TStringGrid: draw lines in OnPrepareCanvas?
lazarus / 39-Graphics

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stem · 2023-12-29 21:37

Hi,

the lines

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
mygrid.Canvas.Pen.Color := clRed;mygrid.Canvas.Line(0, 0, 10, 10);
show no effect in the event "OnPrepareCanvas" of my TStringGrid
whereas

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
mygrid.Canvas.Brush.Color := $004f4fe8;
works perfectly.

What am I doing wrong? Thank you.

stem

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dsiders · 2023-12-30 01:58

Quote from: stem on December 29, 2023, 10:37:56 pmHi,

the lines

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
mygrid.Canvas.Pen.Color := clRed;mygrid.Canvas.Line(0, 0, 10, 10);
show no effect in the event "OnPrepareCanvas" of my TStringGrid
whereas

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
mygrid.Canvas.Brush.Color := $004f4fe8;
works perfectly.

What am I doing wrong? Thank you.

stem

OnPrepareCanvas is not meant for drawing operations... only
configuring the canvas with the brush, pen, and font you need to use
in DrawCell.

https://lazarus-
ccr.sourceforge.io/docs/lcl/grids/tcustomgrid.onpreparecanvas.html
https://lazarus-
ccr.sourceforge.io/docs/lcl/grids/tcustomgrid.ondrawcell.html

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stem · 2024-01-04 21:06

Thank you.