' This method draws a border around the button's image. If the background
' to be rendered belongs to the empty cell, a string is drawn. Otherwise,
' a border is drawn at the edges of the button.
Protected Overrides Sub OnRenderButtonBackground(e As ToolStripItemRenderEventArgs)
MyBase.OnRenderButtonBackground(e)
' Define some local variables for convenience.
Dim g As Graphics = e.Graphics
Dim gs As GridStrip = e.ToolStrip
Dim gsb As ToolStripButton = e.Item
' Calculate the rectangle around which the border is painted.
Dim imageRectangle As New Rectangle(borderThickness, borderThickness, e.Item.Width - 2 * borderThickness, e.Item.Height - 2 * borderThickness)
' If rendering the empty cell background, draw an
' explanatory string, centered in the ToolStripButton.
If gsb Is gs.EmptyCell Then
e.Graphics.DrawString("Drag to here", gsb.Font, SystemBrushes.ControlDarkDark, imageRectangle, style)
Else
' If the button can be a drag source, paint its border red.
' otherwise, paint its border a dark color.
Dim b As Brush = IIf(gs.IsValidDragSource(gsb), Brushes.Red, SystemBrushes.ControlDarkDark)
' Draw the top segment of the border.
Dim borderSegment As New Rectangle(0, 0, e.Item.Width, imageRectangle.Top)
g.FillRectangle(b, borderSegment)
' Draw the right segment.
borderSegment = New Rectangle(imageRectangle.Right, 0, e.Item.Bounds.Right - imageRectangle.Right, imageRectangle.Bottom)
g.FillRectangle(b, borderSegment)
' Draw the left segment.
borderSegment = New Rectangle(0, 0, imageRectangle.Left, e.Item.Height)
g.FillRectangle(b, borderSegment)
' Draw the bottom segment.
borderSegment = New Rectangle(0, imageRectangle.Bottom, e.Item.Width, e.Item.Bounds.Bottom - imageRectangle.Bottom)
g.FillRectangle(b, borderSegment)
End If
End Sub
End Class
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