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 程式師世界 >> 編程語言 >> 更多編程語言 >> Delphi >> 再學GDI+[86]: TGPImage(6) - 拖動圖像

再學GDI+[86]: TGPImage(6) - 拖動圖像

編輯:Delphi

本例效果圖:

代碼文件:unit Unit1;
interface
uses
 Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
 Dialogs;
type
 TForm1 = class(TForm)
  procedure FormCreate(Sender: TObject);
  procedure FormDestroy(Sender: TObject);
  procedure FormPaint(Sender: TObject);
  procedure FormMouseDown(Sender: TObject; Button: TMouseButton;
   Shift: TShiftState; X, Y: Integer);
  procedure FormMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
  procedure FormMouseUp(Sender: TObject; Button: TMouseButton;
   Shift: TShiftState; X, Y: Integer);
 end;
var
 Form1: TForm1;
implementation
{$R *.dfm}
uses GDIPOBJ, GDIPAPI;
var
 img: TGPImage;
 rt: TRect;
 flag: Boolean;
 x1,y1: Integer;
procedure TForm1.FormCreate(Sender: TObject);
const
 ImgPath = 'c:\temp\test.png';
var
 w,h: Integer;
begin
 if not FileExists(ImgPath) then Exit;
 img := TGPImage.Create(ImgPath);
 w := img.GetWidth;
 h := img.GetHeight;
 rt.Left := (ClientWidth - w) div 2;
 rt.Top := (ClientHeight - h) div 2;
 rt.Right := rt.Left + w;
 rt.Bottom := rt.Top + h;
 DoubleBuffered := True;
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
 img.Free;
end;
procedure TForm1.FormPaint(Sender: TObject);
var
 g: TGPGraphics;
begin
 g := TGPGraphics.Create(Canvas.Handle);
 g.DrawImage(img, MakeRect(rt.Left, rt.Top, img.GetWidth, img.GetHeight));
 g.Free;
end;
procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;
 Shift: TShiftState; X, Y: Integer);
begin
 if PtInRect(rt, Point(X,Y)) then
 begin
  x1 := X;
  y1 := Y;
  flag := True;
 end;
end;
procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X,
 Y: Integer);
begin
 if not flag then Exit;
 OffsetRect(rt, X-x1, Y-y1);
 x1 := X;
 y1 := Y;
 Repaint;
end;
procedure TForm1.FormMouseUp(Sender: TObject; Button: TMouseButton;
 Shift: TShiftState; X, Y: Integer);
begin
 flag := False;
end;
end.

窗體文件:object Form1: TForm1
 Left = 0
 Top = 0
 Caption = 'Form1'
 ClientHeight = 190
 ClientWidth = 317
 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
 OnMouseDown = FormMouseDown
 OnMouseMove = FormMouseMove
 OnMouseUp = FormMouseUp
 OnPaint = FormPaint
 PixelsPerInch = 96
 TextHeight = 13
end

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