diff options
Diffstat (limited to 'platform/default/image.cpp')
| -rw-r--r-- | platform/default/image.cpp | 178 |
1 files changed, 178 insertions, 0 deletions
diff --git a/platform/default/image.cpp b/platform/default/image.cpp new file mode 100644 index 0000000000..68d1786913 --- /dev/null +++ b/platform/default/image.cpp @@ -0,0 +1,178 @@ +#include <mbgl/util/image.hpp> + +#include <png.h> + +#include <cassert> +#include <cstdlib> +#include <stdexcept> +#include <cstring> + + +namespace mbgl { +namespace util { + +std::string compress_png(int width, int height, void *rgba) { + png_voidp error_ptr = 0; + png_structp png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, error_ptr, NULL, NULL); + if (!png_ptr) { + fprintf(stderr, "Couldn't create png_ptr\n"); + return ""; + } + + png_infop info_ptr = png_create_info_struct(png_ptr); + if (!png_ptr) { + png_destroy_write_struct(&png_ptr, (png_infopp)0); + fprintf(stderr, "Couldn't create info_ptr\n"); + return ""; + } + + png_set_IHDR(png_ptr, info_ptr, width, height, 8, PNG_COLOR_TYPE_RGB_ALPHA, PNG_INTERLACE_NONE, + PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT); + + jmp_buf *jmp_context = (jmp_buf *)png_get_error_ptr(png_ptr); + if (jmp_context) { + png_destroy_write_struct(&png_ptr, &info_ptr); + return ""; + } + + std::string result; + png_set_write_fn(png_ptr, &result, [](png_structp png_ptr_, png_bytep data, png_size_t length) { + std::string *out = static_cast<std::string *>(png_get_io_ptr(png_ptr_)); + out->append(reinterpret_cast<char *>(data), length); + }, NULL); + + struct ptrs { + ptrs(size_t count) : rows(new png_bytep[count]) {} + ~ptrs() { delete[] rows; } + png_bytep *rows = nullptr; + } pointers(height); + + for (int i = 0; i < height; i++) { + pointers.rows[i] = (png_bytep)((png_bytep)rgba + width * 4 * i); + } + + png_set_rows(png_ptr, info_ptr, pointers.rows); + png_write_png(png_ptr, info_ptr, PNG_TRANSFORM_IDENTITY, NULL); + png_destroy_write_struct(&png_ptr, &info_ptr); + + return result; +} + + +struct Buffer { + Buffer(const std::string& data_) + : data(data_.data()), length(data_.size()) {} + const char *const data = 0; + const size_t length = 0; + size_t pos = 0; +}; + +void readCallback(png_structp png, png_bytep data, png_size_t length) { + Buffer *reader = static_cast<Buffer *>(png_get_io_ptr(png)); + + // Read `length` bytes into `data`. + if (reader->pos + length > reader->length) { + png_error(png, "Read Error"); + } else { + std::memcpy(data, reader->data + reader->pos, length); + reader->pos += length; + } +} + +void errorHandler(png_structp, png_const_charp error_msg) { + throw std::runtime_error(error_msg); +} + +void warningHandler(png_structp, png_const_charp error_msg) { + fprintf(stderr, "PNG: %s\n", error_msg); +} + +Image::Image(const std::string &data) { + Buffer buffer(data); + + if (buffer.length < 8 || !png_check_sig((const png_bytep)buffer.data, 8)) { + fprintf(stderr, "image is not a valid PNG image\n"); + return; + } + + png_structp png = png_create_read_struct(PNG_LIBPNG_VER_STRING, nullptr, errorHandler, warningHandler); + assert(png); + + png_infop info = png_create_info_struct(png); + assert(info); + + int depth, color, interlace; + + try { + png_set_read_fn(png, (png_voidp)&buffer, readCallback); + png_read_info(png, info); + png_get_IHDR(png, info, (png_uint_32*)&width, (png_uint_32*)&height, &depth, &color, &interlace, nullptr, nullptr); + bool alpha = (color & PNG_COLOR_MASK_ALPHA) || png_get_valid(png, info, PNG_INFO_tRNS); + + // From http://trac.mapnik.org/browser/trunk/src/png_reader.cpp + if (color == PNG_COLOR_TYPE_PALETTE) + png_set_expand(png); + if (color == PNG_COLOR_TYPE_GRAY) + png_set_expand(png); + if (png_get_valid(png, info, PNG_INFO_tRNS)) + png_set_expand(png); + if (depth == 16) + png_set_strip_16(png); + if (depth < 8) + png_set_packing(png); + if (color == PNG_COLOR_TYPE_GRAY || + color == PNG_COLOR_TYPE_GRAY_ALPHA) + png_set_gray_to_rgb(png); + + if (interlace == PNG_INTERLACE_ADAM7) + png_set_interlace_handling(png); + + // Always add an alpha channel. + if (!alpha) { + png_set_add_alpha(png, 0xFF, PNG_FILLER_AFTER); + } + + double gamma; + if (png_get_gAMA(png, info, &gamma)) + png_set_gamma(png, 2.2, gamma); + + png_set_alpha_mode(png, PNG_ALPHA_PREMULTIPLIED, 2.2); + + png_read_update_info(png, info); + + png_size_t rowbytes = png_get_rowbytes(png, info); + assert(width * 4 == rowbytes); + + img = ::std::unique_ptr<char[]>(new char[width * height * 4]()); + + char *surface = img.get(); + assert(surface); + + struct ptrs { + ptrs(size_t count) : rows(new png_bytep[count]) {} + ~ptrs() { delete[] rows; } + png_bytep *rows = nullptr; + } pointers(height); + for (unsigned i = 0; i < height; ++i) { + pointers.rows[i] = (png_bytep)(surface + (i * rowbytes)); + } + + // Read image data + png_read_image(png, pointers.rows); + + png_read_end(png, nullptr); + + png_destroy_read_struct(&png, &info, nullptr); + } catch (std::exception& e) { + fprintf(stderr, "loading PNG failed: %s\n", e.what()); + png_destroy_read_struct(&png, &info, nullptr); + if (img) { + img.reset(); + } + width = 0; + height = 0; + } +} + +} +} |