Sunday, February 14, 2010

gnocl::pixBuf #3

Another busy and productive day. With the help fo Tadej at GtkForum I solved the problem of setting the fill colour values. The resulting function used to convert the colour values to the right format is:

static guint32 convertRGBtoPixel ( gchar *clr )
{
GdkColor color;
guint32 pixel;
/* Conversion factor from 16-bit color to 8-bit color (0xff / 0xffff) */
const gdouble f = 0.00389105;
/* create the colour from the supplied string, added by WJG */
gdk_color_parse ( clr, &color );
/* fill with colour */
pixel = ( ( ( guint ) ( color.red * f + 0.5 ) ) << 24 ) | /* R */
( ( ( guint ) ( color.green * f + 0.5 ) ) << 16 ) | /* G */
( ( ( guint ) ( color.blue * f + 0.5 ) ) << 8 ) | /* B */
( 0xff << 0 ); /* A */
return pixel;
}

Of all the obscure things that I've had to work through, the above bitshuffling and base alterations leaves me dumfounded. 

The key functionality added today then includes:

pixbuf commands
   turn
   flip
   rotate
commands
   load

Which will sorta have the following options:

   turn <(int) 0 | 90 | 270 | 180 | -90 | -180 | -270>
   flip -orientation <(str) horizontal (default) | vertical>
   rotate -angle <(dbl) angle> -backgroundColor <(str) colour>

The code for producing the arbitrary rotation is taken from zfuncs. The edge appears aliased and there may be better implementations but this should be sufficient for screen opts.

Other things that I acquired was a pdf of Phillips (1994) Image Processing in C. Gosh it is old. There's a Tcl/Tk front end to the library. Tell it was the published in the days before Python, Ruby and the rise of Perl. Tcl/Tk was 'hot' in those days. Today.....

Also got a nice new desktop today, an Acer Aspire X1301. Its largely to replace my old tower box which, with its many whiring fans sounds like a washing machine on full spin. The new machine, apart from being much higher spec is almost silent -magic! I haven't tried it myself yet but my daughter Georgie has been using it for most of the evening. She unpacked it, set it up and completed the OS installation. Not bad for a nine year old!

No comments: