>From 64aa756cfa5943c8b3494ac1fbb4db712c50ae64 Mon Sep 17 00:00:00 2001 From: Paul Eggert Date: Sun, 25 Aug 2019 10:01:46 -0700 Subject: [PATCH] Fix misdisplay of PNG paletted images Problem reported by Roland Winkler (Bug#37153). Derived from a patch suggested by YAMAMOTO Mitsuharu (Bug#37153#62). * src/image.c (png_get_valid) [WINDOWSNT]: Do not dynamically link this function. (png_get_tRNS) [WINDOWSNT && PNG_tRNS_SUPPORTED]: Dynamically link this function instead. (png_load_body): Do not assume that every paletted image supplies only transparency data. Fix typo in use of transparent_p. --- src/image.c | 34 +++++++++++++++++++++++++--------- 1 file changed, 25 insertions(+), 9 deletions(-) diff --git a/src/image.c b/src/image.c index 81d8cb4e2b..18495612e9 100644 --- a/src/image.c +++ b/src/image.c @@ -6234,7 +6234,10 @@ DEF_DLL_FN (void, png_read_info, (png_structp, png_infop)); DEF_DLL_FN (png_uint_32, png_get_IHDR, (png_structp, png_infop, png_uint_32 *, png_uint_32 *, int *, int *, int *, int *, int *)); -DEF_DLL_FN (png_uint_32, png_get_valid, (png_structp, png_infop, png_uint_32)); +# ifdef PNG_tRNS_SUPPORTED +DEF_DLL_FN (png_uint_32, png_get_tRNS, (png_structp, png_infop, png_bytep *, + int *, png_color_16p *)); +# endif DEF_DLL_FN (void, png_set_strip_16, (png_structp)); DEF_DLL_FN (void, png_set_expand, (png_structp)); DEF_DLL_FN (void, png_set_gray_to_rgb, (png_structp)); @@ -6273,7 +6276,9 @@ init_png_functions (void) LOAD_DLL_FN (library, png_set_sig_bytes); LOAD_DLL_FN (library, png_read_info); LOAD_DLL_FN (library, png_get_IHDR); - LOAD_DLL_FN (library, png_get_valid); +# ifdef PNG_tRNS_SUPPORTED + LOAD_DLL_FN (library, png_get_tRNS); +# endif LOAD_DLL_FN (library, png_set_strip_16); LOAD_DLL_FN (library, png_set_expand); LOAD_DLL_FN (library, png_set_gray_to_rgb); @@ -6304,7 +6309,7 @@ init_png_functions (void) # undef png_get_IHDR # undef png_get_io_ptr # undef png_get_rowbytes -# undef png_get_valid +# undef png_get_tRNS # undef png_longjmp # undef png_read_end # undef png_read_image @@ -6329,7 +6334,7 @@ init_png_functions (void) # define png_get_IHDR fn_png_get_IHDR # define png_get_io_ptr fn_png_get_io_ptr # define png_get_rowbytes fn_png_get_rowbytes -# define png_get_valid fn_png_get_valid +# define png_get_tRNS fn_png_get_tRNS # define png_longjmp fn_png_longjmp # define png_read_end fn_png_read_end # define png_read_image fn_png_read_image @@ -6589,10 +6594,21 @@ png_load_body (struct frame *f, struct image *img, struct png_load_context *c) /* If image contains simply transparency data, we prefer to construct a clipping mask. */ - if (png_get_valid (png_ptr, info_ptr, PNG_INFO_tRNS)) - transparent_p = 1; - else - transparent_p = 0; + transparent_p = false; +# ifdef PNG_tRNS_SUPPORTED + png_bytep trans_alpha; + int num_trans; + if (png_get_tRNS (png_ptr, info_ptr, &trans_alpha, &num_trans, NULL) + && trans_alpha) + { + int i; + for (i = 0; i < num_trans; i++) + if (0 < trans_alpha[i] && trans_alpha[i] < 255) + break; + if (! (i < num_trans)) + transparent_p = true; + } +# endif /* This function is easier to write if we only have to handle one data format: RGB or RGBA with 8 bits per channel. Let's @@ -6680,7 +6696,7 @@ png_load_body (struct frame *f, struct image *img, struct png_load_context *c) /* Create an image and pixmap serving as mask if the PNG image contains an alpha channel. */ if (channels == 4 - && !transparent_p + && transparent_p && !image_create_x_image_and_pixmap (f, img, width, height, 1, &mask_img, 1)) { -- 2.17.1