mapbox-gl-native/src/mbgl/text/glyph_atlas.cpp at da7a67bae8bbd09d0785897539092fffd02c8fa6 · mapbox/mapbox-gl-native · GitHub

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#include <mbgl/text/glyph_atlas.hpp>

#include <mapbox/shelf-pack.hpp>

namespace mbgl {

static constexpr uint32_t padding = 1;

GlyphAtlas makeGlyphAtlas(const GlyphMap& glyphs) {
    GlyphAtlas result;

    mapbox::ShelfPack::ShelfPackOptions options;
    options.autoResize = true;
    mapbox::ShelfPack pack(0, 0, options);

    for (const auto& glyphMapEntry : glyphs) {
        FontStackHash fontStack = glyphMapEntry.first;
        GlyphPositionData& positions = result.positions[fontStack];
        positions.ascender = glyphMapEntry.second.ascender;
        positions.descender = glyphMapEntry.second.descender;
        for (const auto& entry : glyphMapEntry.second.glyphs) {
            if (entry.second && (*entry.second)->bitmap.valid()) {
                const Glyph& glyph = **entry.second;

                const mapbox::Bin& bin = *pack.packOne(-1,
                    glyph.bitmap.size.width + 2 * padding,
                    glyph.bitmap.size.height + 2 * padding);

                result.image.resize({
                    static_cast<uint32_t>(pack.width()),
                    static_cast<uint32_t>(pack.height())
                });

                AlphaImage::copy(glyph.bitmap,
                                 result.image,
                                 { 0, 0 },
                                 {
                                    bin.x + padding,
                                    bin.y + padding
                                 },
                                 glyph.bitmap.size);

                positions.glyphPositionMap.emplace(glyph.id,
                                                   GlyphPosition{Rect<uint16_t>{static_cast<uint16_t>(bin.x),
                                                                                static_cast<uint16_t>(bin.y),
                                                                                static_cast<uint16_t>(bin.w),
                                                                                static_cast<uint16_t>(bin.h)},
                                                                 glyph.metrics});
            }
        }
    }

    pack.shrink();
    result.image.resize({
        static_cast<uint32_t>(pack.width()),
        static_cast<uint32_t>(pack.height())
    });

    return result;
}

} // namespace mbgl