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 "cc/output/begin_frame_args.h"
   6 #include "ui/gfx/frame_time.h"
   7
   8 namespace cc {
   9
  10 BeginFrameArgs::BeginFrameArgs()
  11   : frame_time(base::TimeTicks()),
  12     deadline(base::TimeTicks()),
  13     interval(base::TimeDelta::FromMicroseconds(-1)) {
  14 }
  15
  16 BeginFrameArgs::BeginFrameArgs(base::TimeTicks frame_time,
  17                                base::TimeTicks deadline,
  18                                base::TimeDelta interval)
  19   : frame_time(frame_time),
  20     deadline(deadline),
  21     interval(interval)
  22 {}
  23
  24 BeginFrameArgs BeginFrameArgs::Create(base::TimeTicks frame_time,
  25                                       base::TimeTicks deadline,
  26                                       base::TimeDelta interval) {
  27   return BeginFrameArgs(frame_time, deadline, interval);
  28 }
  29
  30 BeginFrameArgs BeginFrameArgs::CreateForSynchronousCompositor() {
  31   // For WebView/SynchronousCompositor, we always want to draw immediately,
  32   // so we set the deadline to 0 and guess that the interval is 16 milliseconds.
  33   return BeginFrameArgs(gfx::FrameTime::Now(),
  34                         base::TimeTicks(),
  35                         DefaultInterval());
  36 }
  37
  38 BeginFrameArgs BeginFrameArgs::CreateForTesting() {
  39   base::TimeTicks now = gfx::FrameTime::Now();
  40   return BeginFrameArgs(now,
  41                         now + (DefaultInterval() / 2),
  42                         DefaultInterval());
  43 }
  44
  45 BeginFrameArgs BeginFrameArgs::CreateExpiredForTesting() {
  46   base::TimeTicks now = gfx::FrameTime::Now();
  47   return BeginFrameArgs(now,
  48                         now - DefaultInterval(),
  49                         DefaultInterval());
  50 }
  51
  52 // This is a hard-coded deadline adjustment that assumes 60Hz, to be used in
  53 // cases where a good estimated draw time is not known. Using 1/3 of the vsync
  54 // as the default adjustment gives the Browser the last 1/3 of a frame to
  55 // produce output, the Renderer Impl thread the middle 1/3 of a frame to produce
  56 // ouput, and the Renderer Main thread the first 1/3 of a frame to produce
  57 // output.
  58 base::TimeDelta BeginFrameArgs::DefaultDeadlineAdjustment() {
  59   return base::TimeDelta::FromMicroseconds(-16666 / 3);
  60 }
  61
  62 base::TimeDelta BeginFrameArgs::DefaultInterval() {
  63   return base::TimeDelta::FromMicroseconds(16666);
  64 }
  65
  66 base::TimeDelta BeginFrameArgs::DefaultRetroactiveBeginFramePeriod() {
  67   return base::TimeDelta::FromMicroseconds(4444);
  68 }
  69
  70 }  // namespace cc