Move all knowledge of X sampling into SkScaledCodec

src/codec/SkCodec.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 "SkBmpCodec.h"
 #include "SkCodec.h"
 #include "SkData.h"
@@ skipping 134 matching lines @@
     }
 
     if (!this->rewindIfNeeded()) {
         return kCouldNotRewind;
     }
 
     // Default options.
     Options optsStorage;
     if (nullptr == options) {
         options = &optsStorage;
+    } else if (options->fSubset) {
+        SkIRect subset(*options->fSubset);
+        if (!this->onGetValidSubset(&subset) || subset != *options->fSubset) {
+            // FIXME: How to differentiate between not supporting subset at all
+            // and not supporting this particular subset?
+            return kUnimplemented;
+        }
     }
+
+    // FIXME: Support subsets somehow? Note that this works for SkWebpCodec
+    // because it supports arbitrary scaling/subset combinations.
+    if (!this->dimensionsSupported(info.dimensions())) {
+        return kInvalidScale;
+    }
+
     const Result result = this->onGetPixels(info, pixels, rowBytes, *options, ctable, ctableCount);
 
     if ((kIncompleteInput == result || kSuccess == result) && ctableCount) {
         SkASSERT(*ctableCount >= 0 && *ctableCount <= 256);
     }
     return result;
 }
 
 SkCodec::Result SkCodec::getPixels(const SkImageInfo& info, void* pixels, size_t rowBytes) {
     return this->getPixels(info, pixels, rowBytes, nullptr, nullptr, nullptr);
@@ skipping 17 matching lines @@
     }
 
     if (!this->rewindIfNeeded()) {
         return kCouldNotRewind;
     }
 
     // Set options.
     Options optsStorage;
     if (nullptr == options) {
         options = &optsStorage;
+    } else if (options->fSubset) {
+        SkIRect subset(*options->fSubset);
+        if (!this->onGetValidSubset(&subset) || subset != *options->fSubset) {
+            // FIXME: How to differentiate between not supporting subset at all
+            // and not supporting this particular subset?
+            return kUnimplemented;
+        }
+    }
+
+    // FIXME: Support subsets somehow?
+    if (!this->dimensionsSupported(dstInfo.dimensions())) {
+        return kInvalidScale;
     }
 
     const Result result = this->onStartScanlineDecode(dstInfo, *options, ctable, ctableCount);
     if (result != SkCodec::kSuccess) {
         return result;
     }
 
     fCurrScanline = 0;
     fDstInfo = dstInfo;
     fOptions = *options;
     return kSuccess;
 }
 
 SkCodec::Result SkCodec::startScanlineDecode(const SkImageInfo& dstInfo) {
     return this->startScanlineDecode(dstInfo, nullptr, nullptr, nullptr);
 }
 
 SkCodec::Result SkCodec::getScanlines(void* dst, int countLines, size_t rowBytes) {
     if (fCurrScanline < 0) {
         return kScanlineDecodingNotStarted;
     }
 
     SkASSERT(!fDstInfo.isEmpty());
-    if ((rowBytes < fDstInfo.minRowBytes() && countLines > 1 ) || countLines <= 0
-         || fCurrScanline + countLines > fDstInfo.height()) {
+
+    if (countLines <= 0 || fCurrScanline + countLines > fDstInfo.height()) {
         return kInvalidParameters;
     }
 
     const Result result = this->onGetScanlines(dst, countLines, rowBytes);
     fCurrScanline += countLines;
     return result;
 }
 
 SkCodec::Result SkCodec::skipScanlines(int countLines) {
     if (fCurrScanline < 0) {
         return kScanlineDecodingNotStarted;
     }
 
     SkASSERT(!fDstInfo.isEmpty());
     if (fCurrScanline + countLines > fDstInfo.height()) {
         // Arguably, we could just skip the scanlines which are remaining,
         // and return kSuccess. We choose to return invalid so the client
         // can catch their bug.
         return SkCodec::kInvalidParameters;
     }
 
     const Result result = this->onSkipScanlines(countLines);
     fCurrScanline += countLines;
     return result;
 }