Saki's Blog

New Example – Grid in Card Layout

Saki — Tue, 13 Oct 2009 12:49:17 +0000

Hi all,

I’ve just uploaded new example of Grid in Card Layout

Enjoy!

How to Convert DVD to iPhone Video with Subtitles and Chapters on Linux

Saki — Sun, 04 Oct 2009 21:02:44 +0000

iPhone can play video that contains multiple streams and chapters:

video
multiple audio streams (languages)
multiple subtitles (languages)
chapters for easy navigation

After some googling and many trials and errors I found a multiplatform software that can create videos with all the above features. The software is HandBrake. HandBrake for (openSUSE) Linux can be downloaded from Packman.

Let’s convert our DVD to the iPhone video. For that insert an original DVD in the drive, start HandBrake and select source.

Select iPhone & iPod Touch preset and type the file name and the destination directory.

There is not too much to set on Video tab, however, you can play with quality if you want.

In Audio tab, add as many audio tracks as you want:

If you want to “burn” subtitles into video, just select one from the original DVD and you’re done. More difficult is if you want Closed Captioning subtitles (that can be turned off on iPhone). For that you need external files with subtitles in srt format. You can download them from opensubtitles.org. The problem can be that the downloaded subtitles may not be in sync with you video. I haven’t found a better way only to encode the DVD and, if subtitles are out of sync, use Subtitle Composer to adjust the timing(s) and re-encode.

Default settings in H.264 tab do not need any change.

Rename chapters if you want. Names are sometimes on DVD covers, sometimes not.

Start encoding, wait an hour or so and then download the resulting video to your iPhone with iTunes.

How to extract subtitles from DVD

Saki — Fri, 02 Oct 2009 09:11:09 +0000

mencoder dvd://1 -oac copy -ovc copy -o /dev/null -vobsubout output -sid 1

Then use avidemux2_qt4

Keeping modified records of EditorGridPanel while paging

Saki — Mon, 28 Sep 2009 08:59:44 +0000

If you modify records of an editable grid with paging and if you then page-out, your changes are lost. Well, they are not lost in fact unless you have set pruneModifiedRecords:true on the strore. The modifications are still available so we just need to apply them. Here is the code fragment that does it:

var grid = new Ext.grid.EditorGridPanel({
    store:new Ext.data.Store({
         listeners:{
            load:{scope:this, fn:function(store) {
 
                // loop through modified records
                var modified = store.getModifiedRecords();
                for(var i = 0; i < modified.length; i++) {
 
                    // see if we have a record with same id 
                    // and apply changes if yes
                    var r = store.getById(modified[i].id);
                    if(r) {
                        var changes = modified[i].getChanges();
                        for(p in changes) {
                            if(changes.hasOwnProperty(p)) {
                                r.set(p, changes[p]);
                            }
                        } // eo changes loop
                    }
                } // eo modified loop
            }} // eo load listener
        } // eo listeners
 
        // rest of store configuration
 
    })
 
    // rest of grid configuration
 
}) // eo grid

pruneModifiedRecords must be false (the default) for this to work.

New Example – Ext.ux.MsgBus Demo

Saki — Sun, 20 Sep 2009 21:48:38 +0000

Hi there,

I’ve just uploaded demo of Ext.ux.MsgBus Plugin at http://examples.extjs.eu/?ex=msgbus.

Enjoy!

Ext.ux.MsgBus Plugin

Saki — Sun, 20 Sep 2009 12:45:10 +0000

Recently I’ve been looking for a better way of inter-component communication in Ext so I’ve read a couple of posts with Message Bus implementations, I’ve skimmed over OpenAjax Hub page but I haven’t found anything suitable for my needs.

The first approach was Simple Message Bus Example but that is more concept proof than a really usable way in production environment.

I like the concept of message subjects (topics) as dot separated sequence of tokens with the ability to subscribe to messages with specific subjects and with wildcard support.

For example, if a component would subscribe to the subject eu.extjs.desktop.** it would receive message with subject eu.extjs.desktop.wallpaper.set but it wouldn’t receive message eu.extjs.taskbar.hide.

So this plugin was born.

Ext.ux.MsgBus fits in any component that is descendant of Ext.util.Observable and it does not need any other changes/overrides. You would stick it only into the components that must participate in bus messaging. It adds subscribe and publish methods to the component.

Usage example:

var p = new Ext.Panel({
     plugins:['msgbus']
    ,onWallpaper:function(subject, message) {
        // do something
    }
    // the rest of config
});
p.subscribe('eu.extjs.desktop.wallpaper.**', {fn:p.onWallpaper, single:true});

The above would call p.onWallpaper callback once upon the receipt of a “wallpaper” message.

Other example:

p.publish('eu.extjs.this.panel.move', {oldx:100, oldy:200, x:300, y:400});

I haven’t tested it fully yet so take it more as an initial idea than as a bullet-proof, worldwide-tested code. Also, I didn’t try in any means to implement OpenAjax standards and use this plugin for an inter library communication. Consider it as a one possibility of intra-Ext, inter-component communication.

Any comments and/or bug reports are welcome.

// vim: sw=4:ts=4:nu:nospell:fdc=4
/**
 * Message Bus Plugin
 *
 * @author    Ing. Jozef Sakáloš
 * @copyright (c) 2009, by Ing. Jozef Sakáloš
 * @date      19. September 2009
 * @version   $Id: Ext.ux.MsgBus.js 29 2009-09-23 09:51:55Z jozo $
 *
 * @license Ext.ux.MsgBus.js is licensed under the terms of the Open Source
 * LGPL 3.0 license. Commercial use is permitted to the extent that the 
 * code/component(s) do NOT become part of another Open Source or Commercially
 * licensed development library or toolkit without explicit permission.
 * 
 * License details: http://www.gnu.org/licenses/lgpl.html
 */
 
/*global Ext,window */
 
/**
 * @class Ext.ux.MsgBus
 *
 * Creates new Ext.ux.MsgBus object
 * @constructor
 * @param {Object} config The config object
 */
Ext.ux.MsgBus = function(config) {
    Ext.apply(this, config, {
    });
}; // eo constructor
 
Ext.override(Ext.ux.MsgBus, {
    /**
     * @cfg {String} busName Name of the global Observable instance
     */
     busName:'Ext.ux.Bus'
    /**
     * @private
     */
    ,bus:false
    /**
     * Initializes the plugin and component
     * @private
     */
    ,init:function(cmp) {
        this.cmp = cmp;
        cmp.bus = this.getBus();
        cmp.bus.addEvents('message');
        cmp.subs = {};
        this.applyConfig();
    } // eo function init
    // {{{
    /**
     * Returns or creates the global Observable instance
     * @private
     */
    ,getBus:function() {
        var bus = window;
        var a = this.busName.split('.');
        var last = a.pop();
        Ext.each(a, function(n) {
            if(!Ext.isObject(bus[n])) {
                bus = false;
                return false;
            }
            else {
                bus = bus[n];
            }
        }, this);
        if(false === bus) {
            Ext.ns(this.busName);
            return this.getBus();
        }
        if(!(bus[last] instanceof Ext.util.Observable)) {
            bus[last] = new Ext.util.Observable();
        }
        return bus[last];
    } // eo function getBus
    // }}}
    // {{{
    /**
     * Creates RegExp for message filtering.
     * Override it if you need another logic.
     * @param {String} subject The message subject
     * @return {RegExp} RegExp used for message filtering
     */
    ,getFilterRe:function(subject) {
        var a = subject.split('.');
        var last = a.length - 1;
        a[last] = '**' === a[last] ? '.*' : a[last];
        var re = /^\w+$/;
        Ext.each(a, function(token, i) {
            if(!re.test(token) && '*' !== token && '.*' !== token) {
                throw 'Invalid subject: ' + subject;
            }
            if('*' === token) {
                a[i] = '\\w+';
            }
        });
        return new RegExp('^' + a.join('\\.') + '$');
    } // eo function getFilter
    // }}}
    // {{{
    /**
     * Applies new methods to the component
     * @private
     */
    ,applyConfig:function() {
        Ext.applyIf(this.cmp, {
            /**
             * Subscribes to messages (parent component method)
             * @param {String} subject Dotted notation subject with wildcards.
             * See http://www.openajax.org/member/wiki/OpenAjax_Hub_2.0_Specification_Topic_Names
             * @param {Object} config Same as addListener config object
             * @return {Boolean} success true on success, false on failure (subscription exists)
             */
             subscribe:function(subject, config) {
                 var sub = this.subs[subject];
                if(sub) {
                    return false;
                }
                config = config || {};
                config.filter = this.getFilterRe(subject);
                this.subs[subject] = {config:config, fn:this.filterMessage.createDelegate(this, [config], true)};
                this.bus.on('message', this.subs[subject].fn, config.scope || this, config);
                return true;
            }
 
            /**
             * Unsubscribes from messages (parent component method)
             * @param {String} subject Dotted notation subject with wildcards.
             * @return {Boolean} success true on success, false on failure (nonexistent subscription)
             */
            ,unsubscribe:function(subject) {
                var sub = this.subs[subject];
                if(!sub) {
                    return false;
                }
                this.bus.un('message', sub.fn, sub.scope || this, sub.config);
                delete this.subs[subject];
                sub = null;
                return true;
            } // eo function unsubscribe
 
            /**
             * Publishes the message (parent component method)
             * @param {String} subject Message subject
             * @param {Mixed} message Message body, most likely an object
             */
            ,publish:function(subject, message) {
                this.getFilterRe(subject);
                this.bus.fireEvent('message', subject, message);
            } // eo function publish
 
            /**
             * Returns current subscriptions
             * @return {Object} subscriptions
             */
            ,getSubscriptions:function() {
                return this.subs;
            } // eo function
 
            /**
             * @private
             */
            ,getFilterRe:this.getFilterRe
 
            /**
             * Filters incoming messages
             * @private
             */
            ,filterMessage:function(subject, message, config) {
                if(config.filter.test(subject)) {
                    (config.fn || this.onMessage).call(config.scope || this, subject, message);
                }
            } // eo function filterMessage
 
            /**
             * Default message processing function
             * @param {String} subject The message subject
             * @param {Mixed} message The message body
             */
            ,onMessage:Ext.emptyFn
        });
    } // eo function applyConfig
    // }}}
 
}); // eo override
 
// register ptype
Ext.preg('msgbus', Ext.ux.MsgBus); 
 
// eof

Enjoy!

The accompanying example: Ext.ux.MsgBus

New Example – Simple Message Bus

Saki — Sat, 19 Sep 2009 20:02:45 +0000

Hi all,

I’ve just uploaded very simple, extremely simple, example of how to implement Message Bus in Ext using the global Ext.util.Observable instance.

Enjoy!

Simple Message Bus Example

What the hell is mon and mun?

Saki — Fri, 18 Sep 2009 00:31:51 +0000

I’ve run across the following code in some of Ext 3.x examples:

this.mon(toolsUl, 'click', this.onClick, this);

Looks like event handler installation but what it really does anyway?

So I delved into the code and remembered ExtJS Conference and now it is clear to me.

Imagine you create a component and then you need to install an event handler, for example, on its body. Something like:

var handler = function() {
    alert('You clicked my body');
};
var p = new Ext.Panel({
     renderTo:Ext.getBody()
    ,title:'Panel with a listener on the body'
});
p.body.on('click', handler);

Easy enough, we’ve done something like this many times. But, if the panel is ever to be destroyed we need to remove this listener ourselves as Ext knows nothing about it.

Something like:

var p = new Ext.Panel({
     renderTo:Ext.getBody()
    ,title:'Panel with a listener on the body'
    ,beforeDestroy:function() {
        this.body.un('click', handler);
    }
});

If we install our listener as inline function, such as:

p.on('click', function() {alert('You clicked my body')});

then it is impossible to remove this listener selectively, you would need to use

p.body.removeAllListeners();

to remove all body listeners.

Now, if we use mon (m stands for “managed”) this way

p.mon(p.body, 'click', handler);

then the listener is automatically removed by Ext on panel destroy. Nice, isn’t it? Saves a lot of our work and also handles our laziness or forgetfulness about destroying and cleanups of components.

Mind the first argument, that is the element to install the listener to. It can, but not necessarily have to be within the component. Also remember that when you destroy p Ext only removes listener from the element so if the element is outside of p you need to remove it yourself if it is not necessary anymore.

Should you ever need to remove the listener installed by mon you use mun with same arguments. You cannot selectively remove inline listeners.

mon and mun are defined in Component so you can use them from Component down the descendant classes chain.

Warning! mon and mun are not documented (yet?) so there is still (a little) risk that they will change or will be removed.

Mastering Ext.Direct, Part 3

Saki — Thu, 17 Sep 2009 12:20:37 +0000

<<< Mastering Ext.Direct, Part 2

Processing responses

As I’ve already said, you cannot use the return value of an API function call as result is not know at the moment of the call return. It is never stressed enough that

Ext.Direct calls are ASYNCHRONOUS.

Therefore, all Ext.Direct created API functions, for example Example.Car.go() take one extra argument in addition to arguments you have specified in server-side class definition. That argument is callback function.

In our example, Example.Car.go() takes one argument, speed per server side method definition, however, it takes two in fact: Example.Car.go(speed, callback)

Let’s call it with a callback to test it. Type in the Firebug console:

Example.Car.go(80, console.info);

console.info is a function that prints its arguments in a human readable form. We use it as the callback so we see:

that it really gets called when the response arrives
which arguments Ext.Direct passes to the callback

As you can see, the callback is called with two arguments:

response – it is that what is returned by the server-side Car.go() method. It can be string (as in our example), boolean, object, array or void (nothing).
e – it is Ext.Direct.Event object or, being more specific, Ext.Direct.RemotingEvent.

The event e has some useful properties and methods, most important of them are:

status is true if the call was successful, false if the call failed
result contains same value as the first argument – it is server response data
type is rpc in our example but it also can be exception or others
action is the class name
method is name of the method called
getTransaction() is method to retrieve the transaction used in this server round trip. You would use it if you want more data on the transaction.

Processing exceptions

Let’s call go method again:

Example.Car.go(300, console.info);

The callback is called as before but the arguments differ:

response is undefined – no data from server
e has type exception and has property message that contains error message text

An example application

That is almost all we need to know to start using Ext.Direct in an application. I’ve written a simple one so you have something to play with.

First, create file example.js with the following content:

/**
 * Mastering Ext.Direct example script
 *
 * @author     Ing. Jozef Sakalos
 * @copyright  (c) 2009, by Ing. Jozef Sakalos
 * @date       16. September 2009
 * @version    1.0
 * @revision   $Id$
 */
 
Ext.BLANK_IMAGE_URL='ext/resources/images/default/s.gif';
 
Ext.onReady(function() {
    /**
     * This function is called when Ext.Direct request
     * response arrives from the server.
     *
     * @param {String/Object/Array/Null} response 
     * That what is returned by server method
     * @param {Ext.Direct.RemotingEvent/Ext.Direct.ExceptionEvent} e 
     */
    var callback = function(response, e) {
 
        // uncomment if you want to inspect arguments in Firebug Console
//        console.log(response, e);
 
        var status = 'Success'
        var text = '';
 
        // success handling - e.status is success flag: 
        // true is success, false is failure
        if(true === e.status) {
            // response argument is same as e.result
            text = response;
        }
 
        // failure handling
        else {
            status = 'Failure'
 
            // in the case of an exception, we don't have response but message
            text = e.message;
        }
 
        // grab the center body
        var body = win.items.itemAt(1).body;
 
        // display the response
        body.createChild({
             tag:'div'
            ,cls:'response'
            ,html:status + ': ' + text
        });
 
        // scroll down
        body.scrollTo('top', 100000, true);
    };
 
 
    // create Ext.Direct test window
    var win = new Ext.Window({
         title:'Mastering Ext.Direct by Saki'
        ,width:600
        ,height:400
        ,closable:false
        ,layout:'border'
        ,border:false
        ,items:[{
            // west region with buttons
             region:'west'
            ,width:160
            ,minSize:160
            ,split:true
            ,defaults:{minWidth:120}
            ,layout:'table'
            ,bodyStyle:'padding:20px'
            ,layoutConfig:{columns:1, tableAttrs:{style:{width:'100%'}}}
            ,items:[{
                 xtype:'button'
                ,text:'Car.start()'
 
                // a delegate is needed if we want to pass arguments
                ,handler:Example.Car.start.createDelegate(null, [callback])
            },{
                 xtype:'button'
                ,text:'Car.go(80)'
 
                // a delegate is needed if we want to pass arguments
                ,handler:Example.Car.go.createDelegate(null, [80, callback])
            },{
                 xtype:'button'
                ,text:'Car.go(250)'
 
                // a delegate is needed if we want to pass arguments
                ,handler:Example.Car.go.createDelegate(null, [250, callback])
            },{
                 xtype:'button'
                ,text:'Car.stop()'
 
                // a delegate is needed if we want to pass arguments
                ,handler:Example.Car.stop.createDelegate(null, [callback])
            },{
                 xtype:'button'
                ,text:'Send All'
 
                // another option is inline function that executes calls
                ,handler:function() {
 
                    // the following calls will be combined in one request
                    Example.Car.start(callback);
                    Example.Car.go(80, callback);
                    Example.Car.go(250, callback);
                    Example.Car.stop(callback);
                }
            }]
        },{
            // responses are displayed here
             region:'center'
            ,autoScroll:true
            ,tbar:['->', {
                text:'Clear'
               ,handler:function(){win.items.itemAt(1).body.update('')}
            }]
        }]
    });
    win.show();
 
});
 
// eof

Then tune your index.php so that it reads:

("config.php");?>
<html>
<head>
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
  <link rel="stylesheet" type="text/css" href="ext/resources/css/ext-all.css">
  <script type="text/javascript" src="ext/adapter/ext/ext-base.js"></script>
  <script type="text/javascript" src="ext/ext-all-debug.js"></script>
  <title id="page-title">Mastering Ext.Direct by Saki</title>
  <style type="text/css">
      .x-table-layout-cell {
        height:40px;
        text-align:center;
        vertical-align:middle;
    }
    .x-table-layout-cell table {
        margin:auto
    }
    .response {
        padding:4px 0 4px 20px;
        font-size:13px;
    }
  </style>
  <script type="text/javascript" src="api.php"></script>
  <script type="text/javascript">
      Ext.Direct.addProvider(Example.API);
  </script>
  <script type="text/javascript" src="example.js"></script>
</head>
<body>
</body>
</html>

Conclusion

Good! Play with Ext.Direct and let me know what you would like to have in next parts.

Mastering Ext.Direct, Part 2

Saki — Mon, 07 Sep 2009 20:50:58 +0000

<<< Mastering Ext.Direct, Part 1

Adding server-side classes

After completing part 1, we have the basic setup running. Although Ext.Direct PHP stack example classes are fine for demonstrating the functionality we will need our own PHP classes in the real life. I’m not going to explain basics of PHP object oriented programming, anyway, there is a couple of things to point out.

Let’s create (useless) class Car from part1. For that, create file classes/Car.php with the following content:


// vim: sw=4:ts=4:fdc=4:nospell
    class Car {
        /**
          * @remotable
          */
        public function start() {
            return "Started";
        } // eo function start
 
        /**
          * @remotable
          */
        public function go($speed) {
            return "The speed is $speed";
        } // eo function go
 
        /**
          * @remotable
          */
        public function stop() {
            return "Stopped";
        } // eo function stop
 
        public function repair() {
            return "Done";
        } // eo function repair
 
    } // eo class car
// eof

Then edit api.php and add Car to $api->add() call so that it reads:

// ...
$api->add(
    array(
        'Echo' => array('prefix' => 'Class_'),
        'Exception' => array('prefix' => 'Class_'),
        'Time',
        'File',
        'Car'
    )
);
// ...

Reload index.php and type in Firebug console:

Example.Car.start();

You should get the following response:

{"type":"rpc","tid":2,"action":"Car","method":"start","result":"Started"}

Now type:

Example.Car.repair();

Error, yes? Why? Take a deeper look at Car source code. Some methods have comments

        /**
          * @remotable
          */

but repair does not have it. And that is the single reason why it is not exported to API so it is not known to the client application. You can verify it by typing:

Example.API.actions.Car;

in Firebug console.

If you want to know how is it done study ExtDirect_API PHP class in classes/API.php file and ReflectionClass documentation. In any case, it makes our life very easy as we only need to:

write server side classes
add the above comment to the methods that can be called remotely

Can it be simpler?

Returning values

Type in Firebug console:

console.log(Example.Car.start());

Now you see that the return value of the call is undefined despite of the fact that server side method returns string "Started". This leads us to a very important note:

Ext.Direct calls are ASYNCHRONOUS.

That means that the code execution does NOT wait until the call is finished but it immediately continues. So never try to use the return value, neither assume that you have data available at the line that follows the call.

The value returned from the server side method call is wrapped in the request response and it arrives when it arrives. It can take milliseconds or seconds depending on the connection speed, server execution time and other factors.

I will discuss response processing in the next part

Exceptions

Edit go method of our Car class so that it reads:

        /**
          * @remotable
          */
        public function go($speed) {
            if(0 >= $speed || 200 < $speed) {
                throw new Exception("Speed must be between 0 and 200");
            }
            return "The speed is $speed $unit";
        } // eo function go

and execute:

Example.Car.go(300);

You get the following response:

{"type":"exception","tid":3,
"message":"Speed must be between than 0 and 200",
"where":
"#0 [internal function]: Car->go(300)\n
#1 \/ddata1\/devel\/extjs.eu\/direct\/ExtDirect\/Router.php(176): call_user_func_array(Array, Array)\n
#2 \/ddata1\/devel\/extjs.eu\/direct\/ExtDirect\/Router.php(62): ExtDirect_Router->rpc(Object(stdClass))\n
#3 \/ddata1\/devel\/extjs.eu\/direct\/router.php(23): ExtDirect_Router->dispatch()\n
#4 {main}"}

You see that the response type changed from rpc (remote procedure call) to exception and the response contains member message that is the text of the Exception we’ve thrown at server side. So far so good, however, where member contains debugging data that, while useful for debugging, shouldn’t be disclosed in a production environment.

You can freely throw exceptions while debugging your Ext.Direct application but you should consider another method(s) of handling errors for production systems. I will tackle it again later in this series.

Combining requests

Type the following:

Example.Car.start();Example.Car.go(80);Example.Car.stop();

The request is:

[
{"action":"Car","method":"start","data":null,"type":"rpc","tid":4},
{"action":"Car","method":"go","data":[80],"type":"rpc","tid":5},
{"action":"Car","method":"stop","data":null,"type":"rpc","tid":6}
]

and the response is:

[
{"type":"rpc","tid":4,"action":"Car","method":"start","result":"Started"},
{"type":"rpc","tid":5,"action":"Car","method":"go","result":"The speed is 80"},
{"type":"rpc","tid":6,"action":"Car","method":"stop","result":"Stopped"}
]

Ext.Direct combines requests that come within a configurable time frame into one to minimize the server round trips count.

Conclusion

Now we know a couple of basics:

we need to export API from server to client – Ext.Direct stack does a lot of dirty work for us
we can call server side methods directly at client prefixed with a configurable namespace (Example in our case)
we cannot use return values of client calls because calls are asynchronous
to add classes we need to add them to $api->add() call and add /** @remotable */ comments to methods
multiple requests and responses are combined in one if they come fast enough

Saki's Blog

New Example – Grid in Card Layout

How to Convert DVD to iPhone Video with Subtitles and Chapters on Linux

How to extract subtitles from DVD

Keeping modified records of EditorGridPanel while paging

New Example – Ext.ux.MsgBus Demo

Ext.ux.MsgBus Plugin

New Example – Simple Message Bus

What the hell is mon and mun?

Mastering Ext.Direct, Part 3

<<< Mastering Ext.Direct, Part 2

Processing responses

Processing exceptions

An example application

Conclusion

Mastering Ext.Direct, Part 2

<<< Mastering Ext.Direct, Part 1

Adding server-side classes

Returning values

Exceptions

Combining requests

Conclusion

Mastering Ext.Direct, Part 3 >>>