delphi TGPImage 把图像转存为其他格式

代码文件:

unit Unit1;

interface

uses

Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

Dialogs, StdCtrls, ExtCtrls;

type

TForm1 = class(TForm)

OpenDialog1: TOpenDialog;

Button1: TButton;

Button2: TButton;

procedure FormCreate(Sender: TObject);

procedure FormDestroy(Sender: TObject);

procedure FormPaint(Sender: TObject);

procedure Button1Click(Sender: TObject);

procedure Button2Click(Sender: TObject);

end;

var

Form1: TForm1;

implementation

{$R *.dfm}

uses GDIPOBJ, GDIPAPI, GDIPUTIL;

const

OpenFileFilter =

'GDI+ 全部可以读取的图片格式|*.png;*.jpg;*.gif;*.bmp;*.tif;*.emf;*.wmf;*.ico' +

'|*.png|*.png' +

'|*.jpg|*.jpg' +

'|*.gif|*.gif' +

'|*.bmp|*.bmp' +

'|*.tif|*.tif' +

'|*.emf|*.emf' +

'|*.wmf|*.wmf' +

'|*.ico|*.ico';

ArrExt: array[0..4] of String = ('.png', '.jpg', '.gif', '.bmp', '.tif');

ArrEncodeName: array[0..4] of String =

('image/png', 'image/jpeg', 'image/gif', 'image/bmp', 'image/tiff');

var

FileName: string;

img: TGPImage;

procedure TForm1.FormCreate(Sender: TObject);

begin

img := TGPImage.Create;

Button1.Caption := '打开';

Button2.Caption := '保存';

end;

procedure TForm1.FormDestroy(Sender: TObject);

begin

img.Free;

end;

procedure TForm1.FormPaint(Sender: TObject);

var

g: TGPGraphics;

begin

if FileName <> '' then

begin

g := TGPGraphics.Create(Canvas.Handle);

g.DrawImage(img, 10, 10, img.GetWidth, img.GetHeight);

g.Free;

end;

procedure TForm1.Button1Click(Sender: TObject);

begin

OpenDialog1.Filter := OpenFileFilter;

if OpenDialog1.Execute then

begin

FileName := OpenDialog1.FileName;

img.Free;

img := TGPImage.Create(FileName);

Repaint;

end;

procedure TForm1.Button2Click(Sender: TObject);

var

ImgGUID: TGUID;

i: Integer;

begin

if FileName = '' then

begin

ShowMessage('先要打开文件');

Exit;

end;

{一次性保存为 5 种可能的格式}

for i := 0 to 4 do

begin

GetEncoderClsid(ArrEncodeName[i], ImgGUID); {先获取格式编码}

img.Save(ChangeFileExt(FileName, ArrExt[i]), ImgGUID);

end;

Beep;

end;

end.

来源：https://www.cnblogs.com/del/archive/2008/07/07/1237697.html

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