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Re: [Freeciv-Dev] Changes request

Re: [Freeciv-Dev] Changes request

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To: hop@xxxxxxxxxxxxxxxxx
Cc: Jules Bean <jmlb2@xxxxxxxxxxxxxxxx>, freeciv-dev@xxxxxxxxxxx
Subject: Re: [Freeciv-Dev] Changes request
From: Jules Bean <jules@xxxxxxxxxxxxxxx>
Date: Wed, 14 Jul 1999 09:12:47 +0100

hop@xxxxxxxxxxxxxxxxx wrote:
> >> 3) Image data. Xpm is not very good format (as it is noted in some doc)
> >> and other format should be used. Plain RGBA (either 5-5-5-1 or 8-8-8-8)
> >> seems reasonable to me.
> >
> >PNG seems good to me.  It's an open, free format which offers lossless
> >compression.  Free code exists to read it in C, and I imagine Java.
> -- snip snip --
> Just remember, that Xpm has built-in capability for making transparent
> pixels so your images can be non-rectangular in shape. If you don't have
> built-in support for transparent images, it plain sucks doing it the hard
> way. And by the hard way, you have to build a bitmask that tells which
> pixels should be drawn, then bitwise AND the bitmask with the current
> display, then XOR'ing the resulting image with the icon you want to draw.
> Using a format with built-in support for transparent pixels is very
> nice because then you don't have to use customized drawing routines,
> just xpm library calls.
> I don't think PNG can have transparent pixels. I hope I'm mistaken.
> If PNG doesn't support transparent pixels, then you'll have to use
> another format that does use transparent pixels, or roll your own
> parser for the XPM format (whee!).

You're mistaken.  PNG can have transparent pixels.  Indeed, as someone
observed, it can have a full alpha channel.


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