Delphi下的GDI+编程[6] 绘制矩形-DrawRectangle

本例效果图：

//在GDI+中，绘制矩形是通过TGPGraphics类的DrawRectangle方法实现的

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    procedure FormPaint(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

uses GDIPOBJ, GDIPAPI;

procedure TForm1.FormPaint(Sender: TObject);
const
  w = 100;
  h = 50;
var
  g: TGPGraphics;
  p: TGPPen;
  x,y: Single;  //32位单精度浮点型变量
begin
  g := TGPGraphics.Create(Canvas.Handle);
  p := TGPPen.Create(0, 2);
  g.Clear(MakeColor(255,255,255));

  x := 20;
  y := 20;
  p.SetColor(aclRed);  //设置画笔颜色为红色
  g.DrawRectangle(p, x, y, w, h); //画一个矩形
  p.SetColor(aclGold); //设置画笔颜色为黄色
  x := x + w / 2;   {70}
  y := y + h /2;   {45}
  g.DrawRectangle(p, MakeRect(x, y, w, h)); //画另一个矩形

  g.Free;
  p.Free;
end;
end.