Vincent Povirk : windowscodecs: Support color-keyed transparency in PNG images.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: 80adebf76cbb5847ce710226a5beff8cc80b9559
URL:    http://source.winehq.org/git/wine.git/?a=commit;h=80adebf76cbb5847ce710226a5beff8cc80b9559

Author: Vincent Povirk <vincent at codeweavers.com>
Date:   Thu Aug 27 14:07:35 2009 -0500

windowscodecs: Support color-keyed transparency in PNG images.

---

 dlls/windowscodecs/pngformat.c |   29 +++++++++++++++++++++++++++++
 1 files changed, 29 insertions(+), 0 deletions(-)

diff --git a/dlls/windowscodecs/pngformat.c b/dlls/windowscodecs/pngformat.c
index cfc5d2d..be0bd6e 100644
--- a/dlls/windowscodecs/pngformat.c
+++ b/dlls/windowscodecs/pngformat.c
@@ -55,8 +55,11 @@ MAKE_FUNCPTR(png_get_io_ptr);
 MAKE_FUNCPTR(png_get_PLTE);
 MAKE_FUNCPTR(png_get_tRNS);
 MAKE_FUNCPTR(png_set_bgr);
+MAKE_FUNCPTR(png_set_gray_1_2_4_to_8);
 MAKE_FUNCPTR(png_set_gray_to_rgb);
 MAKE_FUNCPTR(png_set_read_fn);
+MAKE_FUNCPTR(png_set_strip_16);
+MAKE_FUNCPTR(png_set_tRNS_to_alpha);
 MAKE_FUNCPTR(png_read_end);
 MAKE_FUNCPTR(png_read_image);
 MAKE_FUNCPTR(png_read_info);
@@ -83,8 +86,11 @@ static void *load_libpng(void)
         LOAD_FUNCPTR(png_get_PLTE);
         LOAD_FUNCPTR(png_get_tRNS);
         LOAD_FUNCPTR(png_set_bgr);
+        LOAD_FUNCPTR(png_set_gray_1_2_4_to_8);
         LOAD_FUNCPTR(png_set_gray_to_rgb);
         LOAD_FUNCPTR(png_set_read_fn);
+        LOAD_FUNCPTR(png_set_strip_16);
+        LOAD_FUNCPTR(png_set_tRNS_to_alpha);
         LOAD_FUNCPTR(png_read_end);
         LOAD_FUNCPTR(png_read_image);
         LOAD_FUNCPTR(png_read_info);
@@ -196,6 +202,10 @@ static HRESULT WINAPI PngDecoder_Initialize(IWICBitmapDecoder *iface, IStream *p
     UINT image_size;
     UINT i;
     int color_type, bit_depth;
+    png_bytep trans;
+    int num_trans;
+    png_uint_32 transparency;
+    png_color_16p trans_values;
     TRACE("(%p,%p,%x)\n", iface, pIStream, cacheOptions);
 
     /* initialize libpng */
@@ -242,6 +252,25 @@ static HRESULT WINAPI PngDecoder_Initialize(IWICBitmapDecoder *iface, IStream *p
     color_type = ppng_get_color_type(This->png_ptr, This->info_ptr);
     bit_depth = ppng_get_bit_depth(This->png_ptr, This->info_ptr);
 
+    /* check for color-keyed alpha */
+    transparency = ppng_get_tRNS(This->png_ptr, This->info_ptr, &trans, &num_trans, &trans_values);
+
+    if (transparency && color_type != PNG_COLOR_TYPE_PALETTE)
+    {
+        /* expand to RGBA */
+        if (color_type == PNG_COLOR_TYPE_GRAY)
+        {
+            if (bit_depth < 8)
+            {
+                ppng_set_gray_1_2_4_to_8(This->png_ptr);
+                bit_depth = 8;
+            }
+            ppng_set_gray_to_rgb(This->png_ptr);
+        }
+        ppng_set_tRNS_to_alpha(This->png_ptr);
+        color_type = PNG_COLOR_TYPE_RGB_ALPHA;
+    }
+
     switch (color_type)
     {
     case PNG_COLOR_TYPE_GRAY: