API to support native scaling by image-generator

src/core/SkImageGenerator.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkImageGenerator.h"
 #include "SkNextID.h"
 
@@ skipping 93 matching lines @@
     return this->onGetYUV8Planes(sizes, planes, rowBytes);
 }
 
 GrTexture* SkImageGenerator::generateTexture(GrContext* ctx, const SkIRect* subset) {
     if (subset && !SkIRect::MakeWH(fInfo.width(), fInfo.height()).contains(*subset)) {
         return nullptr;
     }
     return this->onGenerateTexture(ctx, subset);
 }
 
+bool SkImageGenerator::computeScaledDimensions(SkScalar scale, SupportedSizes* sizes) {
+    if (scale > 0 && scale <= 1) {
+        return this->onComputeScaledDimensions(scale, sizes);
+    }
+    return false;
+}
+
+bool SkImageGenerator::generateScaledPixels(const SkISize& scaledSize,
+                                            const SkIPoint& subsetOrigin,
+                                            const SkPixmap& subsetPixels) {
+    if (scaledSize.width() <= 0 || scaledSize.height() <= 0) {
+        return false;
+    }
+    if (subsetPixels.width() <= 0 || subsetPixels.height() <= 0) {
+        return false;
+    }
+    const SkIRect subset = SkIRect::MakeXYWH(subsetOrigin.x(), subsetOrigin.y(),
+                                             subsetPixels.width(), subsetPixels.height());
+    if (!SkIRect::MakeWH(scaledSize.width(), scaledSize.height()).contains(subset)) {
+        return false;
+    }
+    return this->onGenerateScaledPixels(scaledSize, subsetOrigin, subsetPixels);
+}
+
 /////////////////////////////////////////////////////////////////////////////////////////////
 
 SkData* SkImageGenerator::onRefEncodedData() {
     return nullptr;
 }
 
 bool SkImageGenerator::onGetPixels(const SkImageInfo& info, void* dst, size_t rb,
                                    SkPMColor* colors, int* colorCount) {
     return false;
 }
@@ skipping 90 matching lines @@
     if (nullptr == data) {
         return nullptr;
     }
     if (gFactory) {
         if (SkImageGenerator* generator = gFactory(data)) {
             return generator;
         }
     }
     return SkImageGenerator::NewFromEncodedImpl(data);
 }