void png_reader<T>::read(unsigned x0, unsigned y0,image_data_32& image)
{
stream_.clear();
stream_.seekg(0, std::ios_base::beg);
png_structp png_ptr = png_create_read_struct
(PNG_LIBPNG_VER_STRING,0,0,0);
if (!png_ptr)
{
throw image_reader_exception("failed to allocate png_ptr");
}
// catch errors in a custom way to avoid the need for setjmp
png_set_error_fn(png_ptr, png_get_error_ptr(png_ptr), user_error_fn, user_warning_fn);
png_infop info_ptr;
png_struct_guard sguard(&png_ptr,&info_ptr);
info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr) throw image_reader_exception("failed to create info_ptr");
png_set_read_fn(png_ptr, (png_voidp)&stream_, png_read_data);
png_read_info(png_ptr, info_ptr);
if (color_type_ == PNG_COLOR_TYPE_PALETTE)
png_set_expand(png_ptr);
if (color_type_ == PNG_COLOR_TYPE_GRAY && bit_depth_ < 8)
png_set_expand(png_ptr);
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
png_set_expand(png_ptr);
if (bit_depth_ == 16)
png_set_strip_16(png_ptr);
if (color_type_ == PNG_COLOR_TYPE_GRAY ||
color_type_ == PNG_COLOR_TYPE_GRAY_ALPHA)
png_set_gray_to_rgb(png_ptr);
// quick hack -- only work in >=libpng 1.2.7
png_set_add_alpha(png_ptr,0xff,PNG_FILLER_AFTER); //rgba
double gamma;
if (png_get_gAMA(png_ptr, info_ptr, &gamma))
png_set_gamma(png_ptr, 2.2, gamma);
if (x0 == 0 && y0 == 0 && image.width() >= width_ && image.height() >= height_)
{
if (png_get_interlace_type(png_ptr,info_ptr) == PNG_INTERLACE_ADAM7)
{
png_set_interlace_handling(png_ptr); // FIXME: libpng bug?
// according to docs png_read_image
// "..automatically handles interlacing,
// so you don't need to call png_set_interlace_handling()"
}
png_read_update_info(png_ptr, info_ptr);
// we can read whole image at once
// alloc row pointers
const std::unique_ptr<png_bytep[]> rows(new png_bytep[height_]);
for (unsigned i=0; i<height_; ++i)
rows[i] = (png_bytep)image.getRow(i);
png_read_image(png_ptr, rows.get());
}
else
{
png_read_update_info(png_ptr, info_ptr);
unsigned w=std::min(unsigned(image.width()),width_ - x0);
unsigned h=std::min(unsigned(image.height()),height_ - y0);
unsigned rowbytes=png_get_rowbytes(png_ptr, info_ptr);
const std::unique_ptr<png_byte[]> row(new png_byte[rowbytes]);
//START read image rows
for (unsigned i = 0;i < height_; ++i)
{
png_read_row(png_ptr,row.get(),0);
if (i >= y0 && i < (y0 + h))
{
image.setRow(i-y0,reinterpret_cast<unsigned*>(&row[x0 * 4]),w);
}
}
//END
}
png_read_end(png_ptr,0);
}
void png_reader::read(unsigned x0, unsigned y0,image_data_32& image)
{
FILE *fp=fopen(fileName_.c_str(),"rb");
if (!fp) throw image_reader_exception("cannot open image file "+fileName_);
png_structp png_ptr = png_create_read_struct
(PNG_LIBPNG_VER_STRING,0,0,0);
if (!png_ptr)
{
fclose(fp);
throw image_reader_exception("failed to allocate png_ptr");
}
// catch errors in a custom way to avoid the need for setjmp
png_set_error_fn(png_ptr, png_get_error_ptr(png_ptr), user_error_fn, user_warning_fn);
png_infop info_ptr;
try
{
info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr)
{
png_destroy_read_struct(&png_ptr,0,0);
fclose(fp);
throw image_reader_exception("failed to create info_ptr");
}
}
catch (std::exception const& ex)
{
png_destroy_read_struct(&png_ptr,0,0);
fclose(fp);
throw;
}
png_set_read_fn(png_ptr, (png_voidp)fp, png_read_data);
png_read_info(png_ptr, info_ptr);
if (color_type_ == PNG_COLOR_TYPE_PALETTE)
png_set_expand(png_ptr);
if (color_type_ == PNG_COLOR_TYPE_GRAY && bit_depth_ < 8)
png_set_expand(png_ptr);
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
png_set_expand(png_ptr);
if (bit_depth_ == 16)
png_set_strip_16(png_ptr);
if (color_type_ == PNG_COLOR_TYPE_GRAY ||
color_type_ == PNG_COLOR_TYPE_GRAY_ALPHA)
png_set_gray_to_rgb(png_ptr);
// quick hack -- only work in >=libpng 1.2.7
png_set_add_alpha(png_ptr,0xff,PNG_FILLER_AFTER); //rgba
double gamma;
if (png_get_gAMA(png_ptr, info_ptr, &gamma))
png_set_gamma(png_ptr, 2.2, gamma);
if (x0 == 0 && y0 == 0 && image.width() >= width_ && image.height() >= height_)
{
if (png_get_interlace_type(png_ptr,info_ptr) == PNG_INTERLACE_ADAM7)
{
png_set_interlace_handling(png_ptr); // FIXME: libpng bug?
// according to docs png_read_image
// "..automatically handles interlacing,
// so you don't need to call png_set_interlace_handling()"
}
png_read_update_info(png_ptr, info_ptr);
// we can read whole image at once
// alloc row pointers
boost::scoped_array<png_byte*> rows(new png_bytep[height_]);
for (unsigned i=0; i<height_; ++i)
rows[i] = (png_bytep)image.getRow(i);
png_read_image(png_ptr, rows.get());
}
else
{
png_read_update_info(png_ptr, info_ptr);
unsigned w=std::min(unsigned(image.width()),width_);
unsigned h=std::min(unsigned(image.height()),height_);
unsigned rowbytes=png_get_rowbytes(png_ptr, info_ptr);
boost::scoped_array<png_byte> row(new png_byte[rowbytes]);
//START read image rows
for (unsigned i=0;i<height_;++i)
{
png_read_row(png_ptr,row.get(),0);
if (i>=y0 && i<h)
{
image.setRow(i-y0,reinterpret_cast<unsigned*>(&row[x0]),w);
}
}
//END
}
png_read_end(png_ptr,0);
png_destroy_read_struct(&png_ptr, &info_ptr,0);
fclose(fp);
}