[gtk/matthiasc/color-profile-rebased: 16/43] png: Handle color profiles

[Matthias Clasen <matthiasc src gnome org>]

commit d0694a16f1b606a7dd1833b020745c7b58217b31
Author: Benjamin Otte <otte redhat com>
Date:   Sun May 8 10:12:59 2022 -0400

    png: Handle color profiles

 gdk/loaders/gdkpng.c | 124 ++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 119 insertions(+), 5 deletions(-)
---
diff --git a/gdk/loaders/gdkpng.c b/gdk/loaders/gdkpng.c
index 471216087d..8678c5bf4d 100644
--- a/gdk/loaders/gdkpng.c
+++ b/gdk/loaders/gdkpng.c
@@ -19,6 +19,7 @@
 
 #include "gdkpngprivate.h"
 
+#include "gdkcolorprofileprivate.h"
 #include "gdkintl.h"
 #include "gdkmemoryformatprivate.h"
 #include "gdkmemorytextureprivate.h"
@@ -127,8 +128,102 @@ png_simple_warning_callback (png_structp     png,
 {
 }
 
-/* }}} */
-/* {{{ Public API */
+static GdkColorProfile *
+gdk_png_get_color_profile (png_struct *png,
+                           png_info   *info)
+{
+  GdkColorProfile *profile;
+  guchar *icc_data;
+  png_uint_32 icc_len;
+  char *name;
+  double gamma;
+  cmsCIExyY whitepoint;
+  cmsCIExyYTRIPLE primaries;
+  cmsToneCurve *curve;
+  cmsHPROFILE lcms_profile;
+  int intent;
+
+  if (png_get_iCCP (png, info, &name, NULL, &icc_data, &icc_len))
+    {
+      GBytes *bytes = g_bytes_new (icc_data, icc_len);
+
+      profile = gdk_color_profile_new_from_icc_bytes (bytes, NULL);
+      g_bytes_unref (bytes);
+      if (profile)
+        return profile;
+    }
+
+  if (png_get_sRGB (png, info, &intent))
+    return g_object_ref (gdk_color_profile_get_srgb ());
+
+  /* If neither of those is valid, the result is sRGB */
+  if (!png_get_valid (png, info, PNG_INFO_gAMA) &&
+      !png_get_valid (png, info, PNG_INFO_cHRM))
+    return g_object_ref (gdk_color_profile_get_srgb ());
+
+  if (!png_get_gAMA (png, info, &gamma))
+    gamma = 2.4;
+
+  if (!png_get_cHRM (png, info,
+                     &whitepoint.x, &whitepoint.y,
+                     &primaries.Red.x, &primaries.Red.y,
+                     &primaries.Green.x, &primaries.Green.y,
+                     &primaries.Blue.x, &primaries.Blue.y))
+    {
+      if (gamma == 2.4)
+        return g_object_ref (gdk_color_profile_get_srgb ());
+
+      whitepoint = (cmsCIExyY) { 0.3127, 0.3290, 1.0 };
+      primaries = (cmsCIExyYTRIPLE) {
+                    { 0.6400, 0.3300, 1.0 },
+                    { 0.3000, 0.6000, 1.0 },
+                    { 0.1500, 0.0600, 1.0 }
+                  };
+    }
+  else
+    {
+      primaries.Red.Y = 1.0;
+      primaries.Green.Y = 1.0;
+      primaries.Blue.Y = 1.0;
+    }
+
+  curve = cmsBuildGamma (NULL, 1.0 / gamma);
+  lcms_profile = cmsCreateRGBProfile (&whitepoint,
+                                      &primaries,
+                                      (cmsToneCurve*[3]) { curve, curve, curve });
+  profile = gdk_color_profile_new_from_lcms_profile (lcms_profile, NULL);
+  /* FIXME: errors? */
+  if (profile == NULL)
+    profile = g_object_ref (gdk_color_profile_get_srgb ());
+  cmsFreeToneCurve (curve);
+
+  return profile;
+}
+
+static void
+gdk_png_set_color_profile (png_struct      *png,
+                           png_info        *info,
+                           GdkColorProfile *profile)
+{
+  /* FIXME: allow deconstructing RGB profiles into gAMA and cHRM instead of
+   * falling back to iCCP */
+  if (profile == gdk_color_profile_get_srgb ())
+    {
+      png_set_sRGB_gAMA_and_cHRM (png, info, /* FIXME */ PNG_sRGB_INTENT_PERCEPTUAL);
+    }
+  else
+    {
+      GBytes *bytes = gdk_color_profile_get_icc_profile (profile);
+      png_set_iCCP (png, info,
+                    "ICC profile",
+                    0,
+                    g_bytes_get_data (bytes, NULL),
+                    g_bytes_get_size (bytes));
+    }
+}
+
+ /* }}} */
+ /* {{{ Public API */
 
 GdkTexture *
 gdk_load_png (GBytes  *bytes,
@@ -144,6 +239,7 @@ gdk_load_png (GBytes  *bytes,
   guchar *buffer = NULL;
   guchar **row_pointers = NULL;
   GBytes *out_bytes;
+  GdkColorProfile *color_profile;
   GdkTexture *texture;
   int bpp;
   G_GNUC_UNUSED gint64 before = GDK_PROFILER_CURRENT_TIME;
@@ -247,6 +343,8 @@ gdk_load_png (GBytes  *bytes,
       return NULL;
     }
 
+  color_profile = gdk_png_get_color_profile (png, info);
+
   bpp = gdk_memory_format_bytes_per_pixel (format);
   stride = width * bpp;
   if (stride % 8)
@@ -257,6 +355,7 @@ gdk_load_png (GBytes  *bytes,
 
   if (!buffer || !row_pointers)
     {
+      g_object_unref (color_profile);
       g_free (buffer);
       g_free (row_pointers);
       png_destroy_read_struct (&png, &info, NULL);
@@ -273,8 +372,11 @@ gdk_load_png (GBytes  *bytes,
   png_read_end (png, info);
 
   out_bytes = g_bytes_new_take (buffer, height * stride);
-  texture = gdk_memory_texture_new (width, height, format, out_bytes, stride);
+  texture = gdk_memory_texture_new_with_color_profile (width, height,
+                                                       format, color_profile,
+                                                       out_bytes, stride);
   g_bytes_unref (out_bytes);
+  g_object_unref (color_profile);
 
   g_free (row_pointers);
   png_destroy_read_struct (&png, &info, NULL);
@@ -301,13 +403,17 @@ gdk_save_png (GdkTexture *texture)
   int y;
   GdkMemoryTexture *memtex;
   GdkMemoryFormat format;
+  GdkColorProfile *color_profile;
   int png_format;
   int depth;
 
   width = gdk_texture_get_width (texture);
   height = gdk_texture_get_height (texture);
+  color_profile = gdk_texture_get_color_profile (texture);
   format = gdk_texture_get_format (texture);
 
+  memtex = gdk_memory_texture_from_texture (texture, format, color_profile);
+
   switch (format)
     {
     case GDK_MEMORY_B8G8R8A8_PREMULTIPLIED:
@@ -317,14 +423,22 @@ gdk_save_png (GdkTexture *texture)
     case GDK_MEMORY_A8R8G8B8:
     case GDK_MEMORY_R8G8B8A8:
     case GDK_MEMORY_A8B8G8R8:
+#if G_BYTE_ORDER == G_LITTLE_ENDIAN
       format = GDK_MEMORY_R8G8B8A8;
+#elif G_BYTE_ORDER == G_BIG_ENDIAN
+      format = GDK_MEMORY_A8B8G8R8;
+#endif
       png_format = PNG_COLOR_TYPE_RGB_ALPHA;
       depth = 8;
       break;
 
     case GDK_MEMORY_R8G8B8:
     case GDK_MEMORY_B8G8R8:
+#if G_BYTE_ORDER == G_LITTLE_ENDIAN
       format = GDK_MEMORY_R8G8B8;
+#elif G_BYTE_ORDER == G_BIG_ENDIAN
+      format = GDK_MEMORY_B8G8R8;
+#endif
       png_format = PNG_COLOR_TYPE_RGB;
       depth = 8;
       break;
@@ -369,8 +483,6 @@ gdk_save_png (GdkTexture *texture)
       return NULL;
     }
 
-  memtex = gdk_memory_texture_from_texture (texture, format, gdk_color_profile_get_srgb ());
-
   if (sigsetjmp (png_jmpbuf (png), 1))
     {
       g_object_unref (memtex);
@@ -387,6 +499,8 @@ gdk_save_png (GdkTexture *texture)
                 PNG_COMPRESSION_TYPE_DEFAULT,
                 PNG_FILTER_TYPE_DEFAULT);
 
+  gdk_png_set_color_profile (png, info, color_profile);
+
   png_write_info (png, info);
 
 #if G_BYTE_ORDER == G_LITTLE_ENDIAN