Improve caching of dashed paths in GrStencilAndCoverPathRenderer

src/gpu/GrPath.cpp

Index: src/gpu/GrPath.cpp
diff --git a/src/gpu/GrPath.cpp b/src/gpu/GrPath.cpp
index 3a66865c6e5d3448eaeaefce22db731364340519..4af6cc6beaa6c1dcf8ef9d6738f0d1cea49d3f0b 100644
--- a/src/gpu/GrPath.cpp
+++ b/src/gpu/GrPath.cpp
@@ -7,49 +7,12 @@
 
 #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;
-}