[gtk/gamma-shenanigans: 6/7] Allow conversion to hdr formats

[Matthias Clasen <matthiasc src gnome org>]

commit 8e443b9a15970b3d8e3809f82634ec619329a4f6
Author: Matthias Clasen <mclasen redhat com>
Date:   Wed Sep 8 09:38:34 2021 -0400

    Allow conversion to hdr formats
    
    Add conversion functions that produce
    GDK_MEMORY_R32G32B32A32_PREMULTIPLIED data,
    since we want to allow downloading textures
    in that format. We make use of the new chaining
    abilities here to cut down on the number of
    conversion functions.

 gdk/gdkmemorytexture.c | 168 ++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 167 insertions(+), 1 deletion(-)
---
diff --git a/gdk/gdkmemorytexture.c b/gdk/gdkmemorytexture.c
index 5067c4558e..0a9d86e0bc 100644
--- a/gdk/gdkmemorytexture.c
+++ b/gdk/gdkmemorytexture.c
@@ -550,11 +550,177 @@ static ConversionFunc converters_to_rgba[GDK_MEMORY_N_FORMATS] =
   convert_float_swizzle_3012
 };
 
+static void
+convert_rgba_to_hdr (guchar       *dest_data,
+                     gsize         dest_stride,
+                     GdkMemoryFormat  dest_format,
+                     const guchar *src_data,
+                     gsize         src_stride,
+                     GdkMemoryFormat  src_format,
+                     gsize         width,
+                     gsize         height)
+{
+  gsize x, y;
+
+  for (y = 0; y < height; y++)
+    {
+      guint16 *src = (guint16 *)src_data;
+      float *dest = (float *)dest_data;
+      for (x = 0; x < width; x++)
+        {
+          dest[4 * (y * width + x) + 0] = src[3 * (y * width + x) + 0] / 255.f;
+          dest[4 * (y * width + x) + 1] = src[3 * (y * width + x) + 1] / 255.f;
+          dest[4 * (y * width + x) + 2] = src[3 * (y * width + x) + 2] / 255.f;
+          dest[4 * (y * width + x) + 3] = src[3 * (y * width + x) + 3] / 255.f;
+        }
+      dest_data += dest_stride;
+      src_data += src_stride;
+    }
+}
+
+static void
+convert_8bit_to_hdr (guchar       *dest_data,
+                     gsize         dest_stride,
+                     GdkMemoryFormat  dest_format,
+                     const guchar *src_data,
+                     gsize         src_stride,
+                     GdkMemoryFormat  src_format,
+                     gsize         width,
+                     gsize         height)
+{
+  guchar *data;
+
+  /* TODO: this could perhaps be done in-place */
+  data = g_malloc (width * height * 4);
+
+  gdk_memory_convert (data, 4 * width, GDK_MEMORY_R8G8B8A8_PREMULTIPLIED,
+                      src_data, src_stride, src_format,
+                      width, height);
+  convert_rgba_to_hdr (dest_data, dest_stride, dest_format,
+                       data, 4 * width, GDK_MEMORY_R8G8B8A8_PREMULTIPLIED,
+                       width, height);
+
+  g_free (data);
+}
+
+static void
+convert_16bit_to_hdr (guchar       *dest_data,
+                      gsize         dest_stride,
+                      GdkMemoryFormat  dest_format,
+                      const guchar *src_data,
+                      gsize         src_stride,
+                      GdkMemoryFormat  src_format,
+                      gsize         width,
+                      gsize         height)
+{
+  gsize x, y;
+
+  for (y = 0; y < height; y++)
+    {
+      guint16 *src = (guint16 *)src_data;
+      float *dest = (float *)dest_data;
+      for (x = 0; x < width; x++)
+        {
+          dest[4 * (y * width + x) + 0] = src[3 * (y * width + x) + 0] / 65535.f;
+          dest[4 * (y * width + x) + 1] = src[3 * (y * width + x) + 1] / 65535.f;
+          dest[4 * (y * width + x) + 2] = src[3 * (y * width + x) + 2] / 65535.f;
+          dest[4 * (y * width + x) + 3] = src[3 * (y * width + x) + 3] / 65535.f;
+        }
+      dest_data += dest_stride;
+      src_data += src_stride;
+    }
+}
+
+static void
+convert_fp16_to_hdr (guchar       *dest_data,
+                     gsize         dest_stride,
+                     GdkMemoryFormat  dest_format,
+                     const guchar *src_data,
+                     gsize         src_stride,
+                     GdkMemoryFormat  src_format,
+                     gsize         width,
+                     gsize         height)
+{
+  gsize x, y;
+  int src_bpp;
+
+  if (src_format == GDK_MEMORY_R16G16B16A16_FLOAT_PREMULTIPLIED)
+    src_bpp = 4;
+  else
+    src_bpp = 3;
+
+  for (y = 0; y < height; y++)
+    {
+      guint16 *src = (guint16 *)src_data;
+      float *dest = (float *)dest_data;
+      for (x = 0; x < width; x++)
+        {
+          guint16 h[4];
+
+          h[0] = src[src_bpp * (y * width + x)];
+          h[1] = src[src_bpp * (y * width + x) + 1];
+          h[2] = src[src_bpp * (y * width + x) + 2];
+          if (src_bpp == 4)
+            h[3] = src[src_bpp * (y * width + x) + 3];
+          else
+            h[3] = FP16_ONE;
+          half_to_float4 (h, &dest[4 * (y * width + x)]);
+        }
+      dest_data += dest_stride;
+      src_data += src_stride;
+    }
+}
+
+static void
+convert_float_to_hdr (guchar       *dest_data,
+                      gsize         dest_stride,
+                      GdkMemoryFormat  dest_format,
+                      const guchar *src_data,
+                      gsize         src_stride,
+                      GdkMemoryFormat  src_format,
+                      gsize         width,
+                      gsize         height)
+{
+  gsize x, y;
+
+  for (y = 0; y < height; y++)
+    {
+      float *src = (float *)src_data;
+      float *dest = (float *)dest_data;
+      for (x = 0; x < width; x++)
+        {
+          dest[4 * (y * width + x) + 0] = src[3 * (y * width + x) + 0];
+          dest[4 * (y * width + x) + 1] = src[3 * (y * width + x) + 1];
+          dest[4 * (y * width + x) + 2] = src[3 * (y * width + x) + 2];
+          dest[4 * (y * width + x) + 3] = 1.0;
+        }
+      dest_data += dest_stride;
+      src_data += src_stride;
+    }
+}
+
+static ConversionFunc converters_to_hdr[GDK_MEMORY_N_FORMATS] =
+{
+  convert_8bit_to_hdr,
+  convert_8bit_to_hdr,
+  convert_rgba_to_hdr,
+  convert_8bit_to_hdr,
+  convert_8bit_to_hdr,
+  convert_8bit_to_hdr,
+  convert_8bit_to_hdr,
+  convert_8bit_to_hdr,
+  convert_8bit_to_hdr,
+  convert_16bit_to_hdr,
+  convert_fp16_to_hdr,
+  convert_fp16_to_hdr,
+  convert_float_to_hdr,
+  convert_memcpy
+};
 static ConversionFunc* converters[GDK_MEMORY_N_FORMATS] = {
   converters_to_bgra, converters_to_argb, converters_to_rgba,
   NULL, NULL, NULL, NULL, NULL, NULL,
   NULL, NULL, NULL, NULL,
-  NULL
+  converters_to_hdr
 };
 
 void