Improve caching of dashed paths in GrStencilAndCoverPathRenderer

src/gpu/GrPath.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrPath.h"
 
-template<int NumBits> static uint64_t get_top_n_float_bits(float f) {
-    char* floatData = reinterpret_cast<char*>(&f);
-    uint32_t floatBits = *reinterpret_cast<uint32_t*>(floatData);
-    return floatBits >> (32 - NumBits);
+void GrPath::ComputeKey(const SkPath& path, const GrStrokeInfo& stroke, GrUniqueKey* key) {
+    static const GrUniqueKey::Domain kPathDomain = GrUniqueKey::GenerateDomain();
+    GrUniqueKey::Builder builder(key, kPathDomain,
+                                 2 + stroke.computeUniqueKeyFragmentData32Cnt());
+    builder[0] = path.getGenerationID();
+    builder[1] = path.getFillType();
+    stroke.asUniqueKeyFragment(&builder[2]);

[egdaniel, 2015/05/15 15:28:53]

We should probably Assert here the computeUniqueKeyFragmentData32Cnt is not 0.

[Kimmo Kinnunen, 2015/05/18 06:48:40]

Hmm. I expect you hint at the Builder operator[] assertion? good point. 
The intention is that the stroke decides how big representation it needs. If it
needs 0, it can request that. If this is the decision, then
"asUniqueKeyFragment" would just not write anything. This should be opaque to
the call site. Asserting non-zero would then rise the question: why is this
call-site expecting the stroke to be represented by this specific length or
above?

I could also do an if?

[egdaniel, 2015/05/18 13:43:46]

Yeah it was the builder[2] that I was worried about hitting (which would
Assert). I like the "if" best. You're right that Asserting != 0 would be
strange.

 }
 
-void GrPath::ComputeKey(const SkPath& path, const SkStrokeRec& stroke, GrUniqueKey* key) {
-    static const GrUniqueKey::Domain kDomain = GrUniqueKey::GenerateDomain();
-    GrUniqueKey::Builder builder(key, kDomain, 3);
-    *reinterpret_cast<uint64_t*>(&builder[0]) = ComputeStrokeKey(stroke);
-    builder[2] = path.getGenerationID();
-}
-
-uint64_t GrPath::ComputeStrokeKey(const SkStrokeRec& stroke) {
-    enum {
-        kStyleBits = 2,
-        kJoinBits = 2,
-        kCapBits = 2,
-        kWidthBits = 29,
-        kMiterBits = 29,
-
-        kJoinShift = kStyleBits,
-        kCapShift = kJoinShift + kJoinBits,
-        kWidthShift = kCapShift + kCapBits,
-        kMiterShift = kWidthShift + kWidthBits,
-
-        kBitCount = kMiterShift + kMiterBits
-    };
-
-    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), miter_shift_will_be_wrong);
-    SK_COMPILE_ASSERT(kBitCount == 64, wrong_stroke_key_size);
-
-    if (!stroke.needToApply()) {
-        return SkStrokeRec::kFill_Style;
-    }
-
-    uint64_t key = stroke.getStyle();
-    key |= stroke.getJoin() << kJoinShift;
-    key |= stroke.getCap() << kCapShift;
-    key |= get_top_n_float_bits<kWidthBits>(stroke.getWidth()) << kWidthShift;
-    key |= get_top_n_float_bits<kMiterBits>(stroke.getMiter()) << kMiterShift;
-
-    return key;
-}