cc/output/begin_frame_args.cc

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "base/json/json_writer.h"
   6 #include "cc/output/begin_frame_args.h"
   7 #include "ui/gfx/frame_time.h"
   8
   9 namespace cc {
  10
  11 BeginFrameArgs::BeginFrameArgs()
  12   : frame_time(base::TimeTicks()),
  13     deadline(base::TimeTicks()),
  14     interval(base::TimeDelta::FromMicroseconds(-1)) {
  15 }
  16
  17 BeginFrameArgs::BeginFrameArgs(base::TimeTicks frame_time,
  18                                base::TimeTicks deadline,
  19                                base::TimeDelta interval)
  20   : frame_time(frame_time),
  21     deadline(deadline),
  22     interval(interval)
  23 {}
  24
  25 BeginFrameArgs BeginFrameArgs::Create(base::TimeTicks frame_time,
  26                                       base::TimeTicks deadline,
  27                                       base::TimeDelta interval) {
  28   return BeginFrameArgs(frame_time, deadline, interval);
  29 }
  30
  31 scoped_ptr<base::Value> BeginFrameArgs::AsValue() const {
  32   scoped_ptr<base::DictionaryValue> state(new base::DictionaryValue);
  33   state->SetString("type", "BeginFrameArgs");
  34   state->SetDouble("frame_time_us", frame_time.ToInternalValue());
  35   state->SetDouble("deadline_us", deadline.ToInternalValue());
  36   state->SetDouble("interval_us", interval.InMicroseconds());
  37   return state.PassAs<base::Value>();
  38 }
  39
  40 BeginFrameArgs BeginFrameArgs::CreateForSynchronousCompositor(
  41     base::TimeTicks now) {
  42   // For WebView/SynchronousCompositor, we always want to draw immediately,
  43   // so we set the deadline to 0 and guess that the interval is 16 milliseconds.
  44   if (now.is_null())
  45     now = gfx::FrameTime::Now();
  46   return BeginFrameArgs(now, base::TimeTicks(), DefaultInterval());
  47 }
  48
  49 // This is a hard-coded deadline adjustment that assumes 60Hz, to be used in
  50 // cases where a good estimated draw time is not known. Using 1/3 of the vsync
  51 // as the default adjustment gives the Browser the last 1/3 of a frame to
  52 // produce output, the Renderer Impl thread the middle 1/3 of a frame to produce
  53 // ouput, and the Renderer Main thread the first 1/3 of a frame to produce
  54 // output.
  55 base::TimeDelta BeginFrameArgs::DefaultEstimatedParentDrawTime() {
  56   return base::TimeDelta::FromMicroseconds(16666 / 3);
  57 }
  58
  59 base::TimeDelta BeginFrameArgs::DefaultInterval() {
  60   return base::TimeDelta::FromMicroseconds(16666);
  61 }
  62
  63 base::TimeDelta BeginFrameArgs::DefaultRetroactiveBeginFramePeriod() {
  64   return base::TimeDelta::FromMicroseconds(4444);
  65 }
  66
  67 }  // namespace cc