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