+#ifdef WITH_LIBPNG
+#include <png.h>
+#include "image_png.h"
+#include "image_private.h"
+
+namespace {
+
+void read(png_struct *png, png_byte *data, png_size_t size)
+{
+ Msp::IO::Base *in = reinterpret_cast<Msp::IO::Base *>(png_get_io_ptr(png));
+ in->read(reinterpret_cast<char *>(data), size);
+}
+
+}
+
+
+namespace Msp {
+namespace Graphics {
+
+bool is_png(const void *buf, unsigned len)
+{
+ return !png_sig_cmp(reinterpret_cast<png_byte *>(const_cast<void *>(buf)), 0, len);
+}
+
+void load_png(IO::Base &in, Image::Private &priv)
+{
+ png_struct *png = 0;
+ png_info *info = 0;
+ priv.data = 0;
+
+ try
+ {
+ png = png_create_read_struct(PNG_LIBPNG_VER_STRING, 0, 0, 0);
+ info = png_create_info_struct(png);
+
+ if(setjmp(png_jmpbuf(png)))
+ throw bad_image_data("PNG error");
+
+ png_set_read_fn(png, &in, read);
+ png_read_info(png, info);
+ png_uint_32 width;
+ png_uint_32 height;
+ int depth;
+ int color;
+ png_get_IHDR(png, info, &width, &height, &depth, &color, 0, 0, 0);
+ priv.width = width;
+ priv.height = height;
+ if(depth!=8)
+ throw unsupported_image_format("depth!=8");
+ switch(color)
+ {
+ case PNG_COLOR_TYPE_PALETTE: priv.fmt = COLOR_INDEX; break;
+ case PNG_COLOR_TYPE_GRAY: priv.fmt = LUMINANCE; break;
+ case PNG_COLOR_TYPE_GRAY_ALPHA: priv.fmt = LUMINANCE_ALPHA; break;
+ case PNG_COLOR_TYPE_RGB: priv.fmt = RGB; break;
+ case PNG_COLOR_TYPE_RGB_ALPHA: priv.fmt = RGBA; break;
+ default: throw unsupported_image_format("unknown color type");
+ }
+
+ unsigned nchans = png_get_channels(png, info);
+ if(nchans==4 && priv.fmt==RGB)
+ png_set_strip_alpha(png);
+
+ unsigned rowstride = priv.width*nchans;
+ priv.data = new char[rowstride*priv.height];
+ for(unsigned y=0; y<priv.height; ++y)
+ png_read_row(png, reinterpret_cast<png_byte *>(priv.data+rowstride*(priv.height-1-y)), 0);
+
+ png_read_end(png, 0);
+ png_destroy_read_struct(&png, &info, 0);
+ }
+ catch(...)
+ {
+ png_destroy_read_struct(&png, &info, 0);
+ delete[] priv.data;
+ throw;
+ }
+}
+
+} // namespace Graphics
+} // namespace Msp
+#endif