diff options
Diffstat (limited to 'platform/default/src/mbgl/util/png_reader.cpp')
| -rw-r--r-- | platform/default/src/mbgl/util/png_reader.cpp | 142 |
1 files changed, 142 insertions, 0 deletions
diff --git a/platform/default/src/mbgl/util/png_reader.cpp b/platform/default/src/mbgl/util/png_reader.cpp new file mode 100644 index 0000000000..4d4ee29d1f --- /dev/null +++ b/platform/default/src/mbgl/util/png_reader.cpp @@ -0,0 +1,142 @@ +#include <mbgl/util/image.hpp> +#include <mbgl/util/premultiply.hpp> +#include <mbgl/util/char_array_buffer.hpp> +#include <mbgl/util/logging.hpp> + +#include <istream> +#include <sstream> + +extern "C" +{ +#include <png.h> +} + +template<size_t max, typename... Args> +static std::string sprintf(const char *msg, Args... args) { + char res[max]; + int len = snprintf(res, sizeof(res), msg, args...); + return std::string(res, len); +} + +const static bool png_version_check __attribute__((unused)) = []() { + const png_uint_32 version = png_access_version_number(); + if (version != PNG_LIBPNG_VER) { + throw std::runtime_error(sprintf<96>( + "libpng version mismatch: headers report %d.%d.%d, but library reports %d.%d.%d", + PNG_LIBPNG_VER / 10000, (PNG_LIBPNG_VER / 100) % 100, PNG_LIBPNG_VER % 100, + version / 10000, (version / 100) % 100, version % 100)); + } + return true; +}(); + +namespace mbgl { + +static void user_error_fn(png_structp, png_const_charp error_msg) { + throw std::runtime_error(std::string("failed to read invalid png: '") + error_msg + "'"); +} + +static void user_warning_fn(png_structp, png_const_charp warning_msg) { + Log::Warning(Event::Image, "ImageReader (PNG): %s", warning_msg); +} + +static void png_read_data(png_structp png_ptr, png_bytep data, png_size_t length) { + auto* fin = reinterpret_cast<std::istream*>(png_get_io_ptr(png_ptr)); + fin->read(reinterpret_cast<char*>(data), length); + std::streamsize read_count = fin->gcount(); + if (read_count < 0 || static_cast<png_size_t>(read_count) != length) + { + png_error(png_ptr, "Read Error"); + } +} + +struct png_struct_guard { + png_struct_guard(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr) + : p_(png_ptr_ptr), + i_(info_ptr_ptr) {} + + ~png_struct_guard() { + png_destroy_read_struct(p_,i_,nullptr); + } + + png_structpp p_; + png_infopp i_; +}; + +PremultipliedImage decodePNG(const uint8_t* data, size_t size) { + util::CharArrayBuffer dataBuffer { reinterpret_cast<const char*>(data), size }; + std::istream stream(&dataBuffer); + + png_byte header[8] = { 0 }; + stream.read(reinterpret_cast<char*>(header), 8); + if (stream.gcount() != 8) + throw std::runtime_error("PNG reader: Could not read image"); + + int is_png = !png_sig_cmp(header, 0, 8); + if (!is_png) + throw std::runtime_error("File or stream is not a png"); + + png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, nullptr, nullptr, nullptr); + if (!png_ptr) + throw std::runtime_error("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 std::runtime_error("failed to create info_ptr"); + + png_set_read_fn(png_ptr, &stream, png_read_data); + png_set_sig_bytes(png_ptr, 8); + png_read_info(png_ptr, info_ptr); + + png_uint_32 width = 0; + png_uint_32 height = 0; + int bit_depth = 0; + int color_type = 0; + png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type, nullptr, nullptr, nullptr); + + UnassociatedImage image({ static_cast<uint32_t>(width), static_cast<uint32_t>(height) }); + + 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); + + png_set_add_alpha(png_ptr, 0xff, PNG_FILLER_AFTER); + + 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 row = 0; row < height; ++row) + rows[row] = image.data.get() + row * width * 4; + png_read_image(png_ptr, rows.get()); + + png_read_end(png_ptr, nullptr); + + return util::premultiply(std::move(image)); +} + +} // namespace mbgl |