OLPC Human Interface Guidelines/The Sugar Interface/Input Systems: Difference between revisions
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Latest revision as of 02:00, 1 May 2009
Input Systems
Keyboard
Localized Keyboard Layouts
| API Reference |
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| Module: keymapping TBD |
Softkey Sliders
The slider keys have two modes: "digital" and "analog." In digital mode, the discrete functions printed on the key caps are accessed, four per key. In analog mode, accessed with the Fn key, intermediate key codes are enabled—there are seven positions along the slider; intermediary postions are interpolated in software, turning each of the keys into a 13-position slider.
Keyboard Shortcuts
For the purposes of development, you may want to review the detailed specifications for keys and their codes on the Keyboard Layout page. For a complete list of agreed upon keyboard shortcuts in the Sugar environment, at both system and activity levels, please refer to the Keyboard Shortcuts page. Following is a high level description of the types of shortcuts the available keys should pertain to.
- ◆ CTRL (U+25C6) will be the main modifier key. It will be used to define "base" shortcuts. For instance, ◆A will "select all" in a text editor.
- ◇ ALT (U+25C7) should be used for optional modifications (or ALTernates) to base shortcuts. For instance, ◆S will perform a standard "keep" and ◇S could be "keep as...". ◆V is paste, ◇V is "paste and remove from clipboard."
- ⇧ SHIFT (U+21E7) can work in two ways. Its primary use would be as an inversion modifier, such that it inverts the meaning of the base shortcut. For instance, ◆Z is undo and ⇧◆Z is redo. ◆TAB is next activity, ⇧◆TAB is previous activity. SHIFT can also be used to create a second set of "base" shortcuts which are less often used.
The FN key is reserved solely for system level operations, and generally for those that map to functions which are printed on the keyboard itself.
Trackpad
The laptops employ a capacitive (finger controlled) trackpad.
Only the center region of the trackpad has capacitance, responding to a finger.
Trackpad as Mouse
The use of the finger on the central trackpad area serves as the primary input device for pointing. Though external USB mice will work seamlessly with the laptops, their availability will be limited, and activity designers should not expect that children will have access to them. This means that a certain lack of precision can be expected when moving the cursor about the screen, and activities should not require extremely precise motion. Excessively small controls should also be avoided for similar reasons; details on how to design interface elements reside in the Controls section.
In addition, the laptops have two buttons positioned beneath the trackpad for input. The left button is the primary button with which elements of the interface are selected, pressed, or activated. The right button has secondary functionality. Typically, the right mouse button invokes contextual menus, the content of which pertains directly to the interface element the mouse is positioned over.
Trackpad as Graphics Tablet
No stylus support is currently planned for the XO.
Microphone and Speakers
The laptop has a built-in microphone and stereo speakers to allow for voice communication and recording. You may integrate audio functionality directly into your activities by requesting access to this hardware in the Functional Manifest. There are also an external microphone and speaker jacks.
Need a section on using sounds in activities; particularly in the background...
Camera
The laptops have built-in cameras to allow for still photography and video recording. You may integrate camera functionality directly into your activities by requesting access to this hardware in the Functional Manifest.
"Hand-held" Mode
The laptops feature a hand-held mode of operation in which the screen swivels around 180 degrees and folds flat, similar to a tablet PC. In this mode, the screen covers the keyboard and trackpad; however, the microphone and camera, mounted within the display bezel, remain available for use. Additionally, bezel-mounted controls provide auxiliary input suitable for the activities that Hand-held mode is designed to support: reading an eBook, playing games, etc.
Energy Saving Benefits
The laptop is engineered for extreme operating efficiency—a goal furthered by Hand-held mode. The CPU can be suspended while still displaying on-screen graphics. While reading an eBook, since the screen need only be updated when a page is changed, the time spent reading any given page requires no use of the CPU. The screen can run in reflective (daylight) mode—with the backlight off—for additional energy savings. These factors combine to create an extremely low-power, energy-efficient machine; Hand-held mode provides a usage scenario where maximal energy savings can be attained.
Implementing Hand-held Controls
Unlike a typical tablet PC, the OLPC laptop does not have a touch-sensitive screen. Primary user input comes from two bezel-mounted button sets: the D-pad (directional pad), which has 8 directions of articulation; and the button controller, which houses 4 discrete buttons (labeled ◯, ╳, △, ▢, on the B1 machine).
The Directional Buttons
The D-pad should not be, in general, used to move a cursor around the screen— in fact, the cursor will hide by default in Hand-held mode. Instead, it should be used for more discrete operations, such as flipping through pages, scrolling a view, or jumping to focusable elements on screen. When an interface necessitates focusable elements, these should be visually apparent and arranged in a natural order. In most cases, "natural order" will mean scan-line order, or the way in which one reads a page of text, but this may adapt to suit the needs of the activity. For instance, some activities may opt to scan first by column, then by row; some may use a clockwise ordering some may even zig-zag across the screen. All of these arrangements are acceptable as long as their orderings logically follow from one to the next according to the visuals provided on screen.
Specific activities may in fact benefit from a more traditional cursor. Some games, for instance, may require one. To support these cases, the cursor may be explicitly shown. However, these instances should be carefully considered, since in many cases a cursor will provide a simple yet inefficient solution to a problem for which a better one exists.
The Controller Buttons
Generally speaking, the controller buttons can act either as standard event triggers, or as modifier buttons to the target of the D-pad controls. A common use for standard buttons is as select and cancel buttons. In such instances, the ◯ button should always represent confirmation, selection, or forward progress, while the ╳ button represents cancel, escape, or backward progress. Adhering to these guidelines will make navigation of Hand-held interfaces consistent.
When used as a modifier, the visuals on screen should clearly indicate which of the directions—up, down, left, right—perform actions, and those actions likewise should be clearly indicated. For instance, in the eBook, holding down ∆ displays an overlay listing the book's chapters, and the up/down arrows will have focus within this list while the modifier key remains pressed. The currently selected chapter appears in the center of the screen, and up and down arrows above and below the selected chapter clearly indicate how to scroll through the list. When activities implement a combination of both standard and modifier buttons, we encourage ╳ and ◯ for standard, and △ and ▢ for modifiers, since the former two are easier to hit with natural finger placement.
Built-in Hardware in Hand-held Mode
Both the camera and microphone reside within the display bezel, and as such remain available for activities to use within Hand-held mode. The important trade off to consider before using the camera or microphone is that of energy efficiency: while the laptop conserves energy in Hand-held mode, continued use of either of these two devices requires constant CPU usage, virtually eliminating the benefits. Therefore, do not simply integrate these hardware components unless they provide a fundamental service to your activity—but don't let this deter you from doing so where appropriate.
Screen Rotation
While in Hand-held mode, the laptops support screen rotation; by pressing a small button on the bezel of the display, the interface will rotate 90 degrees to provide a portrait layout of the currently active activity. Just as any activity can implement Hand-held mode, those which can benefit from a vertical aspect ratio may also implement this feature, and we encourage developers to take advantage of this functionality. The Read activity serves as a prime example of the usefulness of such a feature, since a vertical layout is well suited to displaying a single page from a book. This is just the type of activity one might want to do in Hand-held mode, and by providing two orientations a greater number of use cases can be covered.
In the current revisions of the laptops, its important to note that the buttons for interacting with Hand-held mode are slightly less accessible when the laptops are held vertically. For this reason, activities that require heavy or frequent use might not be best suited for this mode. However, OLPC is working hard on introducing touch-screen technology in the near future, which will nearly eliminate the dependency on the physical buttons, expanding the possibilities as every activity can take advantage of screen rotation. Therefore, even if screen rotation doesn't make sense for the first version of your activity, please construct your interface in such a way as to allow future adaptation to this new and potentially useful functionality.