GdiPlus[41]: IGPRegion 区域

// 区域建立:

TGPRegion.Create();   { 参数可以是矩形、路径、HRGN、区域数据, 或无参}

TGPRegion.FromHRGN(); { 从 HRGN 初始化 }



// 区域运算(矩形、路径、或另一个区域):

IGPRegion.Intersect();   { 交集 }

IGPRegion.Union();       { 并集 }

IGPRegion.Exclude();     { 减去 }

IGPRegion.ExclusiveOr(); { 减去交集 }

IGPRegion.Complement();  { 不相交 }



// 其他:

IGPRegion.IsVisible();       { 判断指定的点或矩形是否在区域内 }



IGPRegion.GetData;           { 获取区域数据(IGPBuffer), 其中包含数据指针和数据大小 }

IGPRegion.GetRegionScans();  { 从区域中获取矩形数组, 浮点型 }

IGPRegion.GetRegionScansI(); { 从区域中获取矩形数组, 整型 }



IGPRegion.Translate();       { 偏移 }

IGPRegion.Transform();       { Matrix 变换 }



IGPRegion.MakeInfinite;      { 初始化为无限大 }

IGPRegion.MakeEmpty;         { 初始化为空 }

IGPRegion.IsEmpty();         { 判断区域是否为空 }

IGPRegion.IsInfinite();      { 判断区域是否是无限大 }

IGPRegion.GetBounds();       { 获取边界矩形 }

IGPRegion.GetHRGN();         { 获取 HRGN(Windows 区域的句柄) }

IGPRegion.Clone;             { 复制 }

IGPRegion.Equals();          { 判断是否相同 }


 
   

区域的两个重要用途:

1、IGPRegion.IsVisible();

2、IGPGraphics.Clip 或 IGPGraphics.SetClip();

---

IsVisible 测试:

---

unit Unit1;



interface



uses

  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

  Dialogs;



type

  TForm1 = class(TForm)

    procedure FormCreate(Sender: TObject);

    procedure FormPaint(Sender: TObject);

    procedure FormMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}



uses GdiPlus, GdiPlusHelpers;



var Region: IGPRegion;



procedure TForm1.FormCreate(Sender: TObject);

var

  Rect: TGPRect;

  Path: IGPGraphicsPath;

begin

  Rect.Initialize(ClientRect);

  Rect.Inflate(-20, -20);

  Region := TGPRegion.Create(Rect);



  Rect.Inflate(-2, -2);

  Path := TGPGraphicsPath.Create();

  Path.AddEllipse(Rect);



  Region.Exclude(Path);

end;



procedure TForm1.FormPaint(Sender: TObject);

var

  Brush: IGPHatchBrush;

begin

  Brush := TGPHatchBrush.Create(HatchStyleMin, TGPColor.Silver, TGPColor.Red);

  Canvas.ToGPGraphics.FillRegion(Brush, Region);

end;



procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);

begin

  Text := 'Form1';

  if Region.IsVisible(X, Y) then Text := '在区域中';

end;



end.


 
   

剪切区域测试:

---

uses GdiPlus;



procedure TForm1.FormPaint(Sender: TObject);

const

  Pts: array [0..3] of TGPPoint = (

    (X: 10; Y: 10), (X: 150; Y: 10), (X: 100; Y: 75), (X: 100; Y: 150));

var

  Graphics: IGPGraphics;

  Path: IGPGraphicsPath;

  Region: IGPRegion;

  Pen: IGPPen;

  Font: IGPFont;

  Brush: IGPBrush;

begin

  Graphics := TGPGraphics.Create(Handle);

  Path := TGPGraphicsPath.Create;

  Path.AddPolygon(Pts);

  Region := TGPRegion.Create(Path);

  Pen := TGPPen.Create($FF000000);

  Graphics.DrawPath(Pen, Path);



  Graphics.Clip := Region;

//  Graphics.SetClip(Region); //或者这样

  Font := TGPFont.Create('Arial', 36, [FontStyleBold], UnitPixel);

  Brush := TGPSolidBrush.Create($FFFF0000);

  Graphics.DrawString('A Clipping Region', Font, TGPPointF.Create(15, 25), Brush);

  Graphics.DrawString('A Clipping Region', Font, TGPPointF.Create(15, 68), Brush);

end;