Just expose factories for patheffects

bug: skia:11957
Change-Id: If2983fcd1b520a7ae77650d7e5ab226af9db52e0
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/410782
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Tyler Denniston <tdenniston@google.com>
diff --git a/src/effects/Sk1DPathEffect.cpp b/src/effects/Sk1DPathEffect.cpp
index 24288c0..00fa542 100644
--- a/src/effects/Sk1DPathEffect.cpp
+++ b/src/effects/Sk1DPathEffect.cpp
@@ -16,68 +16,119 @@
 // Put in a governor to limit crash values from looping too long (and allocating too much ram).
 #define MAX_REASONABLE_ITERATIONS   100000
 
-bool Sk1DPathEffect::onFilterPath(SkPath* dst, const SkPath& src,
-                                  SkStrokeRec*, const SkRect*) const {
-    SkPathMeasure   meas(src, false);
-    do {
-        int governor = MAX_REASONABLE_ITERATIONS;
-        SkScalar    length = meas.getLength();
-        SkScalar    distance = this->begin(length);
-        while (distance < length && --governor >= 0) {
-            SkScalar delta = this->next(dst, distance, meas);
-            if (delta <= 0) {
-                break;
+class Sk1DPathEffect : public SkPathEffect {
+public:
+protected:
+    bool onFilterPath(SkPath* dst, const SkPath& src, SkStrokeRec*, const SkRect*) const override {
+        SkPathMeasure   meas(src, false);
+        do {
+            int governor = MAX_REASONABLE_ITERATIONS;
+            SkScalar    length = meas.getLength();
+            SkScalar    distance = this->begin(length);
+            while (distance < length && --governor >= 0) {
+                SkScalar delta = this->next(dst, distance, meas);
+                if (delta <= 0) {
+                    break;
+                }
+                distance += delta;
             }
-            distance += delta;
-        }
-    } while (meas.nextContour());
-    return true;
-}
+        } while (meas.nextContour());
+        return true;
+    }
+
+    /** Called at the start of each contour, returns the initial offset
+        into that contour.
+    */
+    virtual SkScalar begin(SkScalar contourLength) const = 0;
+    /** Called with the current distance along the path, with the current matrix
+        for the point/tangent at the specified distance.
+        Return the distance to travel for the next call. If return <= 0, then that
+        contour is done.
+    */
+    virtual SkScalar next(SkPath* dst, SkScalar dist, SkPathMeasure&) const = 0;
+
+private:
+    // For simplicity, assume fast bounds cannot be computed
+    bool computeFastBounds(SkRect*) const override { return false; }
+
+    using INHERITED = SkPathEffect;
+};
 
 ///////////////////////////////////////////////////////////////////////////////
 
-SkPath1DPathEffect::SkPath1DPathEffect(const SkPath& path, SkScalar advance, SkScalar phase,
-                                       Style style) : fPath(path) {
-    SkASSERT(advance > 0 && !path.isEmpty());
-    SkASSERT((unsigned)style <= kMorph_Style);
+class SkPath1DPathEffectImpl : public Sk1DPathEffect {
+public:
+    SkPath1DPathEffectImpl(const SkPath& path, SkScalar advance, SkScalar phase,
+                           SkPath1DPathEffect::Style style) : fPath(path) {
+        SkASSERT(advance > 0 && !path.isEmpty());
 
-    // Make the path thread-safe.
-    fPath.updateBoundsCache();
-    (void)fPath.getGenerationID();
+        // Make the path thread-safe.
+        fPath.updateBoundsCache();
+        (void)fPath.getGenerationID();
 
-    // cleanup their phase parameter, inverting it so that it becomes an
-    // offset along the path (to match the interpretation in PostScript)
-    if (phase < 0) {
-        phase = -phase;
-        if (phase > advance) {
-            phase = SkScalarMod(phase, advance);
+        // cleanup their phase parameter, inverting it so that it becomes an
+        // offset along the path (to match the interpretation in PostScript)
+        if (phase < 0) {
+            phase = -phase;
+            if (phase > advance) {
+                phase = SkScalarMod(phase, advance);
+            }
+        } else {
+            if (phase > advance) {
+                phase = SkScalarMod(phase, advance);
+            }
+            phase = advance - phase;
         }
-    } else {
-        if (phase > advance) {
-            phase = SkScalarMod(phase, advance);
+        // now catch the edge case where phase == advance (within epsilon)
+        if (phase >= advance) {
+            phase = 0;
         }
-        phase = advance - phase;
-    }
-    // now catch the edge case where phase == advance (within epsilon)
-    if (phase >= advance) {
-        phase = 0;
-    }
-    SkASSERT(phase >= 0);
+        SkASSERT(phase >= 0);
 
-    fAdvance = advance;
-    fInitialOffset = phase;
-
-    if ((unsigned)style > kMorph_Style) {
-        SkDEBUGF("SkPath1DPathEffect style enum out of range %d\n", style);
+        fAdvance = advance;
+        fInitialOffset = phase;
+        fStyle = style;
     }
-    fStyle = style;
-}
 
-bool SkPath1DPathEffect::onFilterPath(SkPath* dst, const SkPath& src,
-                                      SkStrokeRec* rec, const SkRect* cullRect) const {
-    rec->setFillStyle();
-    return this->INHERITED::onFilterPath(dst, src, rec, cullRect);
-}
+    bool onFilterPath(SkPath* dst, const SkPath& src, SkStrokeRec* rec,
+                      const SkRect* cullRect) const override {
+        rec->setFillStyle();
+        return this->INHERITED::onFilterPath(dst, src, rec, cullRect);
+    }
+
+    SkScalar begin(SkScalar contourLength) const override {
+        return fInitialOffset;
+    }
+
+    SkScalar next(SkPath*, SkScalar, SkPathMeasure&) const override;
+
+    static sk_sp<SkFlattenable> CreateProc(SkReadBuffer& buffer) {
+        SkScalar advance = buffer.readScalar();
+        SkPath path;
+        buffer.readPath(&path);
+        SkScalar phase = buffer.readScalar();
+        SkPath1DPathEffect::Style style = buffer.read32LE(SkPath1DPathEffect::kLastEnum_Style);
+        return buffer.isValid() ? SkPath1DPathEffect::Make(path, advance, phase, style) : nullptr;
+    }
+
+    void flatten(SkWriteBuffer& buffer) const override {
+        buffer.writeScalar(fAdvance);
+        buffer.writePath(fPath);
+        buffer.writeScalar(fInitialOffset);
+        buffer.writeUInt(fStyle);
+    }
+
+    Factory getFactory() const override { return CreateProc; }
+    const char* getTypeName() const override { return "SkPath1DPathEffect"; }
+
+private:
+    SkPath                      fPath;          // copied from constructor
+    SkScalar                    fAdvance;       // copied from constructor
+    SkScalar                    fInitialOffset; // computed from phase
+    SkPath1DPathEffect::Style   fStyle;         // copied from constructor
+
+    using INHERITED = Sk1DPathEffect;
+};
 
 static bool morphpoints(SkPoint dst[], const SkPoint src[], int count,
                         SkPathMeasure& meas, SkScalar dist) {
@@ -153,52 +204,29 @@
     }
 }
 
-SkScalar SkPath1DPathEffect::begin(SkScalar contourLength) const {
-    return fInitialOffset;
-}
-
-sk_sp<SkFlattenable> SkPath1DPathEffect::CreateProc(SkReadBuffer& buffer) {
-    SkScalar advance = buffer.readScalar();
-    SkPath path;
-    buffer.readPath(&path);
-    SkScalar phase = buffer.readScalar();
-    Style style = buffer.read32LE(kLastEnum_Style);
-    return buffer.isValid() ? SkPath1DPathEffect::Make(path, advance, phase, style) : nullptr;
-}
-
-void SkPath1DPathEffect::flatten(SkWriteBuffer& buffer) const {
-    buffer.writeScalar(fAdvance);
-    buffer.writePath(fPath);
-    buffer.writeScalar(fInitialOffset);
-    buffer.writeUInt(fStyle);
-}
-
-SkScalar SkPath1DPathEffect::next(SkPath* dst, SkScalar distance,
-                                  SkPathMeasure& meas) const {
+SkScalar SkPath1DPathEffectImpl::next(SkPath* dst, SkScalar distance,
+                                      SkPathMeasure& meas) const {
 #if defined(SK_BUILD_FOR_FUZZER)
     if (dst->countPoints() > 100000) {
         return fAdvance;
     }
 #endif
     switch (fStyle) {
-        case kTranslate_Style: {
+        case SkPath1DPathEffect::kTranslate_Style: {
             SkPoint pos;
             if (meas.getPosTan(distance, &pos, nullptr)) {
                 dst->addPath(fPath, pos.fX, pos.fY);
             }
         } break;
-        case kRotate_Style: {
+        case SkPath1DPathEffect::kRotate_Style: {
             SkMatrix matrix;
             if (meas.getMatrix(distance, &matrix)) {
                 dst->addPath(fPath, matrix);
             }
         } break;
-        case kMorph_Style:
+        case SkPath1DPathEffect::kMorph_Style:
             morphpath(dst, fPath, meas, distance);
             break;
-        default:
-            SkDEBUGFAIL("unknown Style enum");
-            break;
     }
     return fAdvance;
 }
@@ -210,5 +238,9 @@
     if (advance <= 0 || !SkScalarIsFinite(advance) || !SkScalarIsFinite(phase) || path.isEmpty()) {
         return nullptr;
     }
-    return sk_sp<SkPathEffect>(new SkPath1DPathEffect(path, advance, phase, style));
+    return sk_sp<SkPathEffect>(new SkPath1DPathEffectImpl(path, advance, phase, style));
+}
+
+void SkPath1DPathEffect::RegisterFlattenables() {
+    SK_REGISTER_FLATTENABLE(SkPath1DPathEffectImpl);
 }