Method MeasureWidths

scintilla/src/PositionCache.cxx:555–607

}

void PositionCache::MeasureWidths(Surface *surface, ViewStyle &vstyle, unsigned int styleNumber,
	const char *s, unsigned int len, XYPOSITION *positions, Document *pdoc) {

	allClear = false;
	int probe = -1;
	if ((!pces.empty()) && (len < 30)) {
		// Only store short strings in the cache so it doesn't churn with
		// long comments with only a single comment.

		// Two way associative: try two probe positions.
		int hashValue = PositionCacheEntry::Hash(styleNumber, s, len);
		probe = static_cast<int>(hashValue % pces.size());
		if (pces[probe].Retrieve(styleNumber, s, len, positions)) {
			return;
		}
		int probe2 = static_cast<int>((hashValue * 37) % pces.size());
		if (pces[probe2].Retrieve(styleNumber, s, len, positions)) {
			return;
		}
		// Not found. Choose the oldest of the two slots to replace
		if (pces[probe].NewerThan(pces[probe2])) {
			probe = probe2;
		}
	}
	if (len > BreakFinder::lengthStartSubdivision) {
		// Break up into segments
		unsigned int startSegment = 0;
		XYPOSITION xStartSegment = 0;
		while (startSegment < len) {
			unsigned int lenSegment = pdoc->SafeSegment(s + startSegment, len - startSegment, BreakFinder::lengthEachSubdivision);
			surface->MeasureWidths(vstyle.styles[styleNumber].font, s + startSegment, lenSegment, positions + startSegment);
			for (unsigned int inSeg = 0; inSeg < lenSegment; inSeg++) {
				positions[startSegment + inSeg] += xStartSegment;
			}
			xStartSegment = positions[startSegment + lenSegment - 1];
			startSegment += lenSegment;
		}
	} else {
		surface->MeasureWidths(vstyle.styles[styleNumber].font, s, len, positions);
	}
	if (probe >= 0) {
		clock++;
		if (clock > 60000) {
			// Since there are only 16 bits for the clock, wrap it round and
			// reset all cache entries so none get stuck with a high clock.
			for (size_t i=0; i<pces.size(); i++) {
				pces[i].ResetClock();
			}
			clock = 2;
		}
		pces[probe].Set(styleNumber, s, len, positions, clock);
	}
}