Checking for valid colorType, alphaType, colorSpace in SkCodec

* Refactor to share code between SkPngCodec and SkWebpCodec
* Didn't end up sharing with SkJpegCodec but did refactor
  that code a bit
* Disallow conversions to F16 with non-linear color spaces
* Fail to decode if we fail to create a SkColorSpaceXform
  (should be an assert soon).  We used to fallback on a
  legacy decode if we failed to create the transform.
* A bunch of name changes

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2319293003

Review-Url: https://codereview.chromium.org/2319293003

1 files changed, 5 insertions, 34 deletions

diff --git a/src/codec/SkPngCodec.cpp b/src/codec/SkPngCodec.cpp
index 34e6f91131..36ec21f0b8 100644
--- a/src/codec/SkPngCodec.cpp
+++ b/src/codec/SkPngCodec.cpp
@@ -357,25 +357,6 @@ static int bytes_per_pixel(int bitsPerPixel) {
     return bitsPerPixel / 8;
 }
 
-static bool png_conversion_possible(const SkImageInfo& dst, const SkImageInfo& src) {
-    // Ensure the alpha type is valid
-    if (!valid_alpha(dst.alphaType(), src.alphaType())) {
-        return false;
-    }
-
-    // Check for supported color types
-    switch (dst.colorType()) {
-        case kRGBA_8888_SkColorType:
-        case kBGRA_8888_SkColorType:
-        case kRGBA_F16_SkColorType:
-            return true;
-        case kRGB_565_SkColorType:
-            return kOpaque_SkAlphaType == src.alphaType();
-        default:
-            return dst.colorType() == src.colorType();
-    }
-}
-
 void SkPngCodec::allocateStorage(const SkImageInfo& dstInfo) {
     switch (fXformMode) {
         case kSwizzleOnly_XformMode:
@@ -422,7 +403,7 @@ public:
 
     Result onStartScanlineDecode(const SkImageInfo& dstInfo, const Options& options,
             SkPMColor ctable[], int* ctableCount) override {
-        if (!png_conversion_possible(dstInfo, this->getInfo()) ||
+        if (!conversion_possible(dstInfo, this->getInfo()) ||
             !this->initializeXforms(dstInfo, options, ctable, ctableCount))
         {
             return kInvalidConversion;
@@ -489,7 +470,7 @@ public:
 
     Result onStartScanlineDecode(const SkImageInfo& dstInfo, const Options& options,
             SkPMColor ctable[], int* ctableCount) override {
-        if (!png_conversion_possible(dstInfo, this->getInfo()) ||
+        if (!conversion_possible(dstInfo, this->getInfo()) ||
             !this->initializeXforms(dstInfo, options, ctable, ctableCount))
         {
             return kInvalidConversion;
@@ -807,20 +788,10 @@ bool SkPngCodec::initializeXforms(const SkImageInfo& dstInfo, const Options& opt
     fSwizzler.reset(nullptr);
     fColorXform = nullptr;
 
-    bool needsColorXform = needs_color_xform(dstInfo, this->getInfo());
-    if (needsColorXform) {
-        if (kGray_8_SkColorType == dstInfo.colorType() ||
-            kRGB_565_SkColorType == dstInfo.colorType())
-        {
-            return false;
-        }
-
+    if (needs_color_xform(dstInfo, this->getInfo())) {
         fColorXform = SkColorSpaceXform::New(sk_ref_sp(this->getInfo().colorSpace()),
                                              sk_ref_sp(dstInfo.colorSpace()));
-
-        if (!fColorXform && kRGBA_F16_SkColorType == dstInfo.colorType()) {
-            return false;
-        }
+        SkASSERT(fColorXform);
     }
 
     // If the image is RGBA and we have a color xform, we can skip the swizzler.
@@ -907,7 +878,7 @@ SkCodec::Result SkPngCodec::onGetPixels(const SkImageInfo& dstInfo, void* dst,
                                         size_t rowBytes, const Options& options,
                                         SkPMColor ctable[], int* ctableCount,
                                         int* rowsDecoded) {
-    if (!png_conversion_possible(dstInfo, this->getInfo()) ||
+    if (!conversion_possible(dstInfo, this->getInfo()) ||
         !this->initializeXforms(dstInfo, options, ctable, ctableCount))
     {
         return kInvalidConversion;