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

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.

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本例效果图:

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代码文件:

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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.


 
   

窗体文件:

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object Form1: TForm1

  Left = 0

  Top = 0

  Caption = 'Form1'

  ClientHeight = 153

  ClientWidth = 306

  Color = clBtnFace

  Font.Charset = DEFAULT_CHARSET

  Font.Color = clWindowText

  Font.Height = -11

  Font.Name = 'Tahoma'

  Font.Style = []

  OldCreateOrder = False

  Position = poDesktopCenter

  OnCreate = FormCreate

  OnPaint = FormPaint

  PixelsPerInch = 96

  TextHeight = 13

  object Panel1: TPanel

    Left = 207

    Top = 0

    Width = 99

    Height = 153

    Align = alRight

    TabOrder = 0

    ExplicitLeft = 200

    ExplicitHeight = 205

    object TrackBar1: TTrackBar

      Left = 0

      Top = 8

      Width = 97

      Height = 20

      ShowSelRange = False

      TabOrder = 0

      OnChange = TrackBar1Change

    end

    object TrackBar2: TTrackBar

      Left = 0

      Top = 31

      Width = 97

      Height = 20

      ShowSelRange = False

      TabOrder = 1

      OnChange = TrackBar2Change

    end

    object TrackBar3: TTrackBar

      Left = 0

      Top = 55

      Width = 97

      Height = 20

      ShowSelRange = False

      TabOrder = 2

      OnChange = TrackBar3Change

    end

    object TrackBar4: TTrackBar

      Left = 0

      Top = 79

      Width = 97

      Height = 20

      ShowSelRange = False

      TabOrder = 3

      OnChange = TrackBar4Change

    end

    object TrackBar5: TTrackBar

      Left = 0

      Top = 103

      Width = 97

      Height = 20

      ShowSelRange = False

      TabOrder = 4

      OnChange = TrackBar5Change

    end

    object TrackBar6: TTrackBar

      Left = 0

      Top = 127

      Width = 97

      Height = 20

      ShowSelRange = False

      TabOrder = 5

      OnChange = TrackBar6Change

    end

  end

end