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再学GDI+[28]: TGPPen - 自定义画笔的虚线样式 - SetDashPattern

时间:2012-05-05 | 栏目:Delphi教程 | 点击:

自定义的虚线样式依赖与一个数组, 数组的元素分别代表虚线中线与间的长度, 数组大小好 像没有限制;

本例使用了六个元素的数组, 也就是表示虚线有三个线段和和三个间隔构成.

本例效果图:

代码文件:unit Unit1;
interface
uses
 Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
 Dialogs, StdCtrls, ExtCtrls, ComCtrls;
type
 TForm1 = class(TForm)
  Panel1: TPanel;
  TrackBar1: TTrackBar;
  TrackBar2: TTrackBar;
  TrackBar3: TTrackBar;
  TrackBar4: TTrackBar;
  TrackBar5: TTrackBar;
  TrackBar6: TTrackBar;
  procedure FormCreate(Sender: TObject);
  procedure FormPaint(Sender: TObject);
  procedure TrackBar1Change(Sender: TObject);
  procedure TrackBar2Change(Sender: TObject);
  procedure TrackBar3Change(Sender: TObject);
  procedure TrackBar4Change(Sender: TObject);
  procedure TrackBar5Change(Sender: TObject);
  procedure TrackBar6Change(Sender: TObject);
 end;
var
 Form1: TForm1;
implementation
{$R *.dfm}
uses GDIPOBJ, GDIPAPI;
var
 DashArr: array[0..5] of Single;
procedure TForm1.FormCreate(Sender: TObject);
const
 n = 100;
begin
 TrackBar1.Max := n;
 TrackBar2.Max := n;
 TrackBar3.Max := n;
 TrackBar4.Max := n;
 TrackBar5.Max := n;
 TrackBar6.Max := n;
 TrackBar1.Position := n p 2;
 TrackBar2.Position := n p 2;
 TrackBar3.Position := n p 2;
 TrackBar4.Position := n p 2;
 TrackBar5.Position := n p 2;
 TrackBar6.Position := n p 2;
end;
procedure TForm1.FormPaint(Sender: TObject);
var
 g: TGPGraphics;
 p: TGPPen;
 rect: TRect;
begin
 g := TGPGraphics.Create(Canvas.Handle);
 p := TGPPen.Create(aclRed, 4);
 DashArr[0] := TrackBar1.Position / 10;
 DashArr[1] := TrackBar2.Position / 10;
 DashArr[2] := TrackBar3.Position / 10;
 DashArr[3] := TrackBar4.Position / 10;
 DashArr[4] := TrackBar5.Position / 10;
 DashArr[5] := TrackBar6.Position / 10;
 p.SetDashPattern(@DashArr, Length(DashArr)); {设置虚线}
 g.DrawLine(p, 0, 0, ClientWidth - Panel1.Width, ClientHeight);
 rect := Bounds(0, 0, ClientWidth - Panel1.Width, ClientHeight);
 InflateRect(rect, -30, -30);
 g.DrawEllipse(p, MakeRect(rect));
 p.Free;
 g.Free;
end;
procedure TForm1.TrackBar1Change(Sender: TObject);
begin
 Repaint;
end;
procedure TForm1.TrackBar2Change(Sender: TObject);
begin
 Repaint;
end;
procedure TForm1.TrackBar3Change(Sender: TObject);
begin
 Repaint;
end;
procedure TForm1.TrackBar4Change(Sender: TObject);
begin
 Repaint;
end;
procedure TForm1.TrackBar5Change(Sender: TObject);
begin
 Repaint;
end;
procedure TForm1.TrackBar6Change(Sender: TObject);
begin
 Repaint;
end;
end.

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