Fractals: Use constants for screen panning

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@24258 a1c6a512-1295-4272-9138-f99709370657

3 files changed, 10 insertions, 4 deletions

diff --git a/apps/plugins/fractals/fractal_rect.h b/apps/plugins/fractals/fractal_rect.h
index eca6655..9d57c29 100644
--- a/apps/plugins/fractals/fractal_rect.h
+++ b/apps/plugins/fractals/fractal_rect.h
@@ -23,9 +23,6 @@
 
 #include "fractal_sets.h"
 
-#define LCD_SHIFT_X (LCD_WIDTH / 8)
-#define LCD_SHIFT_Y (LCD_HEIGHT / 8)
-
 void rects_queue_init(void);
 void rects_calc_all(int (*calc)(struct fractal_rect *, int (*)(void *), void *),
         int (*button_yield_cb)(void *), void *ctx);
diff --git a/apps/plugins/fractals/fractal_sets.h b/apps/plugins/fractals/fractal_sets.h
index 2d0ff7d..a41de45 100644
--- a/apps/plugins/fractals/fractal_sets.h
+++ b/apps/plugins/fractals/fractal_sets.h
@@ -24,6 +24,14 @@
 #include "lib/grey.h"
 #include "lib/xlcd.h"
 
+#define DELTA 8 /* Panning moves 1/DELTA of screen */
+
+#define LCD_SHIFT_X (LCD_WIDTH / DELTA)
+#define LCD_SHIFT_Y (LCD_HEIGHT / DELTA)
+
+#define X_DELTA(x) (((x) * LCD_WIDTH) / DELTA)
+#define Y_DELTA(y) (((y) * LCD_HEIGHT) / DELTA)
+
 struct fractal_rect
 {
     int px_min;
diff --git a/apps/plugins/fractals/mandelbrot_set.c b/apps/plugins/fractals/mandelbrot_set.c
index 53ac7f2..b8a65d6 100644
--- a/apps/plugins/fractals/mandelbrot_set.c
+++ b/apps/plugins/fractals/mandelbrot_set.c
@@ -139,8 +139,9 @@ static int ilog2_fp(long value) /* calculate integer log2(value_fp_6.26) */
 static void recalc_parameters(void)
 {
     ctx.x_step = (ctx.x_max - ctx.x_min) / LCD_WIDTH;
-    ctx.x_delta = (ctx.x_step * LCD_WIDTH) / 8;
+    ctx.x_delta = X_DELTA(ctx.x_step);
     ctx.y_step = (ctx.y_max - ctx.y_min) / LCD_HEIGHT;
+    ctx.y_delta = Y_DELTA(ctx.y_step);
     ctx.y_delta = (ctx.y_step * LCD_HEIGHT) / 8;
     ctx.step_log2 = ilog2_fp(MIN(ctx.x_step, ctx.y_step));
     ctx.max_iter = MAX(15, -15 * ctx.step_log2 - 45);