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      1 /*
      2  * Copyright (C) 2011 Apple Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  * 1. Redistributions of source code must retain the above copyright
      8  *    notice, this list of conditions and the following disclaimer.
      9  * 2. Redistributions in binary form must reproduce the above copyright
     10  *    notice, this list of conditions and the following disclaimer in the
     11  *    documentation and/or other materials provided with the distribution.
     12  *
     13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
     14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
     17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
     18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
     21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     24  */
     25 
     26 #include "config.h"
     27 #include "LayerChangesFlusher.h"
     28 
     29 #if USE(ACCELERATED_COMPOSITING)
     30 
     31 #include "AbstractCACFLayerTreeHost.h"
     32 #include <wtf/StdLibExtras.h>
     33 #include <wtf/Vector.h>
     34 
     35 namespace WebCore {
     36 
     37 LayerChangesFlusher& LayerChangesFlusher::shared()
     38 {
     39     DEFINE_STATIC_LOCAL(LayerChangesFlusher, flusher, ());
     40     return flusher;
     41 }
     42 
     43 LayerChangesFlusher::LayerChangesFlusher()
     44     : m_hook(0)
     45     , m_isCallingHosts(false)
     46 {
     47 }
     48 
     49 void LayerChangesFlusher::flushPendingLayerChangesSoon(AbstractCACFLayerTreeHost* host)
     50 {
     51     if (!m_hostsWithChangesToFlush.add(host).second || m_hook)
     52         return;
     53 
     54     setHook();
     55 }
     56 
     57 void LayerChangesFlusher::cancelPendingFlush(AbstractCACFLayerTreeHost* host)
     58 {
     59     m_hostsWithChangesToFlush.remove(host);
     60 
     61     if (!m_hostsWithChangesToFlush.isEmpty() || !m_hook)
     62         return;
     63 
     64     // We handle removing the hook when we finish calling out to the hosts, so we shouldn't
     65     // mess with it while we're in the process of calling them.
     66     if (m_isCallingHosts)
     67         return;
     68 
     69     removeHook();
     70 }
     71 
     72 LRESULT LayerChangesFlusher::hookCallback(int code, WPARAM wParam, LPARAM lParam)
     73 {
     74     return shared().hookFired(code, wParam, lParam);
     75 }
     76 
     77 LRESULT LayerChangesFlusher::hookFired(int code, WPARAM wParam, LPARAM lParam)
     78 {
     79     ASSERT(m_hook);
     80 
     81     // Calling out to the hosts can cause m_hostsWithChangesToFlush to be modified, so we copy it
     82     // into a Vector first.
     83     Vector<AbstractCACFLayerTreeHost*> hosts;
     84     copyToVector(m_hostsWithChangesToFlush, hosts);
     85     m_hostsWithChangesToFlush.clear();
     86 
     87     m_isCallingHosts = true;
     88     for (size_t i = 0; i < hosts.size(); ++i)
     89         hosts[i]->flushPendingLayerChangesNow();
     90     m_isCallingHosts = false;
     91 
     92     LRESULT result = ::CallNextHookEx(m_hook, code, wParam, lParam);
     93 
     94     if (m_hostsWithChangesToFlush.isEmpty()) {
     95         // We won't have any work to do next time around, so just remove our hook.
     96         removeHook();
     97     }
     98 
     99     return result;
    100 }
    101 
    102 void LayerChangesFlusher::setHook()
    103 {
    104     ASSERT(!m_hook);
    105     ASSERT(!m_isCallingHosts);
    106 
    107     DWORD threadID = ::GetCurrentThreadId();
    108 
    109     m_hook = ::SetWindowsHookExW(WH_GETMESSAGE, hookCallback, 0, threadID);
    110     ASSERT_WITH_MESSAGE(m_hook, "::SetWindowsHookExW failed with error %lu", ::GetLastError());
    111 
    112     // Post a message to the message queue to prevent ::GetMessage from blocking, which will ensure
    113     // our hook is called soon.
    114     ::PostThreadMessageW(threadID, WM_NULL, 0, 0);
    115 }
    116 
    117 void LayerChangesFlusher::removeHook()
    118 {
    119     ASSERT(m_hook);
    120     ASSERT(!m_isCallingHosts);
    121 
    122     if (!::UnhookWindowsHookEx(m_hook))
    123         ASSERT_WITH_MESSAGE(false, "::UnhookWindowsHookEx failed with error %lu", ::GetLastError());
    124 
    125     m_hook = 0;
    126 }
    127 
    128 } // namespace WebCore
    129 
    130 #endif // USE(ACCELERATED_COMPOSITING)
    131