Fix for PNG, coding style, skip opaque.

tests/ImageDecodingTest.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmap.h"
 #include "SkColorPriv.h"
 #include "SkForceLinking.h"
 #include "SkImageDecoder.h"
 #include "SkOSFile.h"
 #include "SkStream.h"
 #include "SkString.h"
 #include "Test.h"
 
 __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);
     U8CPU b = SkGetPackedB32(c);
     return SkPreMultiplyARGB(a, r, g, b);
 }
 
 /**
+ *  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.
  */
 static void compare_unpremul(skiatest::Reporter* reporter, const SkString& filename) {
     // Decode a resource:
     SkBitmap bm8888;
     SkBitmap bm8888Unpremul;
 
     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;
     }
 
     SkAutoTDelete<SkImageDecoder> decoder(SkImageDecoder::Factory(&stream));
     if (NULL == decoder.get()) {
         SkDebugf("couldn't decode %s\n", filename.c_str());
         return;
     }
 
     bool success = decoder->decode(&stream, &bm8888, SkBitmap::kARGB_8888_Config,
@@ skipping 28 matching lines @@
         return;
     }
 
     // Now compare the two bitmaps.
     for (int i = 0; i < bm8888.width(); ++i) {
         for (int j = 0; j < bm8888.height(); ++j) {
             // "c0" is the color of the premultiplied bitmap at (i, j).
             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));
             int dg = SkAbs32(SkGetPackedG32(c0) - SkGetPackedG32(c1));
             int db = SkAbs32(SkGetPackedB32(c0) - SkGetPackedB32(c1));
 
             // Alpha component must be exactly the same.
             REPORTER_ASSERT(reporter, 0 == da);
             // Other components may differ if rounding is done differently,
             // but currently that is not the case. If an image fails here
@@ skipping 20 matching lines @@
             compare_unpremul(reporter, filename);
         } while (iter.next(&basename));
     } else {
         SkDebugf("Failed to find any files :(\n");
     }
 }
 
 #include "TestClassDef.h"
 DEFINE_TESTCLASS("ImageDecoding", ImageDecodingTestClass,
                  test_imageDecodingTests)