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[libpng17] 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.
This commit is contained in:
Glenn Randers-Pehrson
2015-05-31 16:22:44 -05:00
parent f19f7a6c95
commit 13d83c6948
6 changed files with 29 additions and 557 deletions
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36
png.h
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@@ -1747,46 +1747,18 @@ PNG_EXPORT(67, void, png_set_filter, (png_structrp png_ptr, int method,
PNG_FILTER_AVG | PNG_FILTER_PAETH)
#ifdef PNG_WRITE_SUPPORTED
#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED /* EXPERIMENTAL */
/* The "heuristic_method" is given by one of the PNG_FILTER_HEURISTIC_
* defines, either the default (minimum-sum-of-absolute-differences), or
* the experimental method (weighted-minimum-sum-of-absolute-differences).
*
* Weights are factors >= 1.0, indicating how important it is to keep the
* filter type consistent between rows. Larger numbers mean the current
* filter is that many times as likely to be the same as the "num_weights"
* previous filters. This is cumulative for each previous row with a weight.
* There needs to be "num_weights" values in "filter_weights", or it can be
* NULL if the weights aren't being specified. Weights have no influence on
* the selection of the first row filter. Well chosen weights can (in theory)
* improve the compression for a given image.
*
* Costs are factors >= 1.0 indicating the relative decoding costs of a
* filter type. Higher costs indicate more decoding expense, and are
* therefore less likely to be selected over a filter with lower computational
* costs. There needs to be a value in "filter_costs" for each valid filter
* type (given by PNG_FILTER_VALUE_LAST), or it can be NULL if you aren't
* setting the costs. Costs try to improve the speed of decompression without
* unduly increasing the compressed image size.
*
* A negative weight or cost indicates the default value is to be used, and
* values in the range [0.0, 1.0) indicate the value is to remain unchanged.
* The default values for both weights and costs are currently 1.0, but may
* change if good general weighting/cost heuristics can be found. If both
* the weights and costs are set to 1.0, this degenerates the WEIGHTED method
* to the UNWEIGHTED method, but with added encoding time/computation.
*/
#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED /* DEPRECATED */
PNG_FP_EXPORT(68, void, 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_const_doublep filter_costs) PNG_DEPRECATED)
PNG_FIXED_EXPORT(209, void, 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_const_fixed_point_p filter_costs) PNG_DEPRECATED)
#endif /* WRITE_WEIGHTED_FILTER */
/* Heuristic used for row filter selection. These defines should NOT be
* changed.
* changed. As of libpng-1.7.0beta62, these are no longer used.
*/
#define PNG_FILTER_HEURISTIC_DEFAULT 0 /* Currently "UNWEIGHTED" */
#define PNG_FILTER_HEURISTIC_UNWEIGHTED 1 /* Used by libpng < 0.95 */