Also not groudbreaking (and nearly one-liners) features are pretty to see and can be foundation for more neat things to come.
In Qt-webkit since Qt 4.5 is possible to read and set the position of the page in the scrollable view, (i.e. horizontal and vertical scrollbar values) that gives us the possibility to implement a nice web view that behaves like usual touch screens: scroll with the mouse, just touch the page and drag the thing around
This is the period of the year when Plasma developers exits from under their rocks it seems, so there i am too, i wanted to blog about that since quite some time, but i am really too lazy lazy lazy to blog :p
As Aaron said, last months i’ve been quite busy with the implementation of the new systemtray specification. At Tokamak we gathered around a whiteboard and discussed what sucked about the current X systemtray, so… what if we could design it from scratch? well, let’s do it! this thinghie interested me so much that i jumped over it in a coding frenzy with i hope a sane amount of pauses to think about it and keep the design sane, scrapping stuff when the design direction seemed to take an ugly direction, process that is still ongoing, so all i will talk about here is still subject to changes, rennnames, replacements etc, nothing “production” still :p
Soooo, why we were really unhappy about the system tray we have now so much at the point to want to design a brand new thing? (and enlightenment people too, and this makes me happy since will permit us to have a really cross desktop design from day one)
There are several reasons, so let’s see one by one:
Right now systemtray icons uses the Xembed protocol, that basically means they are windows owned by the client application process (very very roughly and pardon for the inaccuracy, kinda like the systray was their window manager). This means the painting of the icon is controlled exclusively by the client application, the systray itself has not much to say about that.
It means also, since systray icons have windows, i can’t have two system trays, (they would steal icons each other, since the window representing the icon s well, one) and, since plasma is canvas based, the implementation detail of whet xembed is will brutally come out as soon as you try to put another applet over the systray or try to rotate the applet or zoom the view where the applet is, as you can see here :p (yes, that could be kinda achieved with composite, but still a real hack)
Moreover, nowdays our panel is a window that uses argb visuals, so it’s translucent when desktop effects are on (that means basically force 32 bits color depth on all windows representing icons). and that’s a thing that neither X or graphics drivers (or even qt, before 4.5) were ready for, the amount of bug reports about visual garbage into the system tray or icons that becomes invisible (nowdays still happens with intel cards and the problem doesn’t seem to be headed for a solution) were really many and quite discouraging.
Or better, lack of thereof in the current spec. Now, the system tray limits itself to embed all the icons there are around (basically windows with _NET_SYSTEM_TRAY_S atom set) and after that, it knows exactly zero about them. Why it’s useful for those guys to talk to each other? Well, we all know the problem of cruft in the system tray, having 10-20 icons that steals half of the panel length or more is quite common, unfortunately…
Windows starting from XP made a timid attempt to solve the problem, by auto hiding system tray icons that din’t have activity for a given period of time (don’t know how since i don’t know how their protocol works) or alternatively manually hide icons you hate (ideally shouldn’t be necessary but the world is not, nice and fluffy with rocket launcher equipped ponies, misbehavers will always be here)
Now, in KDE (and any desktop that works on X by the way) we can hide icons but only manually, because the system tray has no idea what icons have activity, what are trying to notify something or things like that.
another interesting tought can come by looking at a typical crowded (and not even really crowded) system tray, icon by icon:
So what we have there: several categories:
Application status icons in the future can be integrated into the taskbar for instance (did i heard somebody whispering dock? he will be punished :p), and even the other two categories could be separated in two different system trays, it gives more freedom to implement something that could exit from an usability study, with less fears of saying “ehmm, no sorry that can’t be done actually…”
The icons can have several statuses, we can think about 3:
So we can now display the notifying ones in a different area of the systray, with a different background and we can hide the passive ones, and show them only when the user presses the unhide arrow.
The main implementation skeleton is done, the specification it’s all based on dbus message passing, since it has to be a cross desktop thing. It’s divided in 3 parts: a kded service that keeps the list of the applications that wants to use the system tray (so the list won’t be lost due to a plasma restart) the protocol support in the systemtray applet (our systemtray could already support multiple protocols, since it was designed already with this possibility in mind since the refactor in KDE 4.2) and a client library in playground with a tiny test application used as a proof of concept, that can be seen in this video (yes, not a mind boggling spectacular thing, but still important), with also an interesting feature: when you stop the systemtray bookkeeping daemon, the icon magically falls back to the usual legacy system tray icon, so an application using this new protocol would still get systemtray icons when running
in a desktop environment that doesn’t support the new protocol.
The client library and the dbus interface itself will pass trough a tough api review, so they can still change in a quite significant way (that’s why i didn’t go really in details in this post).
So don’t expect in KDE 4.3 all KDE applications to have been magically converted to this new protocol, but i hope all the plumbing will be there to permit application developers to start considering using this, and i’m really looking forward for other projects to cooperate to have a new unified shiny stuff 😀
Ariya called on who is going to turn the web-based google talk client to a plasmoid, so here i am 🙂
Let’s try with the javascript api:
layout = new LinearLayout(plasmoid); webView = new WebView(); webView.url = "http://talkgadget.google.com/talkgadget/m"; layout.addItem(webView);
And the result is:
You can download it here (warning: trunk required).
The Twitter Microblogging widget is a really useful tiny little utility, unfortunately until now it had severe appearance problems, especially when resizing the thing it did happen that contents could overflow from the applet boundaries.
This was partly due to some problems Qt 4.4 had with QGraphicsLayouts partly to our workarounds to those problems.
In Plasma we’re the childs with the slingshot that terribly enjoy to break stuff, the Qt components that Plasma uses, the QGraphicsView related stuff is a part significantly younger than the other parts of Qt, and we are putting it on a really tough stress test and this, even tough painful at start, it makes the framework mature at a really fast pace.
Now, i’m really impressed with the quantity of bugfixes present in Qt 4.5, so i decided to give the microblogging plasmoid another little quantity of love, and this is the result:
So now the height of individual posts grows and shrinks depending on the text layout inside them and when the size of contents is bigger than the size of the widget it shows (or hides) scrollbars as needed (it’s also kinda touchscreen friendly since it can scroll by dragging the contents themselves). So now works more as it is expected to from day one, that wouldn’t be breaking news per-se, but it demonstrates that the stuff we were uber-early adopters it’s really coming together and show what its real potential was.
What’s more important is that not only the microblogging widget works better now, but it’s also easy to write a new widget like that, since the process produced two new widgets in libplasma (widgets not in the sense of plasmoids, yeah i know it’s confusing:): TextBrowser to be used every time you have to display formatted text simple enough to not require Webkit. The other one is ScrollWidget, where you simply slap another widget in it ant it will automatically decide when cut away a part of the contents and when to show the scrollbars or not.
As I was showing here now Plasma in trunk can also play video/audio files, so what will be there in KDE 4.3? Basically two components:
The first is a media player widget (or applet, or whatever…). It will be the basis for a future media center written totally with Plasma technologies (one of the exciting discussions we had at Tokamak2 🙂 as today it’s in playground and plays video files dropped in plasma, can open arbitrary audio/video files, has some usual control buttons and exposes the standard org.mpris D-bus interface used to control media applications, can be controlled for instance from the now playing widget, as shown here.
The most central component is in libplasma right now and instead is well, a media player widget :p
The difference is that it is a widget in the sense of reusable control to be used in the applets/widgets/plasmoids you write (so, wanna for instance make a youtube browser?:), it uses various components of Phonon, like Videowidget, MediaObject and AudioOutput and has a default set of control buttons that do a nice slide in/slide out on mouse over, and the reallt cool thing is that using it from the javascript bindings is ridicolously easy.
This is a complete plasmoid written in javascript in the minboggling amount of 6 lines of code:
layout = new LinearLayout(plasmoid); video = new VideoWidget(); video.usedControls = DefaultControls; layout.addItem(video); video.url = startupArguments[0]; video.play();
All it does in sequence is: make a layout, make a video widget, enable a default set of buttons, add the widget in the layout, load the argument as the video if any (i.e, the file that was dag and dropped on the desktop), and finally, play.
This thing is in kdebase in the tests folder of the javascript based plasmoids.
Now, switching for a moment in hype-machine mode, think about putting together media content distribution, javascript, plasma, browsers and the not really happy state of these things in Linux right now, really far fetched for now and not for the immediate future, but good things can happen 😀
Yesterday talks were wicked interesting, especially the Alexis talk about the new animation framework was really breathtaking.
Aaanyways, this is kinda a synopsis of what i talked about in my part during
the talk session yesterday at Tokamak, slides
here,
it’s quickly written in few minutes, so the english it’s a total horror,
but i feel it could be kinda interesting anyways 🙂
Pretty much everything you see in Plasma is based on SVG graphics,
this means that you have a really high degree of customizability
controlled by the Plasma theme. This also means that compared to
classical Qt themes the entry barrier is significantly lower, because
of course you have to be a good designer to make one, but not a
programmer, while to do a Qt theme you have to be both and this is a
really really rare thing.
Also, since themes are pure graphics without binary code they are
completely platform independent so they can be distributed trough the
GHNS framework.
Being vector graphics, we can display them without problem from
very little screen to huge monsters when we will have 600dpi screens
that won’t be a problem, specially for the theme elements based on
the FrameSvg concept.
From a programmer point of view using the theme graphics is quite
easy too, because the two main classes that manages Svg themes (Svg
and FrameSvg) are very abstracted, so you won’t have to bother that
the graphics is actually a Svg.
Plasma themes will be installed under your KDE installation prefix
under share/apps/desktopthemes. The filesystem structure inside the
theme has got two main subfolders: widgets, meant for element
drawn on canvas and dialogs, meant for elements that are
actually a top level window. There are two particular and optional
subfolders: the first is locolor, that will have the same two
widgets and dialogs subfolders meant to be used when the theme is
displayed on screens with less than 16 bit color depth.
The other folder is called opaque and has replacements for
the elements that are a top level widget when the desktop effects are
turned off, that’s because in this case we won’t be able to have a
semitransparent window, so we won’t be able to have luxuries like
antialiased borders or drop shadows, if you have a rounded border
there you should use the good old pixelart tecnique from the 80’s.
In order to load an Svg from the current theme is sufficient to
use the setImagePath() function of Plasma::Svg, where you don’t have
to worry neither of the path of the theme or the svg or svgz
extension, so something like “widgets/background” will suffice.
If you are writing a scripted applet you can also include the
graphics alongside the applet code and distribute everything in a
single package, from a javascript applet for instance it will be
sufficient to call the function plasmoid.findSvg(“foo”) and the
proper foo.svg file will be located for you.
That said however now i have to get a bit annoying with some
advices: you should be really really careful when you add custom
graphics in your applet, both when you install it alongside your c++
applet and also when you embed it in the package of your scripted
applet, because your additional graphics must work with as much
themes as possible, and this is an hell lot difficult. You should at
least try it with both a dark and a light theme, but in the end… if
you want to do that, think again 🙂
Usually in your applet won’t have to directly paint Svgs, because
if you just use the default plasma widgets you’ll have the svg
painting done for you, but if you have to draw some svg elements you
have to know two classes: Plasma::Svg and Plasma::FrameSvg.
The mighty machine that manages all the svg painting in Plasma is
the Plasma::svg class, that internally uses the QSvgRenderer class,
but optimizes it as much as possible: in the context of the whole
Plasma application for each svg file we get an unique shared svg
renderer and the rendering result is saved to disk thanks to a
KPixmapCache, that can avoid the creation of renderer to a satisfatry
degree: in the second plasma start won’t be created a single renderer
until you resize something, saving a bit of startup time and some
megs of ram.
The most important functions you are interested if you want to use
a Svg are its several paint functions (overloaded with QPoints or
QRects as parameters) the already mentioned setImagePath() resize()
and various functions to access the svg sub elements like
hasElement(), elementSize() and elementRect().
The other class used in plasma to render Svgs works at a slightly
higher level of abstraction and is Plasma::FrameSvg. Usually widgets
are mostly rectangular things, but even if Svg is scalable that
doesn’t mean the result will look pretty, take a look at the slides
example for instance, where a
default applet background is heavily vertically stretched, so the
horizontal borders become thicker that the vertical ones, and to make
things worse they usually aren’t even an integer number of pixels
making the result to look really blurred.
So, what is there in the default applet background? We can see
there are actually 9 pieces: the corners, the edges and the central
part (called with a great stretch of fantasy center, top, topleft,
topright, left,right,bottom, bottomright and bottomleft). When the
thing will get painted not all elements will be scaled, it’s
important that the corners won’t be never ever scaled, while the
horizontal edges will be scaled only horizontally and similarly the
vertical edges will be scaled only vertically, while the center
element will scale freely.
From a boring code standpoint FrameSvg inherit the Svg class, so
all the stuff that is available in Svg is available in FrameSvg too,
but with the difference that you want to resize the image with
resizeFrame() that uses the method i talked before and you’ll paint
the correctly resize Svg with paintFrame(), while paint() is still
useful to paint single elements in the Svg. Also a single Svg can
contain multiple series of 9 elements, with the names differentiated
by a proper prefix, that can be chosen with the setElementPrefix()
function.
KDE 4.2 has just been released, after many months of hard work by many people.
In this release the huge potentiality of the 4.0 platform is finally going to show up in the end user visible apps, so it’s where the good plans are starting to come together.
/me did just a tiny part, but nevertheless i like considering myself part of that wonderful community, they are wonderful people, congratulations to each one 😀
This is a tiny plasmoid hacked on a boring sunday afternoon in about 20 mins, perhaps a too silly name but i think the effect is kinda fun 🙂
It’s an on-screen magnifying glass with the difference from the usual ones that it doesn’t actually grab the screen, but it just views the Plasma canvas (just another view on the scene, that is), that gives some peculiarities, shown in this video:
All the windows are totally transparent to it, so while is useful to view/magnify just what there is on desktop it can give a quick access on it, when you need both your windows and stuff on desktop (think about a non-fullscreen dashboard, and then think about drag and drop between dolphin and folderview even when you have a maximized window :P)
And the more cute thing is due to the vector nature of the QGraphicsView, you see all the proper vector-based elements like the text to be smoothly scaled and still looking like text, not that usual pixelated/blurry mess that kinda hinders the utility of screen magnifiers as accessibility applications.
It’s amazing what it’s possible to do in plasma with a really limited amount of lines of code (here about 100, perhaps 20 or so could even still be saved:)
The thing now lives in playground and is still really rough, so not definitely 4.2 material, but who feels like can give it a try anyways:)
This looks more like a tweet, but just Merry Christmas people 😀
After many many years, way more of what i would have liked to, today i finished the university, with the defense on my thesis (a weirdo thing about ontologies describing European directives, a PHP+postgresql monster i’m quite proud about after all).
Now even if i will probably continue working in the uni for a (hope not too long) while, it’s really a weeeird sensation knowing that something that took over a quite big chunk of my life it’s actually over.
I hope to be able to continue to hang around and hack on plasma as much as i can, as i feel in the last year KDE became a quite positive part of my life that i’m very happy about 🙂
As long as I will still work for the university it won’t change that much, since i will continue to do pretty much the same thing, and after that, bah, who knows, but for now i don’t want to think about that, just be happy for a bit :p
