a virtual keyboard plasmoid for touchscreens

Mon Mar 23 01:58:33 CET 2009

A Sunday 22 March 2009 23:57:12, Björn Ruberg escreveu:
> Hello plasmafolks,
>
> this mail is about my idea (and implementation) of an virtual keyboard for
> plasma. It is splitted in three sections, so you can skip what you do not
> want to read.
>
> 1. Why I'm interested in a virtual keyboard for plasma and where my ideas
> come from
> 2. Why having such a virtual keyboard is important for kde
> 3. Some technical questions. I need your help
>
> -------------------
> Part 1:
> Some weeks ago I owned a Gigabyte M704. That's an 7-inch touchscreen UMPC
> with a VIA C7 1,2 GHz CPU and 768 MiB of RAM. (I do not have it anymore,
> gave it back because it was not really useful) I had KDE 4.2 running on it
> and it worked suprisingly well.
> Most interesting part of the device was its touchscreen. (It makes fun to
> move plasmoids with your finger.)
> Not really useable was it's keyboard. You can only type with one finger per
> hand, it's not comfortable to hold and you have to open up it up first.
> Conclusion: Nice to have this keyboard in case you don't have a working X,
> but you don't really want to use it for anything else. Exspecially you
> cannot use it for daily work.
> Moreover if you just want to type in a part of an url, you don't want to
> move your finger from the touchscreen for doing that. It's uncomfortable.
>
> So I wanted a virtual keyboard on my desktop which I can use on the
> touchscreen. I wanted it to open up quickly on the screen (one tap for
> that!), type my stuff and close it with only one tap, too.
> And I wanted to use my touchscreen for ten-finger writing. 7-inch should be
> just enough for that. But only if the screen space is used optimally.
>
> So I searched for a virtual keyboard application, but I didn't find
> anything useable for me. None I found could be opened and close with only
> one tap. And most put completly unneeded buttons on the screen. Numpads,
> Function-keys - I didn't need that stuff. But it took so much space that I
> couldn't think of writing with ten fingers. The important alphanumeric
> buttons got too small. By the way, most virtual keyboards were ugly.
>
> That's why I came to the conclusion that there is a virtual keyboard
> plasmoid is needed. And I thought that would be a good for my first real
> KDE contribution.
>
> ------------
> Part 2:
>
> So, why should you care about my story?
> I think any other person who tries out KDE on a system with touchscreen
> will feel very similar. Until now, touchscreens are quite rare. Not many
> people have one. But that is about to change.
> There are more and more cheap touchscreen devices already out there. ASUS
> has a Atom-device which you can place at the wall and use by touchscreen.
> More and more MIDs like the nokia n810 are getting out. And there are the
> first so called netvertibles in the stores, more promising ones will come
> to the stores in the second quarter of the year.
> And perhaps you read that there are ARM-powered devices planned that should
> run ubuntu. As they will be very cheap and slim they have a good potential
> on the market.
>
> So I think the number of devices with touchscreen (and maybe even without a
> keyboard) will drastically increase in the next months. There are
> UserInterfaces for such devices in development, but only for gnome and
> Ubunutu-derivats as far as I can see.
>
> If KDE does not work well with touchscreens, users may be forced to stick
> with gnome. Or more worth, even with Windows.
> Luckily the missing virtual keyboard is the only critical problem KDE has
> with touchscreens, as far as I can tell. Support of certain mousegestures
> (i.e. for grabbing) is another one, but that's only a nice to have, no
> must.
>

+1 KDM i will want to use a touch scren keybord to log on into kdm
 on such a device....

> --------------
> Part 3:
>
> So, luckily I'm not only committing ideas, but even code. You can find my
> first implentation of a virtual keyboard named plasmaboard in playground. I
> think it is even useable. It produces only a german keyboard at the moment,
> but it is possible to switch to the basic latin keyboard by changing only
> one line of code.
> Thanks to notmart for some help in the channel regarding the plasma stuff.
> If you want to have look, check out
> trunk/playground/base/plasma/applets/plasmaboard/
>
> Please share your ideas regarding this applet with me. This is my first
> real programm in C++, Qt and plasma of course. So I'm eager to read your
> suggestions regarding the code.
>
> It's an PopupApplet which puts the keyboard in an extender. The keyboard
> itself consists of 63 hand positioned Plasma::PushButtons. The keyboard
> should be freely resizeable and remember its size. It can be used as an
> applet on the desktop and as an extender in front of your videos. These
> functionalitys are already given by the Extender classes.
>
> I have some question though:
>
> - Where to get the key layouts from?
>   Of course it's not optimal to have key layouts hard coded in the code.
> Although it may even do the job, what other ways are there?
>   The other problem are the keymaps. What key does produce which symbol?
> Currently I hardcoded that too. It may even be a good solution, if I can
> get XKeycodeToKeysym() to work. This Xlib function should recognize the
> xkb-layout and the pressed key modifiers for me, so I don't have to worry
> about it. Does anybody can help me using that function? It's not too well
> documented and I cannot find sourcecode.
>
> - X-Dependency
>   Currently I use the function XTestFakeKeyEvent to produce key events that
> should work with everything you  can have on your desktop. This means that
> plasmaboard needs X to work correctly. Is there any alternative for faking
> key events?
>   Is X-dependency a problem at all? Windows users do indeed have
> alternatives for a virtual keyboard.
>
> - plasma crashes when typing fast
>   When typing a lot and call XTestFakeKeyEvent often, plasma crashs with a
> "X server busy" message. You can probably easy reproduce that by typing
> some sentences with plasmaboard. That's a bug that needs to be solved. Can
> a plasma dev debug it? It may be okay to loose a key when typing, but
> crashing plasma is bad.
>
> - How to find out the display?
>   I currently use KWin::display() to get the acutal display. I need it for
> XTestFakeKeyEvent . It works for me but probably it is totally wrong. Where
> to get the display from correctly?
>
> - Plasma::PushButtons
>   I currently use Plasma::PushButton for my Buttons. I tested svg and
> iconwidget, too, but they didn't work for me. I have currently two problems
> with it: Fist I need a way to put a button in a pressed state (for example
> Control should stay pressed until another key is pressed). I didn't find
> one. Can you help?
>   Second I want a better formed Return-Button. My current overlapping
> solution is not beautiful. Any ideas how I can create a button that is not
> formed as an rectangle?
>
> - Problems with Extender
>   I recently implemented the keyboard as an Extender. Since that I can
> resize the keyboard only horizontally any more. Not vertically. When put on
> the desktop, the keyboard is not resizeable at all. What do I wrong?
>   Moreover, when I drag the keyboard on the desktop and click on the icon
> in the panel again, I only get a small empty window, but no new keyboard.
> How to do it right?
>
>   I noticed the extender to be quite buggy. Moving around my keyboard (but
> it happens with the battery extender as well) is likely to crash plasma. I
> exspecially have a problem when I try to resize the keyboard to full screen
> width. Try it, suddenly around 30 pixels at the left are clipped away.
>
>
> Well, this was a long mail. I appreciate suggestions, tipps, answers and of
> course help in coding. Perhaps somebody can tell me what to do for making
> plasmaboard ready to get into a plasma-package like plasma-addons?
>
> Greetings,
>
> Björn
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