Archive for March, 2010

One week of Glade brought to you by Openismus GmbH

Tuesday, March 30th, 2010

So its Tuesday afternoon prime time on Planet GNOME, here’s an inside look on whats been going on this week for Glade.

Runtime Warnings

Last week we got the GtkToolPalette integrated into Glade and got Glade vertical again, this week I went on a rampage of hunting down startup warnings, warnings caused by loading Glade files and generally any warnings/assertions that can be fired while manipulating projects in Glade.

That effort left us with a couple interesting side effects:

  • Now we introspect if widget classes are scrollable and we don’t allow adding non-scrollable widgets to scrolled windows
  • Now we update treeviews in the workspace seamlessly when the underlying treestore columns are redefined
  • A nasty data corruption bug occurring when loading liststore data that contains gaps (missing unserializable columns) was also fixed.

Once these items were fixed I was pretty much left on my own to fix some issues of my choosing and improve some things in Glade – awesome – so I decided to prioritize on issues that did not need backing support in GTK+, as there has been lots of development there that we haven’t been able to keep up with.

The signal editor

The first issue I decided to tackle was the ‘swapped’ attribute for signal connections defined in Glade – that’s right, until this week Glade was never able to read/write this attribute. To illustrate the importance this has in Glade I want to show you a before shot:

The "before" signal editor

Ok so the editor looks alright at first sight but there are some confusing aspects, for instance the “user data” in the signal can only ever refer to an object in the Glade file – no mention of that is made. Furthermore when one goes through the whole google research to find that the user data is supposed to be an object, they immediately get stumped by GTK+ swapping the object at connection time for seemingly no desired reason – very, very confusing.

Something to keep in mind as well is that signal definitions in Glade have generally been unused. Mostly because of an inability to pass data external to the Glade file as user data to callbacks. Generally people use a parent or controller object as a module pointer to be passed to all callbacks; this technical problem with signals has really been a non-issue ever since the introduction of the gtk_builder_connect_signals() api which takes a default pointer argument to pass to signals for just this purpose.

Well, moving on – after adding the “swapped” attribute to the editor I was quite unable to tear myself away from the editor, it hasn’t seen an update in many years and has been lagging behind the rest of the UI, so without further adieu I present to you:

The "after" signal editor

Now the signal editor is doing a bit better, I didn’t have the time for a full scale rewrite using GtkBuilder for its store, view and renderers as I have been hoping to do for a while but – at least she learned some tricks from her big brother the property editor:

  • Now the signal editor lets you view the documentation for a signal at the click of an icon (Thank you Frédéric Péters for getting DevHelp page contextual searches working again ! sorry for waiting 6 months+ to notice !).
  • The editor does not let you type text for connected objects for user data, instead you get an object selection dialog
  • Now versioning support icons/tooltips show up for signals that are introduced in the future of your project’s target version.
  • Tooltips explaining about the signal editor fields show up on the treeview column headers
  • Signal, Handler and Object fields in the editor are user resizable but allocate a reasonable size.

Actions

So, with a rocking new signal editor in master I still had some hours to kill, I went on to tackle the relationships of GtkActionGroup <–> GtkAction in Glade – I wasn’t able to pull out a customized editor for this yet, but I imagine it will look like the menu or toolbar editor and allow hierarchical configuration of the project’s action groups/actions (currently Glade will only let you add an action to a group via the Inspector widget: Right click -> Add widget here / Paste commands will do the trick).

Glade now also lets you set an accelerator key for a GtkAction, the property only applies to actions which are placed into a group, ideally this will be the ultimate place to define accelerator keys using Glade so that they integrate well with menus and toolbars.

Thank you

A big thankyou to Openismus GmbH who sponsored the project and made all of these unlikely advancements in Glade actually happen.

I’ll be turning my attention away from Glade this week to look at some other serious GNOME issues, keep up with my blog for regular updates on this Openismus sponsored effort.

The Glade palette goes full circle

Friday, March 26th, 2010

It looks like this can be a good year for Glade !

A tale of Palettes

Among some other recent developments, one interesting thing is that the GtkToolPalette; which was previously EggToolPalette dating from 2008 by Mathias Hasselmann modeled to behave as a palette written for Glade by Vincent Geddes back in 2007 (drum roll…) : is now integrated as a drop in replacement for the original palette code in Glade !

This allowed me to remove 3 source files and 3 header files from the Glade tree, but not only that; it was also an enriching experience to see the improvements that have been made on the palette (the built-in drag/drop support, integration with GtkToolItems and better scrolling functionality was noticeable) and to think of all the bright individuals who put work into it from a variety of continents.

All that being said I think there still needs to be a generic way to do context menus for the palette, GtkToolbar exports something like this; currently we are stuck with something of a hack to get our context menus working.

Vertical Glade

Another event of interest this week is that Federico Mena-Quinero came around and showed willingness to fix Glade side effects on that nasty horizontifying bug. After short lapse of thought I agreed to throw away the “orientation” property from Glade and only support it for base classes which are not implicitly oriented – in short; Glade will not do that horizontal weird thing with .ui files that fail to mention the orientation explicitly (likely converted by gtk-builder-convert stript…).

Sponsored by Openismus

It’s truly a pleasure to announce that the GtkToolPalette integration patch along with a few other bugs I closed yesterday are  only the first patches in an effort sponsored by  Openismus GmbH. This effort will be focused partly on Glade and partly on GTK+, I’m very excited and determined to make the most of this time improving GNOME.

Follow my blog for details and updates ;-)

Composite saga continues

Sunday, March 14th, 2010

So I took another Saturday afternoon to look after the whole composite thing I started hacking on last week. It’s surprisingly not a lot of work to do in terms of lines of code written.

First, I went and enhanced GtkBuilder so that you can add a parent widget context to the parse; this way while parsing GtkBuilder fragments you can start them with the <child> tag instead of <object> and have the builder parent the serialized children onto a dynamic runtime instance (in our case, a composite container widget).

Second, I trashed gtkcomposite.[ch] and integrated the code into GtkContainer (following Rafael Villar Burke’s advice); this way any already existing container widget can be extended as a composite widget.

Third thing was, as Torsten Schoenfeld pointed out was missing, I added api for bindings to assign a GtkBuilderConnectFunc to be used on a per class basis, this means that for instance, composite widget code in GTK+ gets connected with regular C callbacks, but derived code of that same widget in another language gets to use a connection algorithm specific for that class vtable for that language… which brings me to..

Finally composite classes can also be extended and each class can optionally pull in a .ui template to define its children, which means with some added magic of gtk_container_get_composite_child() to pull out implicitly defined composite children, GtkBuilder has no problem to “blend in” widgets added from subclasses into internal composite containers exposed from a composite parent (I added a new test case to the bug describing this).

For those who are wondering what the hell kinda crack this guy is cookn’ up, basically… its an api of GtkContainer that lets you associate a GtkBuilder .ui file with any container class you define, automatically assigning any property endpoints you define to the corresponding instances built from the GtkBuilder fragment – at construct time, for free – an effort to completely abstract the packing of widgets from user code, and hide GtkBuilder semantics under the hood.

Thats it for me today… I hope you’re excited !

It was a saturday afternoon patch…

Monday, March 8th, 2010

So it was saturday afternoon this weekend, and I was already tired – of reading all crap being thrown back and forth at one another on our own foundation-list,  that is really a shame because it looks like we could be ready to make some real changes and set a better directive – or at least our OWN directive for GNOME as a foundation – for us – for the hackers.

Obviously feelings are mixed in this debate, and before people started throwing crap at eachother, for misrepresenting each other and correcting each other and basically looking like very professional and like pompous asses, there were some interesting things said. This post by Dave Neary was drowned out in noise twice so far and thats a shame, hopefully linking to it here on planet will help to give his post a better audience, personally I really love the “dangerous and racy” proposal/idea: GNOME hidden in plain sight, if you like you can read why in my post – in a nutshell I think our code base suffers from popularity and we end up writing results-oriented software because of it – because we end up working on what “downstream needs now” instead of the innovative future technology that we should be working on… and everyone here has worked for a corporation – we know that results-oriented code gets thrown in the garbage.

So – partly because I think people are sore about the whole mobile thing (silly but true), and partly because it seems like a perfect time to innovate, and partly because I just miss the days when we would argue vehemently on gtk-devel-list about future apis and if they were perfect enough or what… I think we need a bit more of that excitement in general, to attract more serious hackers, and make GNOME by GNOME for GNOME – an umbrella for free software projects to really get the space, infrastructure and as Dave so elegantly put it; the “stewardship” that these projects need to really flourish and innovate (ok misrepresentation mittens on, no he didnt say “stewardship” exactly like that… but I’m borrowing the word for today).

So because of all those reasons above I just LOST IT and wrote a patch, the patch is something I had in mind for some months now and I’ll try to explain in human terms as best I can what this patch does.

The patch introduces a notion to GTK+ that a GtkBuilder file can be associated with a Widget Class, when a widget is built with a template.ui file assigned to it, then any instances of that class will come with its composite hierarchy prebuilt, signals from its child hierarchy connected to its own class methods – and instance variables already preinitialized to access desired components of a composite widget’s children.

And I need people who implement language bindings to look at this :) ideally, how it should look in super-duper object oriented language ‘x’, would be something like this:

class MyClass:GtkComposite {
    var someObject:GtkAdjustment; // some instance variable
    connectable var someLabel:GtkLabel; // A "connectable" instance variable

    function the_button_clicked (var button:GtkButton) {
        someLabel.setText ("the button was clicked");
    }
}

So, for the user – the idea is they compile a class MyClass, and hopefully he doesnt have to say anything explicit, i.e. when the compiler/interpretor finds that MyClass.language has an accompanying MyClass.ui – the ui should just be compiled into the class and the above code should “just work” after instantiating a “MyClass” object.

For the language binding – it would mean that the language binding would have to install GtkParamSpecComposite properties onto the GObject it creates under the hood for a derived GTK+ widget class (i.e. Im sure this will work for vala but others… dont know) – this way the language can introduce the “connectable” keyword which explicitly asks for a property name <–> child instance name association before any user code runs.

For the devtools front, it means we can have a tool like Glade add a feature that lets you rip out a sub-hierarchy and implement it as an object class in the user’s language of preference, the sub hierarchy would become an independant Glade file and can be re-included with its hierarchy at multiple places in the program/UI.

The general idea of this patch is to push GNOME devtools/GTK+ apis towards catching up with the industry leaders in UI tools, its a migration of coding practice in GNOME uis all across the board.

We can move from: old-school “kinda dynamic” interfaces where an object loads an interface explicitly and then plays god on the widgets, connecting to signals and making the whole thing move from some controller proxy object, or worse, not modular and handle all callbacks in a main “application bussiness logic” zone.

To: A world where if you need a widget to have different functionality – you add to it – always by inserting your code onto the object running in the interface – if you need a form with lots of entries and an OK button – thats a Composite widget, can be reused over and over without any added hassle of using a controller object, can be derived and extended like any object, no controller proxy, no hassle – just a UI inside a widget fully functional after g_object_new() time.

So lets create some hype and lets do some real innovations – we could very easily come up with some tools that leverage GObject and GTK+ in modern ways and smash the competition (I’m thinking Xcode/Interface Builder as an initial “beat them” target, hey what if we had the same API usability and integration of IDE tools, but we werent restricted to Objc, or Cocoa api, and we compile everywhere, and we support every popular language… what could beat us then ?)

Well as I said we need to create some hype – bugzilla is okaaaay but I started a thread for this on gtk-devel-list, ofcourse in the hope to turn some heads and get ṕeople excited about GNOME… please jump in !