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[libpng16] Removed WRITE_WEIGHTED_FILTERED code, to save a few kbytes of the

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compiled library size. It never worked properly and as far as we can
tell, no one uses it. The png_set_filter_heuristics() and
png_set_filter_heuristics_fixed() APIs are retained but deprecated
and do nothing.
This commit is contained in:
Glenn Randers-Pehrson
2015-05-31 22:40:36 -05:00
parent a008dd8344
commit 89edbf8317
5 changed files with 30 additions and 538 deletions
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243
pngwrite.c
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@@ -922,10 +922,6 @@ png_write_flush(png_structrp png_ptr)
}
#endif /* WRITE_FLUSH */
#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
static void png_reset_filter_heuristics(png_structrp png_ptr);/* forward decl */
#endif
/* Free any memory used in png_ptr struct without freeing the struct itself. */
static void
png_write_destroy(png_structrp png_ptr)
@@ -949,15 +945,6 @@ png_write_destroy(png_structrp png_ptr)
png_ptr->tst_row = NULL;
#endif
#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
/* Use this to save a little code space, it doesn't free the filter_costs */
png_reset_filter_heuristics(png_ptr);
png_free(png_ptr, png_ptr->filter_costs);
png_free(png_ptr, png_ptr->inv_filter_costs);
png_ptr->filter_costs = NULL;
png_ptr->inv_filter_costs = NULL;
#endif
#ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
png_free(png_ptr, png_ptr->chunk_list);
png_ptr->chunk_list = NULL;
@@ -1127,174 +1114,18 @@ png_set_filter(png_structrp png_ptr, int method, int filters)
* better compression.
*/
#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED /* GRR 970116 */
/* Convenience reset API. */
static void
png_reset_filter_heuristics(png_structrp png_ptr)
{
/* Clear out any old values in the 'weights' - this must be done because if
* the app calls set_filter_heuristics multiple times with different
* 'num_weights' values we would otherwise potentially have wrong sized
* arrays.
*/
png_ptr->num_prev_filters = 0;
png_ptr->heuristic_method = PNG_FILTER_HEURISTIC_UNWEIGHTED;
if (png_ptr->prev_filters != NULL)
{
png_bytep old = png_ptr->prev_filters;
png_ptr->prev_filters = NULL;
png_free(png_ptr, old);
}
if (png_ptr->filter_weights != NULL)
{
png_uint_16p old = png_ptr->filter_weights;
png_ptr->filter_weights = NULL;
png_free(png_ptr, old);
}
if (png_ptr->inv_filter_weights != NULL)
{
png_uint_16p old = png_ptr->inv_filter_weights;
png_ptr->inv_filter_weights = NULL;
png_free(png_ptr, old);
}
/* Leave the filter_costs - this array is fixed size. */
}
static int
png_init_filter_heuristics(png_structrp png_ptr, int heuristic_method,
int num_weights)
{
if (png_ptr == NULL)
return 0;
/* Clear out the arrays */
png_reset_filter_heuristics(png_ptr);
/* Check arguments; the 'reset' function makes the correct settings for the
* unweighted case, but we must handle the weight case by initializing the
* arrays for the caller.
*/
if (heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
{
int i;
if (num_weights > 0)
{
png_ptr->prev_filters = (png_bytep)png_malloc(png_ptr,
(png_uint_32)((sizeof (png_byte)) * num_weights));
/* To make sure that the weighting starts out fairly */
for (i = 0; i < num_weights; i++)
{
png_ptr->prev_filters[i] = 255;
}
png_ptr->filter_weights = (png_uint_16p)png_malloc(png_ptr,
(png_uint_32)((sizeof (png_uint_16)) * num_weights));
png_ptr->inv_filter_weights = (png_uint_16p)png_malloc(png_ptr,
(png_uint_32)((sizeof (png_uint_16)) * num_weights));
for (i = 0; i < num_weights; i++)
{
png_ptr->inv_filter_weights[i] =
png_ptr->filter_weights[i] = PNG_WEIGHT_FACTOR;
}
/* Safe to set this now */
png_ptr->num_prev_filters = (png_byte)num_weights;
}
/* If, in the future, there are other filter methods, this would
* need to be based on png_ptr->filter.
*/
if (png_ptr->filter_costs == NULL)
{
png_ptr->filter_costs = (png_uint_16p)png_malloc(png_ptr,
(png_uint_32)((sizeof (png_uint_16)) * PNG_FILTER_VALUE_LAST));
png_ptr->inv_filter_costs = (png_uint_16p)png_malloc(png_ptr,
(png_uint_32)((sizeof (png_uint_16)) * PNG_FILTER_VALUE_LAST));
}
for (i = 0; i < PNG_FILTER_VALUE_LAST; i++)
{
png_ptr->inv_filter_costs[i] =
png_ptr->filter_costs[i] = PNG_COST_FACTOR;
}
/* All the arrays are inited, safe to set this: */
png_ptr->heuristic_method = PNG_FILTER_HEURISTIC_WEIGHTED;
/* Return the 'ok' code. */
return 1;
}
else if (heuristic_method == PNG_FILTER_HEURISTIC_DEFAULT ||
heuristic_method == PNG_FILTER_HEURISTIC_UNWEIGHTED)
{
return 1;
}
else
{
png_warning(png_ptr, "Unknown filter heuristic method");
return 0;
}
}
/* Provide floating and fixed point APIs */
/* Provide floating and fixed point APIs (DEPRECATED) */
#ifdef PNG_FLOATING_POINT_SUPPORTED
void PNGAPI
png_set_filter_heuristics(png_structrp png_ptr, int heuristic_method,
int num_weights, png_const_doublep filter_weights,
png_const_doublep filter_costs)
{
png_debug(1, "in png_set_filter_heuristics");
/* The internal API allocates all the arrays and ensures that the elements of
* those arrays are set to the default value.
*/
if (png_init_filter_heuristics(png_ptr, heuristic_method, num_weights) == 0)
return;
/* If using the weighted method copy in the weights. */
if (heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
{
int i;
for (i = 0; i < num_weights; i++)
{
if (filter_weights[i] <= 0.0)
{
png_ptr->inv_filter_weights[i] =
png_ptr->filter_weights[i] = PNG_WEIGHT_FACTOR;
}
else
{
png_ptr->inv_filter_weights[i] =
(png_uint_16)(PNG_WEIGHT_FACTOR*filter_weights[i]+.5);
png_ptr->filter_weights[i] =
(png_uint_16)(PNG_WEIGHT_FACTOR/filter_weights[i]+.5);
}
}
/* Here is where we set the relative costs of the different filters. We
* should take the desired compression level into account when setting
* the costs, so that Paeth, for instance, has a high relative cost at low
* compression levels, while it has a lower relative cost at higher
* compression settings. The filter types are in order of increasing
* relative cost, so it would be possible to do this with an algorithm.
*/
for (i = 0; i < PNG_FILTER_VALUE_LAST; i++) if (filter_costs[i] >= 1.0)
{
png_ptr->inv_filter_costs[i] =
(png_uint_16)(PNG_COST_FACTOR / filter_costs[i] + .5);
png_ptr->filter_costs[i] =
(png_uint_16)(PNG_COST_FACTOR * filter_costs[i] + .5);
}
}
PNG_UNUSED(png_ptr)
PNG_UNUSED(heuristic_method)
PNG_UNUSED(num_weights)
PNG_UNUSED(filter_weights)
PNG_UNUSED(filter_costs)
}
#endif /* FLOATING_POINT */
@@ -1304,63 +1135,11 @@ png_set_filter_heuristics_fixed(png_structrp png_ptr, int heuristic_method,
int num_weights, png_const_fixed_point_p filter_weights,
png_const_fixed_point_p filter_costs)
{
png_debug(1, "in png_set_filter_heuristics_fixed");
/* The internal API allocates all the arrays and ensures that the elements of
* those arrays are set to the default value.
*/
if (png_init_filter_heuristics(png_ptr, heuristic_method, num_weights) == 0)
return;
/* If using the weighted method copy in the weights. */
if (heuristic_method == PNG_FILTER_HEURISTIC_WEIGHTED)
{
int i;
for (i = 0; i < num_weights; i++)
{
if (filter_weights[i] <= 0)
{
png_ptr->inv_filter_weights[i] =
png_ptr->filter_weights[i] = PNG_WEIGHT_FACTOR;
}
else
{
png_ptr->inv_filter_weights[i] = (png_uint_16)
((PNG_WEIGHT_FACTOR*filter_weights[i]+PNG_FP_HALF)/PNG_FP_1);
png_ptr->filter_weights[i] = (png_uint_16)((PNG_WEIGHT_FACTOR*
PNG_FP_1+(filter_weights[i]/2))/filter_weights[i]);
}
}
/* Here is where we set the relative costs of the different filters. We
* should take the desired compression level into account when setting
* the costs, so that Paeth, for instance, has a high relative cost at low
* compression levels, while it has a lower relative cost at higher
* compression settings. The filter types are in order of increasing
* relative cost, so it would be possible to do this with an algorithm.
*/
for (i = 0; i < PNG_FILTER_VALUE_LAST; i++)
if (filter_costs[i] >= PNG_FP_1)
{
png_uint_32 tmp;
/* Use a 32 bit unsigned temporary here because otherwise the
* intermediate value will be a 32 bit *signed* integer (ANSI rules)
* and this will get the wrong answer on division.
*/
tmp = PNG_COST_FACTOR*PNG_FP_1 + (filter_costs[i]/2);
tmp /= filter_costs[i];
png_ptr->inv_filter_costs[i] = (png_uint_16)tmp;
tmp = PNG_COST_FACTOR * filter_costs[i] + PNG_FP_HALF;
tmp /= PNG_FP_1;
png_ptr->filter_costs[i] = (png_uint_16)tmp;
}
}
PNG_UNUSED(png_ptr)
PNG_UNUSED(heuristic_method)
PNG_UNUSED(num_weights)
PNG_UNUSED(filter_weights)
PNG_UNUSED(filter_costs)
}
#endif /* FIXED_POINT */
#endif /* WRITE_WEIGHTED_FILTER */