Initial implementation for decoding HW key events (B3)

 * The combiner should figure out what to do with this.

 */

public class Event {

    // Should the types below be represented by separate classes instead? It would be cleaner

    // but probably a bit too much

    // An event we don't handle in Latin IME, for example pressing Ctrl on a hardware keyboard.

    final public static int EVENT_NOT_HANDLED = 0;

    // A character that is already final, for example pressing an alphabetic character on a

    // hardware qwerty keyboard.

    final public static int EVENT_COMMITTABLE = 1;

    // A dead key, which means a character that should combine with what is coming next. Examples

    // include the "^" character on an azerty keyboard which combines with "e" to make "ê", or

    // AltGr+' on a dvorak international keyboard which combines with "e" to make "é". This is

    // true regardless of the language or combining mode, and should be seen as a property of the

    // key - a dead key followed by another key with which it can combine should be regarded as if

    // the keyboard actually had such a key.

    final public static int EVENT_DEAD = 2;

    // A toggle event is triggered by a key that affects the previous character. An example would

    // be a numeric key on a 10-key keyboard, which would toggle between 1 - a - b - c with

    // repeated presses.

    final public static int EVENT_TOGGLE = 3;

    // A mode event instructs the combiner to change modes. The canonical example would be the

    // hankaku/zenkaku key on a Japanese keyboard, or even the caps lock key on a qwerty keyboard

    // if handled at the combiner level.

    final public static int EVENT_MODE_KEY = 4;

    final private static int NOT_A_CODE_POINT = 0;

    private int mType; // The type of event - one of the constants above

    // The code point associated with the event, if relevant. This is a unicode code point, and

    // has nothing to do with other representations of the key. It is only relevant if this event

    // is the right type: COMMITTABLE or DEAD or TOGGLE, but for a mode key like hankaku/zenkaku or

    // ctrl, there is no code point associated so this should be NOT_A_CODE_POINT to avoid

    // unintentional use of its value when it's not relevant.

    private int mCodePoint;

    static Event obtainEvent() {

        // TODO: create an event pool instead

        return new Event();

    }

    public void setDeadEvent(final int codePoint) {

        mType = EVENT_DEAD;

        mCodePoint = codePoint;

    }

    public void setCommittableEvent(final int codePoint) {

        mType = EVENT_COMMITTABLE;

        mCodePoint = codePoint;

    }

    public void setNotHandledEvent() {

        mType = EVENT_NOT_HANDLED;

        mCodePoint = NOT_A_CODE_POINT; // Just in case

    }

}

package com.android.inputmethod.event;

import android.view.KeyCharacterMap;

import android.view.KeyEvent;

/**

 * A hardware event decoder for a hardware qwerty-ish keyboard.

 *

 * The events are always hardware keypresses, but they can be key down or key up events, they

 * can be dead keys, they can be meta keys like shift or ctrl... This does not deal with

 * 10-key like keyboards; a different decoder is used for this.

 */

public class HardwareKeyboardEventDecoder implements HardwareEventDecoder {

    final int mDeviceId;

    @Override

    public Event decodeHardwareKey(final KeyEvent keyEvent) {

        return Event.obtainEvent();

        final Event event = Event.obtainEvent();

        // KeyEvent#getUnicodeChar() does not exactly returns a unicode char, but rather a value

        // that includes both the unicode char in the lower 21 bits and flags in the upper bits,

        // hence the name "codePointAndFlags". {@see KeyEvent#getUnicodeChar()} for more info.

        final int codePointAndFlags = keyEvent.getUnicodeChar();

        if (keyEvent.isPrintingKey()) {

            if (0 != (codePointAndFlags & KeyCharacterMap.COMBINING_ACCENT)) {

                // A dead key.

                event.setDeadEvent(codePointAndFlags & KeyCharacterMap.COMBINING_ACCENT_MASK);

            } else {

                // A committable character. This should be committed right away, taking into

                // account the current state.

                event.setCommittableEvent(codePointAndFlags);

            }

        } else {

            event.setNotHandledEvent();

        }

        return event;

    }

}

package com.android.inputmethod.event;

/**

 * An event decoder for software events.

 * An event decoder for events out of a software keyboard.

 *

 * This defines the interface for an event decoder that supports events out of a software keyboard.

 * This differs significantly from hardware keyboard event decoders in several respects. First,

 * a software keyboard does not have a scancode/layout system; the keypresses that insert

 * characters output unicode characters directly.

 */

public interface SoftwareEventDecoder extends EventDecoder {

    public Event decodeSoftwareEvent();