再学GDI+[28]: TGPPen

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 div 2;
　TrackBar2.Position := n div 2;
　TrackBar3.Position := n div 2;
　TrackBar4.Position := n div 2;
　TrackBar5.Position := n div 2;
　TrackBar6.Position := n div 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.