WebAPI/BrowserAPI/KeyboardEvent

Dispatch KeyboardEvent across BrowserElements

This is a proposal to enable applications to handle/override the behavior of certain KeyboardEvent.

There are four scenarios which should be fulfilled:

Scenario	Description	Example Keys
SYSTEM-ONLY	For keys which should be handled by mozbrowser embedder iframe only.	'Power', 'VolumeUp', 'VolumeDown', 'VolumeMute', 'DisplaySwap'
SYSTEM-FIRST	For keys which can be handled by mozbrowser embedder iframe first and can also be handled by mozbrowser embedded iframe then.	'Info', 'Settings'
APP-ONLY	For keys which should be handled by mozbrowser embedded iframe only.	'ColorF0Red', 'ColorF1Green', 'ColorF2Yellow', 'ColorF3Blue', 'ColorF4Grey'
APP-FIRST	For keys which keys can be handled by mozbrowser embedded iframe first and can also be handled by mozbrowser embedder iframe then.	'Info', 'Settings'

Note that some keys could be either SYSTEM-FIRST or APP-FIRST. The behavior is decided by the author of applications.

Proposal Concept

Four new events are proposed:

• mozbrowserbeforekeydown
• mozbrowserkeydown
• mozbrowserbeforekeyup
• mozbrowserkeyup

When a key is pressed down, the event sequence would be:

1. 'mozbrowserbeforekeydown' is dispatched to mozbrowser-embedder iframe
2. 'keydown' is dispatched to mozbrowser-embedded iframe
3. 'mozbrowserkeydown' is dispatched to mozbrowser-embedder iframe

Similarly, when a key is released, the event sequence would be:

1. 'mozbrowserbeforekeyup' is dispatched to mozbrowser-embedder iframe
2. 'keyup' is dispatched to mozbrowser-embedded iframe
3. 'mozbrowserkeyup' is dispatched to mozbrowser-embedder iframe

This proposal can be extended to nested mozbrowser iframes. The four new events will be dispatched to all mozbrowser-embedder iframes.

How to Fulfill Scenarios?

Here are some examples for each scenario.

Scenario 1. SYSTEM-ONLY

• mozbrowser-embedder iframe

   window.addEventListener('mozbrowserbeforekeydown') = function(evt) {
     evt.preventDefault();
   };
   window.addEventListener('mozbrowserbeforekeyup') = function(evt) {
     evt.preventDefault();
   };

Order	mozbrowser-embedder iframe	mozbrowser-embedded iframe
1	mozbrowserbeforekeydown
2	mozbrowserbeforekeyup

Scenario 2. SYSTEM-FIRST

• mozbrowser-embedder iframe

   window.addEventListener('mozbrowserbeforekeydown') = function(evt) {
     // do something
   };
   window.addEventListener('mozbrowserbeforekeyup') = function(evt) {
     // do something
   };

• mozbrowser-embedded iframe

   window.addEventListener('keydown') = function(evt) {
     // do something
   };
   window.addEventListener('keyup') = function(evt) {
     // do something
   };

Order	mozbrowser-embedder iframe	mozbrowser-embedded iframe
1	mozbrowserbeforekeydown
2		keydown
3	mozbrowserbeforekeyup
4		keyup

APP-ONLY

• mozbrowser-embedder iframe

   window.addEventListener('mozbrowserkeydown') = function(evt) {
     // evt.embeddedcancelled = true;
   };
   window.addEventListener('mozbrowserkeyup') = function(evt) {
     // evt.embeddedcancelled = true;
   };

• mozbrowser-embedded iframe

   window.addEventListener('keydown') = function(evt) {
     evt.preventDefault();
   };
   window.addEventListener('keyup') = function(evt) {
     evt.preventDefault();
   };

Order	mozbrowser-embedder iframe	mozbrowser-embedded iframe
1		keydown
2	mozbrowserkeydown
3		keyup
4	mozbrowserkeyup

APP-FIRST

• mozbrowser-embedder iframe

   window.addEventListener('mozbrowserkeydown') = function(evt) {
     // evt.embeddedcancelled = false;
   };
   window.addEventListener('mozbrowserkeyup') = function(evt) {
     // evt.embeddedcancelled = false;
   };

• mozbrowser-embedded iframe

   window.addEventListener('keydown') = function(evt) {
     // do something
   };
   window.addEventListener('keyup') = function(evt) {
     // do something
   };

Order	mozbrowser-embedder iframe	mozbrowser-embedded iframe
1		keydown
2	mozbrowserkeydown
3		keyup
4	mozbrowserkeyup

Proposal Details

mozbrowserbeforekeydown

Type	mozbrowserbeforekeydown
Interface	KeyboardEvent
Sync/Async	Sync
Bubbles	Yes
Target	Document, Element
Cancelable	Yes
Default action	keydown event

mozbrowserkeydown

Type	mozbrowserkeydown
Interface	KeyboardEvent
Sync/Async	Sync
Bubbles	Yes
Target	Document, Element
Cancelable	Yes
Default action	None

mozbrowserbeforekeyup

Type	mozbrowserbeforekeyup
Interface	KeyboardEvent
Sync/Async	Sync
Bubbles	Yes
Target	Document, Element
Cancelable	Yes
Default action	keyup event

mozbrowserkeyup

Type	mozbrowserkeyup
Interface	KeyboardEvent
Sync/Async	Sync
Bubbles	Yes
Target	Document, Element
Cancelable	Yes
Default action	None