Clean up SkImageFilter constructors.

src/effects/SkMagnifierImageFilter.cpp

 /*
  * Copyright 2012 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 "SkBitmap.h"
 #include "SkMagnifierImageFilter.h"
 #include "SkColorPriv.h"
@@ skipping 228 matching lines @@
     float width = buffer.readScalar();
     float height = buffer.readScalar();
     fSrcRect = SkRect::MakeXYWH(x, y, width, height);
     fInset = buffer.readScalar();
 
     buffer.validate(SkScalarIsFinite(fInset) && SkIsValidRect(fSrcRect) &&
                     // Negative numbers in src rect are not supported
                     (fSrcRect.fLeft >= 0) && (fSrcRect.fTop >= 0));
 }
 
-// FIXME:  implement single-input semantics
-SkMagnifierImageFilter::SkMagnifierImageFilter(const SkRect& srcRect, SkScalar inset)
-    : INHERITED(0), fSrcRect(srcRect), fInset(inset) {
+SkMagnifierImageFilter::SkMagnifierImageFilter(const SkRect& srcRect, SkScalar inset,
+                                               SkImageFilter* input)
+    : INHERITED(1, &input), fSrcRect(srcRect), fInset(inset) {
     SkASSERT(srcRect.x() >= 0 && srcRect.y() >= 0 && inset >= 0);
 }
 
 #if SK_SUPPORT_GPU
 bool SkMagnifierImageFilter::asNewEffect(GrEffectRef** effect, GrTexture* texture, const SkMatrix&, const SkIRect&) const {
     if (effect) {
         SkScalar yOffset = (texture->origin() == kTopLeft_GrSurfaceOrigin) ? fSrcRect.y() :
                            (texture->height() - (fSrcRect.y() + fSrcRect.height()));
         SkScalar invInset = fInset > 0 ? SkScalarInvert(fInset) : SK_Scalar1;
         *effect = GrMagnifierEffect::Create(texture,
@@ skipping 79 matching lines @@
 
             int x_val = SkPin32(SkScalarFloorToInt(x_interp), 0, width - 1);
             int y_val = SkPin32(SkScalarFloorToInt(y_interp), 0, height - 1);
 
             *dptr = sptr[y_val * width + x_val];
             dptr++;
         }
     }
     return true;
 }