mandelbrot: use correct colors on greyscale targets (FS#10935)

Tested on Clipv1 (sim/target) and Ipod3g (sim)
Each color would be calculated as 0

Note the iteration over the whole range of colors is quite weird, and I
can not really sense what max_iter represents (except it's a number of
different colors, right?)

It should be backported to branch after tomers check if color range is
correct (FS#10935 mentions much smaller range for color targets as well)

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@24377 a1c6a512-1295-4272-9138-f99709370657

1 files changed, 5 insertions, 3 deletions

diff --git a/apps/plugins/fractals/mandelbrot_set.c b/apps/plugins/fractals/mandelbrot_set.c
index fbd527438e..ad5a172f33 100644
--- a/apps/plugins/fractals/mandelbrot_set.c
+++ b/apps/plugins/fractals/mandelbrot_set.c
@@ -31,14 +31,16 @@ static unsigned char imgbuffer[LCD_HEIGHT];
 static fb_data imgbuffer[LCD_HEIGHT];
 #endif
 
-#define NUM_COLORS ((unsigned)(1 << LCD_DEPTH))
-
+#ifdef USEGSLIB
+#define LCOLOR(iter) (iter << 5)
+#else
 /*
  * Spread iter's colors over color range.
  * 345 (=15*26-45) is max_iter maximal value
  * This implementation ignores pixel format, thus it is not uniformly spread
  */
-#define LCOLOR(iter) ((iter * NUM_COLORS) / 345)
+#define LCOLOR(iter) ((iter << LCD_DEPTH) / 345)
+#endif
 
 #ifdef HAVE_LCD_COLOR
 #define COLOR(iter) (fb_data)LCOLOR(iter)