再学GDI+[103]: TGPImage(23)

本例效果图:

代码文件:unit Unit1;
interface
uses
　Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
　Dialogs, StdCtrls;
type
　TForm1 = class(TForm)
　　Button1: TButton;
　　ListBox1: TListBox;
　　OpenDialog1: TOpenDialog;
　　procedure FormCreate(Sender: TObject);
　　procedure FormDestroy(Sender: TObject);
　　procedure Button1Click(Sender: TObject);
　　procedure FormPaint(Sender: TObject);
　　procedure ListBox1Click(Sender: TObject);
　end;
var
　Form1: TForm1;
implementation
{$R *.dfm}
uses GDIPOBJ, GDIPAPI;
var
　img: TGPImage;
　GifFrame, GifFrameCount: Word;
procedure TForm1.FormCreate(Sender: TObject);
begin
　OpenDialog1.Filter := 'GIF 文件|*.gif';
　img := TGPImage.Create;
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
　img.Free;
end;
procedure TForm1.Button1Click(Sender: TObject);
var
　DimensionsCount: Integer;
　DimensionsIDs: PGUID;
　i: Integer;
type
　ArrDimensions = array of TGUID;
begin
　if not OpenDialog1.Execute then Exit;
　img.Free;
　img := TGPImage.Create(OpenDialog1.FileName);
　{获取 Gif 总帧数}
　DimensionsCount := img.GetFrameDimensionsCount;
　GetMem(DimensionsIDs, DimensionsCount * SizeOf(TGUID));
　img.GetFrameDimensionsList(DimensionsIDs, DimensionsCount);
　GifFrameCount := img.GetFrameCount(ArrDimensions(DimensionsIDs)[0]);
　FreeMem(DimensionsIDs);
　Text := Format('共有 %d 帧', [GifFrameCount]);
　{显示帧列表}
　ListBox1.Clear;
　for i := 1 to GifFrameCount do
　　ListBox1.Items.Add(Format('第 %d 帧', [i]));
　Repaint;
end;
procedure TForm1.FormPaint(Sender: TObject);
var
　g: TGPGraphics;
begin
　g := TGPGraphics.Create(Canvas.Handle);
　g.DrawImage(img, ListBox1.Width + 10, 10, img.GetWidth, img.GetHeight);
　g.Free;
end;
procedure TForm1.ListBox1Click(Sender: TObject);
begin
　GifFrame := ListBox1.ItemIndex;
　img.SelectActiveFrame(FrameDimensionTime, GifFrame);
　Repaint;
end;
end.