| /* |
| * Copyright (C) 2016 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 androidx.leanback.widget; |
| |
| import android.animation.ObjectAnimator; |
| import android.animation.PropertyValuesHolder; |
| import android.util.Property; |
| import android.view.animation.LinearInterpolator; |
| |
| /** |
| * ParallaxTarget is responsible for updating the target through the {@link #update(float)} method |
| * or the {@link #directUpdate(Number)} method when {@link #isDirectMapping()} is true. |
| * When {@link #isDirectMapping()} is false, {@link ParallaxEffect} transforms the values of |
| * {@link Parallax}, which represents the current state of UI, into a float value between 0 and 1. |
| * That float value is passed into {@link #update(float)} method. |
| */ |
| public abstract class ParallaxTarget { |
| |
| /** |
| * Implementation class is supposed to update target with the provided fraction |
| * (between 0 and 1). The fraction represents percentage of completed change (e.g. scroll) on |
| * target. Called only when {@link #isDirectMapping()} is false. |
| * |
| * @param fraction Fraction between 0 to 1. |
| * @see #isDirectMapping() |
| */ |
| public void update(float fraction) { |
| } |
| |
| /** |
| * Returns true if the ParallaxTarget is directly mapping from source value, |
| * {@link #directUpdate(Number)} will be used to update value, otherwise update(fraction) will |
| * be called to update value. Default implementation returns false. |
| * |
| * @return True if direct mapping, false otherwise. |
| * @see #directUpdate(Number) |
| * @see #update(float) |
| */ |
| public boolean isDirectMapping() { |
| return false; |
| } |
| |
| /** |
| * Directly update the target using a float or int value. Called when {@link #isDirectMapping()} |
| * is true. |
| * |
| * @param value Either int or float value. |
| * @see #isDirectMapping() |
| */ |
| public void directUpdate(Number value) { |
| } |
| |
| /** |
| * PropertyValuesHolderTarget is an implementation of {@link ParallaxTarget} that uses |
| * {@link PropertyValuesHolder} to update the target object. |
| */ |
| public static final class PropertyValuesHolderTarget extends ParallaxTarget { |
| |
| /** |
| * We simulate a parallax effect on target object using an ObjectAnimator. PSEUDO_DURATION |
| * is used on the ObjectAnimator. |
| */ |
| private static final long PSEUDO_DURATION = 1000000; |
| |
| private final ObjectAnimator mAnimator; |
| private float mFraction; |
| |
| public PropertyValuesHolderTarget(Object targetObject, PropertyValuesHolder values) { |
| mAnimator = ObjectAnimator.ofPropertyValuesHolder(targetObject, values); |
| mAnimator.setInterpolator(new LinearInterpolator()); |
| mAnimator.setDuration(PSEUDO_DURATION); |
| } |
| |
| @Override |
| public void update(float fraction) { |
| mFraction = fraction; |
| mAnimator.setCurrentPlayTime((long) (PSEUDO_DURATION * fraction)); |
| } |
| |
| } |
| |
| /** |
| * DirectPropertyTarget is to support direct mapping into either Integer Property or Float |
| * Property. App uses convenient method {@link ParallaxEffect#target(Object, Property)} to |
| * add a direct mapping. |
| * @param <T> Type of target object. |
| * @param <V> Type of value, either Integer or Float. |
| */ |
| public static final class DirectPropertyTarget<T extends Object, V extends Number> |
| extends ParallaxTarget { |
| |
| Object mObject; |
| Property<T, V> mProperty; |
| |
| /** |
| * @param targetObject Target object for perform Parallax |
| * @param property Target property, either an Integer Property or a Float Property. |
| */ |
| public DirectPropertyTarget(Object targetObject, Property<T, V> property) { |
| mObject = targetObject; |
| mProperty = property; |
| } |
| |
| /** |
| * Returns true as DirectPropertyTarget receives a number to update Property in |
| * {@link #directUpdate(Number)}. |
| */ |
| @Override |
| public boolean isDirectMapping() { |
| return true; |
| } |
| |
| @Override |
| @SuppressWarnings("unchecked") |
| public void directUpdate(Number value) { |
| mProperty.set((T) mObject, (V) value); |
| } |
| } |
| } |