(committing very old stuff) Adds png input stream (IIRC the height is wrongly read)

include/png.hpp

@@ -90,6 +90,98 @@ namespace png{
 	
 	typedef ostream<> colored_ostream;
 	typedef ostream<pixel_formats::gray> gray_ostream;
+	
+	struct istream{
+		//typedef pixel pixel;
+		
+		istream(std::string filename)
+		: fp(0)
+		, png_ptr(0)
+		, info_ptr(0)
+		, row()
+		, stride(0)
+		, x(0)
+		, y(0)
+		{
+			fp = fopen(filename.c_str(), "rb");
+			if(!fp) throw std::runtime_error(filename + " could not be opened");
+			
+			png_byte header[8];
+			fread(header, 1, 8, fp);
+			
+			if(png_sig_cmp(header, 0, 8) != 0) throw std::runtime_error("File is not a PNG file.");
+			
+			png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, 0, 0, 0);
+			if(!png_ptr) throw std::runtime_error("PNG structure could not be allocated");
+			
+			info_ptr = png_create_info_struct(png_ptr);
+			if(!info_ptr) throw std::runtime_error("PNG information structure could not be allocated");
+			
+			png_init_io(png_ptr, fp);
+			
+			png_set_sig_bytes(png_ptr, 8);
+			
+			png_read_info(png_ptr, info_ptr);
+			
+			if(png_get_interlace_type(png_ptr, info_ptr) != PNG_INTERLACE_NONE)
+				throw std::runtime_error("Interalced PNG's are not supported");
+			
+			auto width = png_get_image_width(png_ptr, info_ptr);
+			auto bit_depth = png_get_bit_depth(png_ptr, info_ptr);
+			auto channels = png_get_channels(png_ptr, info_ptr);
+			
+			// number of bytes in one row
+			stride = bit_depth * channels / 8;
+			size_t row_size = width * stride;
+			
+			if(bit_depth < 8) throw std::runtime_error("Bitdepths lower than 8 are not supported (yet)");
+			
+			row.resize(row_size);
+			png_read_row(png_ptr, (png_bytep)row.data(), 0);
+		}
+		
+		~istream(){
+			png_read_end(png_ptr, 0);
+			png_destroy_read_struct(&png_ptr, &info_ptr, 0);
+			fclose(fp);
+		}
+		
+		template <typename Pixel>
+		istream& operator>>(Pixel & p){
+			p = row[x];
+			
+			if(++x >= row.size()){
+				x = 0;
+				++y;
+				if(*this)
+					png_read_row(png_ptr, (png_bytep)row.data(), 0);
+			}
+			
+			return (*this);
+		}
+		
+		operator bool() const {
+			uint32_t height = 183;
+			png_get_IHDR(png_ptr, info_ptr, 0, &height, 0, 0, 0, 0, 0);
+			
+			if(y >= height) return false;
+			else return true;
+		}
+		
+		uint32_t width() const {
+			return  row.size();
+		}
+		
+	private:
+		FILE* fp;
+		png_structp png_ptr;
+		png_infop info_ptr;
+		
+		std::vector<char> row;
+		uint32_t stride;
+		uint32_t x;
+		uint32_t y;
+	};
 }
 
 #endif