Fix colorType/alphaType checks in SkCodec

Make getPixels() and startScanlineDecode() behave
consistently.

Require that kGray8 decodes are opaque.

Assert that creating the swizzler succeeds.

BUG=skia:4203
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1695473002

Review URL: https://codereview.chromium.org/1695473002

1 files changed, 4 insertions, 17 deletions

diff --git a/src/codec/SkBmpMaskCodec.cpp b/src/codec/SkBmpMaskCodec.cpp
index b603de9a03..21d231b15f 100644
--- a/src/codec/SkBmpMaskCodec.cpp
+++ b/src/codec/SkBmpMaskCodec.cpp
@@ -57,25 +57,12 @@ SkCodec::Result SkBmpMaskCodec::onGetPixels(const SkImageInfo& dstInfo,
     return kSuccess;
 }
 
-bool SkBmpMaskCodec::initializeSwizzler(const SkImageInfo& dstInfo, const Options& options) {
-    // Create the swizzler
-    fMaskSwizzler.reset(SkMaskSwizzler::CreateMaskSwizzler(dstInfo, this->getInfo(), fMasks,
-            this->bitsPerPixel(), options));
-
-    if (nullptr == fMaskSwizzler.get()) {
-        return false;
-    }
-
-    return true;
-}
-
 SkCodec::Result SkBmpMaskCodec::prepareToDecode(const SkImageInfo& dstInfo,
         const SkCodec::Options& options, SkPMColor inputColorPtr[], int* inputColorCount) {
-    // Initialize a the mask swizzler
-    if (!this->initializeSwizzler(dstInfo, options)) {
-        SkCodecPrintf("Error: cannot initialize swizzler.\n");
-        return SkCodec::kInvalidConversion;
-    }
+    // Initialize the mask swizzler
+    fMaskSwizzler.reset(SkMaskSwizzler::CreateMaskSwizzler(dstInfo, this->getInfo(), fMasks,
+            this->bitsPerPixel(), options));
+    SkASSERT(fMaskSwizzler);
 
     return SkCodec::kSuccess;
 }