Fix for PNG, coding style, skip opaque.

tests/ImageDecodingTest.cpp

Index: tests/ImageDecodingTest.cpp
diff --git a/tests/ImageDecodingTest.cpp b/tests/ImageDecodingTest.cpp
index 5c9d5c58992745568d1a5b366ddb0762d07747e1..f30a0b25b7c115eed29990fb780ad1d373b95360 100644
--- a/tests/ImageDecodingTest.cpp
+++ b/tests/ImageDecodingTest.cpp
@@ -20,7 +20,7 @@ __SK_FORCE_IMAGE_DECODER_LINKING;
  *  Interprets c as an unpremultiplied color, and returns the
  *  premultiplied equivalent.
  */
-SkPMColor SkPreMultiplyUnPMColor(SkPMColor c) {
+static SkPMColor premultiply_unpmcolor(SkPMColor c) {
     U8CPU a = SkGetPackedA32(c);
     U8CPU r = SkGetPackedR32(c);
     U8CPU g = SkGetPackedG32(c);
@@ -29,6 +29,31 @@ SkPMColor SkPreMultiplyUnPMColor(SkPMColor c) {
 }
 
 /**
+ *  Return true if this stream format should be skipped, due
+ *  to do being an opaque format or not a valid format.
+ */
+static bool skip_image_format(SkImageDecoder::Format format) {
+    switch (format) {
+        case SkImageDecoder::kPNG_Format:
+        case SkImageDecoder::kWEBP_Format:
+            return false;
+        // Skip unknown since it will not be decoded anyway.
+        case SkImageDecoder::kUnknown_Format:
+        // Technically ICO and BMP supports alpha channels, but our image
+        // decoders do not, so skip them as well.
+        case SkImageDecoder::kICO_Format:
+        case SkImageDecoder::kBMP_Format:
+        // The rest of these are opaque.
+        case SkImageDecoder::kWBMP_Format:
+        case SkImageDecoder::kGIF_Format:
+        case SkImageDecoder::kJPEG_Format:
+            return true;
+    }
+    SkASSERT(false);
+    return true;
+}
+
+/**
  *  Test decoding an image in premultiplied mode and unpremultiplied mode and compare
  *  them.
  */
@@ -39,8 +64,8 @@ static void compare_unpremul(skiatest::Reporter* reporter, const SkString& filen
 
     SkFILEStream stream(filename.c_str());
 
-    // JPEG is always opaque, so requesting unpremultiplied does not change anything.
-    if (SkImageDecoder::GetStreamFormat(&stream) == SkImageDecoder::kJPEG_Format) {
+    SkImageDecoder::Format format = SkImageDecoder::GetStreamFormat(&stream);
+    if (skip_image_format(format)) {
         return;
     }
 
@@ -89,7 +114,7 @@ static void compare_unpremul(skiatest::Reporter* reporter, const SkString& filen
             const SkPMColor c0 = *bm8888.getAddr32(i, j);
             // "c1" is the result of premultiplying the color of the unpremultiplied
             // bitmap at (i, j).
-            const SkPMColor c1 = SkPreMultiplyUnPMColor(*bm8888Unpremul.getAddr32(i, j));
+            const SkPMColor c1 = premultiply_unpmcolor(*bm8888Unpremul.getAddr32(i, j));
             // Compute the difference for each component.
             int da = SkAbs32(SkGetPackedA32(c0) - SkGetPackedA32(c1));
             int dr = SkAbs32(SkGetPackedR32(c0) - SkGetPackedR32(c1));