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, 5 insertions, 13 deletions

diff --git a/src/codec/SkBmpStandardCodec.cpp b/src/codec/SkBmpStandardCodec.cpp
index 47b10701d3..39d357be8b 100644
--- a/src/codec/SkBmpStandardCodec.cpp
+++ b/src/codec/SkBmpStandardCodec.cpp
@@ -152,9 +152,9 @@ SkCodec::Result SkBmpStandardCodec::onGetPixels(const SkImageInfo& dstInfo,
     return true;
 }
 
-bool SkBmpStandardCodec::initializeSwizzler(const SkImageInfo& dstInfo, const Options& opts) {
+void SkBmpStandardCodec::initializeSwizzler(const SkImageInfo& dstInfo, const Options& opts) {
     // Get swizzler configuration
-    SkSwizzler::SrcConfig config;
+    SkSwizzler::SrcConfig config = SkSwizzler::kUnknown;
     switch (this->bitsPerPixel()) {
         case 1:
             config = SkSwizzler::kIndex1;
@@ -180,7 +180,6 @@ bool SkBmpStandardCodec::initializeSwizzler(const SkImageInfo& dstInfo, const Op
             break;
         default:
             SkASSERT(false);
-            return false;
     }
 
     // Get a pointer to the color table if it exists
@@ -188,11 +187,7 @@ bool SkBmpStandardCodec::initializeSwizzler(const SkImageInfo& dstInfo, const Op
 
     // Create swizzler
     fSwizzler.reset(SkSwizzler::CreateSwizzler(config, colorPtr, dstInfo, opts));
-
-    if (nullptr == fSwizzler.get()) {
-        return false;
-    }
-    return true;
+    SkASSERT(fSwizzler);
 }
 
 SkCodec::Result SkBmpStandardCodec::prepareToDecode(const SkImageInfo& dstInfo,
@@ -207,11 +202,8 @@ SkCodec::Result SkBmpStandardCodec::prepareToDecode(const SkImageInfo& dstInfo,
     // Copy the color table to the client if necessary
     copy_color_table(dstInfo, this->fColorTable, inputColorPtr, inputColorCount);
 
-    // Initialize a swizzler if necessary
-    if (!this->initializeSwizzler(dstInfo, options)) {
-        SkCodecPrintf("Error: cannot initialize swizzler.\n");
-        return SkCodec::kInvalidConversion;
-    }
+    // Initialize a swizzler
+    this->initializeSwizzler(dstInfo, options);
     return SkCodec::kSuccess;
 }