Solved

TImage.Canvas Polygon

Posted on 1998-12-18
2
649 Views
Last Modified: 2010-05-19
Hi, how do I draw a user defined polygon ? The user clicks
with the mouse on some points. Then a polygon should be drawn. How do I add the points to the polygon and how do I create an array for them ? Source ?
0
Comment
Question by:ItsMe
2 Comments
 
LVL 8

Accepted Solution

by:
ZifNab earned 30 total points
ID: 1351761
Hi ItsMe,

This is a way :

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls, ExtCtrls;

const
  MaxPoints = 10;

type
  TForm1 = class(TForm)
    PaintBox1: TPaintBox;
    StorePoly: TButton;
    DrawPoly: TButton;
    Memo1: TMemo;
    procedure StorePolyClick(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure DrawPolyClick(Sender: TObject);
    procedure PaintBox1MouseDown(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
  private
    { Private declarations }
  public
    { Public declarations }
    StoringMode : Boolean;
    PolygonArray : Array[0..MaxPoints-1] of TPoint;
    PointNumber : 0..MaxPoints-1;
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.StorePolyClick(Sender: TObject);
begin
 {clear canvas}
 with paintbox1.canvas do begin
  Brush.Color := clWhite;
  FillRect(clipRect);
 end;
 memo1.lines.clear;
{clear polygonarray}
 FillChar(PolygonArray,SizeOf(PolygonArray),0);
 PointNumber := 0;
{start storing polygon  }
 storingMode := true;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
 StoringMode := false;
end;

procedure TForm1.DrawPolyClick(Sender: TObject);
begin
 {draw the polygon}
 storingMode := false;
 memo1.Lines.Add('Now drawing Polygon');
 with paintbox1.canvas do begin
  Brush.Color := clBlack;
  Polygon(Slice(PolygonArray,PointNumber));
 end;
end;

procedure TForm1.PaintBox1MouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
 {Store X,Y value in grid}
 if StoringMode then begin
  if PointNumber < MaxPoints then begin
   PolygonArray[PointNumber].X := X;
   PolygonArray[PointNumber].Y := Y;
   Inc(PointNumber);
   {show point}
   PaintBox1.Canvas.Pixels[X,Y] := clRed;
   {put point in memo}
   memo1.Lines.Add('Pointnr. : '+IntToStr(PointNumber)+
                   ' at position [X:'+IntToStr(X)+', Y:'+IntToStr(Y)+']');
  end
   else showmessage('sorry polygon points are limited to: '+IntToStr(MaxPoints));
  end
   else showmessage('please press StorePoly button to start defining the polygon');
end;

end.

Regards, Zif.
0
 

Author Comment

by:ItsMe
ID: 1351762
Adjusted points to 30
0

Featured Post

Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

A lot of questions regard threads in Delphi.   One of the more specific questions is how to show progress of the thread.   Updating a progressbar from inside a thread is a mistake. A solution to this would be to send a synchronized message to the…
In my programming career I have only very rarely run into situations where operator overloading would be of any use in my work.  Normally those situations involved math with either overly large numbers (hundreds of thousands of digits or accuracy re…
Internet Business Fax to Email Made Easy - With eFax Corporate (http://www.enterprise.efax.com), you'll receive a dedicated online fax number, which is used the same way as a typical analog fax number. You'll receive secure faxes in your email, fr…
Internet Business Fax to Email Made Easy - With  eFax Corporate (http://www.enterprise.efax.com), you'll receive a dedicated online fax number, which is used the same way as a typical analog fax number. You'll receive secure faxes in your email, f…

864 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

21 Experts available now in Live!

Get 1:1 Help Now