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png: Do loader conversions in GDK

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Not inside libpng.

We really want to do them in GL, but we don't have a premultiply step
yet.
This commit is contained in:
Benjamin Otte 2021-09-26 06:44:56 +02:00
parent b65b64628d
commit 7b41738979
1 changed files with 22 additions and 81 deletions
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103
gdk/loaders/gdkpng.c
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@ -206,68 +206,6 @@ unpremultiply_float_to_16bit (guchar *data,
}
}
static inline int
multiply_alpha (int alpha, int color)
{
int temp = (alpha * color) + 0x80;
return ((temp + (temp >> 8)) >> 8);
}
static void
premultiply_data (png_structp png,
png_row_infop row_info,
png_bytep data)
{
unsigned int i;
for (i = 0; i < row_info->rowbytes; i += 4)
{
uint8_t *base = &data[i];
uint8_t alpha = base[3];
uint32_t p;
if (alpha == 0)
{
p = 0;
}
else
{
uint8_t red = base[0];
uint8_t green = base[1];
uint8_t blue = base[2];
if (alpha != 0xff)
{
red = multiply_alpha (alpha, red);
green = multiply_alpha (alpha, green);
blue = multiply_alpha (alpha, blue);
}
p = ((uint32_t)alpha << 24) | (red << 16) | (green << 8) | (blue << 0);
}
memcpy (base, &p, sizeof (uint32_t));
}
}
static void
convert_bytes_to_data (png_structp png,
png_row_infop row_info,
png_bytep data)
{
unsigned int i;
for (i = 0; i < row_info->rowbytes; i += 4)
{
uint8_t *base = &data[i];
uint8_t red = base[0];
uint8_t green = base[1];
uint8_t blue = base[2];
uint32_t pixel;
pixel = (0xffu << 24) | (red << 16) | (green << 8) | (blue << 0);
memcpy (base, &pixel, sizeof (uint32_t));
}
}
static void
premultiply_16bit (guchar *data,
int width,
@ -355,9 +293,6 @@ gdk_load_png (GBytes *bytes,
if (png_get_valid (png, info, PNG_INFO_tRNS))
png_set_tRNS_to_alpha (png);
if (depth == 8)
png_set_filler (png, 0xff, PNG_FILLER_AFTER);
if (depth < 8)
png_set_packing (png);
@ -368,18 +303,20 @@ gdk_load_png (GBytes *bytes,
if (interlace != PNG_INTERLACE_NONE)
png_set_interlace_handling (png);
#if G_BYTE_ORDER == G_LITTLE_ENDIAN
png_set_swap (png);
#endif
png_read_update_info (png, info);
png_get_IHDR (png, info,
&width, &height, &depth,
&color_type, &interlace, NULL, NULL);
if ((depth != 8 && depth != 16) ||
!(color_type == PNG_COLOR_TYPE_RGB ||
color_type == PNG_COLOR_TYPE_RGB_ALPHA))
if (depth != 8 && depth != 16)
{
png_destroy_read_struct (&png, &info, NULL);
g_set_error (error,
GDK_TEXTURE_ERROR, GDK_TEXTURE_ERROR_UNSUPPORTED_CONTENT,
_("Failed to parse png image"));
_("Unsupported depth %u in png image"), depth);
return NULL;
}
@ -388,33 +325,37 @@ gdk_load_png (GBytes *bytes,
case PNG_COLOR_TYPE_RGB_ALPHA:
if (depth == 8)
{
format = GDK_MEMORY_DEFAULT;
png_set_read_user_transform_fn (png, premultiply_data);
#if G_BYTE_ORDER == G_LITTLE_ENDIAN
format = GDK_MEMORY_R8G8B8A8;
#elif G_BYTE_ORDER == G_BIG_ENDIAN
format = GDK_MEMORY_A8B8G8R8;
#endif
}
else
{
format = GDK_MEMORY_R16G16B16A16_PREMULTIPLIED;
#if G_BYTE_ORDER == G_LITTLE_ENDIAN
png_set_swap (png);
#endif
}
break;
case PNG_COLOR_TYPE_RGB:
if (depth == 8)
{
format = GDK_MEMORY_DEFAULT;
png_set_read_user_transform_fn (png, convert_bytes_to_data);
#if G_BYTE_ORDER == G_LITTLE_ENDIAN
format = GDK_MEMORY_R8G8B8;
#elif G_BYTE_ORDER == G_BIG_ENDIAN
format = GDK_MEMORY_B8G8R8;
#endif
}
else
else if (depth == 16)
{
format = GDK_MEMORY_R16G16B16;
#if G_BYTE_ORDER == G_LITTLE_ENDIAN
png_set_swap (png);
#endif
}
break;
default:
g_assert_not_reached ();
png_destroy_read_struct (&png, &info, NULL);
g_set_error (error,
GDK_TEXTURE_ERROR, GDK_TEXTURE_ERROR_UNSUPPORTED_CONTENT,
_("Unsupportd color type %u in png image"), color_type);
return NULL;
}
bpp = gdk_memory_format_bytes_per_pixel (format);