Add Gray support to SkPNGImageEncoder

tests/CodecTest.cpp

Index: tests/CodecTest.cpp
diff --git a/tests/CodecTest.cpp b/tests/CodecTest.cpp
index 8023ff219d5873632db3708054a850fe4e8d3025..fcbfadd0680bc25225fd1f0bb1f94d85dc779a60 100644
--- a/tests/CodecTest.cpp
+++ b/tests/CodecTest.cpp
@@ -1074,29 +1074,22 @@ DEF_TEST(Codec_ColorXform, r) {
     check_color_xform(r, "mandrill_512.png");
 }
 
-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);
+static void check_round_trip(skiatest::Reporter* r, const SkBitmap& bm1) {
+    SkColorType origColorType = bm1.colorType();
+    SkAlphaType origAlphaType = bm1.alphaType();
 
     // 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());
+    SkAutoTDelete<SkCodec> codec(SkCodec::NewFromData(data.get()));
+    REPORTER_ASSERT(r, origColorType == codec->getInfo().colorType());
+    REPORTER_ASSERT(r, origAlphaType == codec->getInfo().alphaType());
 
     SkBitmap bm2;
     bm2.allocPixels(codec->getInfo());
-    result = codec->getPixels(codec->getInfo(), bm2.getPixels(), bm2.rowBytes());
+    SkCodec::Result result = codec->getPixels(codec->getInfo(), bm2.getPixels(), bm2.rowBytes());
     REPORTER_ASSERT(r, SkCodec::kSuccess == result);
 
     SkMD5::Digest d1, d2;
@@ -1104,3 +1097,26 @@ DEF_TEST(Codec_Png565, r) {
     md5(bm2, &d2);
     REPORTER_ASSERT(r, d1 == d2);
 }
+
+DEF_TEST(Codec_PngRoundTrip, 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);
+    check_round_trip(r, bm1);
+
+    // Create an arbitrary gray bitmap.
+    path = "grayscale.jpg";
+    stream.reset(resource(path));
+    codec.reset(SkCodec::NewFromStream(stream.release()));
+    SkBitmap bm2;
+    bm2.allocPixels(codec->getInfo());
+    result = codec->getPixels(codec->getInfo(), bm2.getPixels(), bm2.rowBytes());
+    REPORTER_ASSERT(r, SkCodec::kSuccess == result);
+    check_round_trip(r, bm2);
+}