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