Modify SkPngCodec to recognize 565 images from the sBIT chunk

tests/CodecTest.cpp

Index: tests/CodecTest.cpp
diff --git a/tests/CodecTest.cpp b/tests/CodecTest.cpp
index a5df7e3b50a9e00291966f1a578b637bef7f7cce..27a6e10b89fe659fdb0db9fab92a7538d3d412b9 100644
--- a/tests/CodecTest.cpp
+++ b/tests/CodecTest.cpp
@@ -11,6 +11,7 @@
 #include "SkCodec.h"
 #include "SkCodecImageGenerator.h"
 #include "SkData.h"
+#include "SkImageEncoder.h"
 #include "SkFrontBufferedStream.h"
 #include "SkMD5.h"
 #include "SkRandom.h"
@@ -1042,3 +1043,39 @@ DEF_TEST(Codec_jpeg_rewind, r) {
     SkCodec::Result result = codec->getPixels(codec->getInfo(), pixelStorage.get(), rowBytes);
     REPORTER_ASSERT(r, SkCodec::kSuccess == result);
 }
+
+#if !defined(SK_BUILD_FOR_WIN) && !defined(SK_BUILD_FOR_MAC) && !defined(SK_BUILD_FOR_IOS)
+
+// We need to disable this test on Mac and Windows because CG and WIC do not encode 565 as 565.

[mtklein, 2016/08/04 17:52:51]

encode -> tag?

We can't ask them to nicely can we?  Is this feature worth having if it only
works on Linux?

[msarett, 2016/08/04 19:04:10]

I would be in favor of using our encoder as the default on Mac/Win instead of
CG/WIC.

But then I guess we have to keep around the CG/WIC studd for some clients (ex:
Adobe).

+DEF_TEST(Codec_Png565, r) {
+    // Create an arbitrary 565 bitmap.
+    const char* path = "mandrill_512_q075.jpg";
+    SkAutoTDelete<SkStream> stream(resource(path));
+    SkAutoTDelete<SkCodec> codec(SkCodec::NewFromStream(stream.release()));
+    SkImageInfo info565 = codec->getInfo().makeColorType(kRGB_565_SkColorType);
+    SkBitmap bm1;
+    bm1.allocPixels(info565);
+    SkCodec::Result result = codec->getPixels(info565, bm1.getPixels(), bm1.rowBytes());
+    REPORTER_ASSERT(r, SkCodec::kSuccess == result);
+
+    // Encode the image to png.
+    sk_sp<SkData> data =
+            sk_sp<SkData>(SkImageEncoder::EncodeData(bm1, SkImageEncoder::kPNG_Type, 100));
+
+    // Prepare to decode.  The codec should recognize that the PNG is 565.
+    codec.reset(SkCodec::NewFromData(data.get()));
+    REPORTER_ASSERT(r, kRGB_565_SkColorType == codec->getInfo().colorType());
+    REPORTER_ASSERT(r, kOpaque_SkAlphaType == codec->getInfo().alphaType());
+
+    SkBitmap bm2;
+    bm2.allocPixels(codec->getInfo());
+    result = codec->getPixels(codec->getInfo(), bm2.getPixels(), bm2.rowBytes());
+    REPORTER_ASSERT(r, SkCodec::kSuccess == result);
+
+    SkMD5::Digest d1, d2;
+    md5(bm1, &d1);
+    md5(bm2, &d2);
+    REPORTER_ASSERT(r, d1 == d2);
+}
+
+#endif