File size: 2,238 Bytes
2edf277 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 | // FCS Glass - src/core/glyph_cache.cpp. See glyph_cache.h.
#include "core/glyph_cache.h"
#include <cmath>
namespace fcs {
namespace core {
namespace {
std::uint16_t QuantizeTo16(double v, double step) {
if (!(v > 0.0)) return 1; // also catches NaN
const double q = std::floor(v * step + 0.5); // round half up
if (q < 1.0) return 1;
if (q > 65535.0) return 65535;
return static_cast<std::uint16_t>(q);
}
// Order-dependent mix, so (face=1, glyph=2) and (face=2, glyph=1) differ. A plain xor of
// the fields would collide on exactly that swap, which is the likeliest real collision.
std::uint64_t Mix(std::uint64_t h, std::uint64_t v) {
h ^= v + 0x9e3779b97f4a7c15ULL + (h << 6) + (h >> 2);
h *= 0xff51afd7ed558ccdULL;
h ^= h >> 33;
return h;
}
} // namespace
std::uint16_t QuantizeEm(double em_dp) { return QuantizeTo16(em_dp, 16.0); }
std::uint16_t QuantizeScale(double scale) { return QuantizeTo16(scale, 256.0); }
std::size_t GlyphKeyHash::operator()(const GlyphKey& k) const {
std::uint64_t h = 1469598103934665603ULL;
h = Mix(h, k.face);
h = Mix(h, k.glyph);
h = Mix(h, k.em_q);
h = Mix(h, k.scale_q);
h = Mix(h, k.subpx);
return static_cast<std::size_t>(h);
}
GlyphCache::GlyphCache(int atlas_width, int atlas_height, int padding)
: packer_(atlas_width, atlas_height, padding) {}
const GlyphSlot* GlyphCache::Find(const GlyphKey& key) const {
const auto it = map_.find(key);
return it == map_.end() ? nullptr : &it->second;
}
const GlyphSlot* GlyphCache::Insert(const GlyphKey& key, int w, int h, int bearing_x,
int bearing_y, int advance_px) {
const auto existing = map_.find(key);
if (existing != map_.end()) return &existing->second;
GlyphSlot slot;
if (!packer_.Pack(w, h, &slot.rect)) {
overflowed_ = true;
return nullptr;
}
slot.bearing_x = bearing_x;
slot.bearing_y = bearing_y;
slot.advance_px = advance_px;
return &map_.emplace(key, slot).first->second;
}
void GlyphCache::Flush() {
map_.clear();
packer_.Reset();
overflowed_ = false;
++generation_;
}
} // namespace core
} // namespace fcs
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