png: Refactor png saving

Do all the memory format shenanigans in GTK now and support all the PNG
formats.
This commit is contained in:
Benjamin Otte 2021-09-27 05:55:48 +02:00
parent 1e7fb52b21
commit c2368cc605

View File

@ -127,85 +127,6 @@ png_simple_warning_callback (png_structp png,
{
}
/* }}} */
/* {{{ Format conversion */
static void
unpremultiply (guchar *data,
int width,
int height)
{
gsize x, y;
for (y = 0; y < height; y++)
{
for (x = 0; x < width; x++)
{
guchar *b = &data[x * 4];
guint32 pixel;
guchar alpha;
memcpy (&pixel, b, sizeof (guint32));
alpha = (pixel & 0xff000000) >> 24;
if (alpha == 0)
{
b[0] = 0;
b[1] = 0;
b[2] = 0;
b[3] = 0;
}
else
{
b[0] = (((pixel & 0x00ff0000) >> 16) * 255 + alpha / 2) / alpha;
b[1] = (((pixel & 0x0000ff00) >> 8) * 255 + alpha / 2) / alpha;
b[2] = (((pixel & 0x000000ff) >> 0) * 255 + alpha / 2) / alpha;
b[3] = alpha;
}
}
data += width * 4;
}
}
static void
unpremultiply_float_to_16bit (guchar *data,
int width,
int height)
{
gsize x, y;
float *src = (float *)data;;
guint16 *dest = (guint16 *)data;
for (y = 0; y < height; y++)
{
for (x = 0; x < width; x++)
{
float r, g, b, a;
r = src[0];
g = src[1];
b = src[2];
a = src[3];
if (a == 0)
{
dest[0] = 0;
dest[1] = 0;
dest[2] = 0;
dest[3] = 0;
}
else
{
dest[0] = (guint16) CLAMP (65536.f * r / a, 0.f, 65535.f);
dest[1] = (guint16) CLAMP (65536.f * g / a, 0.f, 65535.f);
dest[2] = (guint16) CLAMP (65536.f * b / a, 0.f, 65535.f);
dest[3] = (guint16) CLAMP (65536.f * a, 0.f, 65535.f);
}
dest += 4;
src += 4;
}
}
}
/* }}} */
/* {{{ Public API */
@ -382,11 +303,11 @@ gdk_save_png (GdkTexture *texture)
png_struct *png = NULL;
png_info *info;
png_io io = { NULL, 0, 0 };
guint width, height, stride;
guchar *data = NULL;
guchar *row;
int width, height;
gsize stride;
const guchar *data;
int y;
GdkTexture *mtexture;
GdkMemoryTexture *memtex;
GdkMemoryFormat format;
int png_format;
int depth;
@ -395,8 +316,6 @@ gdk_save_png (GdkTexture *texture)
height = gdk_texture_get_height (texture);
format = gdk_texture_get_format (texture);
mtexture = GDK_TEXTURE (gdk_memory_texture_from_texture (texture, format));
switch (format)
{
case GDK_MEMORY_B8G8R8A8_PREMULTIPLIED:
@ -406,32 +325,42 @@ gdk_save_png (GdkTexture *texture)
case GDK_MEMORY_A8R8G8B8:
case GDK_MEMORY_R8G8B8A8:
case GDK_MEMORY_A8B8G8R8:
case GDK_MEMORY_R8G8B8:
case GDK_MEMORY_B8G8R8:
stride = width * 4;
data = g_malloc_n (stride, height);
gdk_texture_download (mtexture, data, stride);
unpremultiply (data, width, height);
#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_R16G16B16:
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;
case GDK_MEMORY_R16G16B16A16:
case GDK_MEMORY_R16G16B16A16_PREMULTIPLIED:
case GDK_MEMORY_R16G16B16_FLOAT:
case GDK_MEMORY_R16G16B16A16_FLOAT:
case GDK_MEMORY_R16G16B16A16_FLOAT_PREMULTIPLIED:
case GDK_MEMORY_R32G32B32_FLOAT:
case GDK_MEMORY_R32G32B32A32_FLOAT:
case GDK_MEMORY_R32G32B32A32_FLOAT_PREMULTIPLIED:
data = g_malloc_n (width * 16, height);
gdk_texture_download_float (mtexture, (float *)data, width * 4);
unpremultiply_float_to_16bit (data, width, height);
format = GDK_MEMORY_R16G16B16A16;
png_format = PNG_COLOR_TYPE_RGB_ALPHA;
stride = width * 8;
depth = 16;
break;
case GDK_MEMORY_R16G16B16:
case GDK_MEMORY_R16G16B16_FLOAT:
case GDK_MEMORY_R32G32B32_FLOAT:
format = GDK_MEMORY_R16G16B16;
png_format = PNG_COLOR_TYPE_RGB;
depth = 16;
break;
@ -458,12 +387,14 @@ gdk_save_png (GdkTexture *texture)
if (sigsetjmp (png_jmpbuf (png), 1))
{
g_free (data);
g_object_unref (memtex);
g_free (io.data);
png_destroy_read_struct (&png, &info, NULL);
return NULL;
}
memtex = gdk_memory_texture_from_texture (texture, format);
png_set_write_fn (png, &io, png_write_func, png_flush_func);
png_set_IHDR (png, info, width, height, depth,
@ -478,14 +409,16 @@ gdk_save_png (GdkTexture *texture)
png_set_swap (png);
#endif
for (y = 0, row = data; y < height; y++, row += stride)
png_write_rows (png, &row, 1);
data = gdk_memory_texture_get_data (memtex);
stride = gdk_memory_texture_get_stride (memtex);
for (y = 0; y < height; y++)
png_write_row (png, data + y * stride);
png_write_end (png, info);
png_destroy_write_struct (&png, &info);
g_free (data);
g_object_unref (memtex);
return g_bytes_new_take (io.data, io.size);
}