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gdk: Make the optimized premultiply function a macro

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That way, all permutations are possible.  Previously it was only useful
in the cairo renderer, which required rgba8 → premultiplied bgra8, while
the GL renderer required rgba8 → premultiplied rgba8.  Now both are
available.
This commit is contained in:
Emmanuel Gil Peyrot 2022-03-03 14:34:29 +00:00
parent cfeedcc321
commit 3a98b28ab7
1 changed files with 40 additions and 23 deletions
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63
gdk/gdkmemoryformat.c
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@ -166,29 +166,32 @@ r32g32b32a32_float_from_float (guchar *dest,
memcpy (dest, src, sizeof (float) * n * 4);
}
// This one conversion is quite important, it converts from RGBA with straight
// alpha (as found in PNG for instance) to BGRA with premultiplied alpha (the
// sole cairo format available).
static void
r8g8b8a8_to_b8g8r8a8_premultiplied (guchar *dest,
const guchar *src,
gsize n)
{
for (; n > 0; n--)
{
guchar a = src[3];
guint16 r = (guint16)src[0] * a + 127;
guint16 g = (guint16)src[1] * a + 127;
guint16 b = (guint16)src[2] * a + 127;
dest[0] = (b + (b >> 8) + 1) >> 8;
dest[1] = (g + (g >> 8) + 1) >> 8;
dest[2] = (r + (r >> 8) + 1) >> 8;
dest[3] = a;
dest += 4;
src += 4;
}
#define PREMULTIPLY_FUNC(name, R1, G1, B1, A1, R2, G2, B2, A2) \
static void \
name (guchar *dest, \
const guchar *src, \
gsize n) \
{ \
for (; n > 0; n--) \
{ \
guchar a = src[A1]; \
guint16 r = (guint16)src[R1] * a + 127; \
guint16 g = (guint16)src[G1] * a + 127; \
guint16 b = (guint16)src[B1] * a + 127; \
dest[R2] = (r + (r >> 8) + 1) >> 8; \
dest[G2] = (g + (g >> 8) + 1) >> 8; \
dest[B2] = (b + (b >> 8) + 1) >> 8; \
dest[A2] = a; \
dest += 4; \
src += 4; \
} \
}
PREMULTIPLY_FUNC(r8g8b8a8_to_r8g8b8a8_premultiplied, 0, 1, 2, 3, 0, 1, 2, 3)
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)
struct _GdkMemoryFormatDescription
{
GdkMemoryAlpha alpha;
@ -498,15 +501,29 @@ gdk_memory_convert (guchar *dest_data,
const GdkMemoryFormatDescription *src_desc = &memory_formats[src_format];
float *tmp;
gsize y;
void (*func) (guchar *, const guchar *, gsize) = NULL;
g_assert (dest_format < GDK_MEMORY_N_FORMATS);
g_assert (src_format < GDK_MEMORY_N_FORMATS);
if (src_format == GDK_MEMORY_R8G8B8A8 && dest_format == GDK_MEMORY_B8G8R8A8_PREMULTIPLIED)
if (src_format == GDK_MEMORY_R8G8B8A8 && dest_format == GDK_MEMORY_R8G8B8A8_PREMULTIPLIED)
func = r8g8b8a8_to_r8g8b8a8_premultiplied;
else if (src_format == GDK_MEMORY_B8G8R8A8 && dest_format == GDK_MEMORY_R8G8B8A8_PREMULTIPLIED)
func = r8g8b8a8_to_b8g8r8a8_premultiplied;
else if (src_format == GDK_MEMORY_R8G8B8A8 && dest_format == GDK_MEMORY_B8G8R8A8_PREMULTIPLIED)
func = r8g8b8a8_to_b8g8r8a8_premultiplied;
else if (src_format == GDK_MEMORY_B8G8R8A8 && dest_format == GDK_MEMORY_B8G8R8A8_PREMULTIPLIED)
func = r8g8b8a8_to_r8g8b8a8_premultiplied;
else if (src_format == GDK_MEMORY_R8G8B8A8 && dest_format == GDK_MEMORY_A8R8G8B8_PREMULTIPLIED)
func = r8g8b8a8_to_a8r8g8b8_premultiplied;
else if (src_format == GDK_MEMORY_B8G8R8A8 && dest_format == GDK_MEMORY_A8R8G8B8_PREMULTIPLIED)
func = r8g8b8a8_to_a8b8g8r8_premultiplied;
if (func != NULL)
{
for (y = 0; y < height; y++)
{
r8g8b8a8_to_b8g8r8a8_premultiplied (dest_data, src_data, width);
func (dest_data, src_data, width);
src_data += src_stride;
dest_data += dest_stride;
}