SkScaledCodec class

This class does scaling by using a scanlineDecoder.
getScanlines and skipScanlines are used for y sampling,
the swizzler is used for x sampling

this class is currently only working for png and jpeg images
I will update other Codec types to work soon

For SkJpegCodec to implement width wise swizzling it now
uses a swizzler. I ran performance tests on this change.
Here are the performance test results:
https://docs.google.com/a/google.com/spreadsheets/d/1D7-Q_GXD_dI68LZO005NNvb8Wq2Ee0wEBEPG72671yw/edit?usp=sharing

BUG=skia:

Review URL: https://codereview.chromium.org/1260673002

1 files changed, 16 insertions, 8 deletions

diff --git a/dm/DMSrcSink.cpp b/dm/DMSrcSink.cpp
index f555b9fcbd..9826f97822 100644
--- a/dm/DMSrcSink.cpp
+++ b/dm/DMSrcSink.cpp
@@ -27,6 +27,7 @@
 #include "SkScanlineDecoder.h"
 #include "SkStream.h"
 #include "SkXMLWriter.h"
+#include "SkScaledCodec.h"
 
 DEFINE_bool(multiPage, false, "For document-type backends, render the source"
             " into multiple pages");
@@ -84,9 +85,13 @@ Error CodecSrc::draw(SkCanvas* canvas) const {
     if (!encoded) {
         return SkStringPrintf("Couldn't read %s.", fPath.c_str());
     }
-    SkAutoTDelete<SkCodec> codec(SkCodec::NewFromData(encoded));
+    SkAutoTDelete<SkCodec> codec(SkScaledCodec::NewFromData(encoded));
     if (NULL == codec.get()) {
-        return SkStringPrintf("Couldn't create codec for %s.", fPath.c_str());
+        // scaledCodec not supported, try normal codec
+        codec.reset(SkCodec::NewFromData(encoded));
+        if (NULL == codec.get()) {
+            return SkStringPrintf("Couldn't create codec for %s.", fPath.c_str());
+        }
     }
 
     // Choose the color type to decode to
@@ -446,13 +451,16 @@ Error CodecSrc::draw(SkCanvas* canvas) const {
 
 SkISize CodecSrc::size() const {
     SkAutoTUnref<SkData> encoded(SkData::NewFromFileName(fPath.c_str()));
-    SkAutoTDelete<SkCodec> codec(SkCodec::NewFromData(encoded));
-    if (NULL != codec) {
-        SkISize size = codec->getScaledDimensions(fScale);
-        return size;
-    } else {
-        return SkISize::Make(0, 0);
+    SkAutoTDelete<SkCodec> codec(SkScaledCodec::NewFromData(encoded));
+    if (NULL == codec) {
+        // scaledCodec not supported, try regular codec
+        codec.reset(SkCodec::NewFromData(encoded));
+        if (NULL == codec) {
+            return SkISize::Make(0, 0);
+        }
     }
+    SkISize size = codec->getScaledDimensions(fScale);
+    return size;
 }
 
 Name CodecSrc::name() const {