nanogui: PNG and transparency
Subject:
Re: [nanogui] PNG and transparency
From:
"Greg Haerr" ####@####.####
Date:
28 Jul 2009 10:27:33 -0000
Message-Id: <05ea01ca0f22$8b72ed30$6464a8c0@winXP>
: I try to draw transparency PNG images in my nano-X application but all
: the time the transparency's part of it is displayed in black..
Make sure you're using the CVS code, as there were earlier bugs
in transparency. v0.90 is definitely buggy.
: I tried to display it on an window created by
: GrNewWindow(GR_ROOT_WINDOW_ID, 0, 0, 480, 640, 0, WHITE, BLACK);
Using BLACK here is a bad idea, as you can't tell whether the
transparency is being drawn BLACK, or whether BLACK is
showing through.
I don't have the source code handy, but each image decoder
handles transparency differently. I know we support GIF transparency,
I'm not sure whether PNG was added. And below you're
saying the .xpm works. You can check the source
looking for ".transcolor" or "->transcolor" being set
to something other than NOCOLOR. The decoders then
don't draw a pixel when the image color matches transcolor.
:
: I tried with GrLoadImageFromFile plus GrDrawImageToFit and with
: GrDrawImageFromFile too, and same result.
Yes, each of these use the same decoder, depending on image type.
Regards,
Greg
: When I convert this image in .xpm and use the same code (just changing
: th extension of the file to load) everything gonna be ok.
:
: Can anybody help me please ?
:
: Regards,
:
: Vincent BRACH
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