Trying to be consistent when members are allowed to be NULL

src/effects/SkRectShaderImageFilter.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkRectShaderImageFilter.h"
 #include "SkBitmap.h"
 #include "SkCanvas.h"
@@ skipping 15 matching lines @@
 SkRectShaderImageFilter* SkRectShaderImageFilter::Create(SkShader* s, const CropRect* cropRect, uint32_t uniqueID) {
     SkASSERT(s);
     return SkNEW_ARGS(SkRectShaderImageFilter, (s, cropRect, uniqueID));
 }
 
 SkRectShaderImageFilter::SkRectShaderImageFilter(SkShader* s, const CropRect* cropRect,
                                                  uint32_t uniqueID)
   : INHERITED(0, NULL, cropRect, uniqueID)
   , fShader(s) {
     SkASSERT(s);
-    s->ref();
+    SkSafeRef(s);

[sugoi1, 2014/10/29 15:26:12]

This class' destructor calls SkSafeUnref(), so the constructor should call
SkSafeRef().

[reed1, 2014/10/29 15:43:39]

How did we get called with a NULL. Is this guy only access via a factory (e.g.
Create)? If so, seems better to have that guy just return NULL.

[sugoi1, 2014/10/29 18:21:00]

Done.

 }
 
 #ifdef SK_SUPPORT_LEGACY_DEEPFLATTENING
 SkRectShaderImageFilter::SkRectShaderImageFilter(SkReadBuffer& buffer)
   : INHERITED(0, buffer) {
     fShader = buffer.readShader();
 }
 #endif
 
 SkFlattenable* SkRectShaderImageFilter::CreateProc(SkReadBuffer& buffer) {
@@ skipping 24 matching lines @@
     SkAutoTUnref<SkBaseDevice> device(proxy->createDevice(bounds.width(),
                                                           bounds.height()));
     if (NULL == device.get()) {
         return false;
     }
     SkCanvas canvas(device.get());
 
     SkPaint paint;
     SkMatrix matrix(ctx.ctm());
     matrix.postTranslate(SkIntToScalar(-bounds.left()), SkIntToScalar(-bounds.top()));
-    paint.setShader(SkShader::CreateLocalMatrixShader(fShader, matrix))->unref();
+    SkSafeUnref(paint.setShader(SkShader::CreateLocalMatrixShader(fShader, matrix)));

[sugoi1, 2014/10/29 15:26:12]

If fShader can be NULL, then SkShader::CreateLocalMatrixShader() may return
NULL.

 
     SkRect rect = SkRect::MakeWH(SkIntToScalar(bounds.width()), SkIntToScalar(bounds.height()));
     canvas.drawRect(rect, paint);
 
     *result = device.get()->accessBitmap(false);
     offset->fX = bounds.fLeft;
     offset->fY = bounds.fTop;
     return true;
 }