再学 GDI+[103]: TGPImage(23) - 提取 GIF 动画的每一帧

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.


 
   

窗体文件:

---

object Form1: TForm1

  Left = 0

  Top = 0

  Caption = 'Form1'

  ClientHeight = 206

  ClientWidth = 339

  Color = clBtnFace

  Font.Charset = DEFAULT_CHARSET

  Font.Color = clWindowText

  Font.Height = -11

  Font.Name = 'Tahoma'

  Font.Style = []

  OldCreateOrder = False

  OnCreate = FormCreate

  OnDestroy = FormDestroy

  OnPaint = FormPaint

  PixelsPerInch = 96

  TextHeight = 13

  object ListBox1: TListBox

    Left = 0

    Top = 0

    Width = 89

    Height = 206

    Align = alLeft

    ItemHeight = 13

    TabOrder = 0

    OnClick = ListBox1Click

  end

  object Button1: TButton

    Left = 256

    Top = 173

    Width = 75

    Height = 25

    Caption = 'Button1'

    TabOrder = 1

    OnClick = Button1Click

  end

  object OpenDialog1: TOpenDialog

    Left = 160

    Top = 104

  end

end