再学GDI+[51]: 路径

本例效果图:

代码文件:unit Unit1;
interface
uses
　Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
　Dialogs;
type
　TForm1 = class(TForm)
　　procedure FormCreate(Sender: TObject);
　　procedure FormDestroy(Sender: TObject);
　　procedure FormPaint(Sender: TObject);
　　procedure FormMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
　end;
var
　Form1: TForm1;
implementation
{$R *.dfm}
uses GDIPOBJ, GDIPAPI;
var
　path1,path2,path3: TGPGraphicsPath;
　p: TGPPen;
procedure TForm1.FormCreate(Sender: TObject);
var
　r: TRect;
begin
　path1 := TGPGraphicsPath.Create;
　path2 := TGPGraphicsPath.Create;
　path3 := TGPGraphicsPath.Create;
　p := TGPPen.Create(aclRed, 3);
　path1.AddLine(0, 0, ClientWidth, ClientHeight);
　r := ClientRect;
　InflateRect(r, -ClientWidth div 3, -ClientHeight div 3);
　OffsetRect(r, -Trunc((r.Right-r.Left) * 0.6), -Trunc((r.Bottom-r.Top) * 0.6));
　path2.AddRectangle(MakeRect(r));
　OffsetRect(r, r.Right-r.Left, r.Bottom-r.Top);
　path3.AddEllipse(MakeRect(r));
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
　path1.Free;
　path2.Free;
　path3.Free;
　p.Free;
end;
procedure TForm1.FormPaint(Sender: TObject);
var
　g: TGPGraphics;
begin
　g := TGPGraphics.Create(Canvas.Handle);
　g.DrawPath(p, path1);
　g.DrawPath(p, path2);
　g.DrawPath(p, path3);
　g.Free;
end;
procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X,
　Y: Integer);
begin
　Text := '';
//　if path1.IsVisible(MakePoint(X,Y)) then Text := '在 path1 内';
　if path2.IsVisible(MakePoint(X,Y)) then Text := '在矩形内';
　if path3.IsVisible(MakePoint(X,Y)) then Text := '在椭圆内';
　if path1.IsOutlineVisible(X, Y, p) then Text := '在直线上';
　if path2.IsOutlineVisible(X, Y, p) then Text := '在矩形的边线上';
　if path3.IsOutlineVisible(X, Y, p) then Text := '在椭圆的圆周线上';
end;
end.

窗体文件:object Form1: TForm1
　Left = 0
　Top = 0
　Caption = 'Form1'
　ClientHeight = 206
　ClientWidth = 339
　Color = clBtnFace
　Font.Charset = DEFAULT_CHARSET
　Font.Color = clWindowText
　Font.Height = -11
　Font.Name = 'Tahoma'
　Font.Style = []
　OldCreateOrder = False
　Position = poDesktopCenter
　OnCreate = FormCreate
　OnDestroy = FormDestroy
　OnMouseMove = FormMouseMove
　OnPaint = FormPaint
　PixelsPerInch = 96
　TextHeight = 13
end