再学 GDI+[26]: TGPPen - 画笔对齐 - SetAlignment
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)
    RadioGroup1: TRadioGroup;
    procedure FormPaint(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure RadioGroup1Click(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

uses GDIPOBJ, GDIPAPI;

procedure TForm1.FormCreate(Sender: TObject);
begin
  with RadioGroup1 do
  begin
    Align := alBottom;
    Items.Add('PenAlignmentCenter');
    Items.Add('PenAlignmentInset');
    Columns := 2;
    ItemIndex := 0;
  end;
end;

procedure TForm1.FormPaint(Sender: TObject);
var
  g: TGPGraphics;
  p: TGPPen;
  rect: TRect;
begin
  g := TGPGraphics.Create(Canvas.Handle);
  g.Clear($FFFFFFFF);
  p := TGPPen.Create($FFEE82EE, 20);

  rect := ClientRect;
  InflateRect(rect, -50, -50);
  OffsetRect(rect, 0, -20);

  p.SetAlignment(TPenAlignment(RadioGroup1.ItemIndex));
  g.DrawRectangle(p, MakeRect(rect));

  p.SetColor($FF000000);
  p.SetWidth(1.5);
  g.DrawRectangle(p, MakeRect(rect));

  p.Free;
  g.Free;
end;


procedure TForm1.RadioGroup1Click(Sender: TObject);
begin
  Repaint;
end;

end.
窗体文件:
object Form1: TForm1
  Left = 0
  Top = 0
  Caption = 'Form1'
  ClientHeight = 198
  ClientWidth = 277
  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 RadioGroup1: TRadioGroup
    Left = 8
    Top = 152
    Width = 185
    Height = 38
    Caption = 'RadioGroup1'
    TabOrder = 0
    OnClick = RadioGroup1Click
  end
end
画笔对齐方式:

Delphi 微软 说明
PenAlignmentCenter  Center  指定 Pen 对象以理论的线条为中心。
PenAlignmentInset Inset 指定 Pen 被定位于理论的线条内。
无定义 Left 指定将 Pen 定位于理论的线条的左侧。
无定义 Outset 指定将 Pen 定位于理论的线条外。
无定义 Right 指定将 Pen 定位于理论的线条的右侧。