63 lines
1.7 KiB
C++
63 lines
1.7 KiB
C++
#include "mbgl/util/image_reader.hpp"
|
|
#include "mbgl/util/png_reader.hpp"
|
|
#include "mbgl/util/jpeg_reader.hpp"
|
|
|
|
#include <boost/optional.hpp>
|
|
#include <boost/iostreams/device/array.hpp>
|
|
|
|
namespace mbgl { namespace util {
|
|
|
|
inline boost::optional<std::string> type_from_bytes(char const* data, size_t size)
|
|
{
|
|
using result_type = boost::optional<std::string>;
|
|
if (size >= 4)
|
|
{
|
|
unsigned int magic = (data[0] << 24) | (data[1] << 16) | (data[2] << 8) | data[3];
|
|
if (magic == 0x89504E47U)
|
|
{
|
|
return result_type("png");
|
|
}
|
|
else if (magic == 0x49492A00 || magic == 0x4D4D002A)
|
|
{
|
|
return result_type("tiff");
|
|
}
|
|
}
|
|
if (size>=2)
|
|
{
|
|
unsigned int magic = ((data[0] << 8) | data[1]) & 0xffff;
|
|
if (magic == 0xffd8)
|
|
{
|
|
return result_type("jpeg");
|
|
}
|
|
}
|
|
|
|
if (size>=12)
|
|
{
|
|
if (data[0] == 'R' && data[1] == 'I' && data[2] == 'F' && data[3] == 'F' &&
|
|
data[8] == 'W' && data[9] == 'E' && data[10] == 'B' && data[11] == 'P')
|
|
{
|
|
return result_type("webp");
|
|
}
|
|
}
|
|
return result_type();
|
|
}
|
|
|
|
std::unique_ptr<image_reader> get_image_reader(char const* data, size_t size)
|
|
{
|
|
boost::optional<std::string> type = type_from_bytes(data,size);
|
|
if (type)
|
|
{
|
|
if (*type == "png")
|
|
{
|
|
return std::make_unique<png_reader<boost::iostreams::array_source>>(data, size);
|
|
}
|
|
else if (*type == "jpeg")
|
|
{
|
|
return std::make_unique<jpeg_reader<boost::iostreams::array_source>>(data, size);
|
|
}
|
|
}
|
|
throw image_reader_exception("image_reader: can't determine type from input data");
|
|
}
|
|
|
|
}}
|