Add subsetting to SkScaledCodec

src/codec/SkJpegCodec.cpp

Index: src/codec/SkJpegCodec.cpp
diff --git a/src/codec/SkJpegCodec.cpp b/src/codec/SkJpegCodec.cpp
index ed14cdf5c3e6d90f49deb65ca58a5214b6623c3f..9ec3c72719ebf2d75be1320e9b5fb67429cc6b7d 100644
--- a/src/codec/SkJpegCodec.cpp
+++ b/src/codec/SkJpegCodec.cpp
@@ -177,19 +177,19 @@ SkISize SkJpegCodec::onGetScaledDimensions(float desiredScale) const {
     // support these as well
     unsigned int num;
     unsigned int denom = 8;
-    if (desiredScale > 0.875f) {
+    if (desiredScale >= 0.9375) {
         num = 8;
-    } else if (desiredScale > 0.75f) {
+    } else if (desiredScale >= 0.8125) {
         num = 7;
-    } else if (desiredScale > 0.625f) {
+    } else if (desiredScale >= 0.6875f) {
         num = 6;
-    } else if (desiredScale > 0.5f) {
+    } else if (desiredScale >= 0.5625f) {
         num = 5;
-    } else if (desiredScale > 0.375f) {
+    } else if (desiredScale >= 0.4375f) {
         num = 4;
-    } else if (desiredScale > 0.25f) {
+    } else if (desiredScale >= 0.3125f) {
         num = 3;
-    } else if (desiredScale > 0.125f) {
+    } else if (desiredScale >= 0.1875f) {
         num = 2;
     } else {
         num = 1;
@@ -406,8 +406,7 @@ SkSampler* SkJpegCodec::getSampler(bool createIfNecessary) {
             SkASSERT(false);
     }
 
-    fSwizzler.reset(SkSwizzler::CreateSwizzler(srcConfig, nullptr, info,
-                                               this->options().fZeroInitialized));
+    fSwizzler.reset(SkSwizzler::CreateSwizzler(srcConfig, nullptr, info, this->options().fZeroInitialized, 0, 0)); // TODO: get subset info from options object
     if (!fSwizzler) {
         return nullptr;
     }
@@ -418,7 +417,8 @@ SkSampler* SkJpegCodec::getSampler(bool createIfNecessary) {
 }
 
 SkCodec::Result SkJpegCodec::onStartScanlineDecode(const SkImageInfo& dstInfo,
-        const Options& options, SkPMColor ctable[], int* ctableCount) {
+        const Options& options, SkPMColor ctable[], int* ctableCount, int subsetLeft,
+        int subsetWidth) {
     // Set the jump location for libjpeg errors
     if (setjmp(fDecoderMgr->getJmpBuf())) {
         SkCodecPrintf("setjmp: Error from libjpeg\n");