Rectangle Panel Graphic relationship - vb.net

Question

The following code does not work:
Private Sub panelButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles panelButton.Click
Dim myBrush As Brush
myBrush = New SolidBrush(Color.Yellow)
fBitmap = New Bitmap(picturePanel.Width, picturePanel.Height)
Dim gg As Graphics = Graphics.FromImage(fBitmap)
gg.Clear(Color.White)
'<<<<<my attempt<<<<<<
Dim rec As Rectangle
rec = New Rectangle(picturePanel.Location.X, picturePanel.Location.Y, picturePanel.Width, picturePanel.Height)
gg.FillRectangle(myBrush, rec)
'<<<<<<<<<<<<<<<<<<<<<
'gg.FillRectangle(myBrush, gg.ClipBounds) '<<actual answer
gg.Dispose()
picturePanel.Refresh()
End Sub
In the Panel's repaint handler I've got this:
Private Sub picturePanel_Paint(sender As System.Object, e As System.Windows.Forms.PaintEventArgs) Handles picturePanel.Paint
If fBitmap IsNot Nothing Then
e.Graphics.DrawImage(fBitmap, 0, 0)
End If
End Sub
I've included the recommended code (marked as actual answer) but why doesn't the section marked my attempt turn the panel yellow? - can it be tweaked so that it turns the panel yellow?

Answer 1

rec = New Rectangle(picturePanel.Location.X, picturePanel.Location.Y, _
picturePanel.Width, picturePanel.Height)
That's the wrong rectangle. It is relative from the panel's Parent instead of the panel itself. At best you'll see the rectangle at the far right-bottom corner. Or not at all if it is off the bitmap. Draw relative to the bitmap's upper left corner instead. Fix:
rec = New Rectangle(0, 0, fBitmap.Width, fBitmap.Height)
Do note that you'll no longer see any white since you completely overdrew that. It isn't clear what you meant to do. Perhaps more illustrative is to give it a yellow border:
rec = New Rectangle(0, 0, fBitmap.Width-1, fBitmap.Height-1)
gg.DrawRectangle(Pens.Yellow, rec)
Do favor the Using statement instead of the explicit Dispose() call. Also use it on the brush, it should be disposed as well.