unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

uses Wincodec;

procedure TForm1.Button1Click(Sender: TObject);
var
  WicImg: TWICImage;
  Factory: IWICImagingFactory;
  Clipper: IWICBitmapClipper; {修剪图像的接口}
  r: WICRect;
begin
  WicImg := TWICImage.Create;
  WicImg.LoadFromFile('c:\temp\test.jpg');

  Factory := WicImg.ImagingFactory;
  Factory.CreateBitmapClipper(Clipper);

  r.X := WicImg.Width div 4;
  r.Y := WicImg.Height div 4;
  r.Width := WicImg.Width div 2;
  r.Height := WicImg.Height div 2;
  Clipper.Initialize(WicImg.Handle, r);

  WicImg.Handle := IWICBitmap(Clipper);
  Canvas.Draw(0, 0, WicImg);

  Clipper := nil;
  Factory := nil;
  WicImg.Free;
end;

end.