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Fractals: Prevent zooming more than deepest possible zoom

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This prevent the mandelbrost set from being trashed if zooming too much


git-svn-id: svn://svn.rockbox.org/rockbox/trunk@24264 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Tomer Shalev 2010-01-17 21:15:56 +00:00
parent 5b94d44cc0
commit ab450a81ec
3 changed files with 25 additions and 12 deletions
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8
apps/plugins/fractals/fractal.c
View file

@ -167,8 +167,8 @@ enum plugin_status plugin_start(const void* parameter)
if (lastbutton != FRACTAL_ZOOM_OUT_PRE)
break;
#endif
ops->zoom(-1);
redraw = REDRAW_FULL;
if (!ops->zoom(-1))
redraw = REDRAW_FULL;
break;
@ -180,8 +180,8 @@ enum plugin_status plugin_start(const void* parameter)
#ifdef FRACTAL_ZOOM_IN2
case FRACTAL_ZOOM_IN2:
#endif
ops->zoom(1);
redraw = REDRAW_FULL;
if (!ops->zoom(1))
redraw = REDRAW_FULL;
break;
case FRACTAL_UP:

2
apps/plugins/fractals/fractal_sets.h
View file

@ -47,7 +47,7 @@ struct fractal_ops
int (*calc)(struct fractal_rect *rect, int (*button_yield_cb)(void *ctx),
void *button_yield_ctx);
void (*move)(int dx, int dy);
void (*zoom)(int factor);
int (*zoom)(int factor);
int (*precision)(int d);
};

27
apps/plugins/fractals/mandelbrot_set.c
View file

@ -96,7 +96,7 @@ static int mandelbrot_calc_high_prec(struct fractal_rect *rect,
static void mandelbrot_move(int dx, int dy);
static void mandelbrot_zoom(int factor);
static int mandelbrot_zoom(int factor);
static int mandelbrot_precision(int d);
@ -109,13 +109,15 @@ struct fractal_ops mandelbrot_ops =
.precision = mandelbrot_precision,
};
#define LOG2_OUT_OF_BOUNDS -32767
static int ilog2_fp(long value) /* calculate integer log2(value_fp_6.26) */
{
int i = 0;
if (value <= 0)
{
return -32767;
return LOG2_OUT_OF_BOUNDS;
}
else if (value > (1L << 26))
{
@ -136,18 +138,24 @@ static int ilog2_fp(long value) /* calculate integer log2(value_fp_6.26) */
return i;
}
static void recalc_parameters(void)
static int recalc_parameters(void)
{
ctx.x_step = (ctx.x_max - ctx.x_min) / LCD_WIDTH;
ctx.x_delta = X_DELTA(ctx.x_step);
ctx.y_step = (ctx.y_max - ctx.y_min) / LCD_HEIGHT;
ctx.step_log2 = ilog2_fp(MIN(ctx.x_step, ctx.y_step));
if (ctx.step_log2 == LOG2_OUT_OF_BOUNDS)
return 1; /* out of bounds */
ctx.x_delta = X_DELTA(ctx.x_step);
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);
ctx.ops->calc = (ctx.step_log2 <= -10) ?
mandelbrot_calc_high_prec : mandelbrot_calc_low_prec;
return 0;
}
static void mandelbrot_init(void)
@ -368,8 +376,9 @@ static void mandelbrot_move(int dx, int dy)
ctx.y_max += d_y;
}
static void mandelbrot_zoom(int factor)
static int mandelbrot_zoom(int factor)
{
int res;
long factor_x = (long)factor * ctx.x_delta;
long factor_y = (long)factor * ctx.y_delta;
@ -378,7 +387,11 @@ static void mandelbrot_zoom(int factor)
ctx.y_min += factor_y;
ctx.y_max -= factor_y;
recalc_parameters();
res = recalc_parameters();
if (res) /* zoom not possible, revert */
mandelbrot_zoom(-factor);
return res;
}
static int mandelbrot_precision(int d)