Mouse down issue with transparency

Hi, I have a simple WPF drawing tools program (Line, box, ellipse, erase). My problem is that when I add transparency to the window thats being drawn on, it starts to have issues recognizing the mouse down event. With the drawing tools i've made, you don't click-drag-release to draw, you just click-drag-click. It's only the second mousedown having this issue. Any advice?

If a control is transparent, it won't catch Mouse Down events (because the user actually mouse downed on what he/she can see, which is the layer beneath).

Instead of transparent, give it a very faint opacity - either set the opacity to 1 instead of 0, or use an Alpha channel value of 1 rather than 0, depending on how you've put transparency in in the first place.

I've done this, and it worked well. Now my problem is that when I'm drawing a line or a rectangle, the click is hitting the line instead of the form underneath, and is not finishing the draw.

This is my current code for a box tool. For some reason the offset is staying drawn until I start to draw a new box.

Code:

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Private Sub Window_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Input.MouseEventArgs) Handles Me.MouseMove
        Dim tX, tY As Integer
        tX = e.GetPosition(Me).X
        tY = e.GetPosition(Me).Y
        If clickCount = 1 Then
            x2 = tX - 1
            y2 = tY - 1
        End If
        If clickCount = 1 Then

            Select Case CurrentTool
 Case "Box"
                    Dim BoxCanvas As New Canvas

                    Static LastBox As Rectangle
                    Static LastCanvas As Canvas
                    Dim myBox As New Rectangle
                    myBox.Stroke = Brushes.Red
                    BoxCanvas.Children.Remove(LastBox)
                    DrawCanvas.Children.Remove(LastCanvas)

                    Dim myWidth As Integer
                    Dim myHeight As Integer
                    If x2 < x1 Then
                        myWidth = x1 - (x2 - 2)
                        Canvas.SetLeft(BoxCanvas, x2 - 2)
                    Else
                        Canvas.SetLeft(BoxCanvas, x1)
                        myWidth = x2 - x1
                    End If
                    If y2 < y1 Then
                        Canvas.SetTop(BoxCanvas, y2 - 3)
                        myHeight = y1 - (y2 - 3)
                    Else
                        Canvas.SetTop(BoxCanvas, y1)
                        myHeight = y2 - y1
                    End If
                    myBox.Width = myWidth
                    myBox.Height = myHeight
                    myBox.HorizontalAlignment = Windows.HorizontalAlignment.Left
                    myBox.VerticalAlignment = Windows.VerticalAlignment.Top
                    myBox.StrokeThickness = 2
                    LastBox = New Rectangle
                    LastBox = myBox
                    LastCanvas = New Canvas
                    LastCanvas = BoxCanvas
                    BoxCanvas.Children.Add(myBox)
                    DrawCanvas.Children.Add(BoxCanvas)

---

That is the drawing the user sees while they are still making the box. The following code is what actually commits the drawing and leaves it there.

Code:

---

Private Sub CommitBox()
        Dim BoxCanvas As New Canvas

        Static LastBox As Rectangle
        Static LastCanvas As Canvas
        Dim myBox As New Rectangle
        myBox.Stroke = Brushes.Red
        BoxCanvas.Children.Remove(LastBox)
        DrawCanvas.Children.Remove(LastCanvas)

        Dim myWidth As Integer
        Dim myHeight As Integer
        If x2 < x1 Then
            myWidth = x1 - (x2 - 2)
            Canvas.SetLeft(BoxCanvas, x2 - 2)
        Else
            Canvas.SetLeft(BoxCanvas, x1)
            myWidth = x2 - x1
        End If
        If y2 < y1 Then
            Canvas.SetTop(BoxCanvas, y2 - 3)
            myHeight = y1 - (y2 - 3)
        Else
            Canvas.SetTop(BoxCanvas, y1)
            myHeight = y2 - y1
        End If
        myBox.Width = myWidth
        myBox.Height = myHeight
        myBox.HorizontalAlignment = Windows.HorizontalAlignment.Left
        myBox.VerticalAlignment = Windows.VerticalAlignment.Top
        myBox.StrokeThickness = 2
        BoxCanvas.Children.Add(myBox)
        DrawCanvas.Children.Add(BoxCanvas)
    End Sub

---

Any suggestions? Kind of lost here.