Add linker flag -s HTML5_SUPPORT_DEFERRING_USER_SENSITIVE_REQUESTS=0 …

…to allow disabling fullscreen mode and pointer lock request deferring if deferring support is not needed (emscripten-core#10098)

ChangeLog.md

@@ -25,6 +25,9 @@ Current Trunk
 - Added options MEMORY_GROWTH_GEOMETRIC_STEP and MEMORY_GROWTH_GEOMETRIC_CAP
   to allow customizing the heap growth rates.
 - Renamed MEMORY_GROWTH_STEP option to MEMORY_GROWTH_LINEAR_STEP option.
+- Added new linker option -s HTML5_SUPPORT_DEFERRING_USER_SENSITIVE_REQUESTS=0
+  (default enabled) to allow disabling support for deferred fullscreen mode and
+  pointer lock requests for applications that do not need deferring support.
 
 v1.39.5: 12/20/2019
 -------------------

src/library_html5.js

@@ -36,7 +36,9 @@ var LibraryJSEvents = {
         JSEvents._removeHandler(i);
       }
       JSEvents.eventHandlers = [];
+#if HTML5_SUPPORT_DEFERRING_USER_SENSITIVE_REQUESTS
       JSEvents.deferredCalls = [];
+#endif
     },
 
 #if !MINIMAL_RUNTIME // In minimal runtime, there is no concept of the page running vs being closed, and hence __ATEXIT__ is not present
@@ -48,6 +50,7 @@ var LibraryJSEvents = {
     },
 #endif
 
+#if HTML5_SUPPORT_DEFERRING_USER_SENSITIVE_REQUESTS
     deferredCalls: [],
 
     // Queues the given function call to occur the next time we enter an event handler.
@@ -110,6 +113,7 @@ var LibraryJSEvents = {
     inEventHandler: 0,
     // If we are in an event handler, specifies the event handler object from the eventHandlers array that is currently running.
     currentEventHandler: null,
+#endif
 
     // Stores objects representing each currently registered JS event handler.
     eventHandlers: [],
@@ -136,17 +140,21 @@ var LibraryJSEvents = {
 
     registerOrRemoveHandler: function(eventHandler) {
       var jsEventHandler = function jsEventHandler(event) {
+#if HTML5_SUPPORT_DEFERRING_USER_SENSITIVE_REQUESTS
         // Increment nesting count for the event handler.
         ++JSEvents.inEventHandler;
         JSEvents.currentEventHandler = eventHandler;
         // Process any old deferred calls the user has placed.
         JSEvents.runDeferredCalls();
+#endif
         // Process the actual event, calls back to user C code handler.
         eventHandler.handlerFunc(event);
+#if HTML5_SUPPORT_DEFERRING_USER_SENSITIVE_REQUESTS
         // Process any new deferred calls that were placed right now from this event handler.
         JSEvents.runDeferredCalls();
         // Out of event handler - restore nesting count.
         --JSEvents.inEventHandler;
+#endif
       };
 
       if (eventHandler.callbackfunc) {
@@ -255,10 +263,12 @@ var LibraryJSEvents = {
 
     var eventHandler = {
       target: __findEventTarget(target),
+#if HTML5_SUPPORT_DEFERRING_USER_SENSITIVE_REQUESTS
 #if MIN_IE_VERSION != TARGET_NOT_SUPPORTED
       allowsDeferredCalls: JSEvents.isInternetExplorer() ? false : true, // MSIE doesn't allow fullscreen and pointerlock requests from key handlers, others do.
 #else
       allowsDeferredCalls: true,
+#endif
 #endif
       eventTypeString: eventTypeString,
       callbackfunc: callbackfunc,
@@ -485,13 +495,15 @@ var LibraryJSEvents = {
 
     var eventHandler = {
       target: target,
+#if HTML5_SUPPORT_DEFERRING_USER_SENSITIVE_REQUESTS
       allowsDeferredCalls: eventTypeString != 'mousemove' && eventTypeString != 'mouseenter' && eventTypeString != 'mouseleave', // Mouse move events do not allow fullscreen/pointer lock requests to be handled in them!
+#endif
       eventTypeString: eventTypeString,
       callbackfunc: callbackfunc,
       handlerFunc: mouseEventHandlerFunc,
       useCapture: useCapture
     };
-#if MIN_IE_VERSION != TARGET_NOT_SUPPORTED
+#if MIN_IE_VERSION != TARGET_NOT_SUPPORTED && HTML5_SUPPORT_DEFERRING_USER_SENSITIVE_REQUESTS
     // In IE, mousedown events don't either allow deferred calls to be run!
     if (JSEvents.isInternetExplorer() && eventTypeString == 'mousedown') eventHandler.allowsDeferredCalls = false;
 #endif
@@ -628,7 +640,9 @@ var LibraryJSEvents = {
 
     var eventHandler = {
       target: target,
+#if HTML5_SUPPORT_DEFERRING_USER_SENSITIVE_REQUESTS
       allowsDeferredCalls: true,
+#endif
       eventTypeString: eventTypeString,
       callbackfunc: callbackfunc,
 #if MIN_IE_VERSION <= 8 || MIN_SAFARI_VERSION < 130000 // https://caniuse.com/#feat=mdn-api_wheelevent
@@ -710,7 +724,6 @@ var LibraryJSEvents = {
 
     var eventHandler = {
       target: target,
-      allowsDeferredCalls: false, // Neither scroll or resize events allow running requests inside them.
       eventTypeString: eventTypeString,
       callbackfunc: callbackfunc,
       handlerFunc: uiEventHandlerFunc,
@@ -765,7 +778,6 @@ var LibraryJSEvents = {
 
     var eventHandler = {
       target: __findEventTarget(target),
-      allowsDeferredCalls: false,
       eventTypeString: eventTypeString,
       callbackfunc: callbackfunc,
       handlerFunc: focusEventHandlerFunc,
@@ -838,7 +850,6 @@ var LibraryJSEvents = {
 
     var eventHandler = {
       target: __findEventTarget(target),
-      allowsDeferredCalls: false,
       eventTypeString: eventTypeString,
       callbackfunc: callbackfunc,
       handlerFunc: deviceOrientationEventHandlerFunc,
@@ -914,7 +925,6 @@ var LibraryJSEvents = {
 
     var eventHandler = {
       target: __findEventTarget(target),
-      allowsDeferredCalls: false,
       eventTypeString: eventTypeString,
       callbackfunc: callbackfunc,
       handlerFunc: deviceMotionEventHandlerFunc,
@@ -994,7 +1004,6 @@ var LibraryJSEvents = {
 
     var eventHandler = {
       target: target,
-      allowsDeferredCalls: false,
       eventTypeString: eventTypeString,
       callbackfunc: callbackfunc,
       handlerFunc: orientationChangeEventHandlerFunc,
@@ -1114,7 +1123,6 @@ var LibraryJSEvents = {
 
     var eventHandler = {
       target: target,
-      allowsDeferredCalls: false,
       eventTypeString: eventTypeString,
       callbackfunc: callbackfunc,
       handlerFunc: fullscreenChangeEventhandlerFunc,
@@ -1502,6 +1510,7 @@ var LibraryJSEvents = {
       return {{{ cDefine('EMSCRIPTEN_RESULT_INVALID_TARGET') }}};
     }
 
+#if HTML5_SUPPORT_DEFERRING_USER_SENSITIVE_REQUESTS
     var canPerformRequests = JSEvents.canPerformEventHandlerRequests();
 
     // Queue this function call if we're not currently in an event handler and the user saw it appropriate to do so.
@@ -1513,6 +1522,7 @@ var LibraryJSEvents = {
         return {{{ cDefine('EMSCRIPTEN_RESULT_FAILED_NOT_DEFERRED') }}};
       }
     }
+#endif
 
     return _JSEvents_requestFullscreen(target, strategy);
   },
@@ -1526,7 +1536,9 @@ var LibraryJSEvents = {
     strategy.scaleMode = {{{ cDefine('EMSCRIPTEN_FULLSCREEN_SCALE_DEFAULT') }}};
     strategy.canvasResolutionScaleMode = {{{ cDefine('EMSCRIPTEN_FULLSCREEN_CANVAS_SCALE_NONE') }}};
     strategy.filteringMode = {{{ cDefine('EMSCRIPTEN_FULLSCREEN_FILTERING_DEFAULT') }}};
+#if HTML5_SUPPORT_DEFERRING_USER_SENSITIVE_REQUESTS
     strategy.deferUntilInEventHandler = deferUntilInEventHandler;
+#endif
     strategy.canvasResizedCallbackTargetThread = {{{ cDefine('EM_CALLBACK_THREAD_CONTEXT_CALLING_THREAD') }}};
 
     return __emscripten_do_request_fullscreen(target, strategy);
@@ -1540,7 +1552,9 @@ var LibraryJSEvents = {
     strategy.scaleMode = {{{ makeGetValue('fullscreenStrategy', C_STRUCTS.EmscriptenFullscreenStrategy.scaleMode, 'i32') }}};
     strategy.canvasResolutionScaleMode = {{{ makeGetValue('fullscreenStrategy', C_STRUCTS.EmscriptenFullscreenStrategy.canvasResolutionScaleMode, 'i32') }}};
     strategy.filteringMode = {{{ makeGetValue('fullscreenStrategy', C_STRUCTS.EmscriptenFullscreenStrategy.filteringMode, 'i32') }}};
+#if HTML5_SUPPORT_DEFERRING_USER_SENSITIVE_REQUESTS
     strategy.deferUntilInEventHandler = deferUntilInEventHandler;
+#endif
     strategy.canvasResizedCallback = {{{ makeGetValue('fullscreenStrategy', C_STRUCTS.EmscriptenFullscreenStrategy.canvasResizedCallback, 'i32') }}};
     strategy.canvasResizedCallbackUserData = {{{ makeGetValue('fullscreenStrategy', C_STRUCTS.EmscriptenFullscreenStrategy.canvasResizedCallbackUserData, 'i32') }}};
 #if USE_PTHREADS
@@ -1625,8 +1639,10 @@ var LibraryJSEvents = {
   emscripten_exit_fullscreen__sig: 'i',
   emscripten_exit_fullscreen: function() {
     if (!JSEvents.fullscreenEnabled()) return {{{ cDefine('EMSCRIPTEN_RESULT_NOT_SUPPORTED') }}};
+#if HTML5_SUPPORT_DEFERRING_USER_SENSITIVE_REQUESTS
     // Make sure no queued up calls will fire after this.
     JSEvents.removeDeferredCalls(_JSEvents_requestFullscreen);
+#endif
 
     var d = __specialEventTargets[{{{ cDefine('EMSCRIPTEN_EVENT_TARGET_DOCUMENT') }}}];
     if (d.exitFullscreen) {
@@ -1687,7 +1703,6 @@ var LibraryJSEvents = {
 
     var eventHandler = {
       target: target,
-      allowsDeferredCalls: false,
       eventTypeString: eventTypeString,
       callbackfunc: callbackfunc,
       handlerFunc: pointerlockChangeEventHandlerFunc,
@@ -1732,7 +1747,6 @@ var LibraryJSEvents = {
 
     var eventHandler = {
       target: target,
-      allowsDeferredCalls: false,
       eventTypeString: eventTypeString,
       callbackfunc: callbackfunc,
       handlerFunc: pointerlockErrorEventHandlerFunc,
@@ -1835,6 +1849,7 @@ var LibraryJSEvents = {
       return {{{ cDefine('EMSCRIPTEN_RESULT_NOT_SUPPORTED') }}};
     }
 
+#if HTML5_SUPPORT_DEFERRING_USER_SENSITIVE_REQUESTS
     var canPerformRequests = JSEvents.canPerformEventHandlerRequests();
 
     // Queue this function call if we're not currently in an event handler and the user saw it appropriate to do so.
@@ -1846,6 +1861,7 @@ var LibraryJSEvents = {
         return {{{ cDefine('EMSCRIPTEN_RESULT_FAILED_NOT_DEFERRED') }}};
       }
     }
+#endif
 
     return __requestPointerLock(target);
   },
@@ -1854,8 +1870,10 @@ var LibraryJSEvents = {
   emscripten_exit_pointerlock__sig: 'i',
   emscripten_exit_pointerlock__deps: ['$JSEvents', '_requestPointerLock'],
   emscripten_exit_pointerlock: function() {
+#if HTML5_SUPPORT_DEFERRING_USER_SENSITIVE_REQUESTS
     // Make sure no queued up calls will fire after this.
     JSEvents.removeDeferredCalls(__requestPointerLock);
+#endif
 
     if (document.exitPointerLock) {
       document.exitPointerLock();
@@ -1934,7 +1952,6 @@ var LibraryJSEvents = {
 
     var eventHandler = {
       target: target,
-      allowsDeferredCalls: false,
       eventTypeString: eventTypeString,
       callbackfunc: callbackfunc,
       handlerFunc: visibilityChangeEventHandlerFunc,
@@ -2051,7 +2068,9 @@ var LibraryJSEvents = {
 
     var eventHandler = {
       target: target,
+#if HTML5_SUPPORT_DEFERRING_USER_SENSITIVE_REQUESTS
       allowsDeferredCalls: eventTypeString == 'touchstart' || eventTypeString == 'touchend',
+#endif
       eventTypeString: eventTypeString,
       callbackfunc: callbackfunc,
       handlerFunc: touchEventHandlerFunc,
@@ -2145,7 +2164,9 @@ var LibraryJSEvents = {
 
     var eventHandler = {
       target: __findEventTarget(target),
+#if HTML5_SUPPORT_DEFERRING_USER_SENSITIVE_REQUESTS
       allowsDeferredCalls: true,
+#endif
       eventTypeString: eventTypeString,
       callbackfunc: callbackfunc,
       handlerFunc: gamepadEventHandlerFunc,
@@ -2233,7 +2254,6 @@ var LibraryJSEvents = {
 
     var eventHandler = {
       target: __findEventTarget(target),
-      allowsDeferredCalls: false,
       eventTypeString: eventTypeString,
       callbackfunc: callbackfunc,
       handlerFunc: beforeUnloadEventHandlerFunc,
@@ -2289,7 +2309,6 @@ var LibraryJSEvents = {
 
     var eventHandler = {
       target: __findEventTarget(target),
-      allowsDeferredCalls: false,
       eventTypeString: eventTypeString,
       callbackfunc: callbackfunc,
       handlerFunc: batteryEventHandlerFunc,
@@ -2701,7 +2720,6 @@ var LibraryJSEvents = {
 
     var eventHandler = {
       target: __findEventTarget(target),
-      allowsDeferredCalls: false,
       eventTypeString: eventTypeString,
       callbackfunc: callbackfunc,
       handlerFunc: webGlEventHandlerFunc,

src/settings.js

@@ -1640,6 +1640,17 @@ var SUPPORT_LONGJMP = 1;
 // selectors, instead of referring to DOM IDs.
 var DISABLE_DEPRECATED_FIND_EVENT_TARGET_BEHAVIOR = 1;
 
+// Certain browser DOM API operations, such as requesting fullscreen mode
+// transition or pointer lock require that the request originates from within
+// an user initiated event, such as mouse click or keyboard press. Refactoring
+// an application to follow this kind of program structure can be difficult, so
+// HTML5_SUPPORT_DEFERRING_USER_SENSITIVE_REQUESTS=1 flag allows transparent
+// emulation of this by deferring synchronous fullscreen mode and pointer lock
+// requests until a suitable event callback is generated. Set this to 0
+// to disable support for deferring to save code space if your application does
+// not need support for deferred calls.
+var HTML5_SUPPORT_DEFERRING_USER_SENSITIVE_REQUESTS = 1;
+
 // Specifies whether the generated .html file is run through html-minifier. The
 // set of optimization passes run by html-minifier depends on debug and
 // optimization levels. In -g2 and higher, no minification is performed. In -g1,

tests/test_browser.py

@@ -2568,7 +2568,7 @@ def test_doublestart_bug(self):
 
   @requires_threads
   def test_html5(self):
-    for opts in [[], ['-O2', '-g1', '--closure', '1'], ['-s', 'USE_PTHREADS=1', '-s', 'PROXY_TO_PTHREAD=1'], ['-s', 'MIN_FIREFOX_VERSION=0', '-s', 'MIN_SAFARI_VERSION=0', '-s', 'MIN_IE_VERSION=0', '-s', 'MIN_EDGE_VERSION=0', '-s', 'MIN_CHROME_VERSION=0']]:
+    for opts in [[], ['-O2', '-g1', '--closure', '1', '-s', 'HTML5_SUPPORT_DEFERRING_USER_SENSITIVE_REQUESTS=0'], ['-s', 'USE_PTHREADS=1', '-s', 'PROXY_TO_PTHREAD=1'], ['-s', 'MIN_FIREFOX_VERSION=0', '-s', 'MIN_SAFARI_VERSION=0', '-s', 'MIN_IE_VERSION=0', '-s', 'MIN_EDGE_VERSION=0', '-s', 'MIN_CHROME_VERSION=0']]:
       print(opts)
       self.btest(path_from_root('tests', 'test_html5.c'), args=[] + opts, expected='0')