Mouse down issue with transparency

[Nmitton239]

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?

[Evil_Giraffe]

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.

[Nmitton239]

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.

[Nmitton239]

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.

 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.

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.