Wrong transparent background render in page layout file

[Hildo Guillardi Júnior]

To reproduce:

1) Insert an image with transparent background at the "page layout editor";
2) Verify, the image is added correctly with blank/white background;
3) Change the page layout of one Eeschema page using the template above;
4) The images became black.

Version:
Application: kicad
Version: 6.0.0-rc1-unknown-a3d8ab9~66~ubuntu16.04.1, release build
Libraries:
    wxWidgets 3.0.2
    libcurl/7.47.0 OpenSSL/1.0.2g zlib/1.2.8 libidn/1.32 librtmp/2.3
Platform: Linux 4.4.0-141-generic x86_64, 64 bit, Little endian, wxGTK
Build Info:
    wxWidgets: 3.0.2 (wchar_t,wx containers,compatible with 2.8) GTK+ 2.24
    Boost: 1.58.0
    OpenCASCADE Community Edition: 6.8.0
    Curl: 7.47.0
    Compiler: GCC 5.4.0 with C++ ABI 1009

Build settings:
    USE_WX_GRAPHICS_CONTEXT=OFF
    USE_WX_OVERLAY=OFF
    KICAD_SCRIPTING=ON
    KICAD_SCRIPTING_MODULES=ON
    KICAD_SCRIPTING_PYTHON3=OFF
    KICAD_SCRIPTING_WXPYTHON=OFF
    KICAD_SCRIPTING_WXPYTHON_PHOENIX=OFF
    KICAD_SCRIPTING_ACTION_MENU=ON
    BUILD_GITHUB_PLUGIN=ON
    KICAD_USE_OCE=ON
    KICAD_USE_OCC=OFF
    KICAD_SPICE=ON

[Wayne Stambaugh (stambaughw)]

Please include the offending worksheet file so I can confirm this bug. It looks like the new modern canvas implementation is getting the bitmap background wrong.

[Hildo Guillardi Júnior (hildogjr)]

Attacked

[jean-pierre charras (jp-charras)]

Kicad does not support transparent background in bitmaps:

- New draw engines do not support transparent background in bitmaps.
They are not optimized to draw bitmaps.
And (more annoying)
- Plot engines do not support transparent background in bitmaps.

[Hildo Guillardi Júnior (hildogjr)]

Yes, but could be included the workaround of "make the transparent white" or "set the transparent color"? (since Eeschema and Page editor have different behavior to display it)

[Nick Østergaard (nickoe)]

@JP, it is strange that there is a discrepancy on how the pl_editor renders it and eeschema. I guess this is the most confusing part here.

[jean-pierre charras (jp-charras)]

Not strange: pl_editor still uses the legacy canvas, that can displays transparency.

"set the transparent color" is not really a good option, because you don't know what color can be used: the background color can be different for eeschema and pcbnew

[Nick Østergaard (nickoe)]

Ahh, ok, I was not aware of this.

[Hildo Guillardi Júnior (hildogjr)]

Hour about use the environment color settled in each one (page editor, eeschema) to display these images background?
We should be worry about the exportation, because this issue was also affecting the PDF output from eeschema.

[Wayne Stambaugh (stambaughw)]

Is there no way to use transparency with either modern canvas (opengl or cairo)? It seems to me that it should be possible although I have no idea what it would take to implement it.

[KiCad Janitor (kicad-janitor)]

Fixed in revision 3a3bbbb545feb1272ed53eaf7e4b54d534c3f48a
https://git.launchpad.net/kicad/patch/?id=3a3bbbb545feb1272ed53eaf7e4b54d534c3f48a

[Hildo Guillardi Júnior (hildogjr)]

At https://bugs.launchpad.net/kicad/+bug/1814893 fix package is used:

pixel += ( wxALPHA_OPAQUE << 24 );
p[3] = wxALPHA_OPAQUE;

But in this, is used:
pixel += ( 0xff << 24 );
p[3] = 255;

The last appear to be a hard code. Just marking here for an update. Since the issues are correlated (and now, correlated with https://bugs.launchpad.net/kicad/+bug/1815216).