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
