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 程式師世界 >> 編程語言 >> 更多編程語言 >> Delphi >> 再學 GDI+[72]: 區域(1) - 建立區域

再學 GDI+[72]: 區域(1) - 建立區域

編輯:Delphi

建立 GDI+ 的區域有五種辦法:

  1、根據一個矩形建立(矩形區域);

  2、根據路徑建立;

  3、根據 GDI 區域的句柄建立;

  4、根據從區域中獲取的數據建立;

  5、無參數建立.

  本例演示了前三種建立方法.

  本例效果圖:

再學 GDI+[72]: 區域(1) - 建立區域

  代碼文件:unit Unit1;
interface
uses
 Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
 Dialogs, StdCtrls, ExtCtrls;
type
 TForm1 = class(TForm)
  RadioGroup1: TRadioGroup;
  procedure FormCreate(Sender: TObject);
  procedure FormPaint(Sender: TObject);
  procedure RadioGroup1Click(Sender: TObject);
 end;
var
 Form1: TForm1;
implementation
{$R *.dfm}
uses GDIPOBJ, GDIPAPI;
procedure TForm1.FormCreate(Sender: TObject);
begin
 RadioGroup1.Items.CommaText := '矩形通道,橢圓形通道,多邊形通道';
 RadioGroup1.ItemIndex := 0;
end;
procedure TForm1.FormPaint(Sender: TObject);
var
 rt: TGPRect;
 pts: array[0..2] of TPoint;
 RgnHandle: HRGN;
 g: TGPGraphics;
 path: TGPGraphicsPath;
 b: TGPBrush;
 rgn: TGPRegion;
begin
 rt := MakeRect(20, 20, 100, ClIEntHeight-40);
 pts[0] := Point(rt.X + rt.Width div 2, rt.Y);
 pts[1] := Point(rt.X, rt.Y + rt.Height);
 pts[2] := Point(rt.X + rt.Width, rt.Y + rt.Height);
 case RadioGroup1.ItemIndex of
  0: rgn := TGPRegion.Create(rt);    {根據矩形建立(矩形區域)}
  1: begin               {根據路徑建立}
     path := TGPGraphicsPath.Create;
     path.AddEllipse(rt);
     rgn := TGPRegion.Create(path);
     path.Free;
    end;
  2: begin               {根據 GDI 區域的句柄建立}
     RgnHandle := CreatePolygonRgn(pts, Length(pts), WINDING);
     rgn := TGPRegion.Create(RgnHandle);
     DeleteObject(RgnHandle);
    end;
 end;
 g := TGPGraphics.Create(Canvas.Handle);
 b := TGPHatchBrush.Create(HatchStyleDiagonalCross, aclSilver, aclGray);
 g.FillRegion(b, rgn);
 b.Free;
 rgn.Free;
 g.Free;
end;
procedure TForm1.RadioGroup1Click(Sender: TObject);
begin
 Repaint;
end;
end.
窗體文件:object Form1: TForm1
 Left = 0
 Top = 0
 Caption = 'Form1'
 ClIEntHeight = 137
 ClIEntWidth = 238
 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 = 137
  Top = 8
  Width = 91
  Height = 121
  Caption = 'RadioGroup1'
  TabOrder = 0
  OnClick = RadioGroup1Click
 end
end


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