Autoscrolling panel problem

MarkDuncan_74 · May 25, 2005

Hi,

I'm trying to create an image editor similar to paint to include in an app. I've got a scrollable panel with a picturebox on it. Around the picturebox are 8 5x5 labels to act as grabpoints for resizing (i'm sure there is a correct technical name for them but I'm sure you know what I mean). So far, so peachy, if you drag a grabpoint it will resize the image but things are going a bit funny when the image is scrolled. I'll try to describe whats happening.

1. Use the Down grabpoint to extend the image off the screen

2. Scroll down to the bottom of the image

3. Grab the Down grabpoint and move it up 1 pixel at a time to reduce the height of the image

At this point after I have moved the mouse up about 10 pixels it starts auto-scrolling up the screen. I haven't set the autoscroll margin, so its set to zero so I wouldn't expect it to autoscroll until the mouse reached the top of the display.

I've included the project although its a dll

Here's the code

Private _mouseDown As Boolean

Private _rs As String

Private Sub Label1_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) _

Handles resizeR.MouseDown, resizeD.MouseDown, resizeDR.MouseDown

_mouseDown = True

_rs = CType(sender, Windows.Forms.Label).Name

End Sub

Private Sub Label1_MouseUp(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) _

Handles resizeR.MouseUp, resizeD.MouseUp, resizeDR.MouseUp

_mouseDown = False

_rs = ""

End Sub

Private Sub resizeboxMove(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) _

Handles resizeD.MouseMove, resizeR.MouseMove, resizeDR.MouseMove

If _mouseDown Then

Select Case _rs

Case "resizeD"

PictureBox1.Height = Panel1.PointToClient(Panel1.MousePosition).Y - Panel1.AutoScrollPosition.Y

Case "resizeR"

PictureBox1.Width = Panel1.PointToClient(Panel1.MousePosition).X - Panel1.AutoScrollPosition.X

Case "resizeDR"

PictureBox1.Width = Panel1.PointToClient(Panel1.MousePosition).X - Panel1.AutoScrollPosition.X

PictureBox1.Height = Panel1.PointToClient(Panel1.MousePosition).Y - Panel1.AutoScrollPosition.Y

End Select

redrawGrabPoints()

End If

End Sub

Private Sub redrawGrabPoints()

Dim offset As Integer = 5

Dim tempPoint As System.Drawing.Point

tempPoint = New System.Drawing.Point(PictureBox1.Width + offset, 1)

tempPoint.Offset(Panel1.AutoScrollPosition.X, Panel1.AutoScrollPosition.Y)

resizeUR.Location = tempPoint

tempPoint = New System.Drawing.Point(1, PictureBox1.Height + offset)