Revert of Checking for valid colorType, alphaType, colorSpace in SkCodec

src/codec/SkWebpCodec.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 "SkCodecPriv.h"
 #include "SkColorSpaceXform.h"
 #include "SkWebpCodec.h"
@@ skipping 126 matching lines @@
             break;
         default:
             return nullptr;
     }
 
     SkEncodedInfo info = SkEncodedInfo::Make(color, alpha, 8);
     return new SkWebpCodec(features.width, features.height, info, std::move(colorSpace),
                            streamDeleter.release(), demux.release(), std::move(data));
 }
 
+static bool webp_conversion_possible(const SkImageInfo& dst, const SkImageInfo& src,
+                                     SkColorSpaceXform* colorXform) {
+    if (!valid_alpha(dst.alphaType(), src.alphaType())) {
+        return false;
+    }
+
+    switch (dst.colorType()) {
+        case kRGBA_F16_SkColorType:
+            return nullptr != colorXform;
+        case kBGRA_8888_SkColorType:
+        case kRGBA_8888_SkColorType:
+            return true;
+        case kRGB_565_SkColorType:
+            return nullptr == colorXform && src.alphaType() == kOpaque_SkAlphaType;
+        default:
+            return false;
+    }
+}
+
 SkISize SkWebpCodec::onGetScaledDimensions(float desiredScale) const {
     SkISize dim = this->getInfo().dimensions();
     // SkCodec treats zero dimensional images as errors, so the minimum size
     // that we will recommend is 1x1.
     dim.fWidth = SkTMax(1, SkScalarRoundToInt(desiredScale * dim.fWidth));
     dim.fHeight = SkTMax(1, SkScalarRoundToInt(desiredScale * dim.fHeight));
     return dim;
 }
 
 bool SkWebpCodec::onDimensionsSupported(const SkISize& dim) {
@@ skipping 29 matching lines @@
     // decode this exact subset.
     // Leave right and bottom unmodified, so we suggest a slightly larger subset than requested.
     desiredSubset->fLeft = (desiredSubset->fLeft >> 1) << 1;
     desiredSubset->fTop = (desiredSubset->fTop >> 1) << 1;
     return true;
 }
 
 SkCodec::Result SkWebpCodec::onGetPixels(const SkImageInfo& dstInfo, void* dst, size_t rowBytes,
                                          const Options& options, SkPMColor*, int*,
                                          int* rowsDecodedPtr) {
-    if (!conversion_possible(dstInfo, this->getInfo())) {
-        return kInvalidConversion;
-    }
 
     std::unique_ptr<SkColorSpaceXform> colorXform = nullptr;
     if (needs_color_xform(dstInfo, this->getInfo())) {
         colorXform = SkColorSpaceXform::New(sk_ref_sp(this->getInfo().colorSpace()),
                                             sk_ref_sp(dstInfo.colorSpace()));
-        SkASSERT(colorXform);
+    }
+
+    if (!webp_conversion_possible(dstInfo, this->getInfo(), colorXform.get())) {
+        return kInvalidConversion;
     }
 
     WebPDecoderConfig config;
     if (0 == WebPInitDecoderConfig(&config)) {
         // ABI mismatch.
         // FIXME: New enum for this?
         return kInvalidInput;
     }
 
     // Free any memory associated with the buffer. Must be called last, so we declare it first.
@@ skipping 107 matching lines @@
     return result;
 }
 
 SkWebpCodec::SkWebpCodec(int width, int height, const SkEncodedInfo& info,
                          sk_sp<SkColorSpace> colorSpace, SkStream* stream, WebPDemuxer* demux,
                          sk_sp<SkData> data)
     : INHERITED(width, height, info, stream, std::move(colorSpace))
     , fDemux(demux)
     , fData(std::move(data))
 {}