Chromoting plugin to use a backing store

Create a backing store for painting image data through the lifetime of the
plugin instance. This avoids memory fragmentation of creating small blocks
of memory every time it paints.

BUG=71885
TEST=None

Review URL: http://codereview.chromium.org/6661008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@78085 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 26 insertions, 15 deletions

diff --git a/remoting/client/plugin/pepper_view.cc b/remoting/client/plugin/pepper_view.cc
index 510bde6..7015c9d 100644
--- a/remoting/client/plugin/pepper_view.cc
+++ b/remoting/client/plugin/pepper_view.cc
@@ -8,6 +8,7 @@
 #include "ppapi/cpp/graphics_2d.h"
 #include "ppapi/cpp/image_data.h"
 #include "ppapi/cpp/point.h"
+#include "ppapi/cpp/rect.h"
 #include "ppapi/cpp/size.h"
 #include "remoting/base/tracer.h"
 #include "remoting/base/util.h"
@@ -87,6 +88,12 @@ void PepperView::PaintFrame(media::VideoFrame* frame, UpdatedRects* rects) {
   const int kFrameStride = frame->stride(media::VideoFrame::kRGBPlane);
   const int kBytesPerPixel = GetBytesPerPixel(media::VideoFrame::RGB32);
 
+  if (!backing_store_.get() || backing_store_->is_null()) {
+    LOG(ERROR) << "Backing store is not available.";
+    return;
+  }
+
+  // Copy updated regions to the backing store and then paint the regions.
   for (size_t i = 0; i < rects->size(); ++i) {
     // TODO(ajwong): We're assuming the native format is BGRA_PREMUL below. This
     // is wrong.
@@ -96,25 +103,21 @@ void PepperView::PaintFrame(media::VideoFrame* frame, UpdatedRects* rects) {
     if (r.width() <= 0 || r.height() <= 0)
       continue;
 
-    pp::ImageData image(instance_, pp::ImageData::GetNativeImageDataFormat(),
-                        pp::Size(r.width(), r.height()),
-                        false);
-    if (image.is_null()) {
-      LOG(ERROR) << "Unable to allocate image of size: "
-                 << r.width() << "x" << r.height();
-      return;
-    }
-
-    // Copy pixel data into |image|.
     uint8* in = frame_data + kFrameStride * r.y() + kBytesPerPixel * r.x();
-    uint8* out = reinterpret_cast<uint8*>(image.data());
+    uint8* out = reinterpret_cast<uint8*>(backing_store_->data()) +
+        backing_store_->stride() * r.y() + kBytesPerPixel * r.x();
+
+    // TODO(hclam): We really should eliminate this memory copy.
     for (int j = 0; j < r.height(); ++j) {
       memcpy(out, in, r.width() * kBytesPerPixel);
       in += kFrameStride;
-      out += image.stride();
+      out += backing_store_->stride();
     }
 
-    graphics2d_.PaintImageData(image, pp::Point(r.x(), r.y()));
+    // Pepper Graphics 2D has a strange and badly documented API that the
+    // point here is the offset from the source rect. Why?
+    graphics2d_.PaintImageData(*backing_store_.get(), pp::Point(0, 0),
+                               pp::Rect(r.x(), r.y(), r.width(), r.height()));
   }
 
   graphics2d_.Flush(TaskToCompletionCallback(
@@ -192,6 +195,13 @@ void PepperView::SetViewport(int x, int y, int width, int height) {
     return;
   }
 
+  // Allocate the backing store to save the desktop image.
+  backing_store_.reset(
+      new pp::ImageData(instance_, pp::ImageData::GetNativeImageDataFormat(),
+                        pp::Size(viewport_width_, viewport_height_), false));
+  DCHECK(backing_store_.get() && !backing_store_->is_null())
+      << "Not enough memory for backing store.";
+
   instance_->GetScriptableObject()->SetDesktopSize(width, height);
 }
 
@@ -204,8 +214,6 @@ void PepperView::AllocateFrame(media::VideoFrame::Format format,
                                Task* done) {
   DCHECK(CurrentlyOnPluginThread());
 
-  // TODO(ajwong): Implement this to be backed by an pp::ImageData rather than
-  // generic memory.
   media::VideoFrame::CreateFrame(media::VideoFrame::RGB32,
                                  width, height,
                                  base::TimeDelta(), base::TimeDelta(),
diff --git a/remoting/client/plugin/pepper_view.h b/remoting/client/plugin/pepper_view.h
index 119d1ca..2fb463a 100644
--- a/remoting/client/plugin/pepper_view.h
+++ b/remoting/client/plugin/pepper_view.h
@@ -67,6 +67,9 @@ class PepperView : public ChromotingView,
 
   pp::Graphics2D graphics2d_;
 
+  // A backing store that saves the current desktop image.
+  scoped_ptr<pp::ImageData> backing_store_;
+
   int viewport_width_;
   int viewport_height_;