SkScaledCodec class

dm/DM.cpp

Index: dm/DM.cpp
diff --git a/dm/DM.cpp b/dm/DM.cpp
index 9dcdff1a0fce6f98f10228d33595e618a31f4c2e..fe096434c6c499200dd9263ab97a156ddc177e68 100644
--- a/dm/DM.cpp
+++ b/dm/DM.cpp
@@ -212,7 +212,12 @@ static void push_codec_srcs(Path path) {
     // TODO (msarett): Add more scaling tests as we implement more flexible scaling.
     // TODO (msarett): Implement scaling tests for SkImageDecoder in order to compare with these
     //                 tests.  SkImageDecoder supports downscales by integer factors.
-    const float scales[] = { 0.125f, 0.25f, 0.375f, 0.5f, 0.625f, 0.750f, 0.875f, 1.0f };
+    // SkJpegCodec natively supports scaling to: 0.125, 0.25, 0.375, 0.5, 0.625, 0.75, 0.875
+    // 0.1, 0.16, 0.2 etc allow us to test SkScaledCodec with sampleSize 10, 6, 5, etc
+    // 0.4, 0.7 etc allow to test what happens when the client requests a scale that
+    // does not exactly match a sampleSize or native scaling capability
+    const float scales[] = { 0.1f, 0.125f, 0.166f, 0.2f, 0.25f, 0.333f, 0.375f, 0.4f, 0.5f, 0.6f,

[scroggo, 2015/08/05 19:10:04]

This isn't new with your change, but I find all these scales clutter my output
folders. How would you feel about appending the scale to  the name we pass to
push_src when scale is not 1?

e.g.

push_src("image", "codec_kGray8_0.625f", ...

I'm happy to have that be a separate change, but I think it would make it easier
to find the images I want to find.

(or maybe the name should just be "codec_kGray8_scaled"?)

[emmaleer, 2015/08/06 13:45:46]

Okay. So then there would be a lot more folders right?
That might be harder to find mistakes. Since right now, I can just open 1 - 4
folders and glance over all the images to make sure they are okay. But if
there's a folder for each scale, there will be a lot of folders to open and
check.
I think codec_Gray8_scaled would be okay, since there would only be 2X as many
folders to check. 
I can make this change in a separate CL. 

[msarett, 2015/08/06 14:08:59]

I like the codec_Gray8_scaled idea.

[scroggo, 2015/08/06 15:09:10]

It would be more folders, but less to look at within each folder. Currently,
when I run "dm --src image --images resources/ -w <out>", and look in
<out>/8888/image/codec, I see the same image over and over again. Since JPEG is
the only one that currently supports scaling, it's hard to find other images.
With this CL, we'll see scaled images for all types (at least all the ones that
support scanline decoding), so that problem will go away, but we'll see even
more copies of the same image (one more for each new scale). We'll still be able
to compare them all in gold, but it seems to me that it would be simpler to see
one version of each image. Maybe I'm wrong though.

+                             0.625f, 0.750f, 0.8f, 0.875f, 1.0f };
 
     for (float scale : scales) {
         if (scale != 1.0f && (path.endsWith(".webp") || path.endsWith(".WEBP"))) {