// This method initializes an individual ToolStripButton
// control. It copies a subimage from the GridStripRenderer's
// main image, according to the position and size of
// the ToolStripButton.
protected override void InitializeItem(ToolStripItem item)
{
base.InitializeItem(item);
GridStrip gs = item.Owner as GridStrip;
// The empty cell does not receive a subimage.
if ((item is ToolStripButton) &&
(item != gs.EmptyCell))
{
// Copy the subimage from the appropriate
// part of the main image.
Bitmap subImage = bmp.Clone(
item.Bounds,
PixelFormat.Undefined);
// Assign the subimage to the ToolStripButton
// control's Image property.
item.Image = subImage;
}
}
// 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 override void OnRenderButtonBackground(
ToolStripItemRenderEventArgs e)
{
base.OnRenderButtonBackground(e);
// Define some local variables for convenience.
Graphics g = e.Graphics;
GridStrip gs = e.ToolStrip as GridStrip;
ToolStripButton gsb = e.Item as ToolStripButton;
// Calculate the rectangle around which the border is painted.
Rectangle imageRectangle = 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 == gs.EmptyCell)
{
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.
Brush b = gs.IsValidDragSource(gsb) ? b =
Brushes.Red : SystemBrushes.ControlDarkDark;
// Draw the top segment of the border.
Rectangle borderSegment = 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);
}
}
