Revert "Do not return Index8 from SkAndroidCodec::computeOutputColorType"

This reverts commit b6f4767294261dca3beef6f280c4bac69df3f930.

Reason for revert: This breaks CTS tests in Android.  Doh.

Original change's description:
> Do not return Index8 from SkAndroidCodec::computeOutputColorType
> 
> Given that this is the only known use of Index8 color type,
> this is essentially an experimental delete.
> 
> Bug: skia:6620
> Change-Id: Ib363d237e0217f6e7f461a62e54d32892c428095
> Reviewed-on: https://skia-review.googlesource.com/10586
> Reviewed-by: Leon Scroggins <scroggo@google.com>
> Commit-Queue: Matt Sarett <msarett@google.com>

TBR=msarett@google.com,scroggo@google.com,reed@google.com
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:6620

Change-Id: I2b44c695b8b95659520e9532901f636f56e01e2a
Reviewed-on: https://skia-review.googlesource.com/19084
Reviewed-by: Matt Sarett <msarett@google.com>
Commit-Queue: Matt Sarett <msarett@google.com>

1 files changed, 29 insertions, 3 deletions

diff --git a/src/codec/SkAndroidCodec.cpp b/src/codec/SkAndroidCodec.cpp
index 6c9152b08a..b30dd52e4c 100644
--- a/src/codec/SkAndroidCodec.cpp
+++ b/src/codec/SkAndroidCodec.cpp
@@ -105,19 +105,39 @@ SkAndroidCodec* SkAndroidCodec::NewFromData(sk_sp<SkData> data, SkPngChunkReader
 }
 
 SkColorType SkAndroidCodec::computeOutputColorType(SkColorType requestedColorType) {
+    // The legacy GIF and WBMP decoders always decode to kIndex_8_SkColorType.
+    // We will maintain this behavior when we can.
+    const SkColorType suggestedColorType = this->getInfo().colorType();
+    switch ((SkEncodedImageFormat) this->getEncodedFormat()) {
+        case SkEncodedImageFormat::kGIF:
+            if (suggestedColorType == kIndex_8_SkColorType) {
+                return kIndex_8_SkColorType;
+            }
+            break;
+        case SkEncodedImageFormat::kWBMP:
+            return kIndex_8_SkColorType;
+        default:
+            break;
+    }
+
     bool highPrecision = fCodec->getEncodedInfo().bitsPerComponent() > 8;
     switch (requestedColorType) {
         case kARGB_4444_SkColorType:
             return kN32_SkColorType;
         case kN32_SkColorType:
+            // F16 is the Android default for high precision images.
+            return highPrecision ? kRGBA_F16_SkColorType : kN32_SkColorType;
         case kIndex_8_SkColorType:
+            if (kIndex_8_SkColorType == suggestedColorType) {
+                return kIndex_8_SkColorType;
+            }
             break;
         case kAlpha_8_SkColorType:
             // Fall through to kGray_8.  Before kGray_8_SkColorType existed,
             // we allowed clients to request kAlpha_8 when they wanted a
             // grayscale decode.
         case kGray_8_SkColorType:
-            if (kGray_8_SkColorType == this->getInfo().colorType()) {
+            if (kGray_8_SkColorType == suggestedColorType) {
                 return kGray_8_SkColorType;
             }
             break;
@@ -132,8 +152,14 @@ SkColorType SkAndroidCodec::computeOutputColorType(SkColorType requestedColorTyp
             break;
     }
 
-    // F16 is the Android default for high precision images.
-    return highPrecision ? kRGBA_F16_SkColorType : kN32_SkColorType;
+    // Android has limited support for kGray_8 (using kAlpha_8).  We will not
+    // use kGray_8 for Android unless they specifically ask for it.
+    if (kGray_8_SkColorType == suggestedColorType) {
+        return kN32_SkColorType;
+    }
+
+    // |suggestedColorType| may be kN32_SkColorType or kIndex_8_SkColorType.
+    return highPrecision ? kRGBA_F16_SkColorType : suggestedColorType;
 }
 
 SkAlphaType SkAndroidCodec::computeOutputAlphaType(bool requestedUnpremul) {