1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
//! The [`Event`] enum and assorted supporting types.
//!
//! These are sent to the closure given to [`EventLoop::run(...)`], where they get
//! processed and used to modify the program state. For more details, see the root-level documentation.
//!
//! Some of these events represent different "parts" of a traditional event-handling loop. You could
//! approximate the basic ordering loop of [`EventLoop::run(...)`] like this:
//!
//! ```rust,ignore
//! let mut control_flow = ControlFlow::Poll;
//! let mut start_cause = StartCause::Init;
//!
//! while control_flow != ControlFlow::Exit {
//!     event_handler(NewEvents(start_cause), ..., &mut control_flow);
//!
//!     for e in (window events, user events, device events) {
//!         event_handler(e, ..., &mut control_flow);
//!     }
//!     event_handler(MainEventsCleared, ..., &mut control_flow);
//!
//!     for w in (redraw windows) {
//!         event_handler(RedrawRequested(w), ..., &mut control_flow);
//!     }
//!     event_handler(RedrawEventsCleared, ..., &mut control_flow);
//!
//!     start_cause = wait_if_necessary(control_flow);
//! }
//!
//! event_handler(LoopDestroyed, ..., &mut control_flow);
//! ```
//!
//! This leaves out timing details like [`ControlFlow::WaitUntil`] but hopefully
//! describes what happens in what order.
//!
//! [`EventLoop::run(...)`]: crate::event_loop::EventLoop::run
//! [`ControlFlow::WaitUntil`]: crate::event_loop::ControlFlow::WaitUntil
use instant::Instant;
use std::path::PathBuf;

#[cfg(doc)]
use crate::window::Window;
use crate::{
    dpi::{PhysicalPosition, PhysicalSize},
    platform_impl,
    window::{Theme, WindowId},
};

/// Describes a generic event.
///
/// See the module-level docs for more information on the event loop manages each event.
#[derive(Debug, PartialEq)]
pub enum Event<'a, T: 'static> {
    /// Emitted when new events arrive from the OS to be processed.
    ///
    /// This event type is useful as a place to put code that should be done before you start
    /// processing events, such as updating frame timing information for benchmarking or checking
    /// the [`StartCause`][crate::event::StartCause] to see if a timer set by
    /// [`ControlFlow::WaitUntil`](crate::event_loop::ControlFlow::WaitUntil) has elapsed.
    NewEvents(StartCause),

    /// Emitted when the OS sends an event to a winit window.
    WindowEvent {
        window_id: WindowId,
        event: WindowEvent<'a>,
    },

    /// Emitted when the OS sends an event to a device.
    DeviceEvent {
        device_id: DeviceId,
        event: DeviceEvent,
    },

    /// Emitted when an event is sent from [`EventLoopProxy::send_event`](crate::event_loop::EventLoopProxy::send_event)
    UserEvent(T),

    /// Emitted when the application has been suspended.
    ///
    /// # Portability
    ///
    /// Not all platforms support the notion of suspending applications, and there may be no
    /// technical way to guarantee being able to emit a `Suspended` event if the OS has
    /// no formal application lifecycle (currently only Android and iOS do). For this reason,
    /// Winit does not currently try to emit pseudo `Suspended` events before the application
    /// quits on platforms without an application lifecycle.
    ///
    /// Considering that the implementation of `Suspended` and [`Resumed`] events may be internally
    /// driven by multiple platform-specific events, and that there may be subtle differences across
    /// platforms with how these internal events are delivered, it's recommended that applications
    /// be able to gracefully handle redundant (i.e. back-to-back) `Suspended` or [`Resumed`] events.
    ///
    /// Also see [`Resumed`] notes.
    ///
    /// ## Android
    ///
    /// On Android, the `Suspended` event is only sent when the application's associated
    /// [`SurfaceView`] is destroyed. This is expected to closely correlate with the [`onPause`]
    /// lifecycle event but there may technically be a discrepancy.
    ///
    /// [`onPause`]: https://developer.android.com/reference/android/app/Activity#onPause()
    ///
    /// Applications that need to run on Android should assume their [`SurfaceView`] has been
    /// destroyed, which indirectly invalidates any existing render surfaces that may have been
    /// created outside of Winit (such as an `EGLSurface`, [`VkSurfaceKHR`] or [`wgpu::Surface`]).
    ///
    /// After being `Suspended` on Android applications must drop all render surfaces before
    /// the event callback completes, which may be re-created when the application is next [`Resumed`].
    ///
    /// [`SurfaceView`]: https://developer.android.com/reference/android/view/SurfaceView
    /// [Activity lifecycle]: https://developer.android.com/guide/components/activities/activity-lifecycle
    /// [`VkSurfaceKHR`]: https://www.khronos.org/registry/vulkan/specs/1.3-extensions/man/html/VkSurfaceKHR.html
    /// [`wgpu::Surface`]: https://docs.rs/wgpu/latest/wgpu/struct.Surface.html
    ///
    /// ## iOS
    ///
    /// On iOS, the `Suspended` event is currently emitted in response to an
    /// [`applicationWillResignActive`] callback which means that the application is
    /// about to transition from the active to inactive state (according to the
    /// [iOS application lifecycle]).
    ///
    /// [`applicationWillResignActive`]: https://developer.apple.com/documentation/uikit/uiapplicationdelegate/1622950-applicationwillresignactive
    /// [iOS application lifecycle]: https://developer.apple.com/documentation/uikit/app_and_environment/managing_your_app_s_life_cycle
    ///
    /// [`Resumed`]: Self::Resumed
    Suspended,

    /// Emitted when the application has been resumed.
    ///
    /// For consistency, all platforms emit a `Resumed` event even if they don't themselves have a
    /// formal suspend/resume lifecycle. For systems without a standard suspend/resume lifecycle
    /// the `Resumed` event is always emitted after the [`NewEvents(StartCause::Init)`][StartCause::Init]
    /// event.
    ///
    /// # Portability
    ///
    /// It's recommended that applications should only initialize their graphics context and create
    /// a window after they have received their first `Resumed` event. Some systems
    /// (specifically Android) won't allow applications to create a render surface until they are
    /// resumed.
    ///
    /// Considering that the implementation of [`Suspended`] and `Resumed` events may be internally
    /// driven by multiple platform-specific events, and that there may be subtle differences across
    /// platforms with how these internal events are delivered, it's recommended that applications
    /// be able to gracefully handle redundant (i.e. back-to-back) [`Suspended`] or `Resumed` events.
    ///
    /// Also see [`Suspended`] notes.
    ///
    /// ## Android
    ///
    /// On Android, the `Resumed` event is sent when a new [`SurfaceView`] has been created. This is
    /// expected to closely correlate with the [`onResume`] lifecycle event but there may technically
    /// be a discrepancy.
    ///
    /// [`onResume`]: https://developer.android.com/reference/android/app/Activity#onResume()
    ///
    /// Applications that need to run on Android must wait until they have been `Resumed`
    /// before they will be able to create a render surface (such as an `EGLSurface`,
    /// [`VkSurfaceKHR`] or [`wgpu::Surface`]) which depend on having a
    /// [`SurfaceView`]. Applications must also assume that if they are [`Suspended`], then their
    /// render surfaces are invalid and should be dropped.
    ///
    /// Also see [`Suspended`] notes.
    ///
    /// [`SurfaceView`]: https://developer.android.com/reference/android/view/SurfaceView
    /// [Activity lifecycle]: https://developer.android.com/guide/components/activities/activity-lifecycle
    /// [`VkSurfaceKHR`]: https://www.khronos.org/registry/vulkan/specs/1.3-extensions/man/html/VkSurfaceKHR.html
    /// [`wgpu::Surface`]: https://docs.rs/wgpu/latest/wgpu/struct.Surface.html
    ///
    /// ## iOS
    ///
    /// On iOS, the `Resumed` event is emitted in response to an [`applicationDidBecomeActive`]
    /// callback which means the application is "active" (according to the
    /// [iOS application lifecycle]).
    ///
    /// [`applicationDidBecomeActive`]: https://developer.apple.com/documentation/uikit/uiapplicationdelegate/1622956-applicationdidbecomeactive
    /// [iOS application lifecycle]: https://developer.apple.com/documentation/uikit/app_and_environment/managing_your_app_s_life_cycle
    ///
    /// [`Suspended`]: Self::Suspended
    Resumed,

    /// Emitted when all of the event loop's input events have been processed and redraw processing
    /// is about to begin.
    ///
    /// This event is useful as a place to put your code that should be run after all
    /// state-changing events have been handled and you want to do stuff (updating state, performing
    /// calculations, etc) that happens as the "main body" of your event loop. If your program only draws
    /// graphics when something changes, it's usually better to do it in response to
    /// [`Event::RedrawRequested`](crate::event::Event::RedrawRequested), which gets emitted
    /// immediately after this event. Programs that draw graphics continuously, like most games,
    /// can render here unconditionally for simplicity.
    MainEventsCleared,

    /// Emitted after [`MainEventsCleared`] when a window should be redrawn.
    ///
    /// This gets triggered in two scenarios:
    /// - The OS has performed an operation that's invalidated the window's contents (such as
    ///   resizing the window).
    /// - The application has explicitly requested a redraw via [`Window::request_redraw`].
    ///
    /// During each iteration of the event loop, Winit will aggregate duplicate redraw requests
    /// into a single event, to help avoid duplicating rendering work.
    ///
    /// Mainly of interest to applications with mostly-static graphics that avoid redrawing unless
    /// something changes, like most non-game GUIs.
    ///
    ///
    /// ## Platform-specific
    ///
    /// - **macOS / iOS:** Due to implementation difficulties, this will often, but not always, be
    ///   emitted directly inside `drawRect:`, with neither a preceding [`MainEventsCleared`] nor
    ///   subsequent `RedrawEventsCleared`. See [#2640] for work on this.
    ///
    /// [`MainEventsCleared`]: Self::MainEventsCleared
    /// [`RedrawEventsCleared`]: Self::RedrawEventsCleared
    /// [#2640]: https://github.com/rust-windowing/winit/issues/2640
    RedrawRequested(WindowId),

    /// Emitted after all [`RedrawRequested`] events have been processed and control flow is about to
    /// be taken away from the program. If there are no `RedrawRequested` events, it is emitted
    /// immediately after `MainEventsCleared`.
    ///
    /// This event is useful for doing any cleanup or bookkeeping work after all the rendering
    /// tasks have been completed.
    ///
    /// [`RedrawRequested`]: Self::RedrawRequested
    RedrawEventsCleared,

    /// Emitted when the event loop is being shut down.
    ///
    /// This is irreversible - if this event is emitted, it is guaranteed to be the last event that
    /// gets emitted. You generally want to treat this as an "do on quit" event.
    LoopDestroyed,
}

impl<T: Clone> Clone for Event<'static, T> {
    fn clone(&self) -> Self {
        use self::Event::*;
        match self {
            WindowEvent { window_id, event } => WindowEvent {
                window_id: *window_id,
                event: event.clone(),
            },
            UserEvent(event) => UserEvent(event.clone()),
            DeviceEvent { device_id, event } => DeviceEvent {
                device_id: *device_id,
                event: event.clone(),
            },
            NewEvents(cause) => NewEvents(*cause),
            MainEventsCleared => MainEventsCleared,
            RedrawRequested(wid) => RedrawRequested(*wid),
            RedrawEventsCleared => RedrawEventsCleared,
            LoopDestroyed => LoopDestroyed,
            Suspended => Suspended,
            Resumed => Resumed,
        }
    }
}

impl<'a, T> Event<'a, T> {
    pub fn map_nonuser_event<U>(self) -> Result<Event<'a, U>, Event<'a, T>> {
        use self::Event::*;
        match self {
            UserEvent(_) => Err(self),
            WindowEvent { window_id, event } => Ok(WindowEvent { window_id, event }),
            DeviceEvent { device_id, event } => Ok(DeviceEvent { device_id, event }),
            NewEvents(cause) => Ok(NewEvents(cause)),
            MainEventsCleared => Ok(MainEventsCleared),
            RedrawRequested(wid) => Ok(RedrawRequested(wid)),
            RedrawEventsCleared => Ok(RedrawEventsCleared),
            LoopDestroyed => Ok(LoopDestroyed),
            Suspended => Ok(Suspended),
            Resumed => Ok(Resumed),
        }
    }

    /// If the event doesn't contain a reference, turn it into an event with a `'static` lifetime.
    /// Otherwise, return `None`.
    pub fn to_static(self) -> Option<Event<'static, T>> {
        use self::Event::*;
        match self {
            WindowEvent { window_id, event } => event
                .to_static()
                .map(|event| WindowEvent { window_id, event }),
            UserEvent(event) => Some(UserEvent(event)),
            DeviceEvent { device_id, event } => Some(DeviceEvent { device_id, event }),
            NewEvents(cause) => Some(NewEvents(cause)),
            MainEventsCleared => Some(MainEventsCleared),
            RedrawRequested(wid) => Some(RedrawRequested(wid)),
            RedrawEventsCleared => Some(RedrawEventsCleared),
            LoopDestroyed => Some(LoopDestroyed),
            Suspended => Some(Suspended),
            Resumed => Some(Resumed),
        }
    }
}

/// Describes the reason the event loop is resuming.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum StartCause {
    /// Sent if the time specified by [`ControlFlow::WaitUntil`] has been reached. Contains the
    /// moment the timeout was requested and the requested resume time. The actual resume time is
    /// guaranteed to be equal to or after the requested resume time.
    ///
    /// [`ControlFlow::WaitUntil`]: crate::event_loop::ControlFlow::WaitUntil
    ResumeTimeReached {
        start: Instant,
        requested_resume: Instant,
    },

    /// Sent if the OS has new events to send to the window, after a wait was requested. Contains
    /// the moment the wait was requested and the resume time, if requested.
    WaitCancelled {
        start: Instant,
        requested_resume: Option<Instant>,
    },

    /// Sent if the event loop is being resumed after the loop's control flow was set to
    /// [`ControlFlow::Poll`].
    ///
    /// [`ControlFlow::Poll`]: crate::event_loop::ControlFlow::Poll
    Poll,

    /// Sent once, immediately after `run` is called. Indicates that the loop was just initialized.
    Init,
}

/// Describes an event from a [`Window`].
#[derive(Debug, PartialEq)]
pub enum WindowEvent<'a> {
    /// The size of the window has changed. Contains the client area's new dimensions.
    Resized(PhysicalSize<u32>),

    /// The position of the window has changed. Contains the window's new position.
    ///
    /// ## Platform-specific
    ///
    /// - **iOS / Android / Web / Wayland:** Unsupported.
    Moved(PhysicalPosition<i32>),

    /// The window has been requested to close.
    CloseRequested,

    /// The window has been destroyed.
    Destroyed,

    /// A file has been dropped into the window.
    ///
    /// When the user drops multiple files at once, this event will be emitted for each file
    /// separately.
    DroppedFile(PathBuf),

    /// A file is being hovered over the window.
    ///
    /// When the user hovers multiple files at once, this event will be emitted for each file
    /// separately.
    HoveredFile(PathBuf),

    /// A file was hovered, but has exited the window.
    ///
    /// There will be a single `HoveredFileCancelled` event triggered even if multiple files were
    /// hovered.
    HoveredFileCancelled,

    /// The window received a unicode character.
    ///
    /// See also the [`Ime`](Self::Ime) event for more complex character sequences.
    ReceivedCharacter(char),

    /// The window gained or lost focus.
    ///
    /// The parameter is true if the window has gained focus, and false if it has lost focus.
    Focused(bool),

    /// An event from the keyboard has been received.
    KeyboardInput {
        device_id: DeviceId,
        input: KeyboardInput,
        /// If `true`, the event was generated synthetically by winit
        /// in one of the following circumstances:
        ///
        /// * Synthetic key press events are generated for all keys pressed
        ///   when a window gains focus. Likewise, synthetic key release events
        ///   are generated for all keys pressed when a window goes out of focus.
        ///   ***Currently, this is only functional on X11 and Windows***
        ///
        /// Otherwise, this value is always `false`.
        is_synthetic: bool,
    },

    /// The keyboard modifiers have changed.
    ///
    /// ## Platform-specific
    ///
    /// - **Web:** This API is currently unimplemented on the web. This isn't by design - it's an
    ///   issue, and it should get fixed - but it's the current state of the API.
    ModifiersChanged(ModifiersState),

    /// An event from an input method.
    ///
    /// **Note:** You have to explicitly enable this event using [`Window::set_ime_allowed`].
    ///
    /// ## Platform-specific
    ///
    /// - **iOS / Android / Web / Orbital:** Unsupported.
    Ime(Ime),

    /// The cursor has moved on the window.
    CursorMoved {
        device_id: DeviceId,

        /// (x,y) coords in pixels relative to the top-left corner of the window. Because the range of this data is
        /// limited by the display area and it may have been transformed by the OS to implement effects such as cursor
        /// acceleration, it should not be used to implement non-cursor-like interactions such as 3D camera control.
        position: PhysicalPosition<f64>,
        #[deprecated = "Deprecated in favor of WindowEvent::ModifiersChanged"]
        modifiers: ModifiersState,
    },

    /// The cursor has entered the window.
    CursorEntered { device_id: DeviceId },

    /// The cursor has left the window.
    CursorLeft { device_id: DeviceId },

    /// A mouse wheel movement or touchpad scroll occurred.
    MouseWheel {
        device_id: DeviceId,
        delta: MouseScrollDelta,
        phase: TouchPhase,
        #[deprecated = "Deprecated in favor of WindowEvent::ModifiersChanged"]
        modifiers: ModifiersState,
    },

    /// An mouse button press has been received.
    MouseInput {
        device_id: DeviceId,
        state: ElementState,
        button: MouseButton,
        #[deprecated = "Deprecated in favor of WindowEvent::ModifiersChanged"]
        modifiers: ModifiersState,
    },

    /// Touchpad magnification event with two-finger pinch gesture.
    ///
    /// Positive delta values indicate magnification (zooming in) and
    /// negative delta values indicate shrinking (zooming out).
    ///
    /// ## Platform-specific
    ///
    /// - Only available on **macOS**.
    TouchpadMagnify {
        device_id: DeviceId,
        delta: f64,
        phase: TouchPhase,
    },

    /// Smart magnification event.
    ///
    /// On a Mac, smart magnification is triggered by a double tap with two fingers
    /// on the trackpad and is commonly used to zoom on a certain object
    /// (e.g. a paragraph of a PDF) or (sort of like a toggle) to reset any zoom.
    /// The gesture is also supported in Safari, Pages, etc.
    ///
    /// The event is general enough that its generating gesture is allowed to vary
    /// across platforms. It could also be generated by another device.
    ///
    /// Unfortunatly, neither [Windows](https://support.microsoft.com/en-us/windows/touch-gestures-for-windows-a9d28305-4818-a5df-4e2b-e5590f850741)
    /// nor [Wayland](https://wayland.freedesktop.org/libinput/doc/latest/gestures.html)
    /// support this gesture or any other gesture with the same effect.
    ///
    /// ## Platform-specific
    ///
    /// - Only available on **macOS 10.8** and later.
    SmartMagnify { device_id: DeviceId },

    /// Touchpad rotation event with two-finger rotation gesture.
    ///
    /// Positive delta values indicate rotation counterclockwise and
    /// negative delta values indicate rotation clockwise.
    ///
    /// ## Platform-specific
    ///
    /// - Only available on **macOS**.
    TouchpadRotate {
        device_id: DeviceId,
        delta: f32,
        phase: TouchPhase,
    },

    /// Touchpad pressure event.
    ///
    /// At the moment, only supported on Apple forcetouch-capable macbooks.
    /// The parameters are: pressure level (value between 0 and 1 representing how hard the touchpad
    /// is being pressed) and stage (integer representing the click level).
    TouchpadPressure {
        device_id: DeviceId,
        pressure: f32,
        stage: i64,
    },

    /// Motion on some analog axis. May report data redundant to other, more specific events.
    AxisMotion {
        device_id: DeviceId,
        axis: AxisId,
        value: f64,
    },

    /// Touch event has been received
    ///
    /// ## Platform-specific
    ///
    /// - **macOS:** Unsupported.
    Touch(Touch),

    /// The window's scale factor has changed.
    ///
    /// The following user actions can cause DPI changes:
    ///
    /// * Changing the display's resolution.
    /// * Changing the display's scale factor (e.g. in Control Panel on Windows).
    /// * Moving the window to a display with a different scale factor.
    ///
    /// After this event callback has been processed, the window will be resized to whatever value
    /// is pointed to by the `new_inner_size` reference. By default, this will contain the size suggested
    /// by the OS, but it can be changed to any value.
    ///
    /// For more information about DPI in general, see the [`dpi`](crate::dpi) module.
    ScaleFactorChanged {
        scale_factor: f64,
        new_inner_size: &'a mut PhysicalSize<u32>,
    },

    /// The system window theme has changed.
    ///
    /// Applications might wish to react to this to change the theme of the content of the window
    /// when the system changes the window theme.
    ///
    /// ## Platform-specific
    ///
    /// - **iOS / Android / X11 / Wayland / Orbital:** Unsupported.
    ThemeChanged(Theme),

    /// The window has been occluded (completely hidden from view).
    ///
    /// This is different to window visibility as it depends on whether the window is closed,
    /// minimised, set invisible, or fully occluded by another window.
    ///
    /// Platform-specific behavior:
    /// - **iOS / Android / Web / Wayland / Windows / Orbital:** Unsupported.
    Occluded(bool),
}

impl Clone for WindowEvent<'static> {
    fn clone(&self) -> Self {
        use self::WindowEvent::*;
        return match self {
            Resized(size) => Resized(*size),
            Moved(pos) => Moved(*pos),
            CloseRequested => CloseRequested,
            Destroyed => Destroyed,
            DroppedFile(file) => DroppedFile(file.clone()),
            HoveredFile(file) => HoveredFile(file.clone()),
            HoveredFileCancelled => HoveredFileCancelled,
            ReceivedCharacter(c) => ReceivedCharacter(*c),
            Focused(f) => Focused(*f),
            KeyboardInput {
                device_id,
                input,
                is_synthetic,
            } => KeyboardInput {
                device_id: *device_id,
                input: *input,
                is_synthetic: *is_synthetic,
            },
            Ime(preedit_state) => Ime(preedit_state.clone()),
            ModifiersChanged(modifiers) => ModifiersChanged(*modifiers),
            #[allow(deprecated)]
            CursorMoved {
                device_id,
                position,
                modifiers,
            } => CursorMoved {
                device_id: *device_id,
                position: *position,
                modifiers: *modifiers,
            },
            CursorEntered { device_id } => CursorEntered {
                device_id: *device_id,
            },
            CursorLeft { device_id } => CursorLeft {
                device_id: *device_id,
            },
            #[allow(deprecated)]
            MouseWheel {
                device_id,
                delta,
                phase,
                modifiers,
            } => MouseWheel {
                device_id: *device_id,
                delta: *delta,
                phase: *phase,
                modifiers: *modifiers,
            },
            #[allow(deprecated)]
            MouseInput {
                device_id,
                state,
                button,
                modifiers,
            } => MouseInput {
                device_id: *device_id,
                state: *state,
                button: *button,
                modifiers: *modifiers,
            },
            TouchpadMagnify {
                device_id,
                delta,
                phase,
            } => TouchpadMagnify {
                device_id: *device_id,
                delta: *delta,
                phase: *phase,
            },
            SmartMagnify { device_id } => SmartMagnify {
                device_id: *device_id,
            },
            TouchpadRotate {
                device_id,
                delta,
                phase,
            } => TouchpadRotate {
                device_id: *device_id,
                delta: *delta,
                phase: *phase,
            },
            TouchpadPressure {
                device_id,
                pressure,
                stage,
            } => TouchpadPressure {
                device_id: *device_id,
                pressure: *pressure,
                stage: *stage,
            },
            AxisMotion {
                device_id,
                axis,
                value,
            } => AxisMotion {
                device_id: *device_id,
                axis: *axis,
                value: *value,
            },
            Touch(touch) => Touch(*touch),
            ThemeChanged(theme) => ThemeChanged(*theme),
            ScaleFactorChanged { .. } => {
                unreachable!("Static event can't be about scale factor changing")
            }
            Occluded(occluded) => Occluded(*occluded),
        };
    }
}

impl<'a> WindowEvent<'a> {
    pub fn to_static(self) -> Option<WindowEvent<'static>> {
        use self::WindowEvent::*;
        match self {
            Resized(size) => Some(Resized(size)),
            Moved(position) => Some(Moved(position)),
            CloseRequested => Some(CloseRequested),
            Destroyed => Some(Destroyed),
            DroppedFile(file) => Some(DroppedFile(file)),
            HoveredFile(file) => Some(HoveredFile(file)),
            HoveredFileCancelled => Some(HoveredFileCancelled),
            ReceivedCharacter(c) => Some(ReceivedCharacter(c)),
            Focused(focused) => Some(Focused(focused)),
            KeyboardInput {
                device_id,
                input,
                is_synthetic,
            } => Some(KeyboardInput {
                device_id,
                input,
                is_synthetic,
            }),
            ModifiersChanged(modifiers) => Some(ModifiersChanged(modifiers)),
            Ime(event) => Some(Ime(event)),
            #[allow(deprecated)]
            CursorMoved {
                device_id,
                position,
                modifiers,
            } => Some(CursorMoved {
                device_id,
                position,
                modifiers,
            }),
            CursorEntered { device_id } => Some(CursorEntered { device_id }),
            CursorLeft { device_id } => Some(CursorLeft { device_id }),
            #[allow(deprecated)]
            MouseWheel {
                device_id,
                delta,
                phase,
                modifiers,
            } => Some(MouseWheel {
                device_id,
                delta,
                phase,
                modifiers,
            }),
            #[allow(deprecated)]
            MouseInput {
                device_id,
                state,
                button,
                modifiers,
            } => Some(MouseInput {
                device_id,
                state,
                button,
                modifiers,
            }),
            TouchpadMagnify {
                device_id,
                delta,
                phase,
            } => Some(TouchpadMagnify {
                device_id,
                delta,
                phase,
            }),
            SmartMagnify { device_id } => Some(SmartMagnify { device_id }),
            TouchpadRotate {
                device_id,
                delta,
                phase,
            } => Some(TouchpadRotate {
                device_id,
                delta,
                phase,
            }),
            TouchpadPressure {
                device_id,
                pressure,
                stage,
            } => Some(TouchpadPressure {
                device_id,
                pressure,
                stage,
            }),
            AxisMotion {
                device_id,
                axis,
                value,
            } => Some(AxisMotion {
                device_id,
                axis,
                value,
            }),
            Touch(touch) => Some(Touch(touch)),
            ThemeChanged(theme) => Some(ThemeChanged(theme)),
            ScaleFactorChanged { .. } => None,
            Occluded(occluded) => Some(Occluded(occluded)),
        }
    }
}

/// Identifier of an input device.
///
/// Whenever you receive an event arising from a particular input device, this event contains a `DeviceId` which
/// identifies its origin. Note that devices may be virtual (representing an on-screen cursor and keyboard focus) or
/// physical. Virtual devices typically aggregate inputs from multiple physical devices.
#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct DeviceId(pub(crate) platform_impl::DeviceId);

impl DeviceId {
    /// Returns a dummy id, useful for unit testing.
    ///
    /// # Safety
    ///
    /// The only guarantee made about the return value of this function is that
    /// it will always be equal to itself and to future values returned by this function.
    /// No other guarantees are made. This may be equal to a real `DeviceId`.
    ///
    /// **Passing this into a winit function will result in undefined behavior.**
    pub const unsafe fn dummy() -> Self {
        DeviceId(platform_impl::DeviceId::dummy())
    }
}

/// Represents raw hardware events that are not associated with any particular window.
///
/// Useful for interactions that diverge significantly from a conventional 2D GUI, such as 3D camera or first-person
/// game controls. Many physical actions, such as mouse movement, can produce both device and window events. Because
/// window events typically arise from virtual devices (corresponding to GUI cursors and keyboard focus) the device IDs
/// may not match.
///
/// Note that these events are delivered regardless of input focus.
#[derive(Clone, Debug, PartialEq)]
pub enum DeviceEvent {
    Added,
    Removed,

    /// Change in physical position of a pointing device.
    ///
    /// This represents raw, unfiltered physical motion. Not to be confused with [`WindowEvent::CursorMoved`].
    MouseMotion {
        /// (x, y) change in position in unspecified units.
        ///
        /// Different devices may use different units.
        delta: (f64, f64),
    },

    /// Physical scroll event
    MouseWheel {
        delta: MouseScrollDelta,
    },

    /// Motion on some analog axis. This event will be reported for all arbitrary input devices
    /// that winit supports on this platform, including mouse devices.  If the device is a mouse
    /// device then this will be reported alongside the MouseMotion event.
    Motion {
        axis: AxisId,
        value: f64,
    },

    Button {
        button: ButtonId,
        state: ElementState,
    },

    Key(KeyboardInput),

    Text {
        codepoint: char,
    },
}

/// Describes a keyboard input event.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub struct KeyboardInput {
    /// Identifies the physical key pressed
    ///
    /// This should not change if the user adjusts the host's keyboard map. Use when the physical location of the
    /// key is more important than the key's host GUI semantics, such as for movement controls in a first-person
    /// game.
    pub scancode: ScanCode,

    pub state: ElementState,

    /// Identifies the semantic meaning of the key
    ///
    /// Use when the semantics of the key are more important than the physical location of the key, such as when
    /// implementing appropriate behavior for "page up."
    pub virtual_keycode: Option<VirtualKeyCode>,

    /// Modifier keys active at the time of this input.
    ///
    /// This is tracked internally to avoid tracking errors arising from modifier key state changes when events from
    /// this device are not being delivered to the application, e.g. due to keyboard focus being elsewhere.
    #[deprecated = "Deprecated in favor of WindowEvent::ModifiersChanged"]
    pub modifiers: ModifiersState,
}

/// Describes [input method](https://en.wikipedia.org/wiki/Input_method) events.
///
/// This is also called a "composition event".
///
/// Most keypresses using a latin-like keyboard layout simply generate a [`WindowEvent::ReceivedCharacter`].
/// However, one couldn't possibly have a key for every single unicode character that the user might want to type
/// - so the solution operating systems employ is to allow the user to type these using _a sequence of keypresses_ instead.
///
/// A prominent example of this is accents - many keyboard layouts allow you to first click the "accent key", and then
/// the character you want to apply the accent to. This will generate the following event sequence:
/// ```ignore
/// // Press "`" key
/// Ime::Preedit("`", Some((0, 0)))
/// // Press "E" key
/// Ime::Preedit("", None) // Synthetic event generated by winit to clear preedit.
/// Ime::Commit("é")
/// ```
///
/// Additionally, certain input devices are configured to display a candidate box that allow the user to select the
/// desired character interactively. (To properly position this box, you must use [`Window::set_ime_position`].)
///
/// An example of a keyboard layout which uses candidate boxes is pinyin. On a latin keybaord the following event
/// sequence could be obtained:
/// ```ignore
/// // Press "A" key
/// Ime::Preedit("a", Some((1, 1)))
/// // Press "B" key
/// Ime::Preedit("a b", Some((3, 3)))
/// // Press left arrow key
/// Ime::Preedit("a b", Some((1, 1)))
/// // Press space key
/// Ime::Preedit("啊b", Some((3, 3)))
/// // Press space key
/// Ime::Preedit("", None) // Synthetic event generated by winit to clear preedit.
/// Ime::Commit("啊不")
/// ```
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub enum Ime {
    /// Notifies when the IME was enabled.
    ///
    /// After getting this event you could receive [`Preedit`](Self::Preedit) and
    /// [`Commit`](Self::Commit) events. You should also start performing IME related requests
    /// like [`Window::set_ime_position`].
    Enabled,

    /// Notifies when a new composing text should be set at the cursor position.
    ///
    /// The value represents a pair of the preedit string and the cursor begin position and end
    /// position. When it's `None`, the cursor should be hidden. When `String` is an empty string
    /// this indicates that preedit was cleared.
    ///
    /// The cursor position is byte-wise indexed.
    Preedit(String, Option<(usize, usize)>),

    /// Notifies when text should be inserted into the editor widget.
    ///
    /// Right before this event winit will send empty [`Self::Preedit`] event.
    Commit(String),

    /// Notifies when the IME was disabled.
    ///
    /// After receiving this event you won't get any more [`Preedit`](Self::Preedit) or
    /// [`Commit`](Self::Commit) events until the next [`Enabled`](Self::Enabled) event. You should
    /// also stop issuing IME related requests like [`Window::set_ime_position`] and clear pending
    /// preedit text.
    Disabled,
}

/// Describes touch-screen input state.
#[derive(Debug, Hash, PartialEq, Eq, Clone, Copy)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub enum TouchPhase {
    Started,
    Moved,
    Ended,
    Cancelled,
}

/// Represents a touch event
///
/// Every time the user touches the screen, a new [`TouchPhase::Started`] event with an unique
/// identifier for the finger is generated. When the finger is lifted, an [`TouchPhase::Ended`]
/// event is generated with the same finger id.
///
/// After a `Started` event has been emitted, there may be zero or more `Move`
/// events when the finger is moved or the touch pressure changes.
///
/// The finger id may be reused by the system after an `Ended` event. The user
/// should assume that a new `Started` event received with the same id has nothing
/// to do with the old finger and is a new finger.
///
/// A [`TouchPhase::Cancelled`] event is emitted when the system has canceled tracking this
/// touch, such as when the window loses focus, or on iOS if the user moves the
/// device against their face.
///
/// ## Platform-specific
///
/// - **macOS:** Unsupported.
#[derive(Debug, Clone, Copy, PartialEq)]
pub struct Touch {
    pub device_id: DeviceId,
    pub phase: TouchPhase,
    pub location: PhysicalPosition<f64>,
    /// Describes how hard the screen was pressed. May be `None` if the platform
    /// does not support pressure sensitivity.
    ///
    /// ## Platform-specific
    ///
    /// - Only available on **iOS** 9.0+ and **Windows** 8+.
    pub force: Option<Force>,
    /// Unique identifier of a finger.
    pub id: u64,
}

/// Describes the force of a touch event
#[derive(Debug, Clone, Copy, PartialEq)]
pub enum Force {
    /// On iOS, the force is calibrated so that the same number corresponds to
    /// roughly the same amount of pressure on the screen regardless of the
    /// device.
    Calibrated {
        /// The force of the touch, where a value of 1.0 represents the force of
        /// an average touch (predetermined by the system, not user-specific).
        ///
        /// The force reported by Apple Pencil is measured along the axis of the
        /// pencil. If you want a force perpendicular to the device, you need to
        /// calculate this value using the `altitude_angle` value.
        force: f64,
        /// The maximum possible force for a touch.
        ///
        /// The value of this field is sufficiently high to provide a wide
        /// dynamic range for values of the `force` field.
        max_possible_force: f64,
        /// The altitude (in radians) of the stylus.
        ///
        /// A value of 0 radians indicates that the stylus is parallel to the
        /// surface. The value of this property is Pi/2 when the stylus is
        /// perpendicular to the surface.
        altitude_angle: Option<f64>,
    },
    /// If the platform reports the force as normalized, we have no way of
    /// knowing how much pressure 1.0 corresponds to – we know it's the maximum
    /// amount of force, but as to how much force, you might either have to
    /// press really really hard, or not hard at all, depending on the device.
    Normalized(f64),
}

impl Force {
    /// Returns the force normalized to the range between 0.0 and 1.0 inclusive.
    ///
    /// Instead of normalizing the force, you should prefer to handle
    /// [`Force::Calibrated`] so that the amount of force the user has to apply is
    /// consistent across devices.
    pub fn normalized(&self) -> f64 {
        match self {
            Force::Calibrated {
                force,
                max_possible_force,
                altitude_angle,
            } => {
                let force = match altitude_angle {
                    Some(altitude_angle) => force / altitude_angle.sin(),
                    None => *force,
                };
                force / max_possible_force
            }
            Force::Normalized(force) => *force,
        }
    }
}

/// Hardware-dependent keyboard scan code.
pub type ScanCode = u32;

/// Identifier for a specific analog axis on some device.
pub type AxisId = u32;

/// Identifier for a specific button on some device.
pub type ButtonId = u32;

/// Describes the input state of a key.
#[derive(Debug, Hash, PartialEq, Eq, Clone, Copy)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub enum ElementState {
    Pressed,
    Released,
}

/// Describes a button of a mouse controller.
#[derive(Debug, Hash, PartialEq, Eq, Clone, Copy)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub enum MouseButton {
    Left,
    Right,
    Middle,
    Other(u16),
}

/// Describes a difference in the mouse scroll wheel state.
#[derive(Debug, Clone, Copy, PartialEq)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub enum MouseScrollDelta {
    /// Amount in lines or rows to scroll in the horizontal
    /// and vertical directions.
    ///
    /// Positive values indicate that the content that is being scrolled should move
    /// right and down (revealing more content left and up).
    LineDelta(f32, f32),

    /// Amount in pixels to scroll in the horizontal and
    /// vertical direction.
    ///
    /// Scroll events are expressed as a `PixelDelta` if
    /// supported by the device (eg. a touchpad) and
    /// platform.
    ///
    /// Positive values indicate that the content being scrolled should
    /// move right/down.
    ///
    /// For a 'natural scrolling' touch pad (that acts like a touch screen)
    /// this means moving your fingers right and down should give positive values,
    /// and move the content right and down (to reveal more things left and up).
    PixelDelta(PhysicalPosition<f64>),
}

/// Symbolic name for a keyboard key.
#[derive(Debug, Hash, Ord, PartialOrd, PartialEq, Eq, Clone, Copy)]
#[repr(u32)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
pub enum VirtualKeyCode {
    /// The '1' key over the letters.
    Key1,
    /// The '2' key over the letters.
    Key2,
    /// The '3' key over the letters.
    Key3,
    /// The '4' key over the letters.
    Key4,
    /// The '5' key over the letters.
    Key5,
    /// The '6' key over the letters.
    Key6,
    /// The '7' key over the letters.
    Key7,
    /// The '8' key over the letters.
    Key8,
    /// The '9' key over the letters.
    Key9,
    /// The '0' key over the 'O' and 'P' keys.
    Key0,

    A,
    B,
    C,
    D,
    E,
    F,
    G,
    H,
    I,
    J,
    K,
    L,
    M,
    N,
    O,
    P,
    Q,
    R,
    S,
    T,
    U,
    V,
    W,
    X,
    Y,
    Z,

    /// The Escape key, next to F1.
    Escape,

    F1,
    F2,
    F3,
    F4,
    F5,
    F6,
    F7,
    F8,
    F9,
    F10,
    F11,
    F12,
    F13,
    F14,
    F15,
    F16,
    F17,
    F18,
    F19,
    F20,
    F21,
    F22,
    F23,
    F24,

    /// Print Screen/SysRq.
    Snapshot,
    /// Scroll Lock.
    Scroll,
    /// Pause/Break key, next to Scroll lock.
    Pause,

    /// `Insert`, next to Backspace.
    Insert,
    Home,
    Delete,
    End,
    PageDown,
    PageUp,

    Left,
    Up,
    Right,
    Down,

    /// The Backspace key, right over Enter.
    // TODO: rename
    Back,
    /// The Enter key.
    Return,
    /// The space bar.
    Space,

    /// The "Compose" key on Linux.
    Compose,

    Caret,

    Numlock,
    Numpad0,
    Numpad1,
    Numpad2,
    Numpad3,
    Numpad4,
    Numpad5,
    Numpad6,
    Numpad7,
    Numpad8,
    Numpad9,
    NumpadAdd,
    NumpadDivide,
    NumpadDecimal,
    NumpadComma,
    NumpadEnter,
    NumpadEquals,
    NumpadMultiply,
    NumpadSubtract,

    AbntC1,
    AbntC2,
    Apostrophe,
    Apps,
    Asterisk,
    At,
    Ax,
    Backslash,
    Calculator,
    Capital,
    Colon,
    Comma,
    Convert,
    Equals,
    Grave,
    Kana,
    Kanji,
    LAlt,
    LBracket,
    LControl,
    LShift,
    LWin,
    Mail,
    MediaSelect,
    MediaStop,
    Minus,
    Mute,
    MyComputer,
    // also called "Next"
    NavigateForward,
    // also called "Prior"
    NavigateBackward,
    NextTrack,
    NoConvert,
    OEM102,
    Period,
    PlayPause,
    Plus,
    Power,
    PrevTrack,
    RAlt,
    RBracket,
    RControl,
    RShift,
    RWin,
    Semicolon,
    Slash,
    Sleep,
    Stop,
    Sysrq,
    Tab,
    Underline,
    Unlabeled,
    VolumeDown,
    VolumeUp,
    Wake,
    WebBack,
    WebFavorites,
    WebForward,
    WebHome,
    WebRefresh,
    WebSearch,
    WebStop,
    Yen,
    Copy,
    Paste,
    Cut,
}

impl ModifiersState {
    /// Returns `true` if the shift key is pressed.
    pub fn shift(&self) -> bool {
        self.intersects(Self::SHIFT)
    }
    /// Returns `true` if the control key is pressed.
    pub fn ctrl(&self) -> bool {
        self.intersects(Self::CTRL)
    }
    /// Returns `true` if the alt key is pressed.
    pub fn alt(&self) -> bool {
        self.intersects(Self::ALT)
    }
    /// Returns `true` if the logo key is pressed.
    pub fn logo(&self) -> bool {
        self.intersects(Self::LOGO)
    }
}

bitflags! {
    /// Represents the current state of the keyboard modifiers
    ///
    /// Each flag represents a modifier and is set if this modifier is active.
    #[derive(Default)]
    pub struct ModifiersState: u32 {
        // left and right modifiers are currently commented out, but we should be able to support
        // them in a future release
        /// The "shift" key.
        const SHIFT = 0b100;
        // const LSHIFT = 0b010;
        // const RSHIFT = 0b001;
        /// The "control" key.
        const CTRL = 0b100 << 3;
        // const LCTRL = 0b010 << 3;
        // const RCTRL = 0b001 << 3;
        /// The "alt" key.
        const ALT = 0b100 << 6;
        // const LALT = 0b010 << 6;
        // const RALT = 0b001 << 6;
        /// This is the "windows" key on PC and "command" key on Mac.
        const LOGO = 0b100 << 9;
        // const LLOGO = 0b010 << 9;
        // const RLOGO = 0b001 << 9;
    }
}

#[cfg(feature = "serde")]
mod modifiers_serde {
    use super::ModifiersState;
    use serde::{Deserialize, Deserializer, Serialize, Serializer};

    #[derive(Default, Serialize, Deserialize)]
    #[serde(default)]
    #[serde(rename = "ModifiersState")]
    pub struct ModifiersStateSerialize {
        pub shift: bool,
        pub ctrl: bool,
        pub alt: bool,
        pub logo: bool,
    }

    impl Serialize for ModifiersState {
        fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
        where
            S: Serializer,
        {
            let s = ModifiersStateSerialize {
                shift: self.shift(),
                ctrl: self.ctrl(),
                alt: self.alt(),
                logo: self.logo(),
            };
            s.serialize(serializer)
        }
    }

    impl<'de> Deserialize<'de> for ModifiersState {
        fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
        where
            D: Deserializer<'de>,
        {
            let ModifiersStateSerialize {
                shift,
                ctrl,
                alt,
                logo,
            } = ModifiersStateSerialize::deserialize(deserializer)?;
            let mut m = ModifiersState::empty();
            m.set(ModifiersState::SHIFT, shift);
            m.set(ModifiersState::CTRL, ctrl);
            m.set(ModifiersState::ALT, alt);
            m.set(ModifiersState::LOGO, logo);
            Ok(m)
        }
    }
}