TPortableNetworkGraphic & Canvas.Draw vs Remote Desktop Connection
lazarus / 39-Graphics

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upsidasi · 2022-03-08 14:33

Hi,

I wrote a simple piece of code to save a png file using
TPortableNetworkGraphic:
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     img :=
TPortableNetworkGraphic.Create();    img.Width := 100;    img.Height
:= 100;     img.Canvas.Brush.Color := clWhite;   
img.Canvas.FillRect(0, 0, img.Width, img.Height);   
img.Canvas.Pen.Color := clBlack;    img.Canvas.Line(0, 0, img.Width,
img.Height);     img.SaveToFile('test.png'); 
It works fine when I work directly on my Linux computer (test_ok.png),
but it generates an empty image (test_RDP.png) when I access my Linux
over RDP using Remote Desktop Connection from Windows.

I also tested basically the same code but with TBitmap which works
fine in both conditions.

Sadly, both TBitmap and TPortableNetworkGraphic cannot be drawn using
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.Draw(x, y, TGrapihcs) over RDP while using Remote Desktop
Connection (see "BMP Draw" button in the attached project).

Here are my versions:
  Lazarus: 2.0.10
  FPC: 3.2.0

Attached a zip containing the project to reproduce the issues and the
images test_ok.png and test_RDP.png.