src/third_party/webrtc/modules/desktop_capture/screen_capturer_helper.cc

   1 /*
   2  *  Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
   3  *
   4  *  Use of this source code is governed by a BSD-style license
   5  *  that can be found in the LICENSE file in the root of the source
   6  *  tree. An additional intellectual property rights grant can be found
   7  *  in the file PATENTS.  All contributing project authors may
   8  *  be found in the AUTHORS file in the root of the source tree.
   9  */
  10
  11 #include "webrtc/modules/desktop_capture/screen_capturer_helper.h"
  12
  13 #include <assert.h>
  14 #include <algorithm>
  15
  16 #include "webrtc/system_wrappers/interface/logging.h"
  17
  18 namespace webrtc {
  19
  20 ScreenCapturerHelper::ScreenCapturerHelper()
  21     : invalid_region_lock_(RWLockWrapper::CreateRWLock()),
  22       log_grid_size_(0) {
  23 }
  24
  25 ScreenCapturerHelper::~ScreenCapturerHelper() {
  26 }
  27
  28 void ScreenCapturerHelper::ClearInvalidRegion() {
  29   WriteLockScoped scoped_invalid_region_lock(*invalid_region_lock_);
  30   invalid_region_.Clear();
  31 }
  32
  33 void ScreenCapturerHelper::InvalidateRegion(
  34     const DesktopRegion& invalid_region) {
  35   WriteLockScoped scoped_invalid_region_lock(*invalid_region_lock_);
  36   invalid_region_.AddRegion(invalid_region);
  37 }
  38
  39 void ScreenCapturerHelper::InvalidateScreen(const DesktopSize& size) {
  40   WriteLockScoped scoped_invalid_region_lock(*invalid_region_lock_);
  41   invalid_region_.AddRect(DesktopRect::MakeSize(size));
  42 }
  43
  44 void ScreenCapturerHelper::TakeInvalidRegion(
  45     DesktopRegion* invalid_region) {
  46   invalid_region->Clear();
  47
  48   {
  49     WriteLockScoped scoped_invalid_region_lock(*invalid_region_lock_);
  50     invalid_region->Swap(&invalid_region_);
  51   }
  52
  53   if (log_grid_size_ > 0) {
  54     DesktopRegion expanded_region;
  55     ExpandToGrid(*invalid_region, log_grid_size_, &expanded_region);
  56     expanded_region.Swap(invalid_region);
  57
  58     invalid_region->IntersectWith(DesktopRect::MakeSize(size_most_recent_));
  59   }
  60 }
  61
  62 void ScreenCapturerHelper::SetLogGridSize(int log_grid_size) {
  63   log_grid_size_ = log_grid_size;
  64 }
  65
  66 const DesktopSize& ScreenCapturerHelper::size_most_recent() const {
  67   return size_most_recent_;
  68 }
  69
  70 void ScreenCapturerHelper::set_size_most_recent(
  71     const DesktopSize& size) {
  72   size_most_recent_ = size;
  73 }
  74
  75 // Returns the largest multiple of |n| that is <= |x|.
  76 // |n| must be a power of 2. |nMask| is ~(|n| - 1).
  77 static int DownToMultiple(int x, int nMask) {
  78   return (x & nMask);
  79 }
  80
  81 // Returns the smallest multiple of |n| that is >= |x|.
  82 // |n| must be a power of 2. |nMask| is ~(|n| - 1).
  83 static int UpToMultiple(int x, int n, int nMask) {
  84   return ((x + n - 1) & nMask);
  85 }
  86
  87 void ScreenCapturerHelper::ExpandToGrid(const DesktopRegion& region,
  88                                         int log_grid_size,
  89                                         DesktopRegion* result) {
  90   assert(log_grid_size >= 1);
  91   int grid_size = 1 << log_grid_size;
  92   int grid_size_mask = ~(grid_size - 1);
  93
  94   result->Clear();
  95   for (DesktopRegion::Iterator it(region); !it.IsAtEnd(); it.Advance()) {
  96     int left = DownToMultiple(it.rect().left(), grid_size_mask);
  97     int right = UpToMultiple(it.rect().right(), grid_size, grid_size_mask);
  98     int top = DownToMultiple(it.rect().top(), grid_size_mask);
  99     int bottom = UpToMultiple(it.rect().bottom(), grid_size, grid_size_mask);
 100     result->AddRect(DesktopRect::MakeLTRB(left, top, right, bottom));
 101   }
 102 }
 103
 104 }  // namespace webrtc