[GRASS5] Darwin Pre2: PNGDriver

Glynn Clements glynn.clements at virgin.net
Tue Oct 16 02:57:11 EDT 2001

Glynn Clements wrote:

> > > BTW: What does the PNGDriver do?  Is it optional?
> > 
> > Just a comment here: PNGDriver is a nice replacement for
> > CELL driver. The CELL driver writes into the location, while
> > the PNGdriver directly generates PNG files. However,
> > it is also limited to 8bit (what a pity!).
> I'll look into the possibility of using GD-2.0 (currently beta).

OK; PNGdriver should support true-colour images if built with GD-2.0,
provided that the environment variable GRASS_TRUECOLOR is set to the
value TRUE (the literal string).

The structure of the colour-handling code has changed quite a bit, so
the possibility of incompatibility or other problems exists. OTOH,
PNGdriver now behaves more like XDRIVER.

NB: the configure tests for the GD library have grown exponentially;
GD now has four optional dependencies (PNG, JPEG, freetype and Xpm),
resulting in 16 possible combinations (by default, libgd.so.2 doesn't
have any dependency information, so configure has to check them all).

Glynn Clements <glynn.clements at virgin.net>

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