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}

procedure TForm1.Button1Click(Sender: TObject);
var
  WicImg: TWICImage;
begin
  WicImg := TWICImage.Create;
  WicImg.LoadFromFile('c:\temp\test.jpg');

  {在窗体上预览图片}
  Canvas.Draw(0, 0, WicImg);

  {转换为 png}
  WicImg.ImageFormat := TWICImageFormat.wifPng;
  WicImg.SaveToFile('c:\temp\test.png');

  WicImg.Free;
end;

end.