再学 GDI+[27]: TGPPen 画笔样式 SetDashStyle

本例效果图:

---

代码文件:

---

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ExtCtrls;

type
  TForm1 = class(TForm)
    ComboBox1: TComboBox;
    procedure FormCreate(Sender: TObject);
    procedure FormPaint(Sender: TObject);
    procedure ComboBox1Change(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

uses GDIPOBJ, GDIPAPI, TypInfo;

procedure TForm1.FormCreate(Sender: TObject);
var
  i: Integer;
begin
  for i := 0 to 5 do
    ComboBox1.Items.Add(GetEnumName(TypeInfo(TDashStyle), i));
  ComboBox1.ItemIndex := 0;
end;

procedure TForm1.FormPaint(Sender: TObject);
var
  g: TGPGraphics;
  p: TGPPen;
begin
  g := TGPGraphics.Create(Canvas.Handle);
  g.Clear($FFFFFFFF);
  p := TGPPen.Create(aclLimeGreen, 10);

  p.SetDashStyle(TDashStyle(ComboBox1.ItemIndex));
  g.DrawLine(p, 0, 0, ClientWidth, ClientHeight);

  p.Free;
  g.Free;
end;

procedure TForm1.ComboBox1Change(Sender: TObject);
begin
  Repaint;
end;

end.

窗体文件:

---

object Form1: TForm1
  Left = 0
  Top = 0
  Caption = 'Form1'
  ClientHeight = 167
  ClientWidth = 242
  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 ComboBox1: TComboBox
    Left = 89
    Top = 8
    Width = 145
    Height = 21
    ItemHeight = 13
    TabOrder = 0
    Text = 'ComboBox1'
    OnChange = ComboBox1Change
  end
end

画笔样式枚举的定义:

---

DashStyle = (
  DashStyleSolid,      {指定实线}
  DashStyleDash,       {指定由划线段组成的直线}
  DashStyleDot,        {指定由点构成的直线}
  DashStyleDashDot,    {指定由重复的划线点图案构成的直线}
  DashStyleDashDotDot, {指定由重复的划线点点图案构成的直线}
  DashStyleCustom      {指定用户定义的自定义划线段样式}
);
TDashStyle = DashStyle;