Switch SkDownSampleImageFilter over to new onFilterImage interface

src/effects/SkTestImageFilters.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkTestImageFilters.h"
 #include "SkCanvas.h"
-#include "SkDevice.h"
 #include "SkReadBuffer.h"
+#include "SkSpecialImage.h"
+#include "SkSpecialSurface.h"
 #include "SkWriteBuffer.h"
 
-// Simple helper canvas that "takes ownership" of the provided device, so that
-// when this canvas goes out of scope, so will its device. Could be replaced
-// with the following:
-//
-//  SkCanvas canvas(device);
-//  SkAutoTUnref<SkBaseDevice> aur(device);
-//
-class OwnDeviceCanvas : public SkCanvas {
-public:
-    OwnDeviceCanvas(SkBaseDevice* device) : SkCanvas(device) {
-        SkSafeUnref(device);
-    }
-};
-
 ///////////////////////////////////////////////////////////////////////////////
 
-bool SkDownSampleImageFilter::onFilterImageDeprecated(Proxy* proxy, const SkBitmap& src,
-                                                      const Context&,
-                                                      SkBitmap* result, SkIPoint*) const {
-    SkScalar scale = fScale;
-    if (scale > SK_Scalar1 || scale <= 0) {
-        return false;
+sk_sp<SkSpecialImage> SkDownSampleImageFilter::onFilterImage(SkSpecialImage* source,
+                                                             const Context& ctx,
+                                                             SkIPoint* offset) const {
+    if (fScale > SK_Scalar1 || fScale <= 0) {
+        return nullptr;
     }
 
-    int dstW = SkScalarRoundToInt(src.width() * scale);
-    int dstH = SkScalarRoundToInt(src.height() * scale);
+    int dstW = SkScalarRoundToInt(source->width() * fScale);
+    int dstH = SkScalarRoundToInt(source->height() * fScale);
     if (dstW < 1) {
         dstW = 1;
     }
     if (dstH < 1) {
         dstH = 1;
     }
 
-    SkBitmap tmp;
+    sk_sp<SkSpecialImage> tmp;
 
     // downsample
     {
-        SkBaseDevice* dev = proxy->createDevice(dstW, dstH);
-        if (nullptr == dev) {
-            return false;
+        const SkImageInfo info = SkImageInfo::MakeN32Premul(dstW, dstH);
+
+        sk_sp<SkSpecialSurface> surf(source->makeSurface(info));
+        if (!surf) {
+            return nullptr;
         }
-        OwnDeviceCanvas canvas(dev);
+
+        SkCanvas* canvas = surf->getCanvas();
+        SkASSERT(canvas);
+
         SkPaint paint;
+        paint.setFilterQuality(kLow_SkFilterQuality);
 
-        paint.setFilterQuality(kLow_SkFilterQuality);
-        canvas.scale(scale, scale);
-        canvas.drawBitmap(src, 0, 0, &paint);
-        tmp = dev->accessBitmap(false);
+        canvas->scale(fScale, fScale);
+        source->draw(canvas, 0, 0, &paint);
+
+        tmp = surf->makeImageSnapshot();
     }
 
     // upscale
     {
-        SkBaseDevice* dev = proxy->createDevice(src.width(), src.height());
-        if (nullptr == dev) {
-            return false;
+        const SkImageInfo info = SkImageInfo::MakeN32Premul(source->width(), source->height());
+
+        sk_sp<SkSpecialSurface> surf(source->makeSurface(info));
+        if (!surf) {
+            return nullptr;
         }
-        OwnDeviceCanvas canvas(dev);
 
-        canvas.drawBitmapRect(tmp, SkRect::MakeIWH(src.width(), src.height()), nullptr);
-        *result = dev->accessBitmap(false);
+        SkCanvas* canvas = surf->getCanvas();
+        SkASSERT(canvas);
+
+        canvas->scale(1.0f/fScale, 1.0f/fScale);

[Stephen White, 2016/03/31 17:50:15]

SkScalarInvert, so it handles the scalar-is-double case more cleanly?

[robertphillips, 2016/03/31 18:50:40]

Done.

+        tmp->draw(canvas, 0, 0, nullptr);
+
+        return surf->makeImageSnapshot();
     }
-    return true;
 }
 
 SkFlattenable* SkDownSampleImageFilter::CreateProc(SkReadBuffer& buffer) {
     SK_IMAGEFILTER_UNFLATTEN_COMMON(common, 1);
     return Create(buffer.readScalar(), common.getInput(0).get());
 }
 
 void SkDownSampleImageFilter::flatten(SkWriteBuffer& buffer) const {
     this->INHERITED::flatten(buffer);
     buffer.writeScalar(fScale);
 }
 
 #ifndef SK_IGNORE_TO_STRING
 void SkDownSampleImageFilter::toString(SkString* str) const {
     str->appendf("SkDownSampleImageFilter: (");
     str->append(")");
 }
 #endif