DoubleVolumeButtonTreeShortPressPatternMatcher.java

/*
 * Copyright 2015 Google Inc.
 *
 * 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 com.android.talkback.volumebutton;

import android.view.KeyEvent;
import android.view.ViewConfiguration;

import java.util.concurrent.TimeUnit;

public class DoubleVolumeButtonTreeShortPressPatternMatcher extends VolumeButtonPatternMatcher {

    private static final long MULTIPLE_TAP_TIMEOUT = TimeUnit.MINUTES.toMillis(1);
    private static final long LONG_PRESS_TIMEOUT = ViewConfiguration.getLongPressTimeout();

    private int mDoubleButtonPresses;
    private long mLastDoubleButtonPressEndTimestamp;
    private VolumeButtonAction mLastVolumeUpAction;
    private VolumeButtonAction mLastVolumeDownAction;

    public DoubleVolumeButtonTreeShortPressPatternMatcher() {
        super(VolumeButtonPatternDetector.TWO_BUTTONS_THREE_PRESS_PATTERN,
                VolumeButtonPatternDetector.TWO_BUTTONS);
    }

    @Override
    public void onKeyEvent(KeyEvent keyEvent) {
        if (keyEvent.getKeyCode() != KeyEvent.KEYCODE_VOLUME_DOWN &&
                keyEvent.getKeyCode() != KeyEvent.KEYCODE_VOLUME_UP) {
            return;
        }

        if (interruptActionSequence(keyEvent)) {
            clear();
        }

        if (keyEvent.getAction() == KeyEvent.ACTION_DOWN) {
            handleActionDownEvent(keyEvent);
        } else {
            handleActionUpEvent(keyEvent);
        }

        updateCounters();
    }

    private void handleActionDownEvent(KeyEvent event) {
        VolumeButtonAction action = createAction(event);
        if (event.getKeyCode() == KeyEvent.KEYCODE_VOLUME_UP) {
            mLastVolumeUpAction = action;
        } else {
            mLastVolumeDownAction = action;
        }
    }

    private void handleActionUpEvent(KeyEvent event) {
        VolumeButtonAction action;
        if (event.getKeyCode() == KeyEvent.KEYCODE_VOLUME_UP) {
            action = mLastVolumeUpAction;
        } else {
            action = mLastVolumeDownAction;
        }

        if (action != null) {
            action.pressed = false;
            action.endTimestamp = event.getEventTime();
        }
    }

    private boolean interruptActionSequence(KeyEvent keyEvent) {
        if (keyEvent.getAction() == KeyEvent.ACTION_DOWN) {
            return isDownEventInterruptsActionSequence(keyEvent);
        } else {
            return isUpEventInterruptsActionSequence(keyEvent);
        }
    }

    private boolean isDownEventInterruptsActionSequence(KeyEvent keyEvent) {
        if (mDoubleButtonPresses != 0 &&
            keyEvent.getEventTime() - mLastDoubleButtonPressEndTimestamp > MULTIPLE_TAP_TIMEOUT) {
            // too long timeout between previous double volume buttons pushes
            return true;
        }

        VolumeButtonAction otherAction = getOtherAction(keyEvent);
        //noinspection RedundantIfStatement
        if (otherAction != null && !otherAction.pressed) {
            // other button was released before current action pressed
            return true;
        }

        return false;
    }

    private boolean isUpEventInterruptsActionSequence(KeyEvent keyEvent) {
        VolumeButtonAction currentAction = getCurrentAction(keyEvent);
        VolumeButtonAction otherAction = getOtherAction(keyEvent);
        if (currentAction == null) {
            // up on non-pressed button
            return true;
        }

        if (otherAction == null) {
            // click detected while other button was not pressed
            return true;
        }

        //noinspection RedundantIfStatement
        if (keyEvent.getEventTime() - currentAction.startTimestamp > LONG_PRESS_TIMEOUT) {
            // button was pressed too long
            return true;
        }

        return false;
    }

    private VolumeButtonAction getCurrentAction(KeyEvent keyEvent) {
        if (keyEvent.getKeyCode() == KeyEvent.KEYCODE_VOLUME_UP) {
            return mLastVolumeUpAction;
        } else {
            return mLastVolumeDownAction;
        }
    }

    private VolumeButtonAction getOtherAction(KeyEvent keyEvent) {
        if (keyEvent.getKeyCode() == KeyEvent.KEYCODE_VOLUME_UP) {
            return mLastVolumeDownAction;
        } else {
            return mLastVolumeUpAction;
        }
    }

    private void updateCounters() {
        if (mLastVolumeUpAction != null && !mLastVolumeUpAction.pressed &&
                mLastVolumeDownAction != null && !mLastVolumeDownAction.pressed) {
            mDoubleButtonPresses++;
            mLastDoubleButtonPressEndTimestamp = Math.max(mLastVolumeUpAction.endTimestamp,
                    mLastVolumeDownAction.endTimestamp);
            mLastVolumeUpAction = null;
            mLastVolumeDownAction = null;
        }
    }

    @Override
    public boolean checkMatch() {
        return mDoubleButtonPresses >= 3;
    }

    @Override
    public void clear() {
        mDoubleButtonPresses = 0;
        mLastDoubleButtonPressEndTimestamp = 0;
        mLastVolumeUpAction = null;
        mLastVolumeDownAction = null;
    }
}