(→The touchscreen: typo)
m (multitouch on resistive touchscreen)
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* The output is the center of the bounding box of the touched area
* The touch point skips instantly on double touch
* Pressure has no effect on a single touch, on a double touchrelative pressures will a skewing effect towards the harder touch
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* no pressure
* no pressure
does one see when sliding two fingers in parallel up(L,R)->down(L,R)?
does one see when narrowing two fingers in slide (=zoom effect on iphone)
====Graphics and computational capabilities====
====Graphics and computational capabilities====
Revision as of 13:21, 2 April 2007
Obviously the tools are in the wild to build interfaces that could rival (or better IMO) anything Apple comes up with. We just need to organize this stuff. This would need hardware that can support dynamic interfaces. I can help here, too. firstname.lastname@example.org
Finding inspiration ...
Ergonomy - Human/Machine papers
What exactly does the touchscreen see when you touch the screen with 2 fingers at the same time, when you move them, when you move only one of the 2, etc. I'm also interested in knowing how precise the touchscreen is (ex: refresh rate, possible pressure indication, ...)?
- The output is the center of the bounding box of the touched area
- The touch point skips instantly on double touch
- Pressure has almost no effect on a single touch, but not so on a double touch. The relative pressures will cause a significant skewing effect towards the harder touch. You can easily move the pointer along the line between your two fingers by changing the relative pressure.
- we can detect double touch as jumps, and that's all
- no pressure
What does one see when sliding two fingers in parallel up(L,R)->down(L,R)?
- In theory you see a slide along the center line between your two fingers. In practice, you can't keep the pressure equal, so you will see some kind of zig-zag line somewhere between the two pressure points in the direction of your slide.
What does one see when narrowing two fingers in slide (=zoom effect on iphone)?
- In theory you see the pointer stay at the center of the zoom movement. In practice, you can't keep the pressure equal for both fingers, so the pointer will move towards one of the two pressure points.
Graphics and computational capabilities
It would be good to report what performance the current hardware allows.
Areas of improvement
- OpenGL for fuild zooming interfaces (2D: the infinite sphere model, 1D: the infinite wheel of fortune/ribbon model, exposé)
- Physics-model based improvements: inertia and friction
- multi touch screen for natural handgestures
If we want to add eye candy & useability to the UI (such as smooth realistic list scrolling, as seen in apple's iphone demo on contacts lists), we'll need a physics engine, so that moves & animations aren't all linear.
The most used technique for calculating trajectories and systems of related geometrical objects seems to be verlet integration implementation; it is an alternative to Euler's integration method, using fast approximation.
We may have no need for such a mathematical method at first, but perhaps there are other use cases. For instance, it may be useful to gesture recognition (i'm not aware if existing gesture recognition engines measure speed, acceleration...).
If you want to take a quick look at the code: svn co http://svn.kiba-dock.org/akamaru/ akamaru
The only (AFAIK) application using this library is kiba-dock, a *fun* app launcher, but we may find another use to it in the future.
As suggested on the mailing list, it is mostly overkill for the uses we intend to have, but this library may be optimized already, the API can spare some time for too. Furthermore, Qui peut le plus, peut le moins.
Verlet integration implementation from e17
There's an undergoing verlet integration implementation into the e17 project (by rephorm) see http://rephorm.com/news/tag/physics , so we may see some UI physics integration into e17 someday.
Compositing seems to give zooming interfaces reality (at last!).
Well, considering recent changes in destkop applications, opengl has a definite future. For instance, the expose (be it apple's or beryl's) is a very interesting and usable feature. Using compositing allows the physics metaphore: the human brain doesn't like "gaps"/jumps (for instance while scrolling a text), it needs continuity. When you look at apple's iphone prototype, it's not just eye candy, it's maybe the most natural/human way of navigating, because it's sufficiently realistic for the brain to forget the non-physical nature of what's inside.
So, opengl hardware will be needed in a more or less distant hardware, for 100% fluid operation.
And, if we really want deep changes, multi touch screen if essential too :( (example: zooming with fingers)...
Clutter, an openedhand project, is an open source software library for creating fast, visually rich graphical user interfaces. The most obvious example of potential usage is in media center type applications. We hope however it can be used for a lot more.
Clutter uses OpenGL (and soon optionally OpenGL ES) for rendering but with an API which hides the underlying GL complexity from the developer. The Clutter API is intended to be easy to use, efficient and flexible.
From the wikipedia article, OpenGL ES (OpenGL for Embedded Systems) is a subset of the OpenGL 3D graphics API designed for embedded devices such as mobile phones, PDAs, and video game consoles.
Please add here any idea that seems of relevance.
1D Scrolling: n-sided uniform prism
Take an item list (ex: adress book), print it on a ribbon of paper, and glue it on a wheel (on the tire). You're looking in the front of it, so when you want to go from the A to Z, you touch the wheel and drag it up. When you let the wheel go, it goes furter, taken by it's inertia. Stop the wheel when you got your contact. Got the idea? That's why we may speak of an "infinite wheel", so that the surface is flat. For our case here, we always want to display square content, so the n-sided uniform prism analogy is mathematically more exact.
Why this wheel model? Because if the modelisation is coherent: - weight: the more heavy, the fastest it goes = the biggest the item list, the faster it scrolls; that way, you don't have to wait too long for big lists, and you don't miss your item on shorter lists - friction: there is friction where the wheel is fixed, so that the wheel doesn't turn infinitely - the initial speed and acceleration vector you give it determines it's futher rotation - it's "round"/cyclic, so you can browse the list in two directions
We can add "parallel wheels", symbolizing different sorting methods. Slide long to the left / right to look at a different wheel = items organization.
- Sliding up/down = Single click + maintained for a minimal distance
Effect: scroll in an inverted/negated fashion (slide down = scroll up, slide up = scroll down)
When finger is released (i.e. touchscreen doesn't detect any press):
if (last_speed_seen > value ) then keep this speed and
acceleration, with friction (so that it slows down)
else stop scrolling
Scrolling here is seen as unidimensional, but can apply to bidimensional situations (ex: zoomed image) too
- Action = quick double tap
- Details/select = short single tap
- Right click = long tap
- Sliding left/right: switch sorting method
Parts to "hack"
Having a scroll that isn't a 1:1 map to the user's action isn't hard. It's just an extra calculation in the scroll code.
<---- Where is the scroll code? :)
I'm wondering what layer of openmoko has to be hacked, i.e. if working at openmoko layer allows enough possibilities for this; if i'm not mistaken, this is part of libmokoui, but i'm pretty afraid that patching gtk itself woud be needed. Working on the lower level would apply changes to every application, not only openmoko's.
- remove the scrolling slider on finger mode
- make the entire list a "scrolling zone", i.e. an overlay transparent scrolling slider
- define controls
1D Scrolling: inertia friction integration into openmoko's finger wheel
The same, but for the wheel. It can be very short to do: you don't have 1:1 anymore, but, for example, 1/4 wheel turn = 1 item. It's demultiplicated, but has inertia.
2D Scrolling: the infinite sphere model / non-infinite polyhedron
The same model as the infinite wheel can apply to 2D navigation, except that your wheel becomes an infinite "floating sphere" for image/webpage navigation.
- zoomed image
- zoomed internet webpage
- browsing maps
When we want to navigate files, mp3s in an mp3 player, etc... Every control that the application needs is a button. What about looking at the polyhedrons ?
Advanced/Natural handgesture recognition
Gestures can be interesting, especially for "jumps" (when the cursor jumps from upper left corner to down right). Jump is different of sliding, and appears only with touchpads and touchscreeds; it can be detected as different from a button press if done fast enough (so you don't have to "aim" precisely).
The interesting jumps are:
- left <-> right
- middle up <-> middle down
- top left <-> down right
- down left <-> top right
- will the neo/openmoko graphics system be powerful enough for such uses? I suspect apple to do opengl acceleration on this device,
which is waaaaay impossible for us for now
- how does the touchscreen behave? We need a detailed touchscreen wiki information page, with visual traces. How hardware-specific is it?
- without multitouch, is there really room for improvement?