Solved

canvas to procedure

Posted on 1997-03-26
5
262 Views
Last Modified: 2010-04-04
If I have a procedure which does some drawing on a canvas, how can I tell the procedure on WHICH canvas it should draw?
0
Comment
Question by:remcodek
  • 3
  • 2
5 Comments
 
LVL 3

Accepted Solution

by:
mheacock earned 100 total points
ID: 1334962
You could pass a pointer to the canvas to the procedure...

type
  PCanvas = ^Canvas;

procedure Draw (i_pCanvas: PCanvas);
begin
   ...
   i_pCanvas^.Method(...);
   ...
end;

var
  cv: PCanvas;
begin
  pcv := @Form1.Canvas;
  Draw(pcv);
end;

Or something like this...test this out before grading me.
If you have further questions, feel free to comment.
0
 

Author Comment

by:remcodek
ID: 1334963
It looks like an elegant solution, yet Delphi won't swallow the type-declaration. On PCanvas=^canvas it replies Undeclared Identifier:'canvas'. What did I do wrong?
0
 
LVL 3

Expert Comment

by:mheacock
ID: 1334964
My mistake...I apologize...

type
   PCanvas = ^TCanvas;

I made a simple mistake in the declaration...should be TCanvas...not Canvas.  Sorry.
0
 
LVL 3

Expert Comment

by:mheacock
ID: 1334965
Oops...also...

  cv: PCanvas;

should be

  pcv: PCanvas;

I gotta proofread my answers being clicking the submit button.
0
 

Author Comment

by:remcodek
ID: 1334966
It's very simple:

procedure(x,y:integer;wCanvas:TCanvas);

begin
  wcanvas.pixels[x,y]:=.....
end;

works just fine.
0

Featured Post

U.S. Department of Agriculture and Acronis Access

With the new era of mobile computing, smartphones and tablets, wireless communications and cloud services, the USDA sought to take advantage of a mobilized workforce and the blurring lines between personal and corporate computing resources.

Question has a verified solution.

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

This article explains how to create forms/units independent of other forms/units object names in a delphi project. Have you ever created a form for user input in a Delphi project and then had the need to have that same form in a other Delphi proj…
Have you ever had your Delphi form/application just hanging while waiting for data to load? This is the article to read if you want to learn some things about adding threads for data loading in the background. First, I'll setup a general applica…
This Micro Tutorial will give you a basic overview how to record your screen with Microsoft Expression Encoder. This program is still free and open for the public to download. This will be demonstrated using Microsoft Expression Encoder 4.
Email security requires an ever evolving service that stays up to date with counter-evolving threats. The Email Laundry perform Research and Development to ensure their email security service evolves faster than cyber criminals. We apply our Threat…

770 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