再学 GDI+[99]: TGPImage(19) - 把图像转存为其他格式

本例效果图:

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代码文件:

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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;

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;

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.


 
   

窗体文件:

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object Form1: TForm1

  Left = 0

  Top = 0

  Caption = 'Form1'

  ClientHeight = 207

  ClientWidth = 299

  Color = clBtnFace

  Font.Charset = DEFAULT_CHARSET

  Font.Color = clWindowText

  Font.Height = -11

  Font.Name = 'Tahoma'

  Font.Style = []

  OldCreateOrder = False

  Position = poDesktopCenter

  OnCreate = FormCreate

  OnDestroy = FormDestroy

  OnPaint = FormPaint

  PixelsPerInch = 96

  TextHeight = 13

  object Button1: TButton

    Left = 135

    Top = 174

    Width = 75

    Height = 25

    Caption = 'Button1'

    TabOrder = 0

    OnClick = Button1Click

  end

  object Button2: TButton

    Left = 216

    Top = 174

    Width = 75

    Height = 25

    Caption = 'Button2'

    TabOrder = 1

    OnClick = Button2Click

  end

  object OpenDialog1: TOpenDialog

    Left = 152

    Top = 104

  end

end