本例效果图:
![](https://www.cnblogs.com/images/cnblogs_com/del/142973/o_8724.gif)
代码文件:
![](https://www.cnblogs.com/images/cnblogs_com/del/142973/o_8724.gif)
代码文件:
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.窗体文件:
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