne.io/fyne/v2"
 	"fyne.io/fyne/v2/app"
+	"fyne.io/fyne/v2/canvas"
 	"fyne.io/fyne/v2/container"
 	"fyne.io/fyne/v2/widget"
 )
@@ -29,6 +30,67 @@ func forceanim(diagramWidget *diagramwidget.DiagramWidget) {
 	}
 }
 
+// ModifiedDragNode illustrates how to extend a node. This particular example
+// disables vertical movement and vertical resizing
+type ModifiedDragNode struct {
+	diagramwidget.BaseDiagramNode
+	label *widget.Label
+}
+
+// NewModifiedDragNode returns an instance of an ExtendedNode
+func NewModifiedDragNode(nodeID string, diagramWidget *diagramwidget.DiagramWidget) diagramwidget.DiagramNode {
+	newNode := &ModifiedDragNode{}
+	newNode.label = widget.NewLabel("Vertical Changes Not Alloweed")
+	diagramwidget.InitializeBaseDiagramNode(newNode, diagramWidget, newNode.label, nodeID)
+	newNode.Refresh()
+	return newNode
+}
+
+// Dragged passes the DragEvent to the diagram for processing after removing any Y value changes
+func (en *ModifiedDragNode) Dragged(event *fyne.DragEvent) {
+	modifiedDelta := fyne.Delta{
+		DX: event.Dragged.DX,
+		DY: 0,
+	}
+	modifiedDragEvent := &fyne.DragEvent{
+		PointEvent: event.PointEvent,
+		Dragged:    modifiedDelta,
+	}
+	en.GetDiagram().DiagramNodeDragged(&en.BaseDiagramNode, modifiedDragEvent)
+}
+
+// HandleDragged passes the HandleDragged event to the BasseDiagramNode after removing any Y value changes
+func (en *ModifiedDragNode) HandleDragged(handle *diagramwidget.Handle, event *fyne.DragEvent) {
+	modifiedDelta := fyne.Delta{
+		DX: event.Dragged.DX,
+		DY: 0,
+	}
+	modifiedDragEvent := &fyne.DragEvent{
+		PointEvent: event.PointEvent,
+		Dragged:    modifiedDelta,
+	}
+	en.BaseDiagramNode.HandleDragged(handle, modifiedDragEvent)
+}
+
+// ModifiedPadsNode removes the default rectangle pad on the perimeter and adds two point pads,
+// one at each side of the node
+type ModifiedPadsNode struct {
+	diagramwidget.BaseDiagramNode
+	label *widget.Label
+}
+
+// NewModifiedPadsNode creates and initializes a ModifiedPadsNode
+func NewModifiedPadsNode(nodeID string, diagramWidget *diagramwidget.DiagramWidget) diagramwidget.DiagramNode {
+	newNode := &ModifiedPadsNode{}
+	newNode.label = widget.NewLabel("Connection pads on left and right")
+	diagramwidget.InitializeBaseDiagramNode(newNode, diagramWidget, newNode.label, nodeID)
+	// Get rid of the default pad on the perimeter
+	newNode.SetConnectionPad(nil, "default")
+	newNode.SetConnectionPad(diagramwidget.NewPointPad(newNode.GetProperties().PadStrokeWidth), "left")
+	newNode.SetConnectionPad(diagramwidget.NewPointPad(newNode.GetProperties().PadStrokeWidth), "right")
+	return newNode
+}
+
 func main() {
 	app := app.New()
 	w := app.NewWindow("Diagram Demo")
@@ -37,10 +99,19 @@ func main() {
 
 	diagramWidget := diagramwidget.NewDiagramWidget("Diagram1")
 
-	scrollContainer := container.NewScroll(diagramWidget)
-
 	go forceanim(diagramWidget)
 
+	background := canvas.NewCircle(color.RGBA{
+		R: 252,
+		G: 244,
+		B: 3,
+		A: 255,
+	})
+
+	background.Resize(fyne.NewSize(200, 200))
+
+	diagramWidget.SetBackground(background)
+
 	// Node 0
 	node0Label := widget.NewLabel("Node0")
 	node0 := diagramwidget.NewDiagramNode(diagramWidget, node0Label, "Node0")
@@ -91,9 +162,29 @@ func main() {
 	}), "Node4")
 	node4.Move(fyne.Position{X: 400, Y: 400})
 
-	node5 := diagramwidget.NewDiagramNode(diagramWidget, widget.NewLabel("Node5"), "Node5")
+	node5 := diagramwidget.NewDiagramNode(diagramWidget, widget.NewButton("Node5: Toggle Background Graphic", func() {
+		if diagramWidget.GetBackground() == nil {
+			diagramWidget.SetBackground(background)
+		} else {
+			diagramWidget.SetBackground(nil)
+		}
+	}), "Node5")
 	node5.Move(fyne.NewPos(600, 200))
 
+	node6 := NewModifiedDragNode("Node6", diagramWidget)
+	node6.Move(fyne.NewPos(500, 0))
+
+	node7 := NewModifiedPadsNode("Node7", diagramWidget)
+	node7Size := node7.Size()
+	halfPointPadSize := diagramwidget.PointPadSize / 2
+	node7Pads := node7.GetConnectionPads()
+	node7DefaultPadPosition := fyne.NewPos(-halfPointPadSize, node7Size.Height/2-halfPointPadSize)
+	node7Pads["left"].Move(node7DefaultPadPosition)
+	node7RightPadPosition := fyne.NewPos(node7Size.Width-halfPointPadSize, node7Size.Height/2-halfPointPadSize)
+	node7Pads["right"].Move(node7RightPadPosition)
+	node7.Move(fyne.NewPos(500, 50))
+	node7.Refresh()
+
 	// Link0
 	link0 := diagramwidget.NewDiagramLink(diagramWidget, "Link0")
 	link0.SetSourcePad(node0.GetEdgePad())
@@ -146,7 +237,15 @@ func main() {
 	link5.AddMidpointAnchoredText("linkName", "Link 5")
 	link5.AddTargetDecoration(diagramwidget.NewArrowhead())
 
-	w.SetContent(scrollContainer)
+	link6 := diagramwidget.NewDiagramLink(diagramWidget, "Link6")
+	link6.SetSourcePad(node6.GetEdgePad())
+	link6.SetTargetPad(node7.GetConnectionPads()["left"])
+
+	link7 := diagramwidget.NewDiagramLink(diagramWidget, "Link7")
+	link7.SetSourcePad(node6.GetEdgePad())
+	link7.SetTargetPad(node7.GetConnectionPads()["right"])
+
+	w.SetContent(diagramWidget)
 
 	w.Resize(fyne.NewSize(600, 400))
 	w.ShowAndRun()

widget/diagramwidget/anchoredtext.go

@@ -19,7 +19,8 @@ import (
 // move by the same amount
 type AnchoredText struct {
 	widget.BaseWidget
-	link                 *BaseDiagramLink
+	diagramElement       DiagramElement
+	ID                   string
 	offset               r2.Vec2
 	referencePosition    fyne.Position
 	displayedTextBinding binding.String
@@ -30,12 +31,15 @@ type AnchoredText struct {
 // NewAnchoredText creates an textual annotation for a link. After it is created, one of the
 // three Add<position>AnchoredText methods must be called on the link to actually associate the
 // anchored text with the appropriate reference point on the link.
-func NewAnchoredText(text string) *AnchoredText {
+func NewAnchoredText(text string, id ...string) *AnchoredText {
 	at := &AnchoredText{
 		offset:            r2.MakeVec2(0, 0),
 		ForegroundColor:   theme.ForegroundColor(),
 		referencePosition: fyne.Position{X: 0, Y: 0},
 	}
+	if len(id) > 0 {
+		at.ID = id[0]
+	}
 	at.displayedTextBinding = binding.NewString()
 	at.displayedTextBinding.Set(text)
 	at.textEntry = widget.NewEntryWithData(at.displayedTextBinding)
@@ -59,16 +63,28 @@ func (at *AnchoredText) CreateRenderer() fyne.WidgetRenderer {
 
 // DataChanged is the callback function for the displayedTextBinding.
 func (at *AnchoredText) DataChanged() {
+	callback := at.diagramElement.GetDiagram().AnchoredTextChangedCallback
+	if callback != nil {
+		callback(at)
+	}
 	at.Refresh()
 }
 
 // Displace moves the anchored text relative to its reference position.
 func (at *AnchoredText) Displace(delta fyne.Position) {
 	at.Move(at.Position().Add(delta))
+	callback := at.diagramElement.GetDiagram().AnchoredTextChangedCallback
+	if callback != nil {
+		callback(at)
+	}
 }
 
 // DragEnd is one of the required methods for a draggable widget. It just refreshes the widget.
 func (at *AnchoredText) DragEnd() {
+	callback := at.diagramElement.GetDiagram().AnchoredTextChangedCallback
+	if callback != nil {
+		callback(at)
+	}
 	at.Refresh()
 }
 
@@ -77,14 +93,33 @@ func (at *AnchoredText) DragEnd() {
 func (at *AnchoredText) Dragged(event *fyne.DragEvent) {
 	delta := fyne.Position{X: event.Dragged.DX, Y: event.Dragged.DY}
 	at.Move(at.Position().Add(delta))
+	callback := at.diagramElement.GetDiagram().AnchoredTextChangedCallback
+	if callback != nil {
+		callback(at)
+	}
 	at.Refresh()
 }
 
+// GetDiagramElement returns the diagram element to which the anchored text belongs
+func (at *AnchoredText) GetDiagramElement() DiagramElement {
+	return at.diagramElement
+}
+
 // GetDisplayedTextBinding returns the binding for the displayed text
 func (at *AnchoredText) GetDisplayedTextBinding() binding.String {
 	return at.displayedTextBinding
 }
 
+// GetOffset returns the X and Y values of the anchored text's offset from the reference position
+func (at *AnchoredText) GetOffset() (X float64, Y float64) {
+	return at.offset.X, at.offset.Y
+}
+
+// GetReferencePosition returns the X and Y values of the anchored text's reference position
+func (at *AnchoredText) GetReferencePosition() (X float64, Y float64) {
+	return float64(at.referencePosition.X), float64(at.referencePosition.Y)
+}
+
 // GetTextEntry returns the entry widget
 func (at *AnchoredText) GetTextEntry() *widget.Entry {
 	return at.textEntry
@@ -114,8 +149,12 @@ func (at *AnchoredText) MouseOut() {
 // and then calls the normal BaseWidget.Move method.
 func (at *AnchoredText) Move(position fyne.Position) {
 	delta := r2.MakeVec2(float64(position.X-at.Position().X), float64(position.Y-at.Position().Y))
-	at.offset = at.offset.Add(delta)
-	at.BaseWidget.Move(position)
+	newOffset := at.offset.Add(delta)
+	at.SetOffsetNoCallback(newOffset.X, newOffset.Y)
+	callback := at.diagramElement.GetDiagram().AnchoredTextChangedCallback
+	if callback != nil {
+		callback(at)
+	}
 }
 
 // SetForegroundColor sets the text color
@@ -124,13 +163,53 @@ func (at *AnchoredText) SetForegroundColor(fc color.Color) {
 	at.Refresh()
 }
 
+// SetOffset sets the X and Y values of the anchored text's offset from the reference position
+func (at *AnchoredText) SetOffset(X float64, Y float64) {
+	if at.offset.X != X || at.offset.Y != Y {
+		at.SetOffsetNoCallback(X, Y)
+		callback := at.diagramElement.GetDiagram().AnchoredTextChangedCallback
+		if callback != nil {
+			callback(at)
+		}
+	}
+}
+
+// SetOffsetNoCallback sets the X and Y values of the anchored text's offset from the reference position
+func (at *AnchoredText) SetOffsetNoCallback(X float64, Y float64) {
+	if at.offset.X != X || at.offset.Y != Y {
+		at.offset.X = X
+		at.offset.Y = Y
+		delta := fyne.Delta{DX: float32(X), DY: float32(Y)}
+		at.BaseWidget.Move(at.referencePosition.Add(delta))
+	}
+}
+
 // SetReferencePosition sets the reference position of the anchored text and calls
 // the BaseWidget.Move() method to actually move the displayed text
 func (at *AnchoredText) SetReferencePosition(position fyne.Position) {
-	delta := fyne.Delta{DX: float32(position.X - at.referencePosition.X), DY: float32(position.Y - at.referencePosition.Y)}
-	// We don't want to change the offset here, so we call the BaseWidget.Move directly
-	at.BaseWidget.Move(at.Position().Add(delta))
-	at.referencePosition = position
+	if position != at.referencePosition {
+		at.SetReferencePositionNoCallback(position)
+		callback := at.diagramElement.GetDiagram().AnchoredTextChangedCallback
+		if callback != nil {
+			callback(at)
+		}
+	}
+}
+
+// SetReferencePositionNoCallback sets the reference position of the anchored text and calls
+// the BaseWidget.Move() method to actually move the displayed text
+func (at *AnchoredText) SetReferencePositionNoCallback(position fyne.Position) {
+	if position != at.referencePosition {
+		delta := fyne.Delta{DX: float32(position.X - at.referencePosition.X), DY: float32(position.Y - at.referencePosition.Y)}
+		// We don't want to change the offset here, so we call the BaseWidget.Move directly
+		at.BaseWidget.Move(at.Position().Add(delta))
+		at.referencePosition = position
+	}
+}
+
+// SetText sets the anchored text without invoking the callback
+func (at *AnchoredText) SetText(text string) {
+	at.displayedTextBinding.Set(text)
 }
 
 // anchoredTextRenderer