[gtk/gtk-4-6] gdk: Add a rgb8 → rgba8 conversion macro

[Matthias Clasen <matthiasc src gnome org>]

commit b8d01bf0415217d71db5105acc4d8e55f0d69f4b
Author: Emmanuel Gil Peyrot <linkmauve linkmauve fr>
Date:   Thu Mar 3 14:36:57 2022 +0000

    gdk: Add a rgb8 → rgba8 conversion macro
    
    This one can be used for both premultiplied and non-premultiplied alpha
    formats, since alpha is always 255.  It is useful for opaque PNG upload
    on both cairo and GL renderers.

 gdk/gdkmemoryformat.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)
---
diff --git a/gdk/gdkmemoryformat.c b/gdk/gdkmemoryformat.c
index adfa26610b..5bd7b228d4 100644
--- a/gdk/gdkmemoryformat.c
+++ b/gdk/gdkmemoryformat.c
@@ -192,6 +192,28 @@ PREMULTIPLY_FUNC(r8g8b8a8_to_b8g8r8a8_premultiplied, 0, 1, 2, 3, 2, 1, 0, 3)
 PREMULTIPLY_FUNC(r8g8b8a8_to_a8r8g8b8_premultiplied, 0, 1, 2, 3, 1, 2, 3, 0)
 PREMULTIPLY_FUNC(r8g8b8a8_to_a8b8g8r8_premultiplied, 0, 1, 2, 3, 3, 2, 1, 0)
 
+#define ADD_ALPHA_FUNC(name, R1, G1, B1, R2, G2, B2, A2) \
+static void \
+name (guchar *dest, \
+      const guchar *src, \
+      gsize n) \
+{ \
+  for (; n > 0; n--) \
+    { \
+      dest[R2] = src[R1]; \
+      dest[G2] = src[G1]; \
+      dest[B2] = src[B1]; \
+      dest[A2] = 255; \
+      dest += 4; \
+      src += 3; \
+    } \
+}
+
+ADD_ALPHA_FUNC(r8g8b8_to_r8g8b8a8, 0, 1, 2, 0, 1, 2, 3)
+ADD_ALPHA_FUNC(r8g8b8_to_b8g8r8a8, 0, 1, 2, 2, 1, 0, 3)
+ADD_ALPHA_FUNC(r8g8b8_to_a8r8g8b8, 0, 1, 2, 1, 2, 3, 0)
+ADD_ALPHA_FUNC(r8g8b8_to_a8b8g8r8, 0, 1, 2, 3, 2, 1, 0)
+
 struct _GdkMemoryFormatDescription
 {
   GdkMemoryAlpha alpha;
@@ -518,6 +540,30 @@ gdk_memory_convert (guchar              *dest_data,
     func = r8g8b8a8_to_a8r8g8b8_premultiplied;
   else if (src_format == GDK_MEMORY_B8G8R8A8 && dest_format == GDK_MEMORY_A8R8G8B8_PREMULTIPLIED)
     func = r8g8b8a8_to_a8b8g8r8_premultiplied;
+  else if (src_format == GDK_MEMORY_R8G8B8 && dest_format == GDK_MEMORY_R8G8B8A8_PREMULTIPLIED)
+    func = r8g8b8_to_r8g8b8a8;
+  else if (src_format == GDK_MEMORY_B8G8R8 && dest_format == GDK_MEMORY_R8G8B8A8_PREMULTIPLIED)
+    func = r8g8b8_to_b8g8r8a8;
+  else if (src_format == GDK_MEMORY_R8G8B8 && dest_format == GDK_MEMORY_B8G8R8A8_PREMULTIPLIED)
+    func = r8g8b8_to_b8g8r8a8;
+  else if (src_format == GDK_MEMORY_B8G8R8 && dest_format == GDK_MEMORY_B8G8R8A8_PREMULTIPLIED)
+    func = r8g8b8_to_r8g8b8a8;
+  else if (src_format == GDK_MEMORY_R8G8B8 && dest_format == GDK_MEMORY_A8R8G8B8_PREMULTIPLIED)
+    func = r8g8b8_to_a8r8g8b8;
+  else if (src_format == GDK_MEMORY_B8G8R8 && dest_format == GDK_MEMORY_A8R8G8B8_PREMULTIPLIED)
+    func = r8g8b8_to_a8b8g8r8;
+  else if (src_format == GDK_MEMORY_R8G8B8 && dest_format == GDK_MEMORY_R8G8B8A8)
+    func = r8g8b8_to_r8g8b8a8;
+  else if (src_format == GDK_MEMORY_B8G8R8 && dest_format == GDK_MEMORY_R8G8B8A8)
+    func = r8g8b8_to_b8g8r8a8;
+  else if (src_format == GDK_MEMORY_R8G8B8 && dest_format == GDK_MEMORY_B8G8R8A8)
+    func = r8g8b8_to_b8g8r8a8;
+  else if (src_format == GDK_MEMORY_B8G8R8 && dest_format == GDK_MEMORY_B8G8R8A8)
+    func = r8g8b8_to_r8g8b8a8;
+  else if (src_format == GDK_MEMORY_R8G8B8 && dest_format == GDK_MEMORY_A8R8G8B8)
+    func = r8g8b8_to_a8r8g8b8;
+  else if (src_format == GDK_MEMORY_B8G8R8 && dest_format == GDK_MEMORY_A8R8G8B8)
+    func = r8g8b8_to_a8b8g8r8;
 
   if (func != NULL)
     {