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#include <mbgl/text/glyph_pbf.hpp>
#include <protozero/pbf_reader.hpp>
namespace mbgl {
std::tuple<std::vector<Glyph>, int32_t, int32_t> parseGlyphPBF(const GlyphRange& glyphRange, const std::string& data) {
std::vector<Glyph> glyphs;
glyphs.reserve(256);
int32_t ascender{0}, descender{0};
bool ascenderSet{false}, descenderSet{false};
protozero::pbf_reader glyphs_pbf(data);
while (glyphs_pbf.next(1)) {
auto readGlyphMetrics = [glyphRange, &glyphs](protozero::pbf_reader& fontstack_pbf) {
auto glyph_pbf = fontstack_pbf.get_message();
Glyph glyph;
protozero::data_view glyphData;
bool hasID = false, hasWidth = false, hasHeight = false, hasLeft = false,
hasTop = false, hasAdvance = false;
while (glyph_pbf.next()) {
switch (glyph_pbf.tag()) {
case 1: // id
glyph.id = glyph_pbf.get_uint32();
hasID = true;
break;
case 2: // bitmap
glyphData = glyph_pbf.get_view();
break;
case 3: // width
glyph.metrics.width = glyph_pbf.get_uint32();
hasWidth = true;
break;
case 4: // height
glyph.metrics.height = glyph_pbf.get_uint32();
hasHeight = true;
break;
case 5: // left
glyph.metrics.left = glyph_pbf.get_sint32();
hasLeft = true;
break;
case 6: // top
glyph.metrics.top = glyph_pbf.get_sint32();
hasTop = true;
break;
case 7: // advance
glyph.metrics.advance = glyph_pbf.get_uint32();
hasAdvance = true;
break;
default:
glyph_pbf.skip();
break;
}
}
// Only treat this glyph as a correct glyph if it has all required fields. It also
// needs to satisfy a few metrics conditions that ensure that the glyph isn't bogus.
// All other glyphs are malformed. We're also discarding all glyphs that are outside
// the expected glyph range.
if (!hasID || !hasWidth || !hasHeight || !hasLeft || !hasTop || !hasAdvance || glyph.metrics.width >= 256 ||
glyph.metrics.height >= 256 || glyph.metrics.left < -128 || glyph.metrics.left >= 128 ||
glyph.metrics.top < -128 || glyph.metrics.top >= 128 || glyph.metrics.advance >= 256 ||
glyph.id < glyphRange.first || glyph.id > glyphRange.second) {
return;
}
// If the area of width/height is non-zero, we need to adjust the expected size
// with the implicit border size, otherwise we expect there to be no bitmap at all.
if (glyph.metrics.width && glyph.metrics.height) {
const Size size{glyph.metrics.width + 2 * Glyph::borderSize,
glyph.metrics.height + 2 * Glyph::borderSize};
if (size.area() != glyphData.size()) {
return;
}
glyph.bitmap = AlphaImage(size, reinterpret_cast<const uint8_t*>(glyphData.data()), glyphData.size());
}
glyphs.push_back(std::move(glyph));
};
auto fontstack_pbf = glyphs_pbf.get_message();
while (fontstack_pbf.next()) {
switch (fontstack_pbf.tag()) {
case 3: {
readGlyphMetrics(fontstack_pbf);
break;
}
case 4: {
// ascender value for one fontstack shall keep the same, if different values appear, set ascender to
// be 0/invalid.
const auto value = fontstack_pbf.get_sint32();
if (!ascenderSet) {
ascender = value;
ascenderSet = true;
} else if (ascender != value) {
ascender = 0;
}
break;
}
case 5: {
// descender value for one fontstack shall keep the same, if different values appear, set descender
// to be 0/invalid.
const auto value = fontstack_pbf.get_sint32();
if (!descenderSet) {
descender = value;
descenderSet = true;
} else if (descender != value) {
descender = 0;
}
break;
}
default: {
fontstack_pbf.skip();
break;
}
}
}
}
return std::make_tuple(std::move(glyphs), ascender, descender);
}
} // namespace mbgl
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