再学 GDI+[76]: 区域(5) GetDataSize、GetData

本来这个例子是要获取区域的详细信息的, 但非常遗憾, 这个版本的 GDI+ 的头文件少定义了一个 TRegionData 类!
不过也不要紧, 通过 TRegionData 主要也是获取区域中的矩形数据, GetRegionScans 函数可以完成这个任务!

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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;

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

var
  Form1: TForm1;

implementation

{$R *.dfm}

uses GDIPOBJ, GDIPAPI;

procedure TForm1.FormPaint(Sender: TObject);
var
  g: TGPGraphics;
  p: TGPPen;
  b: TGPSolidBrush;
  path: TGPGraphicsPath;
  rgn1,rgn2: TGPRegion;
  RgnData: PByte;
  rt: TGPRect;
begin
  g := TGPGraphics.Create(Canvas.Handle);
  p := TGPPen.Create(aclRed);
  b := TGPSolidBrush.Create(MakeColor(50, 0, 0, 255));

  {建立并填充第一个区域}
  path := TGPGraphicsPath.Create;
  path.AddEllipse(MakeRect(20, 20, ClientWidth-40, ClientHeight-40));
  rgn1 := TGPRegion.Create(path);
  g.FillRegion(b, rgn1);

  {根据第一个区域的数据创建第二个区域}
  GetMem(RgnData, rgn1.GetDataSize);                   {分配空间}
  rgn1.GetData(RgnData, rgn1.GetDataSize);             {获取数据}
  rgn2 := TGPRegion.Create(RgnData, rgn1.GetDataSize); {建立第二个区域}
  rgn2.GetBounds(rt, g);                               {获取第二个区域的矩形范围}
  g.DrawRectangle(p, rt);                              {画这个矩形}
  FreeMem(RgnData);                                    {释放内存}

  {如果不是为了测试 GetData,下面三行即可代替上面六行}
//  rgn2 := rgn1.Clone;
//  rgn2.GetBounds(rt, g);
//  g.DrawRectangle(p, rt);

  rgn1.Free;
  rgn2.Free;
  path.Free;
  b.Free;
  p.Free;
  g.Free;
end;

end.

窗体文件:

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object Form1: TForm1
  Left = 0
  Top = 0
  Caption = 'Form1'
  ClientHeight = 171
  ClientWidth = 243
  Color = clBtnFace
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'Tahoma'
  Font.Style = []
  OldCreateOrder = False
  Position = poDesktopCenter
  OnPaint = FormPaint
  PixelsPerInch = 96
  TextHeight = 13
end