remove unused (by the outside) SkImage::newSurface, and simplify newImage -> newSubset

samplecode/SampleFilterQuality.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 "gm.h"
 
 #include "Resources.h"
@@ skipping 28 matching lines @@
     path.setFillType(SkPath::kEvenOdd_FillType);
 
     path.addRect(SkRect::MakeWH(N/2, N));
     path.addRect(SkRect::MakeWH(N, N/2));
     path.moveTo(0, 0); path.lineTo(N, 0); path.lineTo(0, N); path.close();
 
     canvas->drawPath(path, SkPaint());
     return surface->newImageSnapshot();
 }
 
-static SkImage* zoom_up(SkImage* orig) {
+static SkImage* zoom_up(SkSurface* origSurf, SkImage* orig) {
     const SkScalar S = 8;    // amount to scale up
     const int D = 2;    // dimension scaling for the offscreen
     // since we only view the center, don't need to produce the entire thing
     
     SkImageInfo info = SkImageInfo::MakeN32(orig->width() * D, orig->height() * D,
                                             kOpaque_SkAlphaType);
-    SkAutoTUnref<SkSurface> surface(orig->newSurface(info));
+    SkAutoTUnref<SkSurface> surface(origSurf->newSurface(info));
     SkCanvas* canvas = surface->getCanvas();
     canvas->drawColor(SK_ColorWHITE);
     canvas->scale(S, S);
     canvas->translate(-SkScalarHalf(orig->width()) * (S - D) / S,
                       -SkScalarHalf(orig->height()) * (S - D) / S);
     canvas->drawImage(orig, 0, 0, nullptr);
     
     if (S > 3) {
         SkPaint paint;
         paint.setColor(SK_ColorWHITE);
@@ skipping 147 matching lines @@
             canvas->drawColor(SK_ColorWHITE);
             size.set(info.width(), info.height());
         } else {
             canvas->translate(SkScalarHalf(fCell.width() - fImage->width()),
                               SkScalarHalf(fCell.height() - fImage->height()));
         }
         this->drawTheImage(canvas, size, filter, dx, dy);
 
         if (surface) {
             SkAutoTUnref<SkImage> orig(surface->newImageSnapshot());
-            SkAutoTUnref<SkImage> zoomed(zoom_up(orig));
+            SkAutoTUnref<SkImage> zoomed(zoom_up(surface, orig));
             origCanvas->drawImage(zoomed,
                                   SkScalarHalf(fCell.width() - zoomed->width()),
                                   SkScalarHalf(fCell.height() - zoomed->height()));
         }
     }
 
     void drawBorders(SkCanvas* canvas) {
         SkPaint p;
         p.setStyle(SkPaint::kStroke_Style);
         p.setColor(SK_ColorBLUE);
@@ skipping 53 matching lines @@
     }
 
 private:
     typedef SampleView INHERITED;
 };
 
 //////////////////////////////////////////////////////////////////////////////
 
 static SkView* MyFactory() { return new FilterQualityView; }
 static SkViewRegister reg(MyFactory);