Expand GrStyle's interface.

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) {
+    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) {
+    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));
+
+        int32_t count = style.dashIntervalCnt();
+        // Dash count should always be even.
+        SkASSERT(0 == (count & 0x1));
+        const SkScalar *intervals = style.dashIntervals();
+        int intervalByteCnt = count * sizeof(SkScalar);
+        memcpy(&key[i], intervals, intervalByteCnt);
+        i += count;
+    } else {
+        SkASSERT(!style.pathEffect());
+    }
+
+    if (Apply::kPathEffectAndStrokeRec == apply && style.strokeRec().needToApply()) {
+        enum {
+            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));
+        key[i++] = style.strokeRec().getStyle() |
+                   style.strokeRec().getJoin() << kJoinShift |
+                   style.strokeRec().getCap() << 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));
+    }
+    SkASSERT(KeySize(style, apply) == i);
+}
+
 void GrStyle::initPathEffect(SkPathEffect* pe) {
+    SkASSERT(!fPathEffect)
+    SkASSERT(SkPathEffect::kNone_DashType == fDashInfo.fType);
+    SkASSERT(0 == fDashInfo.fIntervals.count());
     if (!pe) {
-        fDashInfo.fType = SkPathEffect::kNone_DashType;
         return;
     }
     SkPathEffect::DashInfo info;
     if (SkPathEffect::kDash_DashType == pe->asADash(&info)) {
-        if (fStrokeRec.getStyle() == SkStrokeRec::kFill_Style) {
-            fPathEffect.reset(nullptr);
-        } else {
-            fPathEffect.reset(SkSafeRef(pe));
+        if (fStrokeRec.getStyle() != SkStrokeRec::kFill_Style) {
             fDashInfo.fType = SkPathEffect::kDash_DashType;
             fDashInfo.fIntervals.reset(info.fCount);
             fDashInfo.fPhase = info.fPhase;
             info.fIntervals = fDashInfo.fIntervals.get();
             pe->asADash(&info);
-            return;
+            fPathEffect.reset(SkSafeRef(pe));
         }
     } else {
         fPathEffect.reset(SkSafeRef(pe));
     }
-    fDashInfo.fType = SkPathEffect::kNone_DashType;
-    fDashInfo.fIntervals.reset(0);
 }
+
+static inline bool apply_path_effect(SkPath* dst, SkStrokeRec* strokeRec,
+                                     const sk_sp<SkPathEffect>& pe, const SkPath& src) {
+    if (!pe) {
+        return false;
+    }
+    if (!pe->filterPath(dst, src, strokeRec, nullptr)) {
+        return false;
+    }
+    dst->setIsVolatile(true);
+    return true;
+}
+
+bool GrStyle::applyPathEffectToPath(SkPath *dst, SkStrokeRec *remainingStroke,
+                                    const SkPath &src) const {
+    SkASSERT(dst);
+    SkStrokeRec strokeRec = fStrokeRec;
+    if (!apply_path_effect(dst, &strokeRec, fPathEffect, src)) {
+        return false;
+    }
+    *remainingStroke = strokeRec;
+    return true;
+}
+
+bool GrStyle::applyToPath(SkPath* dst, SkStrokeRec::InitStyle* style, const SkPath& src) const {
+    SkASSERT(style);
+    SkASSERT(dst);
+    SkStrokeRec strokeRec = fStrokeRec;
+    if (!apply_path_effect(dst, &strokeRec, fPathEffect, src)) {
+        return false;
+    }
+    if (strokeRec.needToApply()) {
+        if (!strokeRec.applyToPath(dst, *dst)) {
+            return false;
+        }
+        *style = SkStrokeRec::kFill_InitStyle;
+    } else {
+        SkASSERT(SkStrokeRec::kFill_Style == strokeRec.getStyle() ||
+                 SkStrokeRec::kHairline_Style == strokeRec.getStyle());
+        *style = strokeRec.getStyle() == SkStrokeRec::kFill_Style

[egdaniel, 2016/05/04 13:49:38]

since you have the assert above why the need for the ternary here? Why not just
set it to strokeRec.getStyle()?

[bsalomon, 2016/05/04 14:29:17]

That returns a SkStrokeRec::Style: 
    enum Style {
        kHairline_Style,
        kFill_Style,
        kStroke_Style,
        kStrokeAndFill_Style
    };

I need a SkStrokeRec::InitStyle:
    enum InitStyle {
        kHairline_InitStyle,
        kFill_InitStyle
    };


InitStyles are the styles that don't further apply to the geometry.

[egdaniel, 2016/05/04 15:01:49]

Ah missed the Init part in there

+                 ? SkStrokeRec::kFill_InitStyle
+                 : SkStrokeRec::kHairline_InitStyle;
+    }
+    return true;
+}