+ id=0;
+#endif
+#ifdef WITH_LIBPNG
+ fmt=RGB;
+ width=0;
+ height=0;
+ data=0;
+#endif
+}
+
+
+namespace {
+
+#ifdef WITH_LIBPNG
+void read(png_struct *png, png_byte *data, png_size_t size)
+{
+ IO::Base *in=reinterpret_cast<IO::Base *>(png_get_io_ptr(png));
+ in->read(reinterpret_cast<char *>(data), size);
+}
+
+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 Exception("Error loading PNG image");
+
+ 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 Exception("Only 8-bit PNG images are supported");
+ 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 Exception("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;
+ }
+}
+#endif
+
+#ifdef WITH_DEVIL
+void ensure_devil_image(unsigned &id)
+{