Bugzilla

(In reply to C.M.Chang[:chunmin] from comment #67)
> Created attachment 9091931 [details]
> Bug 1112032 - P4: Correct MediaSessionActionDetails for seek operations.

In the current implementation, I have trouble to meet the following [requirement](https://w3c.github.io/mediasession/#handle-media-session-action):

> Run handler with the details parameter set to:
>   - MediaSessionSeekActionDetails, if action is seekbackward or seekforward.
>   - MediaSessionSeekToActionDetails, if action is seekto.
>   - Otherwise, with MediaSessionActionDetails. 



I cannot read the `MediaSessionSeekToActionDetails.seekTime` from the `MediaSessionActionHandler`'s parameter when the callback/handler is for `seekto` in the javascript test file. The following code demonstrates the problem specifically:

```javascript
navigator.mediaSession.setActionHandler("seekto", function(details) {
  console.log(details.action); // ok, it's "seekto".
  console.log(details.seekTime); // undefined, but it's a `required` members in MediaSessionSeekToActionDetails
});
```

I guess the reason is because the type of `details` is `MediaSessionActionDetails` instead of `MediaSessionSeekToActionDetails`. 

I created a test-only function `notifySeekToHandler` to trigger the handler for `seekto`. `notifySeekToHandler` will get a `MediaSessionSeekToActionDetails` object form the caller and pass it directly to the handler. The handler type is `MediaSessionActionHandler`, which is defined as `void(MediaSessionActionDetails details)`.  However, the parameter `details` in the handler has no `seekTime` member. I guess the reason is that `details` is a `MediaSessionActionDetails` instead of `MediaSessionSeekToActionDetails`. Not sure if there is a way to make js realize the `details` is actually a `MediaSessionSeekToActionDetails`.

```
enum MediaSessionAction {
  "play",
  ...
  "seekto"
};

callback MediaSessionActionHandler = void(MediaSessionActionDetails details);

[Exposed=Window]
interface MediaSession {
  ...
  void setActionHandler(MediaSessionAction action, MediaSessionActionHandler? handler);
  ...

  // Test-only function to notify the `seekto` handler
  [ChromeOnly]
  void notifySeekToHandler(MediaSessionSeekToActionDetails details);
};

dictionary MediaSessionActionDetails {
  required MediaSessionAction action;
};

dictionary MediaSessionSeekToActionDetails : MediaSessionActionDetails {
  required double seekTime;
  ...
};
```

(In reply to C.M.Chang[:chunmin] from comment #67)
> Created attachment 9091931 [details]
> Bug 1112032 - P4: Correct MediaSessionActionDetails for seek operations.

In the current implementation, I have trouble to meet the following [requirement](https://w3c.github.io/mediasession/#handle-media-session-action):

> Run handler with the details parameter set to:
>   - MediaSessionSeekActionDetails, if action is seekbackward or seekforward.
>   - MediaSessionSeekToActionDetails, if action is seekto.
>   - Otherwise, with MediaSessionActionDetails. 



I cannot read the `MediaSessionSeekToActionDetails.seekTime` from the `MediaSessionActionHandler`'s parameter when the callback/handler is for `seekto` in the javascript test file. The following code demonstrates the problem specifically:

```javascript
navigator.mediaSession.setActionHandler("seekto", function(details) {
  console.log(details.action); // ok, it's "seekto".
  console.log(details.seekTime); // undefined, but it's a `required` members in MediaSessionSeekToActionDetails
});
```

I guess the reason is because the type of `details` is `MediaSessionActionDetails` instead of `MediaSessionSeekToActionDetails`. 

I created a test-only function `notifySeekToHandler` to trigger the handler for `seekto`. `notifySeekToHandler` will get a `MediaSessionSeekToActionDetails` object form the caller and pass it directly to the handler. The handler type is `MediaSessionActionHandler`, which is defined as `void(MediaSessionActionDetails details)`.  However, the parameter `details` in the handler has no `seekTime` member. I guess the reason is that `details` is a `MediaSessionActionDetails` instead of `MediaSessionSeekToActionDetails`. Not sure if there is a way to make js realize the `details` is actually a `MediaSessionSeekToActionDetails`.

```
[Exposed=Window]
partial interface Navigator {
  [SameObject] readonly attribute MediaSession mediaSession;
};

enum MediaSessionAction {
  "play",
  ...
  "seekto"
};

callback MediaSessionActionHandler = void(MediaSessionActionDetails details);

[Exposed=Window]
interface MediaSession {
  ...
  void setActionHandler(MediaSessionAction action, MediaSessionActionHandler? handler);
  ...

  // Test-only function to notify the `seekto` handler
  [ChromeOnly]
  void notifySeekToHandler(MediaSessionSeekToActionDetails details);
};

dictionary MediaSessionActionDetails {
  required MediaSessionAction action;
};

dictionary MediaSessionSeekToActionDetails : MediaSessionActionDetails {
  required double seekTime;
  ...
};
```

(In reply to C.M.Chang[:chunmin] from comment #67)
> Created attachment 9091931 [details]
> Bug 1112032 - P4: Correct MediaSessionActionDetails for seek operations.

In the current implementation, I have trouble to meet the following [requirement](https://w3c.github.io/mediasession/#handle-media-session-action):

> Run handler with the details parameter set to:
>   - MediaSessionSeekActionDetails, if action is seekbackward or seekforward.
>   - MediaSessionSeekToActionDetails, if action is seekto.
>   - Otherwise, with MediaSessionActionDetails. 



I cannot read the `MediaSessionSeekToActionDetails.seekTime` from the `MediaSessionActionHandler`'s parameter when the callback/handler is for `seekto` in the _javascript_ test file. The following code demonstrates the problem specifically:

```javascript
navigator.mediaSession.setActionHandler("seekto", function(details) {
  console.log(details.action); // ok, it's "seekto".
  console.log(details.seekTime); // undefined, but it's a `required` members in MediaSessionSeekToActionDetails
});
```

I guess the reason is because the type of `details` is `MediaSessionActionDetails` instead of `MediaSessionSeekToActionDetails`. 

I created a test-only function `notifySeekToHandler` to trigger the handler for `seekto`. `notifySeekToHandler` will get a `MediaSessionSeekToActionDetails` object form the caller and pass it directly to the handler. The handler type is `MediaSessionActionHandler`, which is defined as `void(MediaSessionActionDetails details)`.  However, the parameter `details` in the handler has no `seekTime` member. I guess the reason is that `details` is a `MediaSessionActionDetails` instead of `MediaSessionSeekToActionDetails`. Not sure if there is a way to make _js_ realize the `details` is actually a `MediaSessionSeekToActionDetails`.

```
[Exposed=Window]
partial interface Navigator {
  [SameObject] readonly attribute MediaSession mediaSession;
};

enum MediaSessionAction {
  "play",
  ...
  "seekto"
};

callback MediaSessionActionHandler = void(MediaSessionActionDetails details);

[Exposed=Window]
interface MediaSession {
  ...
  void setActionHandler(MediaSessionAction action, MediaSessionActionHandler? handler);
  ...

  // Test-only function to notify the `seekto` handler
  [ChromeOnly]
  void notifySeekToHandler(MediaSessionSeekToActionDetails details);
};

dictionary MediaSessionActionDetails {
  required MediaSessionAction action;
};

dictionary MediaSessionSeekToActionDetails : MediaSessionActionDetails {
  required double seekTime;
  ...
};
```



In general, I need to figure out how to make the following _javascript_ code works:

```javascript
let baseDict = { type: "base" };
let derivedDict = { type: "derived",  num: 3.14 };

let foo = new Foo();

foo.setHandler("base",, function(dict) {
  console.log(dict.type); // "base"
  console.log(dict.num); // undefined
});

foo.setHandler("derived", function(dict) {
  console.log(dict.type); // "derived"
  console.log(dict.num); // 3.14
});

runHandlerForBase(baseDict);
runHandlerForDerived(derivedDict );

```

with the following _WebIDL_ interface
```webidl
enum Type {
  "base",
  "derived"
};

dictionary Base {
  required Type type;
};

dictionary Derived : Base {
  required double num;
};

// For "base", the `dict` is `Base`
// For "derived", the `dict` is `Derived`
callback Handler = void(Base dict);

interface Foo {
  void setHandler(Type type, Handler handler);
  void runHandlerForBase(Base dict);
  void runHandlerForDerived(Derived dict);
}
```