{
Copyright © 1999 by Delphi 5 Developer's Guide - Xavier Pacheco and Steve Teixeira
}

unit MainFrm;

interface

uses
 SysUtils, Windows, Messages, Classes, Graphics, Controls, Forms, Dialogs,
 StdCtrls, ExtCtrls;

type

 TMainForm = class(TForm)
 imgCopyTo: TImage;
 imgCopyFrom: TImage;
 cbCopyMode: TComboBox;
 btnDrawImages: TButton;
 btnCopy: TButton;
 procedure FormShow(Sender: TObject);
 procedure btnCopyClick(Sender: TObject);
 procedure btnDrawImagesClick(Sender: TObject);
 private
 procedure DrawImages;
 procedure GetCanvasRect(AImage: TImage; var ARect: TRect);
 end;

var
 MainForm: TMainForm;

implementation

{$R *.DFM}

procedure TMainForm.GetCanvasRect(AImage: TImage; var ARect: TRect);
var
 R: TRect;
 R2: TRect;
begin
 R := AImage.Canvas.ClipRect;
 with AImage do
 begin
 ARect.TopLeft := Point(0, 0);
 ARect.BottomRight := Point(Width, Height);
 end;
 R2 := ARect;
 ARect := R2;
end;

procedure TMainForm.DrawImages;
var
 R: TRect;
begin
 // Draw an ellipse in img1
 with imgCopyTo.Canvas do
 begin
 Brush.Style := bsSolid;
 Brush.Color := clWhite;
 GetCanvasRect(imgCopyTo, R);
 FillRect(R);
 Brush.Color := clRed;
 Ellipse(10, 10, 100, 100);
 end;

 // Draw an ellipse in img2
 with imgCopyFrom.Canvas do
 begin
 Brush.Style := bsSolid;
 Brush.Color := clWhite;
 GetCanvasRect(imgCopyFrom, R);
 FillRect(R);
 Brush.Color := clBlue;
 Ellipse(30, 30, 120, 120);
 end;

end;

procedure TMainForm.FormShow(Sender: TObject);
begin
 // Initialize the combobox to the first item
 cbCopyMode.ItemIndex := 0;
 DrawImages;
end;

procedure TMainForm.btnCopyClick(Sender: TObject);
var
 cm: Longint;
 CopyToRect,
 CopyFromRect: TRect;
begin
 // Determine the copy mode based on the combo box selection
 case cbCopyMode.ItemIndex of
 0: cm := cmBlackNess;
 1: cm := cmDstInvert;
 2: cm := cmMergeCopy;
 3: cm := cmMergePaint;
 4: cm := cmNotSrcCopy;
 5: cm := cmNotSrcErase;
 6: cm := cmPatCopy;
 7: cm := cmPatInvert;
 8: cm := cmPatPaint;
 9: cm := cmSrcAnd;
 10: cm := cmSrcCopy;
 11: cm := cmSrcErase;
 12: cm := cmSrcInvert;
 13: cm := cmSrcPaint;
 14: cm := cmWhiteness;
 else
 cm := cmSrcCopy;
 end;

 // Assign the selected copymode to Image1's CopyMode property.
 imgCopyTo.Canvas.CopyMode := cm;

 GetCanvasRect(imgCopyTo, CopyToRect);
 GetCanvasRect(imgCopyFrom, CopyFromRect);

 // Now copy Image2 onto Image1 using Image1's CopyMode setting
 imgCopyTo.Canvas.CopyRect(CopyToRect, imgCopyFrom.Canvas, CopyFromRect);
end;

procedure TMainForm.btnDrawImagesClick(Sender: TObject);
begin
 DrawImages;
end;

end.