add deferred config to DM

dm/DMSrcSink.cpp

Index: dm/DMSrcSink.cpp
diff --git a/dm/DMSrcSink.cpp b/dm/DMSrcSink.cpp
index 9811f9e4268ee7eb95014d6a67fea09faa700583..7501fba7e49abd8873c790ead1e1f279f224af6c 100644
--- a/dm/DMSrcSink.cpp
+++ b/dm/DMSrcSink.cpp
@@ -10,6 +10,7 @@
 #include "SkCommonFlags.h"
 #include "SkCodec.h"
 #include "SkData.h"
+#include "SkDeferredCanvas.h"
 #include "SkDocument.h"
 #include "SkError.h"
 #include "SkImageGenerator.h"
@@ -590,6 +591,41 @@ Error ViaPipe::draw(const Src& src, SkBitmap* bitmap, SkWStream* stream, SkStrin
 }
 
 /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
+    
+ViaDeferred::ViaDeferred(Sink* sink) : fSink(sink) {}
+
+Error ViaDeferred::draw(const Src& src, SkBitmap* bitmap, SkWStream* stream, SkString* log) const {

[robertphillips, 2015/05/05 14:45:42]

update comment

[reed1, 2015/05/05 14:55:25]

Done.

+    // We turn ourselves into another Src that draws our argument into bitmap/stream via pipe.

[mtklein, 2015/05/05 14:45:30]

update / delete?

[reed1, 2015/05/05 14:55:25]

Done.

+    struct ProxySrc : public Src {
+        const Src& fSrc;
+        ProxySrc(const Src& src) : fSrc(src) {}
+
+        Error draw(SkCanvas* canvas) const override {
+            SkISize size = this->size();
+            SkImageInfo info = SkImageInfo::MakeN32Premul(size.width(), size.height());

[mtklein, 2015/05/05 14:45:30]

Is it useful to have the deferred canvas match the color type of the ultimate
destination, or is this N32-is-good-enough-for-anyone?

[reed1, 2015/05/05 14:55:25]

Good point, I think I can use the same "info"

+            SkAutoTUnref<SkSurface> surface(canvas->newSurface(info));
+            if (!surface.get()) {
+                return Error("can make surface for deferred canvas");

[mtklein, 2015/05/05 14:45:30]

can -> can't?

[reed1, 2015/05/05 14:55:25]

Done.

+            }
+            SkAutoTDelete<SkDeferredCanvas> defcan(SkDeferredCanvas::Create(surface));
+            Error err = fSrc.draw(defcan);
+            if (err.isEmpty()) {

[mtklein, 2015/05/05 14:45:30]

Seems like you're swallowing the error when it's not empty?

Error err = fSrc.draw(defcan);
if (!err.isEmpty()) {
  return err;
}
...
return "";

[reed1, 2015/05/05 14:55:25]

Done.

+                SkAutoTUnref<SkImage> image(defcan->newImageSnapshot());
+                if (image) {
+                    canvas->drawImage(image, 0, 0, NULL);
+                } else {
+                    return Error("failed to create deferred image snapshot");

[mtklein, 2015/05/05 14:45:30]

FYI, you can just write
  return "Failed to create deferred image snapshot.";

[reed1, 2015/05/05 14:55:25]

Acknowledged.

+                }
+            }
+            return "";
+        }
+        SkISize size() const override { return fSrc.size(); }
+        Name name() const override { sk_throw(); return ""; }  // No one should be calling this.
+    } proxy(src);
+    return fSink->draw(proxy, bitmap, stream, log);
+}
+    
+/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
 
 ViaSerialization::ViaSerialization(Sink* sink) : fSink(sink) {}