src/com/android/gallery3d/ui/CaptureAnimation.java

/*
 * Copyright (C) 2012 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 com.android.gallery3d.ui;

import android.view.animation.AccelerateDecelerateInterpolator;
import android.view.animation.AccelerateInterpolator;
import android.view.animation.DecelerateInterpolator;
import android.view.animation.Interpolator;

public class CaptureAnimation {
    // The amount of change for zooming out.
    private static final float ZOOM_DELTA = 0.2f;
    // Pre-calculated value for convenience.
    private static final float ZOOM_IN_BEGIN = 1f - ZOOM_DELTA;

    private static final Interpolator sZoomOutInterpolator =
            new DecelerateInterpolator();
    private static final Interpolator sZoomInInterpolator =
            new AccelerateInterpolator();
    private static final Interpolator sSlideInterpolator =
        new AccelerateDecelerateInterpolator();

    // Calculate the slide factor based on the give time fraction.
    public static float calculateSlide(float fraction) {
        return sSlideInterpolator.getInterpolation(fraction);
    }

    // Calculate the scale factor based on the given time fraction.
    public static float calculateScale(float fraction) {
        float value;
        if (fraction <= 0.5f) {
            // Zoom in for the beginning.
            value = 1f - ZOOM_DELTA *
                    sZoomOutInterpolator.getInterpolation(fraction * 2);
        } else {
            // Zoom out for the ending.
            value = ZOOM_IN_BEGIN + ZOOM_DELTA *
                    sZoomInInterpolator.getInterpolation((fraction - 0.5f) * 2f);
        }
        return value;
    }
}