Re: printing images

[Martin Kretzschmar <m_kretzschmar gmx net>]

Hi Robert

Am Mittwoch, den 03.11.2004, 20:16 +0100 schrieb Robert Roebling:
> [...] I'm just trying to print RGB right
> now. I use
> 
> gnome_print_moveto( gpc, x,y );
> gnome_print_rgbimage( gpc, (chunk of RGB data), 32, 32, 32*3 );
> 
> but nothing shows up in the printout. It is
> there in the file, but something is wrong.
> I've included the PS output for a simple test
> file (8Kb is hopefully OK). It shows a few lines
> and on page 1 one large rectangle and a small one.
> The image should be where the small rectangle is,
> but it is not. 
> I'm aware that this might be an obvious error,
> but I don't see it. Maybe the positioning is
> outside the visible bounds or the image in
> shrunk to zero?

It is not shrunk to zero, but gnome_print_rgbimage "Draws RGB color
image into unit square (0,0 - 1,1) in current coordinate
system." So it's shrunk to one ;)

You have to adjust the current transformation matrix (ctm) to transform
that square to the size you actually want.

Look at libgnomeprint/tests/generate.c (my_draw_image) for example code.
But ignore the pixbuf generation code ;).

And you could play with the "[1 0 0 1 0 0]cm" in your file, a few lines
above the image data, to see how the ctm affects the image.

HTH,
	Martin