//
// Expands RGB to ARGB allocating new buffer for it.
//
static gpointer
expand_rgb_to_argb (MoonPixbuf *pixbuf)
{
guchar *pb_pixels = pixbuf->GetPixels ();
guchar *p;
int w = pixbuf->GetWidth ();
int h = pixbuf->GetHeight ();
int stride = w * 4;
guchar *data = (guchar *) g_malloc (stride * h);
guchar *out;
for (int y = 0; y < h; y ++) {
p = pb_pixels + y * pixbuf->GetRowStride ();
out = data + y * (stride);
for (int x = 0; x < w; x ++) {
guchar r, g, b;
get_pixel_bgr_p (p, b, g, r);
set_pixel_bgra (out, 0, r, g, b, 255);
p += 3;
out += 4;
}
}
return (gpointer) data;
}
//
// Converts RGBA unmultiplied alpha to ARGB pre-multiplied alpha.
//
static gpointer
premultiply_rgba (MoonPixbuf *pixbuf)
{
guchar *pb_pixels = pixbuf->GetPixels ();
guchar *p;
int w = pixbuf->GetWidth ();
int h = pixbuf->GetHeight ();
int stride = w * 4;
guchar *data = (guchar *) g_malloc (stride * h);
guchar *out;
for (int y = 0; y < h; y ++) {
p = pb_pixels + y * pixbuf->GetRowStride ();
out = data + y * (stride);
for (int x = 0; x < w; x ++) {
guchar r, g, b, a;
get_pixel_bgra (p, b, g, r, a);
/* pre-multipled alpha */
if (a == 0) {
r = g = b = 0;
}
else if (a < 255) {
r = pre_multiplied_table [r][a];
g = pre_multiplied_table [g][a];
b = pre_multiplied_table [b][a];
}
/* store it back, swapping red and blue */
set_pixel_bgra (out, 0, r, g, b, a);
p += 4;
out += 4;
}
}
return (gpointer) data;
}
static GpStatus
gdip_load_png_image_from_file_or_stream (FILE *fp, GetBytesDelegate getBytesFunc, GpImage **image)
{
png_structp png_ptr = NULL;
png_infop info_ptr = NULL;
png_infop end_info_ptr = NULL;
BYTE *rawdata = NULL;
GpImage *result = NULL;
GpStatus status = InvalidParameter;
int bit_depth;
int channels;
BYTE color_type;
png_ptr = png_create_read_struct (PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
if (!png_ptr) {
goto error;
}
if (setjmp(png_jmpbuf(png_ptr))) {
/* png detected error occured */
goto error;
}
info_ptr = png_create_info_struct (png_ptr);
if (info_ptr == NULL) {
goto error;
}
end_info_ptr = png_create_info_struct (png_ptr);
if (end_info_ptr == NULL) {
goto error;
}
if (fp != NULL) {
png_init_io (png_ptr, fp);
} else {
png_set_read_fn (png_ptr, getBytesFunc, _gdip_png_stream_read_data);
}
png_read_png (png_ptr, info_ptr, 0, NULL);
bit_depth = png_get_bit_depth (png_ptr, info_ptr);
channels = png_get_channels (png_ptr, info_ptr);
color_type = png_get_color_type (png_ptr, info_ptr);
/* 2bpp is a special case (promoted to 32bpp ARGB by MS GDI+) */
if ((bit_depth <= 8) && (bit_depth != 2) && (channels == 1) &&
((color_type == PNG_COLOR_TYPE_PALETTE) || (color_type == PNG_COLOR_TYPE_GRAY))) {
int width;
int height;
int source_stride;
int dest_stride;
png_bytep *row_pointers;
BYTE *rawptr;
int num_colours;
int palette_entries;
ColorPalette *palette;
ImageFlags colourspace_flag;
int i;
int j;
width = png_get_image_width (png_ptr, info_ptr);
height = png_get_image_height (png_ptr, info_ptr);
source_stride = (width * bit_depth + 7) / 8;
dest_stride = source_stride;
gdip_align_stride (dest_stride);
/* Copy image data. */
row_pointers = png_get_rows (png_ptr, info_ptr);
rawdata = GdipAlloc(dest_stride * height);
for (i=0; i < height; i++) {
memcpy (rawdata + i * dest_stride, row_pointers[i], source_stride);
}
/* Copy palette. */
num_colours = 1 << bit_depth;
if (png_get_color_type (png_ptr, info_ptr) == PNG_COLOR_TYPE_GRAY) {
/* A gray-scale image; generate a palette fading from black to white. */
colourspace_flag = ImageFlagsColorSpaceGRAY;
palette = gdip_create_greyscale_palette (num_colours);
palette->Flags = PaletteFlagsGrayScale;
} else {
/* Copy the palette data into the GDI+ structure. */
colourspace_flag = ImageFlagsColorSpaceRGB;
palette_entries = num_colours;
if (palette_entries > info_ptr->num_palette) {
palette_entries = info_ptr->num_palette;
}
palette = GdipAlloc (sizeof(ColorPalette) + (num_colours - 1) * sizeof(ARGB));
palette->Flags = 0;
palette->Count = num_colours;
for (i=0; i < palette_entries; i++) {
set_pixel_bgra (&palette->Entries[i], 0,
info_ptr->palette[i].blue,
info_ptr->palette[i].green,
info_ptr->palette[i].red,
0xFF); /* alpha */
}
}
/* Make sure transparency is respected. */
if (info_ptr->num_trans > 0) {
palette->Flags |= PaletteFlagsHasAlpha;
colourspace_flag |= ImageFlagsHasAlpha;
if (info_ptr->num_trans > info_ptr->num_palette) {
info_ptr->num_trans = info_ptr->num_palette;
}
for (i=0; i < info_ptr->num_trans; i++) {
set_pixel_bgra(&palette->Entries[i], 0,
info_ptr->palette[i].blue,
info_ptr->palette[i].green,
info_ptr->palette[i].red,
#if PNG_LIBPNG_VER > 10399
info_ptr->trans_alpha [i]); /* alpha */
#else
info_ptr->trans[i]); /* alpha */
#endif
}
}
