widgets/external_ip: port to javaScripCore #27

ricardomv · 2014-03-03T17:19:52Z

this creates a new object "externalIp" with one method "get_address"
witch can be accessed with externalIp.get_address()

ricardomv · 2014-03-03T17:24:30Z

this is the simplest widget we have. @Lokaltog How do you want to do the merge? all the widgets at the same time and you update the theme too or you want to update the theme one by one?

Lokaltog · 2014-03-03T17:27:31Z

I think it'll be more practical to update the theme in one go, after porting all the widgets.

Lokaltog · 2014-03-03T17:27:51Z

src/widgets/external_ip.c

+};
+
+/* Callback - JavaScript window object has been cleared */
+void add_class_extennal_ip(WebKitWebView  *web_view,


Typo: extennal -> external

ricardomv · 2014-03-03T17:39:03Z

fixed typo, what happens when you call an object that it's not defined in js? how are we going to handle not having the widget that exists in the theme?

Lokaltog · 2014-03-03T17:40:13Z

With the webview it will only print an error to the console. We can wrap every API call in a try...catch block and it won't be an issue.

ricardomv · 2014-03-03T20:26:29Z

This patch is wrong(i can't add more widgets) im going to have to call each widget in window_object_cleared_cb

ricardomv · 2014-03-03T22:30:40Z

@Lokaltog can you take a look this patch i updated it, now the volume class is also visible.
i am just having trouble with updating it, i nedd to create a thread or use something other than alsa . i'm not very comfortable with glib, can you fix it? the way i am testing this is setting the bar height to 260 and droping this file into it

Lokaltog · 2014-03-03T22:40:51Z

I'd still prefer if wkline used threads like they do currently, and provide data updates through JS callbacks. Your JS file asks for C to call the onChange callback, but I can't see it in the C code in the patch.

Side note: Is it even possible to have several widgets waiting for system information without using threads?

ricardomv · 2014-03-03T22:58:28Z

the call to onChange should be on the thread i can't create. as it is now none of the widgets locks the program to do anyting even load them. the idea to use jscore is to avoid threads when we dont need them for example the external_ip example and talking to dbus

Lokaltog · 2014-03-03T23:18:25Z

I'm sorry, I'm just a bit confused regarding how this is supposed to work. Have I understood it correctly if:

Widgets that don't wait for data (external_ip, weather) will expose an object with a data retrieving method (e.g. Weather.get_temperature(), ExternalIP.get_address()) to Javascript, and the JS theme will call this method on an interval, like this:

setInterval(function () {
   var temp = Weather.get_temperature();
   updateWeatherWidget(temp);
}, 600000); // 10 minutes

C widgets that wait for data (volume, mpd) will still have a thread in C(?) that waits for the data, and exposes a method like Volume.onChange to JS that accepts a JS function as a callback. C will then call this callback from the C thread that waits for data and provide updated data to JS, like this:

Volume.onChange(function (volume) {
   updateVolumeWidget(volume);
});

// pseudocode
function store_callback(js_function *callback) {
   // store ptr to js function here, will be called in the C thread
   js_callback volume_change_callback = callback;
}
js_add_method("onChange", store_callback);

// in thread:
function update_volume () {
   while (wait_for_change) {
      // get new volume
      volume_change_callback(volume); // will call the callback function set in .onChange() in the JS file above
   }
}

This is how I picture stuff to work, but I might have completely misunderstood. Let me know if I'm wrong! I'm calling it a night, I'll see if I can get some work done on this issue tomorrow morning.

ricardomv · 2014-03-03T23:32:50Z

the js update can be something more like this

<html>
<head>
  <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
</head>
<body>
  <h1>Extending JavaScript with WebKit. externalIp class.</h1>
  <script type="text/javascript">
    document.write("IP: " + externalIp.get_address() + "<br>");
    var display = function () {
    document.write("IP: " + Volume.get_volume() + "<br>");
    }
    var volume = new Volume();
    volume.onChange = display;
    display();
  </script>
</body>
</html>

and in the thread what the C code does is calling the js function assigned to "onChange",
we dont save the ptr to "onChange" because it can change every time we need to update (if you do in js Volume.onChange = notdisplay).
the thread would be more like

while (1) {
      //wait_for_change
      //call function to update js which will get the volume
   }

corrupted double linked list

ricardomv · 2014-03-04T02:30:57Z

i give up alsa is just not for me

Lokaltog · 2014-03-04T12:10:06Z

Ah, I think I understand what you mean now. The problem is that there's a pretty strict convention in JS to provide the updated data when a callback is called, so requiring the user to manually do Volume.get_volume() in the callback to actually get the volume isn't ideal. But the part of assigning the callback to a variable like Volume.onUpdate = function is totally fine.

Worst case we could rename onUpdate and wrap the functionality in JS like so:

Volume.onDataChanged = function () { // notify event sent to this method
   var volume = Volume.get_volume()
   if (typeof this.onUpdate === 'function')
      this.onUpdate(volume)
}

I'll look into the issue and see if I can come up with a solution.

Lokaltog · 2014-03-04T12:49:31Z

Looking at the example code from the tutorial it appears it should be fairly simple to pass arguments to an onChange callback function. We just need to provide the volume data as a JSValue array here.

ricardomv · 2014-03-04T15:14:51Z

my problem is just with alsa the jscore is working fine (i think), it's just that alsa is not thread safe and even if have it all in the same function (waiting and getting the volume) it crashes anyway. i want to keep the js as simple as possible. please see my code

Lokaltog · 2014-03-04T15:28:16Z

I'll look into it, I'll do some experimenting and see if I can get it working tonight.

ricardomv · 2014-03-06T01:02:49Z

@Lokaltog can you take a look at the code i just committed, i finally got volume to work but i can't get it to update the html code. i added a test html file (changed in the last commit) can you take a look?

Lokaltog reviewed Mar 3, 2014
View reviewed changes

widgets: port to javaScripCore

f415d99

widgets/volume: crash when changing sound

1a96334

corrupted double linked list

ricardomv added 2 commits March 5, 2014 21:49

add html test file

093a3a8

widget volume working but not updating html

45d38e0

Lokaltog added the enhancement label Mar 6, 2014

Lokaltog mentioned this pull request Mar 10, 2014

Update config system #44

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Lokaltog closed this in f630793 Mar 19, 2014

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widgets/external_ip: port to javaScripCore #27

widgets/external_ip: port to javaScripCore #27

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widgets/external_ip: port to javaScripCore #27

widgets/external_ip: port to javaScripCore #27

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