| /* |
| * Copyright 2018 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.core.animation; |
| |
| import android.content.Context; |
| import android.content.res.Resources; |
| import android.content.res.Resources.Theme; |
| import android.content.res.TypedArray; |
| import android.util.AttributeSet; |
| |
| import androidx.annotation.FloatRange; |
| import androidx.annotation.NonNull; |
| |
| /** |
| * An interpolator where the rate of change starts out slowly and |
| * and then accelerates. |
| */ |
| public class AccelerateInterpolator implements Interpolator { |
| private final float mFactor; |
| private final double mDoubleFactor; |
| |
| /** |
| * Creates a new instance of {@link AccelerateInterpolator} with y=x^2 parabola. |
| */ |
| public AccelerateInterpolator() { |
| mFactor = 1.0f; |
| mDoubleFactor = 2.0; |
| } |
| |
| /** |
| * Creates a new instance of {@link AccelerateInterpolator}. |
| * |
| * @param factor Degree to which the animation should be eased. Setting |
| * factor to 1.0f produces a y=x^2 parabola. Increasing factor above |
| * 1.0f exaggerates the ease-in effect (i.e., it starts even |
| * slower and ends evens faster) |
| */ |
| public AccelerateInterpolator(float factor) { |
| mFactor = factor; |
| mDoubleFactor = 2 * mFactor; |
| } |
| |
| /** |
| * Creates a new instance of {@link AccelerateInterpolator} from XML. |
| * |
| * @param context The context. |
| * @param attrs The AttributeSet from XML. |
| */ |
| public AccelerateInterpolator(@NonNull Context context, @NonNull AttributeSet attrs) { |
| this(context.getResources(), context.getTheme(), attrs); |
| } |
| |
| AccelerateInterpolator(Resources res, Theme theme, AttributeSet attrs) { |
| TypedArray a; |
| if (theme != null) { |
| a = theme.obtainStyledAttributes(attrs, |
| AndroidResources.STYLEABLE_ACCELERATE_INTERPOLATOR, 0, 0); |
| } else { |
| a = res.obtainAttributes(attrs, AndroidResources.STYLEABLE_ACCELERATE_INTERPOLATOR); |
| } |
| |
| mFactor = a.getFloat(AndroidResources.STYLEABLE_ACCELERATE_INTERPOLATOR_FACTOR, 1.0f); |
| mDoubleFactor = 2 * mFactor; |
| a.recycle(); |
| } |
| |
| @Override |
| @FloatRange(from = 0, to = 1) |
| public float getInterpolation(@FloatRange(from = 0, to = 1) float input) { |
| if (mFactor == 1.0f) { |
| return input * input; |
| } else { |
| return (float) Math.pow(input, mDoubleFactor); |
| } |
| } |
| } |