Let SkCoverageDeltaList store width and use it during blitting

Otherwise, out/Debug/viewer -m complexclip_bw_invert may crash using
the threaded backend because the clip in the initFn may be wider
than the clip in the drawFn.

Bug: skia:
Change-Id: I3b3ddc9a912fcc155bd30a6bc1f87e24739d1ca6
Reviewed-on: https://skia-review.googlesource.com/121327
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Yuqian Li <liyuqian@google.com>

4 files changed, 22 insertions, 10 deletions

diff --git a/src/core/SkBlitter.cpp b/src/core/SkBlitter.cpp
index df67ffb63a..572150a173 100644
--- a/src/core/SkBlitter.cpp
+++ b/src/core/SkBlitter.cpp
@@ -108,7 +108,16 @@ void SkBlitter::blitCoverageDeltas(SkCoverageDeltaList* deltas, const SkIRect& c
         // This is such an important optimization that will bring ~2x speedup for benches like
         // path_fill_small_long_line and path_stroke_small_sawtooth.
         if (canUseMask && !deltas->sorted(y) && deltas->count(y) << 3 >= clip.width()) {
+#ifdef SK_SUPPORT_LEGACY_THREADED_DAA_BUGS
             SkIRect rowIR = SkIRect::MakeLTRB(clip.fLeft, y, clip.fRight, y + 1);
+#else
+            // Note that deltas->left()/right() may be different than clip.fLeft/fRight because in
+            // the threaded backend, deltas are generated in the initFn with full clip, while
+            // blitCoverageDeltas is called in drawFn with a subclip. For inverse fill, the clip
+            // might be wider than deltas' bounds (which is clippedIR).
+            SkIRect rowIR = SkIRect::MakeLTRB(SkTMin(clip.fLeft, deltas->left()), y,
+                                              SkTMax(clip.fRight, deltas->right()), y + 1);
+#endif
             SkSTArenaAlloc<SkCoverageDeltaMask::MAX_SIZE> alloc;
             SkCoverageDeltaMask mask(&alloc, rowIR);
             for(int i = 0; i < deltas->count(y); ++i) {
diff --git a/src/core/SkCoverageDelta.cpp b/src/core/SkCoverageDelta.cpp
index defdcf2b7b..8ead98de09 100644
--- a/src/core/SkCoverageDelta.cpp
+++ b/src/core/SkCoverageDelta.cpp
@@ -7,12 +7,14 @@
 
 #include "SkCoverageDelta.h"
 
-SkCoverageDeltaList::SkCoverageDeltaList(SkArenaAlloc* alloc, int top, int bottom, bool forceRLE) {
+SkCoverageDeltaList::SkCoverageDeltaList(SkArenaAlloc* alloc, const SkIRect& bounds, bool forceRLE) {
     fAlloc              = alloc;
-    fTop                = top;
-    fBottom             = bottom;
+    fBounds             = bounds;
     fForceRLE           = forceRLE;
 
+    int top             = bounds.fTop;
+    int bottom          = bounds.fBottom;
+
     // Init the anti-rect to be empty
     fAntiRect.fY        = bottom;
     fAntiRect.fHeight   = 0;
diff --git a/src/core/SkCoverageDelta.h b/src/core/SkCoverageDelta.h
index 62dee61043..9a7a41d5ac 100644
--- a/src/core/SkCoverageDelta.h
+++ b/src/core/SkCoverageDelta.h
@@ -48,10 +48,12 @@ public:
     static constexpr int INIT_ROW_SIZE = 32;
 #endif
 
-    SkCoverageDeltaList(SkArenaAlloc* alloc, int top, int bottom, bool forceRLE);
+    SkCoverageDeltaList(SkArenaAlloc* alloc, const SkIRect& bounds, bool forceRLE);
 
-    int  top() const { return fTop; }
-    int  bottom() const { return fBottom; }
+    int  top() const { return fBounds.fTop; }
+    int  bottom() const { return fBounds.fBottom; }
+    int  left() const { return fBounds.fLeft; }
+    int  right() const { return fBounds.fRight; }
     bool forceRLE() const { return fForceRLE; }
     int  count(int y) const { this->checkY(y); return fCounts[y]; }
     bool sorted(int y) const { this->checkY(y); return fSorted[y]; }
@@ -84,12 +86,11 @@ private:
     bool*                       fSorted;
     int*                        fCounts;
     int*                        fMaxCounts;
-    int                         fTop;
-    int                         fBottom;
+    SkIRect                     fBounds;
     SkAntiRect                  fAntiRect;
     bool                        fForceRLE;
 
-    void checkY(int y) const { SkASSERT(y >= fTop && y < fBottom); }
+    void checkY(int y) const { SkASSERT(y >= fBounds.fTop && y < fBounds.fBottom); }
 
     SK_ALWAYS_INLINE void push_back(int y, const SkCoverageDelta& delta) {
         this->checkY(y);
diff --git a/src/core/SkScan_DAAPath.cpp b/src/core/SkScan_DAAPath.cpp
index a0d656f6b9..329e69e120 100644
--- a/src/core/SkScan_DAAPath.cpp
+++ b/src/core/SkScan_DAAPath.cpp
@@ -367,7 +367,7 @@ void SkScan::DAAFillPath(const SkPath& path, SkBlitter* blitter, const SkIRect&
         } else {
             record->fType = SkDAARecord::Type::kList;
             SkCoverageDeltaList* deltaList = alloc->make<SkCoverageDeltaList>(
-                    alloc, clippedIR.fTop, clippedIR.fBottom, forceRLE);
+                    alloc, clippedIR, forceRLE);
             gen_alpha_deltas(path, clippedIR, clipBounds, *deltaList, blitter, skipRect,
                              containedInClip);
             record->fList = deltaList;