Artifacts when displaying transparent png in timage

[wp]

Did you try loading the image by means of the graphics classes as I showed above? This seems to work even for gtk2 and gkt3 (Manjaro Linux KDE24.1.2, Mint 21.1 Cinnamon).

Code: Pascal  [Select][+][-]

1.     program test;
2.      
3.     uses
4.       Interfaces, Classes, Graphics,
5.       Forms, ExtCtrls;
6.      
7.     var
8.       frmMain: TForm;
9.       imgForm: TImage;
10.      
11.     begin
12.       Application.Initialize;
13.       Application.CreateForm(TForm,frmMain);
14.       frmMain.Width := 600;
15.       frmMain.Height := 600;
16.       frmMain.Color := clYellow;
17.       imgForm := TImage.Create(frmMain);
18.       imgForm.Parent := frmMain;
19.       imgForm.Proportional := True;
20.       imgForm.Stretch := True;
21.       //imgForm.Transparent := True;
22.       imgForm.BoundsRect := frmMain.BoundsRect;
23.       imgForm.Picture.LoadFromFile('test.png');
24.       Application.Run;
25.     end.

[Jonny]

Did you try loading the image by means of the graphics classes as I showed above?

Yes, your method of directly loading the file into the TImage component works correctly.

But I pass the image through a TFPMemoryImage because I need to manipulate it.

Code: Pascal  [Select][+][-]

1. program test;
2.  
3. uses
4.   Interfaces, Classes, Graphics,
5.   Forms, ExtCtrls, FPImage, FPReadPNG;
6.  
7. var
8.   frmMain: TForm;
9.   imgForm: TImage;
10.   imgLogo: TFPMemoryImage;
11.   imgReader: TFPReaderPNG;
12.  
13. begin
14.   Application.Initialize;
15.   Application.CreateForm(TForm,frmMain);
16.   frmMain.Width := 600;
17.   frmMain.Height := 600;
18.   frmMain.Color := clYellow;
19.   imgForm := TImage.Create(frmMain);
20.   imgForm.Parent := frmMain;
21.   imgForm.Proportional := True;
22.   imgForm.Stretch := True;
23.   //imgForm.Transparent := True;
24.   imgForm.BoundsRect := frmMain.BoundsRect;
25.  
26. //  imgForm.Picture.LoadFromFile('test.png');  // do not load directly
27.   imgLogo := TFPMemoryImage.Create(0,0);  // instead load to TFPMemoryImage
28.   imgReader := TFPReaderPNG.Create;
29.   imgLogo.LoadFromFile('test.png',imgReader);
30. //  Manipulate the image in my program (not necessary to show the bug here)
31.   imgForm.Picture.Assign(imgLogo);
32.  
33.   Application.Run;
34. end.
35.  

This causes the break in GTK2 only.

[lainz]

Try with BGRABitmap.

[TRon]

Try with BGRABitmap.

Nothing personal but that answer pisses me off so badly you have no idea 

Ofc that works but is besides the point.

[Jonny]

Try with BGRABitmap.

I am afraid that due to external factors here, I cannot use BGRABitmap or any other third party components.

(BGRABitmap may be very nice but it is a monster - something that I would avoid even if I had a choice)

Besides, if there is a bug, why ignore it, can we confirm the issue and maybe address it?

[TRon]

So confused - is this a bug then?

It tells us that assign does not seem to handle the alpha channel properly while the standard graphic loaders seem to do it correctly.

It would probably require a pixel by pixel check (actually check the alpha channel) comparing both methods in order to try locate the difference between the two.

I consider it a bug though wp mentioned issues with transparency as well so his opinion might differ. Know that wp is better versed in that regards.

[Jonny]

Thanks. Not sure what you want me to do. Happy to perform tests if you provide simple instructions.

[TRon]

Nothing you can currently do that I am aware. I can confirm the results (both the original issue as well as the workaround) as presented by your examples.

If nobody disputes it as being a bug then by logic it becomes one (and should be reported as such).

I am trying to figure out if I am able to determine what might be the culprit tough I do hope it isn't something going as deep as being related to gtk2 because in that case I'm pretty much lost.

PS: the todo note inside the source of assign method of rasterimage when the source is a TFPCustomImage (ancestor of TFPMemoryimage) might be there for a reason.

[lainz]

Try with BGRABitmap.

Nothing personal but that answer pisses me off so badly you have no idea 

Ofc that works but is besides the point.

 

Try with BGRABitmap.

I am afraid that due to external factors here, I cannot use BGRABitmap or any other third party components.

(BGRABitmap may be very nice but it is a monster - something that I would avoid even if I had a choice)

Besides, if there is a bug, why ignore it, can we confirm the issue and maybe address it?

You can use the 'lite' version, with less stuff not a big monster..

core version of BGRABitmap available: by adding the library to the project include path and setting BGRABITMAP_CORE directive (see test/testcore sample)

No packages to install, just add path relative or inside your project folder... No need to install bgracontrols, use it with a normal canvas.

[Jonny]

You can use the 'lite' version, with less stuff not a big monster..

core version of BGRABitmap available: by adding the library to the project include path and setting BGRABITMAP_CORE directive (see test/testcore sample)

No packages to install, just add path relative or inside your project folder... No need to install bgracontrols, use it with a normal canvas.

OK, so I took the last snippet of working code that was posted.

- Added BGRABitmap to the uses clause.

- Add compiler options: -dBGRABITMAP_CORE

- Compiled with GTK2 widgetset

Code: [Select]

$ ls -la --time-style='+' test.gtk2
-rwxr-xr-x 1 user user 2957824  test.gtk2

$ ls -la --time-style='+' bgratest/test.gtk2
-rwxr-xr-x 1 user user 3859232  bgratest/test.gtk2

$ size -G test.gtk2
      text       data        bss      total filename
   2007720     939693     110312    3057725 test.gtk2

$ size -G bgratest/test.gtk2
      text       data        bss      total filename
   2717064    1133857     185272    4036193 bgratest/test.gtk2

The executable grows by almost 1Mb, and requires countless source files (I tried working out which ones but gave up).

As I shall be deploying to a small embedded system with very limited resources, I am trying to reduce all footprints.

BGRABitmap may be great for bigger projects, but for my current use-case it is, unfortunately a monster.

[lainz]

I see. Limited hardware is a thing. Hope you can fix the bug.