学步园

http://www.cnblogs.com/del/archive/2008/05/31/1211441.html

相关函数: OffsetViewportOrgEx

本例效果图:

代码文件:

unit<br /> Unit1;<br /> interface<br /> uses<br /> Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls, ComCtrls, ExtCtrls;<br /> type<br /> TForm1 = class(TForm)<br /> Button1: TButton;<br /> procedure FormCreate(Sender: TObject);<br /> procedure FormDestroy(Sender: TObject);<br /> procedure FormPaint(Sender: TObject);<br /> procedure FormMouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);<br /> procedure FormMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);<br /> procedure FormMouseUp(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);</p> <p>end;</p> <p>var<br /> Form1: TForm1;<br /> implementation<br /> {$R *.dfm}<br /> var<br /> cvs: TCanvas;<br /> bit: TBitmap;<br /> f: Boolean;<br /> x1,y1: Integer;</p> <p>procedure TForm1.FormCreate(Sender: TObject);<br /> begin<br /> bit := TBitmap.Create;<br /> bit.LoadFromFile('c:/temp/test.bmp'<br /> );<br /> cvs := TCanvas.Create;<br /> cvs.Handle := GetDC(Handle);<br /> end;<br /> procedure TForm1.FormPaint(Sender: TObject);<br /> const str = 'Delphi';<br /> var x,y: Integer;<br /> begin<br /> {在图片中绘制文本}<br /> bit.Canvas.Font.Size := 24;<br /> bit.Canvas.Font.Style := [fsBold];<br /> bit.Canvas.Font.Color := 0;<br /> bit.Canvas.Brush.Style := bsClear;<br /> x := (bit.Width - bit.Canvas.TextWidth(str)) div 2;<br /> y := (bit.Height - bit.Canvas.TextHeight(str)) div 2 + 32;<br /> bit.Canvas.TextOut(x, y, str);<br /> {在窗体上绘制图片}<br /> x := (ClientWidth - bit.Width) div 2;<br /> y := (ClientHeight - bit.Height) div 2;<br /> cvs.Draw(x, y, bit);<br /> end;<br /> procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);<br /> begin<br /> f := True;<br /> x1 := X;<br /> y1 := Y;<br /> end;<br /> procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);<br /> begin<br /> if f then<br /> begin<br /> OffsetWindowOrgEx(cvs.Handle, -(X-x1), -(Y-y1), nil);<br /> x1 := X;<br /> y1 := Y;<br /> Repaint;<br /> end;<br /> end;<br /> procedure TForm1.FormMouseUp(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);<br /> begin<br /> f := False;<br /> end;<br /> procedure TForm1.FormDestroy(Sender: TObject);<br /> begin<br /> bit.Free;<br /> cvs.Free;<br /> end;<br /> end.<br />

窗体文件:

object
 Form1: TForm1
  Left = 212
  Top = 116
  Caption = 'Form1'
  ClientHeight = 204
  ClientWidth = 262
  Color = clBtnFace
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'Tahoma'
  Font.Style = []
  OldCreateOrder = False
  Position = poDesigned
  OnCreate = FormCreate
  OnDestroy = FormDestroy
  OnMouseDown = FormMouseDown
  OnMouseMove = FormMouseMove
  OnMouseUp = FormMouseUp
  OnPaint = FormPaint
  PixelsPerInch = 96
  TextHeight = 13
  object Button1: TButton
    Left = 96
    Top = 171
    Width = 75
    Height = 25
    Caption = 'Button1'
    TabOrder = 0
  end
end