WinAPI: SetWindowOrgEx - 设置窗口坐标原点-优快云博客

本文介绍了一个使用 Delphi 实现的视口坐标调整示例。通过滚动条改变窗口坐标原点，实现在有限的窗口内平移展示大型图像，并在图像上绘制文字。此示例涉及 GetWindowOrgEx 和 SetWindowOrgEx 函数的应用。

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http://www.cnblogs.com/del/archive/2008/05/31/1211431.html

相关函数: GetWindowOrgEx、SetViewportOrgEx(设置视口坐标原点)、SetViewportOrgEx

本例效果图:

代码文件:

unit Unit1; interface uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,Dialogs, StdCtrls, ComCtrls, ExtCtrls; type TForm1 = class (TForm) ScrollBar1: TScrollBar; ScrollBar2: TScrollBar; procedure FormCreate(Sender: TObject); procedure FormShow(Sender: TObject); procedure FormDestroy(Sender: TObject); procedure FormPaint(Sender: TObject); procedure ScrollBar1Change(Sender: TObject); procedure ScrollBar2Change(Sender: TObject); end; var Form1: TForm1; implementation {$R *.dfm} var cvs: TCanvas; bit: TBitmap; procedure TForm1.FormCreate(Sender: TObject); begin bit := TBitmap.Create; bit.LoadFromFile('c:/temp/test.bmp'); cvs := TCanvas.Create; cvs.Handle := GetDC(Handle); ScrollBar1.Align := alBottom; ScrollBar1.Max := ClientWidth - bit.Width; ScrollBar1.LargeChange := 16; ScrollBar2.Kind := sbVertical; ScrollBar2.Align := alRight; ScrollBar2.Max := ClientHeight - bit.Height; ScrollBar2.LargeChange := 16; end; procedure TForm1.FormShow(Sender: TObject); begin ScrollBar1.Position := ScrollBar1.Max div 2; ScrollBar2.Position := ScrollBar2.Max div 2; end; procedure TForm1.FormPaint(Sender: TObject); const str = 'Delphi'; var x,y: Integer; begin {在图片中绘制文本} bit.Canvas.Font.Size := 24; bit.Canvas.Font.Style := [fsBold]; bit.Canvas.Font.Color := clWhite; bit.Canvas.Brush.Style := bsClear; x := (bit.Width - bit.Canvas.TextWidth(str)) div 2; y := (bit.Height - bit.Canvas.TextHeight(str)) div 2 + 32; bit.Canvas.TextOut(x, y, str); {在窗体上绘制图片} x := ClientWidth - bit.Width; y := ClientHeight - bit.Height; cvs.Draw(x, y, bit); end; procedure TForm1.ScrollBar1Change(Sender: TObject); begin {关键代码: 调整窗口坐标原点} SetWindowOrgEx(cvs.Handle, ScrollBar1.Position, ScrollBar2.Position, nil); Repaint; end; procedure TForm1.ScrollBar2Change(Sender: TObject); begin ScrollBar1Change(Sender); end; procedure TForm1.FormDestroy(Sender: TObject); begin bit.Free; cvs.Free; end; end.

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 OnPaint = FormPaint OnShow = FormShow PixelsPerInch = 96 TextHeight = 13 object ScrollBar1: TScrollBar Left = 80 Top = 80 Width = 121 Height = 17 PageSize = 0 TabOrder = 0 OnChange = ScrollBar1Change end object ScrollBar2: TScrollBar Left = 80 Top = 120 Width = 121 Height = 17 PageSize = 0 TabOrder = 1 OnChange = ScrollBar2Change end end