Make cap only affect the keys of GrShapes that are possibly-open

src/gpu/GrStyle.cpp

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrStyle.h"
 
-int GrStyle::KeySize(const GrStyle &style, Apply apply) {
+int GrStyle::KeySize(const GrStyle &style, Apply apply, uint32_t flags) {
     GR_STATIC_ASSERT(sizeof(uint32_t) == sizeof(SkScalar));
     int size = 0;
     if (style.isDashed()) {
         // One scalar for dash phase and one for each dash value.
         size += 1 + style.dashIntervalCnt();
     } else if (style.pathEffect()) {
         // No key for a generic path effect.
         return -1;
     }
 
     if (Apply::kPathEffectOnly == apply) {
         return size;
     }
 
     if (style.strokeRec().needToApply()) {
         // One for style/cap/join, 2 for miter and width.
         size += 3;
     }
     return size;
 }
 
-void GrStyle::WriteKey(uint32_t *key, const GrStyle &style, Apply apply) {
+void GrStyle::WriteKey(uint32_t *key, const GrStyle &style, Apply apply, uint32_t flags) {
     SkASSERT(key);
     SkASSERT(KeySize(style, apply) >= 0);
     GR_STATIC_ASSERT(sizeof(uint32_t) == sizeof(SkScalar));
 
     int i = 0;
     if (style.isDashed()) {
         GR_STATIC_ASSERT(sizeof(style.dashPhase()) == sizeof(uint32_t));
         SkScalar phase = style.dashPhase();
         memcpy(&key[i++], &phase, sizeof(SkScalar));
 
@@ skipping 13 matching lines @@
             kStyleBits = 2,
             kJoinBits = 2,
             kCapBits = 32 - kStyleBits - kJoinBits,
 
             kJoinShift = kStyleBits,
             kCapShift = kJoinShift + kJoinBits,
         };
         GR_STATIC_ASSERT(SkStrokeRec::kStyleCount <= (1 << kStyleBits));
         GR_STATIC_ASSERT(SkPaint::kJoinCount <= (1 << kJoinBits));
         GR_STATIC_ASSERT(SkPaint::kCapCount <= (1 << kCapBits));
+        // The cap type only matters for unclosed shapes. However, a path effect could unclose
+        // the shape before it is stroked.
+        SkPaint::Cap cap;
+        if ((flags & kClosed_KeyFlag) && !style.pathEffect()) {
+            cap = SkPaint::kButt_Cap;
+        } else {
+            cap = style.strokeRec().getCap();
+        }
         key[i++] = style.strokeRec().getStyle() |
                    style.strokeRec().getJoin() << kJoinShift |
-                   style.strokeRec().getCap() << kCapShift;
+                   cap << kCapShift;
 
         SkScalar scalar;
         // Miter limit only affects miter joins
         scalar = SkPaint::kMiter_Join == style.strokeRec().getJoin()
                  ? style.strokeRec().getMiter()
                  : -1.f;
         memcpy(&key[i++], &scalar, sizeof(scalar));
 
         scalar = style.strokeRec().getWidth();
         memcpy(&key[i++], &scalar, sizeof(scalar));
@@ skipping 60 matching lines @@
         *style = SkStrokeRec::kFill_InitStyle;
     } else {
         SkASSERT(SkStrokeRec::kFill_Style == strokeRec.getStyle() ||
                  SkStrokeRec::kHairline_Style == strokeRec.getStyle());
         *style = strokeRec.getStyle() == SkStrokeRec::kFill_Style
                  ? SkStrokeRec::kFill_InitStyle
                  : SkStrokeRec::kHairline_InitStyle;
     }
     return true;
 }