Implement an SkPaint-based image filter

src/core/SkPathEffect.cpp

 
 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkPathEffect.h"
 #include "SkPath.h"
@@ skipping 49 matching lines @@
         fPE1->toString(str);
     }
 }
 #endif
 
 ///////////////////////////////////////////////////////////////////////////////
 
 SkFlattenable* SkComposePathEffect::CreateProc(SkReadBuffer& buffer) {
     SkAutoTUnref<SkPathEffect> pe0(buffer.readPathEffect());
     SkAutoTUnref<SkPathEffect> pe1(buffer.readPathEffect());
-    return SkComposePathEffect::Create(pe0, pe1);
+    if (pe0 && pe1) {
+        return SkComposePathEffect::Create(pe0, pe1);
+    } else {
+        return nullptr;
+    }
 }
 
 bool SkComposePathEffect::filterPath(SkPath* dst, const SkPath& src,
                              SkStrokeRec* rec, const SkRect* cullRect) const {
     // we may have failed to unflatten these, so we have to check
     if (!fPE0 || !fPE1) {
         return false;
     }
 
     SkPath          tmp;
@@ skipping 12 matching lines @@
     this->INHERITED::toString(str);
     str->appendf(")");
 }
 #endif
 
 ///////////////////////////////////////////////////////////////////////////////
 
 SkFlattenable* SkSumPathEffect::CreateProc(SkReadBuffer& buffer) {
     SkAutoTUnref<SkPathEffect> pe0(buffer.readPathEffect());
     SkAutoTUnref<SkPathEffect> pe1(buffer.readPathEffect());
-    return SkSumPathEffect::Create(pe0, pe1);
+    if (pe0 && pe1) {
+        return SkSumPathEffect::Create(pe0, pe1);
+    } else {
+        return nullptr;
+    }
 }
 
 bool SkSumPathEffect::filterPath(SkPath* dst, const SkPath& src,
                              SkStrokeRec* rec, const SkRect* cullRect) const {
     // use bit-or so that we always call both, even if the first one succeeds
     return fPE0->filterPath(dst, src, rec, cullRect) |
            fPE1->filterPath(dst, src, rec, cullRect);
 }
 
 
 #ifndef SK_IGNORE_TO_STRING
 void SkSumPathEffect::toString(SkString* str) const {
     str->appendf("SkSumPathEffect: (");
     this->INHERITED::toString(str);
     str->appendf(")");
 }
 #endif