Outline SkImageFilter Make methods

src/core/SkLocalMatrixImageFilter.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkLocalMatrixImageFilter.h"
 #include "SkReadBuffer.h"
 #include "SkSpecialImage.h"
 #include "SkString.h"
 
+sk_sp<SkImageFilter> SkLocalMatrixImageFilter::Make(const SkMatrix& localM,
+                                                    sk_sp<SkImageFilter> input) {
+    if (!input) {
+        return nullptr;
+    }
+    if (localM.getType() & (SkMatrix::kAffine_Mask | SkMatrix::kPerspective_Mask)) {
+        return nullptr;
+    }
+    if (localM.isIdentity()) {
+        return input;
+    }
+    return sk_sp<SkImageFilter>(new SkLocalMatrixImageFilter(localM, input));
+}
+
 SkLocalMatrixImageFilter::SkLocalMatrixImageFilter(const SkMatrix& localM,
                                                    sk_sp<SkImageFilter> input)
     : INHERITED(&input, 1, nullptr)
     , fLocalM(localM) {
 }
 
 sk_sp<SkFlattenable> SkLocalMatrixImageFilter::CreateProc(SkReadBuffer& buffer) {
     SK_IMAGEFILTER_UNFLATTEN_COMMON(common, 1);
     SkMatrix lm;
     buffer.readMatrix(&lm);
@@ skipping 16 matching lines @@
                                                  MapDirection direction) const {
     return this->getInput(0)->filterBounds(src, SkMatrix::Concat(matrix, fLocalM), direction);
 }
 
 #ifndef SK_IGNORE_TO_STRING
 void SkLocalMatrixImageFilter::toString(SkString* str) const {
     str->append("SkLocalMatrixImageFilter: (");
     str->append(")");
 }
 #endif