get rid of O(n^2) loop from apply_deltas_to_points
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157a414bd9
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49252c42bb
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@ -577,6 +577,9 @@ struct gvar
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return (1.f - r) * prev_delta + r * next_delta;
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}
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static unsigned int next_index (unsigned int i, unsigned int start, unsigned int end)
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{ return (i >= end)? start: (i + 1); }
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public:
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bool apply_deltas_to_points (hb_codepoint_t glyph,
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const int *coords, unsigned int coord_count,
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@ -646,27 +649,45 @@ struct gvar
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for (unsigned int c = 0; c < end_points.length; c++)
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{
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unsigned int end_point = end_points[c];
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for (unsigned int i = start_point; i <= end_point; i++)
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unsigned int i, j;
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/* Check the number of unreferenced points in a contour. If no unref points or no ref points, nothing to do. */
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unsigned int unref_count = 0;
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for (i = start_point; i <= end_point; i++)
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if (!deltas[i].flag) unref_count++;
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if (unref_count == 0 || unref_count > end_point - start_point)
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goto no_more_gaps;
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j = start_point;
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for (;;)
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{
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if (deltas[i].flag) continue;
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/* search in both directions within the contour for a pair of referenced points */
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unsigned int prev;
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for (prev = i;;)
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{
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if (prev-- <= start_point) prev = end_point;
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if (prev == i || deltas[prev].flag) break;
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/* Locate the next gap of unreferenced points between two referenced points prev and next.
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* Note that a gap may wrap around at left (start_point) and/or at right (end_point).
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*/
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unsigned int prev, next;
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for (;;) {
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i = j;
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j = next_index (i, start_point, end_point);
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if (deltas[i].flag && !deltas[j].flag) break;
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}
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if (prev == i) continue; /* no (previous) referenced point was found */
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unsigned int next;
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for (next = i;;)
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{
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if (next++ >= end_point) next = start_point;
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if (next == i || deltas[next].flag) break;
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prev = j = i;
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for (;;) {
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i = j;
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j = next_index (i, start_point, end_point);
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if (!deltas[i].flag && deltas[j].flag) break;
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}
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assert (next != i);
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next = j;
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/* Infer deltas for all unref points in the gap between prev and next */
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i = prev;
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for (;;) {
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i = next_index (i, start_point, end_point);
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if (i == next) break;
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deltas[i].x = infer_delta<x_getter> (orig_points.as_array (), deltas.as_array (), i, prev, next);
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deltas[i].y = infer_delta<y_getter> (orig_points.as_array (), deltas.as_array (), i, prev, next);
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if (--unref_count == 0) goto no_more_gaps;
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}
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}
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no_more_gaps:
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start_point = end_point + 1;
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}
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