再学 GDI+[51]: 路径 IsVisible、IsOutlineVisible

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;

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