diff options
Diffstat (limited to 'src/plugins/platforms/wasm/qwasmeventdispatcher.cpp')
| -rw-r--r-- | src/plugins/platforms/wasm/qwasmeventdispatcher.cpp | 181 |
1 files changed, 181 insertions, 0 deletions
diff --git a/src/plugins/platforms/wasm/qwasmeventdispatcher.cpp b/src/plugins/platforms/wasm/qwasmeventdispatcher.cpp new file mode 100644 index 0000000000..41355d72ae --- /dev/null +++ b/src/plugins/platforms/wasm/qwasmeventdispatcher.cpp @@ -0,0 +1,181 @@ +/**************************************************************************** +** +** Copyright (C) 2018 The Qt Company Ltd. +** Contact: https://www.qt.io/licensing/ +** +** This file is part of the plugins of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:GPL$ +** Commercial License Usage +** Licensees holding valid commercial Qt licenses may use this file in +** accordance with the commercial license agreement provided with the +** Software or, alternatively, in accordance with the terms contained in +** a written agreement between you and The Qt Company. For licensing terms +** and conditions see https://www.qt.io/terms-conditions. For further +** information use the contact form at https://www.qt.io/contact-us. +** +** GNU General Public License Usage +** Alternatively, this file may be used under the terms of the GNU +** General Public License version 3 or (at your option) any later version +** approved by the KDE Free Qt Foundation. The licenses are as published by +** the Free Software Foundation and appearing in the file LICENSE.GPL3 +** included in the packaging of this file. Please review the following +** information to ensure the GNU General Public License requirements will +** be met: https://www.gnu.org/licenses/gpl-3.0.html. +** +** $QT_END_LICENSE$ +** +****************************************************************************/ + +#include "qwasmeventdispatcher.h" + +#include <QtCore/qcoreapplication.h> + +#include <emscripten.h> + +class QWasmEventDispatcherPrivate : public QEventDispatcherUNIXPrivate +{ + +}; + +QWasmEventDispatcher *g_htmlEventDispatcher; + +QWasmEventDispatcher::QWasmEventDispatcher(QObject *parent) + : QUnixEventDispatcherQPA(parent) +{ + + g_htmlEventDispatcher = this; +} + +QWasmEventDispatcher::~QWasmEventDispatcher() +{ + g_htmlEventDispatcher = nullptr; +} + +bool QWasmEventDispatcher::registerRequestUpdateCallback(std::function<void(void)> callback) +{ + if (!g_htmlEventDispatcher || !g_htmlEventDispatcher->m_hasMainLoop) + return false; + + g_htmlEventDispatcher->m_requestUpdateCallbacks.append(callback); + emscripten_resume_main_loop(); + return true; +} + +void QWasmEventDispatcher::maintainTimers() +{ + if (!g_htmlEventDispatcher || !g_htmlEventDispatcher->m_hasMainLoop) + return; + + g_htmlEventDispatcher->doMaintainTimers(); +} + +bool QWasmEventDispatcher::processEvents(QEventLoop::ProcessEventsFlags flags) +{ + // WaitForMoreEvents is not supported (except for in combination with EventLoopExec below), + // and we don't want the unix event dispatcher base class to attempt to wait either. + flags &= ~QEventLoop::WaitForMoreEvents; + + // Handle normal processEvents. + if (!(flags & QEventLoop::EventLoopExec)) + return QUnixEventDispatcherQPA::processEvents(flags); + + // Handle processEvents from QEventLoop::exec(): + // + // At this point the application has created its root objects on + // the stack and has called app.exec() which has called into this + // function via QEventLoop. + // + // The application now expects that exec() will not return until + // app exit time. However, the browser expects that we return + // control to it periodically, also after initial setup in main(). + + // EventLoopExec for nested event loops is not supported. + Q_ASSERT(!m_hasMainLoop); + m_hasMainLoop = true; + + // Call emscripten_set_main_loop_arg() with a callback which processes + // events. Also set simulateInfiniteLoop to true which makes emscripten + // return control to the browser without unwinding the C++ stack. + auto callback = [](void *eventDispatcher) { + QWasmEventDispatcher *that = static_cast<QWasmEventDispatcher *>(eventDispatcher); + + // Save and clear updateRequest callbacks so we can register new ones + auto requestUpdateCallbacksCopy = that->m_requestUpdateCallbacks; + that->m_requestUpdateCallbacks.clear(); + + // Repaint all windows + for (auto callback : qAsConst(requestUpdateCallbacksCopy)) + callback(); + + // Pause main loop if no updates were requested. Updates will be + // restarted again by registerRequestUpdateCallback(). + if (that->m_requestUpdateCallbacks.isEmpty()) + emscripten_pause_main_loop(); + + that->doMaintainTimers(); + }; + int fps = 0; // update using requestAnimationFrame + int simulateInfiniteLoop = 1; + emscripten_set_main_loop_arg(callback, this, fps, simulateInfiniteLoop); + + // Note: the above call never returns, not even at app exit + return false; +} + +void QWasmEventDispatcher::doMaintainTimers() +{ + Q_D(QWasmEventDispatcher); + + // This functon schedules native timers in order to wake up to + // process events and activate Qt timers. This is done using the + // emscripten_async_call() API which schedules a new timer. + // There is unfortunately no way to cancel or update a current + // native timer. + + // Schedule a zero-timer to continue processing any pending events. + if (!m_hasZeroTimer && hasPendingEvents()) { + auto callback = [](void *eventDispatcher) { + QWasmEventDispatcher *that = static_cast<QWasmEventDispatcher *>(eventDispatcher); + that->m_hasZeroTimer = false; + that->QUnixEventDispatcherQPA::processEvents(QEventLoop::AllEvents); + + // Processing events may have posted new events or created new timers + that->doMaintainTimers(); + }; + + emscripten_async_call(callback, this, 0); + m_hasZeroTimer = true; + return; + } + + auto timespecToNanosec = [](timespec ts) -> uint64_t { return ts.tv_sec * 1000 + ts.tv_nsec / (1000 * 1000); }; + + // Get current time and time-to-first-Qt-timer. This polls for system + // time, and we use this time as the current time for the duration of this call. + timespec toWait; + bool hasTimers = d->timerList.timerWait(toWait); + if (!hasTimers) + return; // no timer needed + + uint64_t currentTime = timespecToNanosec(d->timerList.currentTime); + uint64_t toWaitDuration = timespecToNanosec(toWait); + + // The currently scheduled timer target is stored in m_currentTargetTime. + // We can re-use it if the new target is equivalent or later. + uint64_t newTargetTime = currentTime + toWaitDuration; + if (newTargetTime >= m_currentTargetTime) + return; // existing timer is good + + // Schedule a native timer with a callback which processes events (and timers) + auto callback = [](void *eventDispatcher) { + QWasmEventDispatcher *that = static_cast<QWasmEventDispatcher *>(eventDispatcher); + that->m_currentTargetTime = std::numeric_limits<uint64_t>::max(); + that->QUnixEventDispatcherQPA::processEvents(QEventLoop::AllEvents); + + // Processing events may have posted new events or created new timers + that->doMaintainTimers(); + }; + emscripten_async_call(callback, this, toWaitDuration); + m_currentTargetTime = newTargetTime; +} |