Improve caching of dashed paths in GrStencilAndCoverPathRenderer

src/gpu/GrStrokeInfo.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrStrokeInfo.h"
-
+#include "GrResourceKey.h"
 #include "SkDashPathPriv.h"
 
 bool GrStrokeInfo::applyDashToPath(SkPath* dst, GrStrokeInfo* dstStrokeInfo,
                                    const SkPath& src) const {
     if (this->isDashed()) {
         SkPathEffect::DashInfo info;
         info.fIntervals = fIntervals.get();
         info.fCount = fIntervals.count();
         info.fPhase = fDashPhase;
         GrStrokeInfo filteredStroke(*this, false);
         if (SkDashPath::FilterDashPath(dst, src, &filteredStroke, NULL, info)) {
             *dstStrokeInfo = filteredStroke;
             return true;
         }
     }
     return false;
 }
+
+void GrStrokeInfo::asUniqueKeyFragment(uint32_t* data) const {
+    const int kSkScalarData32Cnt = sizeof(SkScalar) / sizeof(uint32_t);
+    enum {
+        kStyleBits = 2,
+        kJoinBits = 2,
+        kCapBits = 32 - kStyleBits - kJoinBits,
+
+        kJoinShift = kStyleBits,
+        kCapShift = kJoinShift + kJoinBits,
+    };
+
+    SK_COMPILE_ASSERT(SkStrokeRec::kStyleCount <= (1 << kStyleBits), style_shift_will_be_wrong);
+    SK_COMPILE_ASSERT(SkPaint::kJoinCount <= (1 << kJoinBits), cap_shift_will_be_wrong);
+    SK_COMPILE_ASSERT(SkPaint::kCapCount <= (1 << kCapBits), cap_does_not_fit);
+    uint32_t styleKey = this->getStyle();
+    if (this->needToApply()) {
+        styleKey |= this->getJoin() << kJoinShift;
+        styleKey |= this->getCap() << kCapShift;
+    }
+    int i = 0;
+    data[i++] = styleKey;
+
+    // Memcpy the scalar fields. Does not "reinterpret_cast<SkScalar&>(data[i]) = ..." due to
+    // scalars having more strict alignment requirements than what data can guarantee. The
+    // compiler should optimize memcpys to assignments.
+    SkScalar scalar;
+    scalar = this->getMiter();
+    memcpy(&data[i], &scalar, sizeof(scalar));
+    i += kSkScalarData32Cnt;
+
+    scalar = this->getWidth();
+    memcpy(&data[i], &scalar, sizeof(scalar));
+    i += kSkScalarData32Cnt;
+
+    if (this->isDashed()) {
+        SkScalar phase = this->getDashPhase();
+        memcpy(&data[i], &phase, sizeof(phase));
+        i += kSkScalarData32Cnt;
+
+        int32_t count = this->getDashCount() & static_cast<int32_t>(~1);
+        SkASSERT(count == this->getDashCount());
+        const SkScalar* intervals = this->getDashIntervals();
+        int intervalByteCnt = count * sizeof(SkScalar);
+        memcpy(&data[i], intervals, intervalByteCnt);
+        // Enable the line below if fields are added after dashing.
+        SkDEBUGCODE(i += kSkScalarData32Cnt * count);
+    }
+
+    SkASSERT(this->computeUniqueKeyFragmentData32Cnt() == i);
+}
+