再學 GDI+[57]: 路徑 - Widen

路徑的 Widen 方法可以把路徑中的線, 根據指定畫筆的寬度與樣式, 轉換為一個范圍(有點類似區域); 但轉換後再描繪路徑就只能使用 FillPath 而不是 DrawPath 了. 本例沒有測試它的兩個默認參數, 因為前面已多次提到了.

　　本例效果圖:

　　代碼文件:unit Unit1;
interface
uses
　Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
　Dialogs, StdCtrls;
type
　TForm1 = class(TForm)
　　CheckBox1: TCheckBox;
　　CheckBox2: TCheckBox;
　　procedure FormCreate(Sender: TObject);
　　procedure FormPaint(Sender: TObject);
　　procedure CheckBox1Click(Sender: TObject);
　　procedure CheckBox2Click(Sender: TObject);
　end;
var
　Form1: TForm1;
implementation
{$R *.dfm}
uses GDIPOBJ, GDIPAPI;
procedure TForm1.FormCreate(Sender: TObject);
begin
　CheckBox1.Caption := '執行 Widen';
　CheckBox2.Caption := '顯示路徑中所有的點';
end;
procedure TForm1.FormPaint(Sender: TObject);
var
　g: TGPGraphics;
　p: TGPPen;
　b1,b2: TGPBrush;
　path: TGPGraphicsPath;
　pts: array of TGPPoint;
　i: Integer;
begin
　g := TGPGraphics.Create(Canvas.Handle);
　p := TGPPen.Create(aclSlateGray, 20);
　p.SetEndCap(LineCapArrowAnchor);
　b1 := TGPSolidBrush.Create(aclRed);
　b2 := TGPHatchBrush.Create(HatchStyleDiagonalCross, aclSilver, aclSlateGray);
　path := TGPGraphicsPath.Create;
　path.AddLine(40, 50, ClIEntWidth-40, 50);
　if CheckBox1.Checked then
　begin
　　path.Widen(p);
　　g.FillPath(b2, path);
　end else g.DrawPath(p, path);
　if CheckBox2.Checked then
　begin
　　SetLength(pts, path.GetPointCount);
　　path.GetPathPoints(PGPPoint(pts), Length(pts));
　　TGPSolidBrush(b1).SetColor(aclRed);
　　for i := 0 to Length(pts) - 1 do
　　　g.FillRectangle(b1, pts[i].X-3, pts[i].Y-3, 6, 6);
　end;
　path.Free;
　b1.Free;
　b2.Free;
　p.Free;
　g.Free;
end;
procedure TForm1.CheckBox1Click(Sender: TObject);
begin
　Repaint;
end;
procedure TForm1.CheckBox2Click(Sender: TObject);
begin
　Repaint;
end;
end.窗體文件:object Form1: TForm1
　Left = 0
　Top = 0
　Caption = 'Form1'
　ClIEntHeight = 136
　ClIEntWidth = 287
　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 CheckBox1: TCheckBox
　　Left = 43
　　Top = 104
　　Width = 97
　　Height = 17
　　Caption = 'CheckBox1'
　　TabOrder = 0
　　OnClick = CheckBox1Click
　end
　object CheckBox2: TCheckBox
　　Left = 138
　　Top = 104
　　Width = 125
　　Height = 17
　　Caption = 'CheckBox2'
　　TabOrder = 1
　　OnClick = CheckBox2Click
　end
end