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[libpng17] correct low-depth-gray code and enable tests

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The low-bit-depth gray tests were disabled in prior versions of libpng because
of problems which should have been fixed by the recent changes to libpng17,
enabling the tests reveals bugs in those changes which are fixed by this commit.

Signed-off-by: John Bowler <jbowler@acm.org>
This commit is contained in:
John Bowler
2015-09-16 21:09:10 -07:00
parent bb4e79c947
commit 601ae5387e
3 changed files with 237 additions and 84 deletions
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25
contrib/libtests/pngvalid.c
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@@ -5661,10 +5661,13 @@ image_pixel_convert_PLTE(image_pixel *this)
/* Add an alpha channel; this will import the tRNS information because tRNS is
* not valid in an alpha image. The bit depth will invariably be set to at
* least 8 prior to 1.7.0. Palette images will be converted to alpha (using
* the above API).
* the above API). With png_set_background the alpha channel is never expanded
* but this routine is used by pngvalid to simplify code; 'for_background'
* records this.
*/
static void
image_pixel_add_alpha(image_pixel *this, const standard_display *display)
image_pixel_add_alpha(image_pixel *this, const standard_display *display,
int for_background)
{
if (this->colour_type == PNG_COLOR_TYPE_PALETTE)
image_pixel_convert_PLTE(this);
@@ -5674,7 +5677,7 @@ image_pixel_add_alpha(image_pixel *this, const standard_display *display)
if (this->colour_type == PNG_COLOR_TYPE_GRAY)
{
# if PNG_LIBPNG_VER < 10700
if (this->bit_depth < 8)
if (!for_background && this->bit_depth < 8)
this->bit_depth = this->sample_depth = 8;
# endif
@@ -5684,7 +5687,7 @@ image_pixel_add_alpha(image_pixel *this, const standard_display *display)
* tRNS chunk to expand at this point.
*/
# if PNG_LIBPNG_VER >= 10700
if (this->bit_depth < 8)
if (!for_background && this->bit_depth < 8)
this->bit_depth = this->sample_depth = 8;
# endif
@@ -6574,7 +6577,7 @@ image_transform_png_set_tRNS_to_alpha_mod(const image_transform *this,
if (that->colour_type != PNG_COLOR_TYPE_PALETTE &&
(that->colour_type & PNG_COLOR_MASK_ALPHA) == 0)
# endif
image_pixel_add_alpha(that, &display->this);
image_pixel_add_alpha(that, &display->this, 0/*!for background*/);
#if PNG_LIBPNG_VER < 10700
/* LIBPNG BUG: otherwise libpng still expands to 8 bits! */
@@ -6638,7 +6641,7 @@ image_transform_png_set_gray_to_rgb_mod(const image_transform *this,
* doesn't do this, so we don't either.
*/
if ((that->colour_type & PNG_COLOR_MASK_COLOR) == 0 && that->have_tRNS)
image_pixel_add_alpha(that, &display->this);
image_pixel_add_alpha(that, &display->this, 0/*!for background*/);
/* Simply expand the bit depth and alter the colour type as required. */
if (that->colour_type == PNG_COLOR_TYPE_GRAY)
@@ -6702,7 +6705,7 @@ image_transform_png_set_expand_mod(const image_transform *this,
that->sample_depth = that->bit_depth = 8;
if (that->have_tRNS)
image_pixel_add_alpha(that, &display->this);
image_pixel_add_alpha(that, &display->this, 0/*!for background*/);
this->next->mod(this->next, that, pp, display);
}
@@ -6812,7 +6815,7 @@ image_transform_png_set_expand_16_mod(const image_transform *this,
image_pixel_convert_PLTE(that);
if (that->have_tRNS)
image_pixel_add_alpha(that, &display->this);
image_pixel_add_alpha(that, &display->this, 0/*!for background*/);
if (that->bit_depth < 16)
that->sample_depth = that->bit_depth = 16;
@@ -7755,7 +7758,7 @@ image_transform_png_set_background_mod(const image_transform *this,
{
/* Check for tRNS first: */
if (that->have_tRNS && that->colour_type != PNG_COLOR_TYPE_PALETTE)
image_pixel_add_alpha(that, &display->this);
image_pixel_add_alpha(that, &display->this, 1/*for background*/);
/* This is only necessary if the alpha value is less than 1. */
if (that->alphaf < 1)
@@ -11109,9 +11112,9 @@ int main(int argc, char **argv)
# endif
pm.test_lbg = 0;
pm.test_lbg_gamma_threshold = 1;
pm.test_lbg_gamma_transform = 0/*PNG_LIBPNG_VER >= 10700*/;
pm.test_lbg_gamma_transform = PNG_LIBPNG_VER >= 10600;
pm.test_lbg_gamma_sbit = 1;
pm.test_lbg_gamma_composition = 0;
pm.test_lbg_gamma_composition = PNG_LIBPNG_VER >= 10700;
/* And the test encodings */
pm.encodings = test_encodings;