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      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
    105