unit1.pas

《Delphi7编程100例》代码,书配资料

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls,Jpeg, ComCtrls, ExtCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Edit1: TEdit;
    OpenDialog1: TOpenDialog;
    SaveDialog1: TSaveDialog;
    Button2: TButton;
    Edit2: TEdit;
    Button3: TButton;
    Label1: TLabel;
    Image1: TImage;
    TrackBar1: TTrackBar;
    Label2: TLabel;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
    procedure TrackBar1Change(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
begin
  with OpenDialog1 do
    if Execute then
    begin
      Edit1.Text := Filename;//打开BMP图象文件
    end;
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
  with saveDialog1 do
    if Execute then
    begin
      Edit2.Text := filename;//确定输出文件
    end;
end;

procedure TForm1.Button3Click(Sender: TObject);
var myjpeg:TJpegimage;
    mybmp:tbitmap;
begin
  Image1.Picture.Assign(Nil);//清空显示
    mybmp:=tbitmap.create;//建立TBitmap
    with mybmp do
    try
      loadfromfile(openDialog1.filename);//加载图象
      myjpeg:=tjpegimage.Create;//建立TJpeg
      with myjpeg do
        begin
           assign(mybmp);//加载图象
           compressionquality:=TrackBar1.Position;//压缩比例
           compress; //压缩动作
           savetofile(SaveDialog1.Filename);//保存
           free;//释放myjpeg
        end;
     finally
     free;//释放mybmp
     end;
  Image1.Picture.LoadFromFile(SaveDialog1.Filename);
  //显示转换效果
end;

procedure TForm1.TrackBar1Change(Sender: TObject);
begin
  //显示压缩比
  Label2.Caption:=IntToStr(TrackBar1.Position);
end;

end.