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WinRT: Miscellaneous app-backgrounding/restoring event fixes and addi…
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SDL_WINDOWEVENT_FOCUS_LOST is now sent when an app's native window is hidden.
Likewise, SDL_WINDOWEVENT_FOCUS_GAINED is sent when an app's window is shown.
This mimicks behavior seen on iOS and Android.

SDL_WINDOWEVENT_MINIMIZED and SDL_WINDOWEVENT_RESTORED are now sent when the
app's native window is hidden and shown.  Previously, these were sent when an
app was suspended and resumed.  On Windows 8.x/RT, an app may be sent to the
background without being suspended, which previously meant that
SDL_WINDOWEVENT_MINIMIZED might never have been sent.  (On Windows Phone 8,
however, this seems to be different, whereby apps sent to the background appear
to always get suspended.)
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@DavidLudwig
DavidLudwig committed Mar 23, 2014
1 parent 50ee99e commit c224309
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Showing 2 changed files with 63 additions and 55 deletions.
116 changes: 61 additions & 55 deletions src/core/winrt/SDL_winrtapp_direct3d.cpp
View file
Expand Up @@ -418,16 +418,62 @@ void SDL_WinRTApp::Run()
}
}

static bool IsSDLWindowEventPending(SDL_WindowEventID windowEventID)
{
SDL_Event events[128];
const int count = SDL_PeepEvents(events, sizeof(events)/sizeof(SDL_Event), SDL_PEEKEVENT, SDL_WINDOWEVENT, SDL_WINDOWEVENT);
for (int i = 0; i < count; ++i) {
if (events[i].window.event == windowEventID) {
return true;
}
}
return false;
}

bool SDL_WinRTApp::ShouldWaitForAppResumeEvents()
{
/* Don't wait if the app is visible: */
if (m_windowVisible) {
return false;
}

/* Don't wait until the window-hide events finish processing.
* Do note that if an app-suspend event is sent (as indicated
* by SDL_APP_WILLENTERBACKGROUND and SDL_APP_DIDENTERBACKGROUND
* events), then this code may be a moot point, as WinRT's
* own event pump (aka ProcessEvents()) will pause regardless
* of what we do here. This happens on Windows Phone 8, to note.
* Windows 8.x apps, on the other hand, may get a chance to run
* these.
*/
if (IsSDLWindowEventPending(SDL_WINDOWEVENT_HIDDEN)) {
return false;
} else if (IsSDLWindowEventPending(SDL_WINDOWEVENT_FOCUS_LOST)) {
return false;
} else if (IsSDLWindowEventPending(SDL_WINDOWEVENT_MINIMIZED)) {
return false;
}

return true;
}

void SDL_WinRTApp::PumpEvents()
{
if (!m_windowClosed)
{
if (m_windowVisible)
{
if (!m_windowClosed) {
if (!ShouldWaitForAppResumeEvents()) {
/* This is the normal way in which events should be pumped.
* 'ProcessAllIfPresent' will make ProcessEvents() process anywhere
* from zero to N events, and will then return.
*/
CoreWindow::GetForCurrentThread()->Dispatcher->ProcessEvents(CoreProcessEventsOption::ProcessAllIfPresent);
}
else
{
} else {
/* This style of event-pumping, with 'ProcessOneAndAllPending',
* will cause anywhere from one to N events to be processed. If
* at least one event is processed, the call will return. If
* no events are pending, then the call will wait until one is
* available, and will not return (to the caller) until this
* happens! This should only occur when the app is hidden.
*/
CoreWindow::GetForCurrentThread()->Dispatcher->ProcessEvents(CoreProcessEventsOption::ProcessOneAndAllPending);
}
}
Expand Down Expand Up @@ -511,8 +557,12 @@ void SDL_WinRTApp::OnVisibilityChanged(CoreWindow^ sender, VisibilityChangedEven

if (args->Visible) {
SDL_SendWindowEvent(WINRT_GlobalSDLWindow, SDL_WINDOWEVENT_SHOWN, 0, 0);
SDL_SendWindowEvent(WINRT_GlobalSDLWindow, SDL_WINDOWEVENT_FOCUS_GAINED, 0, 0);
SDL_SendWindowEvent(WINRT_GlobalSDLWindow, SDL_WINDOWEVENT_RESTORED, 0, 0);
} else {
SDL_SendWindowEvent(WINRT_GlobalSDLWindow, SDL_WINDOWEVENT_HIDDEN, 0, 0);
SDL_SendWindowEvent(WINRT_GlobalSDLWindow, SDL_WINDOWEVENT_FOCUS_LOST, 0, 0);
SDL_SendWindowEvent(WINRT_GlobalSDLWindow, SDL_WINDOWEVENT_MINIMIZED, 0, 0);
}

// HACK: Prevent SDL's window-hide handling code, which currently
Expand All @@ -538,26 +588,6 @@ void SDL_WinRTApp::OnActivated(CoreApplicationView^ applicationView, IActivatedE
CoreWindow::GetForCurrentThread()->Activate();
}

static int SDLCALL RemoveAppSuspendAndResumeEvents(void * userdata, SDL_Event * event)
{
if (event->type == SDL_WINDOWEVENT)
{
switch (event->window.event)
{
case SDL_WINDOWEVENT_MINIMIZED:
case SDL_WINDOWEVENT_RESTORED:
// Return 0 to indicate that the event should be removed from the
// event queue:
return 0;
default:
break;
}
}

// Return 1 to indicate that the event should stay in the event queue:
return 1;
}

void SDL_WinRTApp::OnSuspending(Platform::Object^ sender, SuspendingEventArgs^ args)
{
// Save app state asynchronously after requesting a deferral. Holding a deferral
Expand All @@ -577,24 +607,13 @@ void SDL_WinRTApp::OnSuspending(Platform::Object^ sender, SuspendingEventArgs^ a
SuspendingDeferral^ deferral = args->SuspendingOperation->GetDeferral();
create_task([this, deferral]()
{
// Send a window-minimized event immediately to observers.
// Send an app did-enter-background event immediately to observers.
// CoreDispatcher::ProcessEvents, which is the backbone on which
// SDL_WinRTApp::PumpEvents is built, will not return to its caller
// once it sends out a suspend event. Any events posted to SDL's
// event queue won't get received until the WinRT app is resumed.
// SDL_AddEventWatch() may be used to receive app-suspend events on
// WinRT.
//
// In order to prevent app-suspend events from being received twice:
// first via a callback passed to SDL_AddEventWatch, and second via
// SDL's event queue, the event will be sent to SDL, then immediately
// removed from the queue.
if (WINRT_GlobalSDLWindow)
{
SDL_SendWindowEvent(WINRT_GlobalSDLWindow, SDL_WINDOWEVENT_MINIMIZED, 0, 0); // TODO: see if SDL_WINDOWEVENT_SIZE_CHANGED should be getting triggered here (it is, currently)
SDL_FilterEvents(RemoveAppSuspendAndResumeEvents, 0);
}

SDL_SendAppEvent(SDL_APP_DIDENTERBACKGROUND);

deferral->Complete();
Expand All @@ -603,24 +622,11 @@ void SDL_WinRTApp::OnSuspending(Platform::Object^ sender, SuspendingEventArgs^ a

void SDL_WinRTApp::OnResuming(Platform::Object^ sender, Platform::Object^ args)
{
// Restore any data or state that was unloaded on suspend. By default, data
// and state are persisted when resuming from suspend. Note that these events
// do not occur if the app was previously terminated.
SDL_SendAppEvent(SDL_APP_WILLENTERFOREGROUND);
SDL_SendAppEvent(SDL_APP_DIDENTERFOREGROUND);

// Restore any data or state that was unloaded on suspend. By default, data
// and state are persisted when resuming from suspend. Note that this event
// does not occur if the app was previously terminated.
if (WINRT_GlobalSDLWindow)
{
SDL_SendWindowEvent(WINRT_GlobalSDLWindow, SDL_WINDOWEVENT_RESTORED, 0, 0); // TODO: see if SDL_WINDOWEVENT_SIZE_CHANGED should be getting triggered here (it is, currently)

// Remove the app-resume event from the queue, as is done with the
// app-suspend event.
//
// TODO, WinRT: consider posting this event to the queue even though
// its counterpart, the app-suspend event, effectively has to be
// processed immediately.
SDL_FilterEvents(RemoveAppSuspendAndResumeEvents, 0);
}
}

void SDL_WinRTApp::OnExiting(Platform::Object^ sender, Platform::Object^ args)
Expand Down
2 changes: 2 additions & 0 deletions src/core/winrt/SDL_winrtapp_direct3d.h
View file
Expand Up @@ -39,6 +39,8 @@ ref class SDL_WinRTApp sealed : public Windows::ApplicationModel::Core::IFramewo
void PumpEvents();

protected:
bool ShouldWaitForAppResumeEvents();

// Event Handlers.

#if WINAPI_FAMILY == WINAPI_FAMILY_APP // for Windows 8/8.1/RT apps... (and not Phone apps)
Expand Down

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