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Diffstat (limited to 'examples/example_png_info.cpp')
| -rw-r--r-- | examples/example_png_info.cpp | 349 |
1 files changed, 349 insertions, 0 deletions
diff --git a/examples/example_png_info.cpp b/examples/example_png_info.cpp new file mode 100644 index 0000000..cd2eca6 --- /dev/null +++ b/examples/example_png_info.cpp @@ -0,0 +1,349 @@ +/* +LodePNG Examples + +Copyright (c) 2005-2012 Lode Vandevenne + +This software is provided 'as-is', without any express or implied +warranty. In no event will the authors be held liable for any damages +arising from the use of this software. + +Permission is granted to anyone to use this software for any purpose, +including commercial applications, and to alter it and redistribute it +freely, subject to the following restrictions: + + 1. The origin of this software must not be misrepresented; you must not + claim that you wrote the original software. If you use this software + in a product, an acknowledgment in the product documentation would be + appreciated but is not required. + + 2. Altered source versions must be plainly marked as such, and must not be + misrepresented as being the original software. + + 3. This notice may not be removed or altered from any source + distribution. +*/ + +//g++ lodepng.cpp example_png_info.cpp -ansi -pedantic -Wall -Wextra -lSDL -O3 + +/* +This sample shows a lot of information in the console about a PNG file, +including color type, text chunks, the names of all chunks in the image, +etc... +*/ + + +#include "lodepng.h" +#include <iostream> + +/* +Display general info about the PNG. +*/ +void displayPNGInfo(const LodePNGInfo& info) +{ + const LodePNGColorMode& color = info.color; + + std::cout << "Compression method: " << info.compression_method << std::endl; + std::cout << "Filter method: " << info.filter_method << std::endl; + std::cout << "Interlace method: " << info.interlace_method << std::endl; + std::cout << "Color type: " << color.colortype << std::endl; + std::cout << "Bit depth: " << color.bitdepth << std::endl; + std::cout << "Bits per pixel: " << lodepng_get_bpp(&color) << std::endl; + std::cout << "Channels per pixel: " << lodepng_get_channels(&color) << std::endl; + std::cout << "Is greyscale type: " << lodepng_is_greyscale_type(&color) << std::endl; + std::cout << "Can have alpha: " << lodepng_can_have_alpha(&color) << std::endl; + std::cout << "Palette size: " << color.palettesize << std::endl; + std::cout << "Has color key: " << color.key_defined << std::endl; + if(color.key_defined) + { + std::cout << "Color key r: " << color.key_r << std::endl; + std::cout << "Color key g: " << color.key_g << std::endl; + std::cout << "Color key b: " << color.key_b << std::endl; + } + std::cout << "Texts: " << info.text_num << std::endl; + for(size_t i = 0; i < info.text_num; i++) + { + std::cout << "Text: " << info.text_keys[i] << ": " << info.text_strings[i] << std::endl << std::endl; + } + std::cout << "International texts: " << info.itext_num << std::endl; + for(size_t i = 0; i < info.itext_num; i++) + { + std::cout << "Text: " + << info.itext_keys[i] << ", " + << info.itext_langtags[i] << ", " + << info.itext_transkeys[i] << ": " + << info.itext_strings[i] << std::endl << std::endl; + } + std::cout << "Time defined: " << info.time_defined << std::endl; + if(info.time_defined) + { + const LodePNGTime& time = info.time; + std::cout << "year: " << time.year << std::endl; + std::cout << "month: " << time.month << std::endl; + std::cout << "day: " << time.day << std::endl; + std::cout << "hour: " << time.hour << std::endl; + std::cout << "minute: " << time.minute << std::endl; + std::cout << "second: " << time.second << std::endl; + } + std::cout << "Physics defined: " << info.phys_defined << std::endl; + if(info.phys_defined) + { + std::cout << "physics X: " << info.phys_x << std::endl; + std::cout << "physics Y: " << info.phys_y << std::endl; + std::cout << "physics unit: " << info.phys_unit << std::endl; + } +} + + +/* +Display the names and sizes of all chunks in the PNG file. +*/ +void displayChunkNames(const std::vector<unsigned char>& buffer) +{ + // Listing chunks is based on the original file, not the decoded png info. + const unsigned char *chunk, *begin, *end, *next; + end = &buffer.back() + 1; + begin = chunk = &buffer.front() + 8; + + std::cout << std::endl << "Chunks:" << std::endl; + std::cout << " type: length(s)"; + std::string last_type; + while(chunk + 8 < end && chunk >= begin) + { + char type[5]; + lodepng_chunk_type(type, chunk); + if(std::string(type).size() != 4) + { + std::cout << "this is probably not a PNG" << std::endl; + return; + } + + if(last_type != type) + { + std::cout << std::endl; + std::cout << " " << type << ": "; + } + last_type = type; + + std::cout << lodepng_chunk_length(chunk) << ", "; + + next = lodepng_chunk_next_const(chunk); + if (next <= chunk) break; // integer overflow + chunk = next; + } + std::cout << std::endl; +} + + +/* +Show ASCII art preview of the image +*/ +void displayAsciiArt(const std::vector<unsigned char>& image, unsigned w, unsigned h) +{ + if(w > 0 && h > 0) + { + std::cout << std::endl << "ASCII Art Preview: " << std::endl; + unsigned w2 = 48; + if(w < w2) w2 = w; + unsigned h2 = h * w2 / w; + h2 = (h2 * 2) / 3; //compensate for non-square characters in terminal + if(h2 > (w2 * 2)) h2 = w2 * 2; //avoid too large output + + std::cout << '+'; + for(unsigned x = 0; x < w2; x++) std::cout << '-'; + std::cout << '+' << std::endl; + for(unsigned y = 0; y < h2; y++) + { + std::cout << "|"; + for(unsigned x = 0; x < w2; x++) + { + unsigned x2 = x * w / w2; + unsigned y2 = y * h / h2; + int r = image[y2 * w * 4 + x2 * 4 + 0]; + int g = image[y2 * w * 4 + x2 * 4 + 1]; + int b = image[y2 * w * 4 + x2 * 4 + 2]; + int a = image[y2 * w * 4 + x2 * 4 + 3]; + int lightness = ((r + g + b) / 3) * a / 255; + int min = (r < g && r < b) ? r : (g < b ? g : b); + int max = (r > g && r > b) ? r : (g > b ? g : b); + int saturation = max - min; + int letter = 'i'; //i for grey, or r,y,g,c,b,m for colors + if(saturation > 32) + { + int h = lightness >= (min + max) / 2; + if(h) letter = (min == r ? 'c' : (min == g ? 'm' : 'y')); + else letter = (max == r ? 'r' : (max == g ? 'g' : 'b')); + } + int symbol = ' '; + if(lightness > 224) symbol = '@'; + else if(lightness > 128) symbol = letter - 32; + else if(lightness > 32) symbol = letter; + else if(lightness > 16) symbol = '.'; + std::cout << (char)symbol; + } + std::cout << "|"; + std::cout << std::endl; + } + std::cout << '+'; + for(unsigned x = 0; x < w2; x++) std::cout << '-'; + std::cout << '+' << std::endl; + } +} + + +/* +Show the filtertypes of each scanline in this PNG image. +*/ +void displayFilterTypes(const std::vector<unsigned char>& buffer, bool ignore_checksums) +{ + //Get color type and interlace type + lodepng::State state; + if(ignore_checksums) + { + state.decoder.ignore_crc = 1; + state.decoder.zlibsettings.ignore_adler32 = 1; + } + unsigned w, h; + unsigned error; + error = lodepng_inspect(&w, &h, &state, &buffer[0], buffer.size()); + + if(error) + { + std::cout << "inspect error " << error << ": " << lodepng_error_text(error) << std::endl; + return; + } + + if(state.info_png.interlace_method == 1) + { + std::cout << "showing filtertypes for interlaced PNG not supported by this example" << std::endl; + return; + } + + //Read literal data from all IDAT chunks + const unsigned char *chunk, *begin, *end, *next; + end = &buffer.back() + 1; + begin = chunk = &buffer.front() + 8; + + std::vector<unsigned char> zdata; + + while(chunk + 8 < end && chunk >= begin) + { + char type[5]; + lodepng_chunk_type(type, chunk); + if(std::string(type).size() != 4) + { + std::cout << "this is probably not a PNG" << std::endl; + return; + } + + if(std::string(type) == "IDAT") + { + const unsigned char* cdata = lodepng_chunk_data_const(chunk); + unsigned clength = lodepng_chunk_length(chunk); + if(chunk + clength + 12 > end || clength > buffer.size() || chunk + clength + 12 < begin) { + std::cout << "invalid chunk length" << std::endl; + return; + } + + for(unsigned i = 0; i < clength; i++) + { + zdata.push_back(cdata[i]); + } + } + + next = lodepng_chunk_next_const(chunk); + if (next <= chunk) break; // integer overflow + chunk = next; + } + + //Decompress all IDAT data + std::vector<unsigned char> data; + error = lodepng::decompress(data, &zdata[0], zdata.size()); + + if(error) + { + std::cout << "decompress error " << error << ": " << lodepng_error_text(error) << std::endl; + return; + } + + //A line is 1 filter byte + all pixels + size_t linebytes = 1 + lodepng_get_raw_size(w, 1, &state.info_png.color); + + if(linebytes == 0) + { + std::cout << "error: linebytes is 0" << std::endl; + return; + } + + std::cout << "Filter types: "; + for(size_t i = 0; i < data.size(); i += linebytes) + { + std::cout << (int)(data[i]) << " "; + } + std::cout << std::endl; + +} + + +/* +Main +*/ +int main(int argc, char *argv[]) /*list the chunks*/ +{ + bool ignore_checksums = false; + std::string filename = ""; + for (int i = 1; i < argc; i++) + { + if(std::string(argv[i]) == "--ignore_checksums") ignore_checksums = true; + else filename = argv[i]; + } + if(filename == "") + { + std::cout << "Please provide a filename to preview" << std::endl; + return 0; + } + + std::vector<unsigned char> buffer; + std::vector<unsigned char> image; + unsigned w, h; + + lodepng::load_file(buffer, filename); //load the image file with given filename + + lodepng::State state; + if(ignore_checksums) + { + state.decoder.ignore_crc = 1; + state.decoder.zlibsettings.ignore_adler32 = 1; + } + + unsigned error = lodepng::decode(image, w, h, state, buffer); + + if(error) + { + std::cout << "decoder error " << error << ": " << lodepng_error_text(error) << std::endl; + return 0; + } + + std::cout << "Filesize: " << buffer.size() << " (" << buffer.size() / 1024 << "K)" << std::endl; + std::cout << "Width: " << w << std::endl; + std::cout << "Height: " << h << std::endl; + std::cout << "Num pixels: " << w * h << std::endl; + + if(w > 0 && h > 0) + { + std::cout << "Top left pixel color:" + << " r: " << (int)image[0] + << " g: " << (int)image[1] + << " b: " << (int)image[2] + << " a: " << (int)image[3] + << std::endl; + } + + + displayPNGInfo(state.info_png); + std::cout << std::endl; + displayChunkNames(buffer); + std::cout << std::endl; + displayFilterTypes(buffer, ignore_checksums); + std::cout << std::endl; + displayAsciiArt(image, w, h); +} |