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sw_engine rle: fix RLE intersect.

Browse source 
IntersectSpansRegion() wasn't working correctly,
as it didn't take care of some corner cases.

This fix makes the algorithm more accurate.
This commit is contained in:
Hermet Park 2023-04-14 13:32:20 +09:00
parent b26672a1f6
commit bd695c6631
1 changed files with 33 additions and 35 deletions
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68
src/lib/sw_engine/tvgSwRle.cpp
View file

@ -773,54 +773,52 @@ static int _genRle(RleWorker& rw)
}
static SwSpan* _intersectSpansRegion(const SwRleData *clip, const SwRleData *targetRle, SwSpan *outSpans, uint32_t spanCnt)
static SwSpan* _intersectSpansRegion(const SwRleData *clip, const SwRleData *target, SwSpan *outSpans)
{
auto out = outSpans;
auto spans = targetRle->spans;
auto end = targetRle->spans + targetRle->size;
auto spans = target->spans;
auto end = target->spans + target->size;
auto clipSpans = clip->spans;
auto clipEnd = clip->spans + clip->size;
while (spanCnt > 0 && spans < end) {
if (clipSpans == clipEnd) {
spans = end;
break;
}
while (spans < end && clipSpans < clipEnd) {
//align y cooridnates.
if (clipSpans->y > spans->y) {
++spans;
continue;
}
if (spans->y != clipSpans->y) {
if (spans->y > clipSpans->y) {
++clipSpans;
continue;
}
auto sx1 = spans->x;
auto sx2 = sx1 + spans->len;
auto cx1 = clipSpans->x;
auto cx2 = cx1 + clipSpans->len;
if (cx1 < sx1 && cx2 < sx1) {
++clipSpans;
continue;
//Try clipping with all clip spans which have a same y coordinate.
auto temp = clipSpans;
while(temp->y == clipSpans->y) {
auto sx1 = spans->x;
auto sx2 = sx1 + spans->len;
auto cx1 = temp->x;
auto cx2 = cx1 + temp->len;
//The span must be left(x1) to right(x2) direction. Not intersected.
if (cx2 < sx1 || sx2 < cx1) {
++temp;
continue;
}
//clip span region.
auto x = sx1 > cx1 ? sx1 : cx1;
auto len = (sx2 < cx2 ? sx2 : cx2) - x;
if (len > 0) {
out->x = x;
out->y = temp->y;
out->len = len;
out->coverage = (uint8_t)(((spans->coverage * temp->coverage) + 0xff) >> 8);
++out;
}
++temp;
}
else if (sx1 < cx1 && sx2 < cx1) {
++spans;
continue;
}
auto x = sx1 > cx1 ? sx1 : cx1;
auto len = (sx2 < cx2 ? sx2 : cx2) - x;
if (len) {
auto spansCorverage = spans->coverage;
auto clipSpansCoverage = clipSpans->coverage;
out->x = sx1 > cx1 ? sx1 : cx1;
out->len = (sx2 < cx2 ? sx2 : cx2) - out->x;
out->y = spans->y;
out->coverage = (uint8_t)(((spansCorverage * clipSpansCoverage) + 0xff) >> 8);
++out;
--spanCnt;
}
if (sx2 < cx2) ++spans;
else ++clipSpans;
++spans;
}
return out;
}
@ -1122,7 +1120,7 @@ void rleClipPath(SwRleData *rle, const SwRleData *clip)
if (rle->size == 0 || clip->size == 0) return;
auto spanCnt = rle->size > clip->size ? rle->size : clip->size;
auto spans = static_cast<SwSpan*>(malloc(sizeof(SwSpan) * (spanCnt)));
auto spansEnd = _intersectSpansRegion(clip, rle, spans, spanCnt);
auto spansEnd = _intersectSpansRegion(clip, rle, spans);
_replaceClipSpan(rle, spans, spansEnd - spans);