Form Canvas Strange
lazarus / 39-Graphics

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milen_prg · 2025-02-17 18:18

Why this code:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i Procedure
TForm1.FormPaint(Sender: TObject);Begin     Brush.Color := clRed;   
 Canvas.Rectangle(0, 0, Width div 2, Height);     Brush.Color :=
clGreen;     Canvas.Rectangle(Width div 2, 0, Width, Height);end;    
    
Do not draw window with left half Red and right half Green?
After refresh it draws just one vertical green line at the Form
middle.

And if I change the last row (for example)
from
Canvas.Rectangle(Width div 2, 0, Width, Height);
to
Canvas.Rectangle(Width div 2, 0, Width div 2, Height);

The right half become Green, but, the left is White, no Red at all.
And this is not what the Rectangle procedure must do!

Generally, Help, please!

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olatov · 2025-02-17 18:39

Maybe try assigning the color to the Canvas' brush, that is
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
Canvas.Brush.Color := clRed;..Canvas.Brush.Color := clGreen;..

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cdbc · 2025-02-17 18:46

Hi
Try this:Code: Pascal  [Select][+][-]window.onload = function(){var x1
= document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i Procedure
TForm1.FormPaint(Sender: TObject);Begin     Brush.Color := clRed;   
 Canvas.Rectangle(1, 1, (Width div 2)-1, Height-1);     Brush.Color :=
clGreen;     Canvas.Rectangle((Width div 2)+1, 1, Width-1,
Height-1);end;There are bevels to take into account and if you draw 2
lines with the same coordinates after another, the last one wins...
Regards Benny

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wp · 2025-02-17 18:58

Nimbus is right. This works (tested):
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TForm1.FormPaint(Sender: TObject);begin  Canvas.Brush.Color := clRed; 
Canvas.Rectangle(0, 0, Width div 2, Height);  Canvas.Brush.Color :=
clGreen;  Canvas.Rectangle(Width div 2, 0, Width, Height);end;

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milen_prg · 2025-02-17 19:07

Quote from: Nimbus on February 17, 2025, 07:39:56 pmMaybe try
assigning the color to the Canvas' brush, that is
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
Canvas.Brush.Color := clRed;..Canvas.Brush.Color := clGreen;.. 
Yes, Nimbus is right!
Thank, you!
But WHY the compiler allows this?! Or what actually did the Brush of
the Form itself (not its Canvas)?!