DeferredDisplayList API proposal

Chrome would like to perform cpu-side preprocessing for gpu draws in parallel. 
They do not want to go through a picture (since they have their own display list format).


The general idea is that we add a new SkDeferredDisplayListRecorder class to
perform all of Ganesh's cpu-side preprocessing ahead of time and in parallel.

The SkDDLRecorder operates like SkPictureRecorder. The user can get an SkCanvas
from the SkDDLRecorder and feed it draw operations. Once finished, the user
calls 'detach' to get an SkDeferredDisplayList. All the work up to and 
including the 'detach' call can be done in parallel and will not touch
the GPU. To actually get pixels the client must call SkSurface::draw(SkDDL)
on an SkSurface that is "compatible" with the surface characterization
initially given to the SkDDLMaker.

The surface characterization contains the minimum amount of information Ganesh needs 
to know about the ultimate destination in order to perform its cpu-side work
(i.e., caps, width, height, config).



Change-Id: I75faa483ab5a6b779c8de56ea56b9d90b990f43a
Reviewed-on: https://skia-review.googlesource.com/30140
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/dm/DMSrcSink.h b/dm/DMSrcSink.h
index c1af4d01b5..26c32f59b7 100644
--- a/dm/DMSrcSink.h
+++ b/dm/DMSrcSink.h
@@ -248,6 +248,18 @@ private:
     Path fPath;
 };
 
+// DeferredDisplayList flavor
+class DDLSKPSrc : public Src {
+public:
+    explicit DDLSKPSrc(Path path);
+
+    Error draw(SkCanvas*) const override;
+    SkISize size() const override;
+    Name name() const override;
+private:
+    Path fPath;
+};
+
 #if defined(SK_XML)
 } // namespace DM