ET++: A sample application: iconedit

ET++ application implement their actions using a Command class, which, like the standard Command pattern, supports undo, redo, etc. iconedit implements a number of commands to do things like copy, paste, draw rectangles, and move selections. Below is part of the code to the BitMover command, which moves the portion of the icon currently selected, and is a fairly standard example of an ET++ mouse-based command. Basic Do/Undo support is provided in the superclass ImageCommand, which is superclass to most iconedit commands. 

BitMover::BitMover(FatIconView *iv, Rectangle sel, bool cp)
		: ImageCommand(iv, cp ? "Copy Bits" : "Move Bits")
{
	selection= sel;
	copy= cp;
}

void BitMover::TrackFeedback(Point, Point, bool)
{
	GrSetPenSize(2);
	Rectangle r(selection+delta);
	r.Clip(Rectangle(im->Size()));
	GrStrokeRect(iconview->PixelToRect(r));
}

Command *BitMover::TrackMouse(TrackPhase atp, Point ap, Point, Point np)
{
	delta= iconview->PointToPixel(np)-iconview->PointToPixel(ap);
	if (atp == eTrackRelease && delta == gPoint0)
		return gNoChanges;
	return this;
}

[ ... constrain movement to the icon ... ]

void BitMover::BitDoIt()
{
	iconview->SetSelection(selection+delta);
	if (!copy)
		im->FillRect(selection, bgpixel);
	im->CopyPixel(selection+delta, savebm, selection.origin);
}

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