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
35namespace WebCore {
36
37LayerChangesFlusher& LayerChangesFlusher::shared()
38{
39    DEFINE_STATIC_LOCAL(LayerChangesFlusher, flusher, ());
40    return flusher;
41}
42
43LayerChangesFlusher::LayerChangesFlusher()
44    : m_hook(0)
45    , m_isCallingHosts(false)
46{
47}
48
49void LayerChangesFlusher::flushPendingLayerChangesSoon(AbstractCACFLayerTreeHost* host)
50{
51    if (!m_hostsWithChangesToFlush.add(host).second || m_hook)
52        return;
53
54    setHook();
55}
56
57void 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
72LRESULT LayerChangesFlusher::hookCallback(int code, WPARAM wParam, LPARAM lParam)
73{
74    return shared().hookFired(code, wParam, lParam);
75}
76
77LRESULT 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
102void 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
117void 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