org.solovyev.android.calculator.drag.SimpleDragListener.java Source code

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Here is the source code for org.solovyev.android.calculator.drag.SimpleDragListener.java

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/*
 * Copyright 2013 serso aka se.solovyev
 *
 * 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.
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 * Contact details
 *
 * Email: se.solovyev@gmail.com
 * Site:  http://se.solovyev.org
 */

package org.solovyev.android.calculator.drag;

import android.content.Context;
import android.support.v4.view.ViewConfigurationCompat;
import android.view.MotionEvent;
import android.view.ViewConfiguration;

import org.solovyev.android.calculator.R;
import org.solovyev.common.MutableObject;
import org.solovyev.common.interval.Interval;
import org.solovyev.common.interval.Intervals;
import org.solovyev.common.math.Maths;
import org.solovyev.common.math.Point2d;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;

import java.util.EnumMap;

public class SimpleDragListener implements DragListener {

    @Nonnull
    private static final Point2d axis = new Point2d(0, 1);

    @Nonnull
    private static final EnumMap<DragDirection, Interval<Float>> sAngleIntervals = new EnumMap<>(
            DragDirection.class);

    static {
        for (DragDirection direction : DragDirection.values()) {
            sAngleIntervals.put(direction, makeAngleInterval(direction, 0, 45));
        }
    }

    @Nonnull
    private final DragProcessor processor;

    private final float minDistancePxs;

    public SimpleDragListener(@Nonnull DragProcessor processor, @Nonnull Context context) {
        this.processor = processor;
        this.minDistancePxs = context.getResources().getDimensionPixelSize(R.dimen.cpp_min_drag_distance);
    }

    @Override
    public boolean onDrag(@Nonnull DragButton dragButton, @Nonnull DragEvent event) {
        boolean consumed = false;

        final MotionEvent motionEvent = event.getMotionEvent();

        final Point2d start = event.getStartPoint();
        final Point2d end = new Point2d(motionEvent.getX(), motionEvent.getY());
        final float distance = Maths.getDistance(start, end);

        final MutableObject<Boolean> right = new MutableObject<>();
        final double angle = Math.toDegrees(Maths.getAngle(start, Maths.sum(start, axis), end, right));

        final long duration = motionEvent.getEventTime() - motionEvent.getDownTime();
        final DragDirection direction = getDirection(distance, (float) angle, right.getObject());
        if (direction != null && duration > 40 && duration < 2500) {
            consumed = processor.processDragEvent(direction, dragButton, start, motionEvent);
        }

        return consumed;
    }

    @Nullable
    private DragDirection getDirection(float distance, float angle, boolean right) {
        if (distance > minDistancePxs) {
            for (DragDirection direction : DragDirection.values()) {
                final Interval<Float> angleInterval = sAngleIntervals.get(direction);
                final boolean wrongDirection = (direction == DragDirection.left && right)
                        || (direction == DragDirection.right && !right);
                if (!wrongDirection && angleInterval.contains(angle)) {
                    return direction;
                }
            }
        }
        return null;
    }

    @Override
    public boolean isSuppressOnClickEvent() {
        return true;
    }

    public interface DragProcessor {

        boolean processDragEvent(@Nonnull DragDirection dragDirection, @Nonnull DragButton dragButton,
                @Nonnull Point2d startPoint2d, @Nonnull MotionEvent motionEvent);
    }

    @Nonnull
    private static Interval<Float> makeAngleInterval(@Nonnull DragDirection direction, float leftLimit,
            float rightLimit) {
        final Float newLeftLimit;
        final Float newRightLimit;
        switch (direction) {
        case up:
            newLeftLimit = 180f - rightLimit;
            newRightLimit = 180f - leftLimit;
            break;
        case down:
            newLeftLimit = leftLimit;
            newRightLimit = rightLimit;
            break;
        case left:
            newLeftLimit = 90f - rightLimit;
            newRightLimit = 90f + rightLimit;
            break;
        case right:
            newLeftLimit = 90f - rightLimit;
            newRightLimit = 90f + rightLimit;
            break;
        default:
            throw new AssertionError();
        }

        return Intervals.newClosedInterval(newLeftLimit, newRightLimit);
    }
}