https://source.android.com/ 
/*
 * Copyright (C) 2006 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.text.method;

import android.text.Editable;
import android.text.NoCopySpan;
import android.text.Spannable;
import android.text.Spanned;
import android.view.KeyCharacterMap;
import android.view.KeyEvent;
import android.view.View;


This base class encapsulates the behavior for tracking the state of
meta keys such as SHIFT, ALT and SYM as well as the pseudo-meta state of selecting text.


Key listeners that care about meta state should inherit from this class;
you should not instantiate this class directly in a client.


This class provides two mechanisms for tracking meta state that can be used
together or independently.




 The behavior of this class varies according to the keyboard capabilities described by the KeyCharacterMap of the keyboard device such as the key modifier behavior. 
 MetaKeyKeyListener implements chorded and toggled key modifiers. When key modifiers are toggled into a latched or locked state, the state of the modifier is stored in the Editable text buffer or in a meta state integer managed by the client. These latched or locked modifiers should be considered to be held in addition to those that the keyboard already reported as being pressed in KeyEvent.getMetaState(). In other words, the MetaKeyKeyListener augments the meta state provided by the keyboard; it does not replace it. This distinction is important to ensure that meta keys not handled by MetaKeyKeyListener such as KeyEvent.KEYCODE_CAPS_LOCK or KeyEvent.KEYCODE_NUM_LOCK are taken into consideration. 

To ensure correct meta key behavior, the following pattern should be used
when mapping key codes to characters:



private char getUnicodeChar(TextKeyListener listener, KeyEvent event, Editable textBuffer) {
    // Use the combined meta states from the event and the key listener.
    int metaState = event.getMetaState() | listener.getMetaState(textBuffer);
    return event.getUnicodeChar(metaState);
}


/**
 * This base class encapsulates the behavior for tracking the state of
 * meta keys such as SHIFT, ALT and SYM as well as the pseudo-meta state of selecting text.
 * <p>
 * Key listeners that care about meta state should inherit from this class;
 * you should not instantiate this class directly in a client.
 * </p><p>
 * This class provides two mechanisms for tracking meta state that can be used
 * together or independently.
 * </p>
 * <ul>
 * <li>Methods such as {@link #handleKeyDown(long, int, KeyEvent)} and
 * {@link #getMetaState(long)} operate on a meta key state bit mask.</li>
 * <li>Methods such as {@link #onKeyDown(View, Editable, int, KeyEvent)} and
 * {@link #getMetaState(CharSequence, int)} operate on meta key state flags stored
 * as spans in an {@link Editable} text buffer.  The spans only describe the current
 * meta key state of the text editor; they do not carry any positional information.</li>
 * </ul>
 * <p>
 * The behavior of this class varies according to the keyboard capabilities
 * described by the {@link KeyCharacterMap} of the keyboard device such as
 * the {@link KeyCharacterMap#getModifierBehavior() key modifier behavior}.
 * </p><p>
 * {@link MetaKeyKeyListener} implements chorded and toggled key modifiers.
 * When key modifiers are toggled into a latched or locked state, the state
 * of the modifier is stored in the {@link Editable} text buffer or in a
 * meta state integer managed by the client.  These latched or locked modifiers
 * should be considered to be held <b>in addition to</b> those that the
 * keyboard already reported as being pressed in {@link KeyEvent#getMetaState()}.
 * In other words, the {@link MetaKeyKeyListener} augments the meta state
 * provided by the keyboard; it does not replace it.  This distinction is important
 * to ensure that meta keys not handled by {@link MetaKeyKeyListener} such as
 * {@link KeyEvent#KEYCODE_CAPS_LOCK} or {@link KeyEvent#KEYCODE_NUM_LOCK} are
 * taken into consideration.
 * </p><p>
 * To ensure correct meta key behavior, the following pattern should be used
 * when mapping key codes to characters:
 * </p>
 * <code>
 * private char getUnicodeChar(TextKeyListener listener, KeyEvent event, Editable textBuffer) {
 *     // Use the combined meta states from the event and the key listener.
 *     int metaState = event.getMetaState() | listener.getMetaState(textBuffer);
 *     return event.getUnicodeChar(metaState);
 * }
 * </code>
 */
public abstract class MetaKeyKeyListener {
    
Flag that indicates that the SHIFT key is on. Value equals KeyEvent.META_SHIFT_ON. 
/**
     * Flag that indicates that the SHIFT key is on.
     * Value equals {@link KeyEvent#META_SHIFT_ON}.
     */
    public static final int META_SHIFT_ON = KeyEvent.META_SHIFT_ON;
    
Flag that indicates that the ALT key is on. Value equals KeyEvent.META_ALT_ON. 
/**
     * Flag that indicates that the ALT key is on.
     * Value equals {@link KeyEvent#META_ALT_ON}.
     */
    public static final int META_ALT_ON = KeyEvent.META_ALT_ON;
    
Flag that indicates that the SYM key is on. Value equals KeyEvent.META_SYM_ON. 
/**
     * Flag that indicates that the SYM key is on.
     * Value equals {@link KeyEvent#META_SYM_ON}.
     */
    public static final int META_SYM_ON = KeyEvent.META_SYM_ON;

    
Flag that indicates that the SHIFT key is locked in CAPS mode.

/**
     * Flag that indicates that the SHIFT key is locked in CAPS mode.
     */
    public static final int META_CAP_LOCKED = KeyEvent.META_CAP_LOCKED;
    
Flag that indicates that the ALT key is locked.

/**
     * Flag that indicates that the ALT key is locked.
     */
    public static final int META_ALT_LOCKED = KeyEvent.META_ALT_LOCKED;
    
Flag that indicates that the SYM key is locked.

/**
     * Flag that indicates that the SYM key is locked.
     */
    public static final int META_SYM_LOCKED = KeyEvent.META_SYM_LOCKED;

    
@hidepending API review
/**
     * @hide pending API review
     */
    public static final int META_SELECTING = KeyEvent.META_SELECTING;

    // These bits are privately used by the meta key key listener.
    // They are deliberately assigned values outside of the representable range of an 'int'
    // so as not to conflict with any meta key states publicly defined by KeyEvent.
    private static final long META_CAP_USED = 1L << 32;
    private static final long META_ALT_USED = 1L << 33;
    private static final long META_SYM_USED = 1L << 34;

    private static final long META_CAP_PRESSED = 1L << 40;
    private static final long META_ALT_PRESSED = 1L << 41;
    private static final long META_SYM_PRESSED = 1L << 42;

    private static final long META_CAP_RELEASED = 1L << 48;
    private static final long META_ALT_RELEASED = 1L << 49;
    private static final long META_SYM_RELEASED = 1L << 50;

    private static final long META_SHIFT_MASK = META_SHIFT_ON
            | META_CAP_LOCKED | META_CAP_USED
            | META_CAP_PRESSED | META_CAP_RELEASED;
    private static final long META_ALT_MASK = META_ALT_ON
            | META_ALT_LOCKED | META_ALT_USED
            | META_ALT_PRESSED | META_ALT_RELEASED;
    private static final long META_SYM_MASK = META_SYM_ON
            | META_SYM_LOCKED | META_SYM_USED
            | META_SYM_PRESSED | META_SYM_RELEASED;

    private static final Object CAP = new NoCopySpan.Concrete();
    private static final Object ALT = new NoCopySpan.Concrete();
    private static final Object SYM = new NoCopySpan.Concrete();
    private static final Object SELECTING = new NoCopySpan.Concrete();

    private static final int PRESSED_RETURN_VALUE = 1;
    private static final int LOCKED_RETURN_VALUE = 2;

    
Resets all meta state to inactive.

/**
     * Resets all meta state to inactive.
     */
    public static void resetMetaState(Spannable text) {
        text.removeSpan(CAP);
        text.removeSpan(ALT);
        text.removeSpan(SYM);
        text.removeSpan(SELECTING);
    }

    
Gets the state of the meta keys.

Params:
  • text – the buffer in which the meta key would have been pressed.
Returns:an integer in which each bit set to one represents a pressed
        or locked meta key.
/**
     * Gets the state of the meta keys.
     *
     * @param text the buffer in which the meta key would have been pressed.
     *
     * @return an integer in which each bit set to one represents a pressed
     *         or locked meta key.
     */
    public static final int getMetaState(CharSequence text) {
        return getActive(text, CAP, META_SHIFT_ON, META_CAP_LOCKED) |
               getActive(text, ALT, META_ALT_ON, META_ALT_LOCKED) |
               getActive(text, SYM, META_SYM_ON, META_SYM_LOCKED) |
               getActive(text, SELECTING, META_SELECTING, META_SELECTING);
    }

    
Gets the state of the meta keys for a specific key event.
For input devices that use toggled key modifiers, the `toggled' state
is stored into the text buffer. This method retrieves the meta state
for this event, accounting for the stored state. If the event has been
created by a device that does not support toggled key modifiers, like
a virtual device for example, the stored state is ignored.

Params:
  • text – the buffer in which the meta key would have been pressed.
  • event – the event for which to evaluate the meta state.
Returns:an integer in which each bit set to one represents a pressed
        or locked meta key.
/**
     * Gets the state of the meta keys for a specific key event.
     *
     * For input devices that use toggled key modifiers, the `toggled' state
     * is stored into the text buffer. This method retrieves the meta state
     * for this event, accounting for the stored state. If the event has been
     * created by a device that does not support toggled key modifiers, like
     * a virtual device for example, the stored state is ignored.
     *
     * @param text the buffer in which the meta key would have been pressed.
     * @param event the event for which to evaluate the meta state.
     * @return an integer in which each bit set to one represents a pressed
     *         or locked meta key.
     */
    public static final int getMetaState(final CharSequence text, final KeyEvent event) {
        int metaState = event.getMetaState();
        if (event.getKeyCharacterMap().getModifierBehavior()
                == KeyCharacterMap.MODIFIER_BEHAVIOR_CHORDED_OR_TOGGLED) {
            metaState |= getMetaState(text);
        }
        return metaState;
    }

    // As META_SELECTING is @hide we should not mention it in public comments, hence the
    // omission in @param meta
    
Gets the state of a particular meta key.

Params:
  • meta – META_SHIFT_ON, META_ALT_ON, META_SYM_ON
  • text – the buffer in which the meta key would have been pressed.
Returns:0 if inactive, 1 if active, 2 if locked.
/**
     * Gets the state of a particular meta key.
     *
     * @param meta META_SHIFT_ON, META_ALT_ON, META_SYM_ON
     * @param text the buffer in which the meta key would have been pressed.
     *
     * @return 0 if inactive, 1 if active, 2 if locked.
     */
    public static final int getMetaState(CharSequence text, int meta) {
        switch (meta) {
            case META_SHIFT_ON:
                return getActive(text, CAP, PRESSED_RETURN_VALUE, LOCKED_RETURN_VALUE);

            case META_ALT_ON:
                return getActive(text, ALT, PRESSED_RETURN_VALUE, LOCKED_RETURN_VALUE);

            case META_SYM_ON:
                return getActive(text, SYM, PRESSED_RETURN_VALUE, LOCKED_RETURN_VALUE);

            case META_SELECTING:
                return getActive(text, SELECTING, PRESSED_RETURN_VALUE, LOCKED_RETURN_VALUE);

            default:
                return 0;
        }
    }

    
Gets the state of a particular meta key to use with a particular key event.
If the key event has been created by a device that does not support toggled
key modifiers, like a virtual keyboard for example, only the meta state in
the key event is considered.

Params:
  • meta – META_SHIFT_ON, META_ALT_ON, META_SYM_ON
  • text – the buffer in which the meta key would have been pressed.
  • event – the event for which to evaluate the meta state.
Returns:0 if inactive, 1 if active, 2 if locked.
/**
     * Gets the state of a particular meta key to use with a particular key event.
     *
     * If the key event has been created by a device that does not support toggled
     * key modifiers, like a virtual keyboard for example, only the meta state in
     * the key event is considered.
     *
     * @param meta META_SHIFT_ON, META_ALT_ON, META_SYM_ON
     * @param text the buffer in which the meta key would have been pressed.
     * @param event the event for which to evaluate the meta state.
     * @return 0 if inactive, 1 if active, 2 if locked.
     */
    public static final int getMetaState(final CharSequence text, final int meta,
            final KeyEvent event) {
        int metaState = event.getMetaState();
        if (event.getKeyCharacterMap().getModifierBehavior()
                == KeyCharacterMap.MODIFIER_BEHAVIOR_CHORDED_OR_TOGGLED) {
            metaState |= getMetaState(text);
        }
        if (META_SELECTING == meta) {
            // #getMetaState(long, int) does not support META_SELECTING, but we want the same
            // behavior as #getMetaState(CharSequence, int) so we need to do it here
            if ((metaState & META_SELECTING) != 0) {
                // META_SELECTING is only ever set to PRESSED and can't be LOCKED, so return 1
                return 1;
            }
            return 0;
        }
        return getMetaState(metaState, meta);
    }

    private static int getActive(CharSequence text, Object meta,
                                 int on, int lock) {
        if (!(text instanceof Spanned)) {
            return 0;
        }

        Spanned sp = (Spanned) text;
        int flag = sp.getSpanFlags(meta);

        if (flag == LOCKED) {
            return lock;
        } else if (flag != 0) {
            return on;
        } else {
            return 0;
        }
    }

    
Call this method after you handle a keypress so that the meta
state will be reset to unshifted (if it is not still down)
or primed to be reset to unshifted (once it is released).

/**
     * Call this method after you handle a keypress so that the meta
     * state will be reset to unshifted (if it is not still down)
     * or primed to be reset to unshifted (once it is released).
     */
    public static void adjustMetaAfterKeypress(Spannable content) {
        adjust(content, CAP);
        adjust(content, ALT);
        adjust(content, SYM);
    }

    
Returns true if this object is one that this class would use to
keep track of any meta state in the specified text.

/**
     * Returns true if this object is one that this class would use to
     * keep track of any meta state in the specified text.
     */
    public static boolean isMetaTracker(CharSequence text, Object what) {
        return what == CAP || what == ALT || what == SYM ||
               what == SELECTING;
    }

    
Returns true if this object is one that this class would use to
keep track of the selecting meta state in the specified text.

/**
     * Returns true if this object is one that this class would use to
     * keep track of the selecting meta state in the specified text.
     */
    public static boolean isSelectingMetaTracker(CharSequence text, Object what) {
        return what == SELECTING;
    }

    private static void adjust(Spannable content, Object what) {
        int current = content.getSpanFlags(what);

        if (current == PRESSED)
            content.setSpan(what, 0, 0, USED);
        else if (current == RELEASED)
            content.removeSpan(what);
    }

    
Call this if you are a method that ignores the locked meta state
(arrow keys, for example) and you handle a key.

/**
     * Call this if you are a method that ignores the locked meta state
     * (arrow keys, for example) and you handle a key.
     */
    protected static void resetLockedMeta(Spannable content) {
        resetLock(content, CAP);
        resetLock(content, ALT);
        resetLock(content, SYM);
        resetLock(content, SELECTING);
    }

    private static void resetLock(Spannable content, Object what) {
        int current = content.getSpanFlags(what);

        if (current == LOCKED)
            content.removeSpan(what);
    }

    
Handles presses of the meta keys.

/**
     * Handles presses of the meta keys.
     */
    public boolean onKeyDown(View view, Editable content, int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_SHIFT_LEFT || keyCode == KeyEvent.KEYCODE_SHIFT_RIGHT) {
            press(content, CAP);
            return true;
        }

        if (keyCode == KeyEvent.KEYCODE_ALT_LEFT || keyCode == KeyEvent.KEYCODE_ALT_RIGHT
                || keyCode == KeyEvent.KEYCODE_NUM) {
            press(content, ALT);
            return true;
        }

        if (keyCode == KeyEvent.KEYCODE_SYM) {
            press(content, SYM);
            return true;
        }

        return false; // no super to call through to
    }

    private void press(Editable content, Object what) {
        int state = content.getSpanFlags(what);

        if (state == PRESSED)
            ; // repeat before use
        else if (state == RELEASED)
            content.setSpan(what, 0, 0, LOCKED);
        else if (state == USED)
            ; // repeat after use
        else if (state == LOCKED)
            content.removeSpan(what);
        else
            content.setSpan(what, 0, 0, PRESSED);
    }

    
Start selecting text.

@hidepending API review
/**
     * Start selecting text.
     * @hide pending API review
     */
    public static void startSelecting(View view, Spannable content) {
        content.setSpan(SELECTING, 0, 0, PRESSED);
    }

    
Stop selecting text. This does not actually collapse the selection; call Selection.setSelection too. 
@hidepending API review
/**
     * Stop selecting text.  This does not actually collapse the selection;
     * call {@link android.text.Selection#setSelection} too.
     * @hide pending API review
     */
    public static void stopSelecting(View view, Spannable content) {
        content.removeSpan(SELECTING);
    }

    
Handles release of the meta keys.

/**
     * Handles release of the meta keys.
     */
    public boolean onKeyUp(View view, Editable content, int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_SHIFT_LEFT || keyCode == KeyEvent.KEYCODE_SHIFT_RIGHT) {
            release(content, CAP, event);
            return true;
        }

        if (keyCode == KeyEvent.KEYCODE_ALT_LEFT || keyCode == KeyEvent.KEYCODE_ALT_RIGHT
                || keyCode == KeyEvent.KEYCODE_NUM) {
            release(content, ALT, event);
            return true;
        }

        if (keyCode == KeyEvent.KEYCODE_SYM) {
            release(content, SYM, event);
            return true;
        }

        return false; // no super to call through to
    }

    private void release(Editable content, Object what, KeyEvent event) {
        int current = content.getSpanFlags(what);

        switch (event.getKeyCharacterMap().getModifierBehavior()) {
            case KeyCharacterMap.MODIFIER_BEHAVIOR_CHORDED_OR_TOGGLED:
                if (current == USED)
                    content.removeSpan(what);
                else if (current == PRESSED)
                    content.setSpan(what, 0, 0, RELEASED);
                break;

            default:
                content.removeSpan(what);
                break;
        }
    }

    public void clearMetaKeyState(View view, Editable content, int states) {
        clearMetaKeyState(content, states);
    }

    public static void clearMetaKeyState(Editable content, int states) {
        if ((states&META_SHIFT_ON) != 0) content.removeSpan(CAP);
        if ((states&META_ALT_ON) != 0) content.removeSpan(ALT);
        if ((states&META_SYM_ON) != 0) content.removeSpan(SYM);
        if ((states&META_SELECTING) != 0) content.removeSpan(SELECTING);
    }

    
Call this if you are a method that ignores the locked meta state
(arrow keys, for example) and you handle a key.

/**
     * Call this if you are a method that ignores the locked meta state
     * (arrow keys, for example) and you handle a key.
     */
    public static long resetLockedMeta(long state) {
        if ((state & META_CAP_LOCKED) != 0) {
            state &= ~META_SHIFT_MASK;
        }
        if ((state & META_ALT_LOCKED) != 0) {
            state &= ~META_ALT_MASK;
        }
        if ((state & META_SYM_LOCKED) != 0) {
            state &= ~META_SYM_MASK;
        }
        return state;
    }

    // ---------------------------------------------------------------------
    // Version of API that operates on a state bit mask
    // ---------------------------------------------------------------------

    
Gets the state of the meta keys.

Params:
  • state – the current meta state bits.
Returns:an integer in which each bit set to one represents a pressed
        or locked meta key.
/**
     * Gets the state of the meta keys.
     *
     * @param state the current meta state bits.
     *
     * @return an integer in which each bit set to one represents a pressed
     *         or locked meta key.
     */
    public static final int getMetaState(long state) {
        int result = 0;

        if ((state & META_CAP_LOCKED) != 0) {
            result |= META_CAP_LOCKED;
        } else if ((state & META_SHIFT_ON) != 0) {
            result |= META_SHIFT_ON;
        }

        if ((state & META_ALT_LOCKED) != 0) {
            result |= META_ALT_LOCKED;
        } else if ((state & META_ALT_ON) != 0) {
            result |= META_ALT_ON;
        }

        if ((state & META_SYM_LOCKED) != 0) {
            result |= META_SYM_LOCKED;
        } else if ((state & META_SYM_ON) != 0) {
            result |= META_SYM_ON;
        }

        return result;
    }

    
Gets the state of a particular meta key.

Params:
  • state – the current state bits.
  • meta – META_SHIFT_ON, META_ALT_ON, or META_SYM_ON
Returns:0 if inactive, 1 if active, 2 if locked.
/**
     * Gets the state of a particular meta key.
     *
     * @param state the current state bits.
     * @param meta META_SHIFT_ON, META_ALT_ON, or META_SYM_ON
     *
     * @return 0 if inactive, 1 if active, 2 if locked.
     */
    public static final int getMetaState(long state, int meta) {
        switch (meta) {
            case META_SHIFT_ON:
                if ((state & META_CAP_LOCKED) != 0) return LOCKED_RETURN_VALUE;
                if ((state & META_SHIFT_ON) != 0) return PRESSED_RETURN_VALUE;
                return 0;

            case META_ALT_ON:
                if ((state & META_ALT_LOCKED) != 0) return LOCKED_RETURN_VALUE;
                if ((state & META_ALT_ON) != 0) return PRESSED_RETURN_VALUE;
                return 0;

            case META_SYM_ON:
                if ((state & META_SYM_LOCKED) != 0) return LOCKED_RETURN_VALUE;
                if ((state & META_SYM_ON) != 0) return PRESSED_RETURN_VALUE;
                return 0;

            default:
                return 0;
        }
    }

    
Call this method after you handle a keypress so that the meta
state will be reset to unshifted (if it is not still down)
or primed to be reset to unshifted (once it is released).  Takes
the current state, returns the new state.

/**
     * Call this method after you handle a keypress so that the meta
     * state will be reset to unshifted (if it is not still down)
     * or primed to be reset to unshifted (once it is released).  Takes
     * the current state, returns the new state.
     */
    public static long adjustMetaAfterKeypress(long state) {
        if ((state & META_CAP_PRESSED) != 0) {
            state = (state & ~META_SHIFT_MASK) | META_SHIFT_ON | META_CAP_USED;
        } else if ((state & META_CAP_RELEASED) != 0) {
            state &= ~META_SHIFT_MASK;
        }

        if ((state & META_ALT_PRESSED) != 0) {
            state = (state & ~META_ALT_MASK) | META_ALT_ON | META_ALT_USED;
        } else if ((state & META_ALT_RELEASED) != 0) {
            state &= ~META_ALT_MASK;
        }

        if ((state & META_SYM_PRESSED) != 0) {
            state = (state & ~META_SYM_MASK) | META_SYM_ON | META_SYM_USED;
        } else if ((state & META_SYM_RELEASED) != 0) {
            state &= ~META_SYM_MASK;
        }
        return state;
    }

    
Handles presses of the meta keys.

/**
     * Handles presses of the meta keys.
     */
    public static long handleKeyDown(long state, int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_SHIFT_LEFT || keyCode == KeyEvent.KEYCODE_SHIFT_RIGHT) {
            return press(state, META_SHIFT_ON, META_SHIFT_MASK,
                    META_CAP_LOCKED, META_CAP_PRESSED, META_CAP_RELEASED, META_CAP_USED);
        }

        if (keyCode == KeyEvent.KEYCODE_ALT_LEFT || keyCode == KeyEvent.KEYCODE_ALT_RIGHT
                || keyCode == KeyEvent.KEYCODE_NUM) {
            return press(state, META_ALT_ON, META_ALT_MASK,
                    META_ALT_LOCKED, META_ALT_PRESSED, META_ALT_RELEASED, META_ALT_USED);
        }

        if (keyCode == KeyEvent.KEYCODE_SYM) {
            return press(state, META_SYM_ON, META_SYM_MASK,
                    META_SYM_LOCKED, META_SYM_PRESSED, META_SYM_RELEASED, META_SYM_USED);
        }
        return state;
    }

    private static long press(long state, int what, long mask,
            long locked, long pressed, long released, long used) {
        if ((state & pressed) != 0) {
            // repeat before use
        } else if ((state & released) != 0) {
            state = (state &~ mask) | what | locked;
        } else if ((state & used) != 0) {
            // repeat after use
        } else if ((state & locked) != 0) {
            state &= ~mask;
        } else {
            state |= what | pressed;
        }
        return state;
    }

    
Handles release of the meta keys.

/**
     * Handles release of the meta keys.
     */
    public static long handleKeyUp(long state, int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_SHIFT_LEFT || keyCode == KeyEvent.KEYCODE_SHIFT_RIGHT) {
            return release(state, META_SHIFT_ON, META_SHIFT_MASK,
                    META_CAP_PRESSED, META_CAP_RELEASED, META_CAP_USED, event);
        }

        if (keyCode == KeyEvent.KEYCODE_ALT_LEFT || keyCode == KeyEvent.KEYCODE_ALT_RIGHT
                || keyCode == KeyEvent.KEYCODE_NUM) {
            return release(state, META_ALT_ON, META_ALT_MASK,
                    META_ALT_PRESSED, META_ALT_RELEASED, META_ALT_USED, event);
        }

        if (keyCode == KeyEvent.KEYCODE_SYM) {
            return release(state, META_SYM_ON, META_SYM_MASK,
                    META_SYM_PRESSED, META_SYM_RELEASED, META_SYM_USED, event);
        }
        return state;
    }

    private static long release(long state, int what, long mask,
            long pressed, long released, long used, KeyEvent event) {
        switch (event.getKeyCharacterMap().getModifierBehavior()) {
            case KeyCharacterMap.MODIFIER_BEHAVIOR_CHORDED_OR_TOGGLED:
                if ((state & used) != 0) {
                    state &= ~mask;
                } else if ((state & pressed) != 0) {
                    state |= what | released;
                }
                break;

            default:
                state &= ~mask;
                break;
        }
        return state;
    }

    
Clears the state of the specified meta key if it is locked.

Params:
/**
     * Clears the state of the specified meta key if it is locked.
     * @param state the meta key state
     * @param which meta keys to clear, may be a combination of {@link #META_SHIFT_ON},
     * {@link #META_ALT_ON} or {@link #META_SYM_ON}.
     */
    public long clearMetaKeyState(long state, int which) {
        if ((which & META_SHIFT_ON) != 0 && (state & META_CAP_LOCKED) != 0) {
            state &= ~META_SHIFT_MASK;
        }
        if ((which & META_ALT_ON) != 0 && (state & META_ALT_LOCKED) != 0) {
            state &= ~META_ALT_MASK;
        }
        if ((which & META_SYM_ON) != 0 && (state & META_SYM_LOCKED) != 0) {
            state &= ~META_SYM_MASK;
        }
        return state;
    }

    
The meta key has been pressed but has not yet been used.

/**
     * The meta key has been pressed but has not yet been used.
     */
    private static final int PRESSED =
        Spannable.SPAN_MARK_MARK | (1 << Spannable.SPAN_USER_SHIFT);

    
The meta key has been pressed and released but has still
not yet been used.

/**
     * The meta key has been pressed and released but has still
     * not yet been used.
     */
    private static final int RELEASED =
        Spannable.SPAN_MARK_MARK | (2 << Spannable.SPAN_USER_SHIFT);

    
The meta key has been pressed and used but has not yet been released.

/**
     * The meta key has been pressed and used but has not yet been released.
     */
    private static final int USED =
        Spannable.SPAN_MARK_MARK | (3 << Spannable.SPAN_USER_SHIFT);

    
The meta key has been pressed and released without use, and then
pressed again; it may also have been released again.

/**
     * The meta key has been pressed and released without use, and then
     * pressed again; it may also have been released again.
     */
    private static final int LOCKED =
        Spannable.SPAN_MARK_MARK | (4 << Spannable.SPAN_USER_SHIFT);
}