1 /* 2 * Copyright (C) 2006 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package android.view.animation; 18 19 import android.content.Context; 20 import android.content.res.TypedArray; 21 import android.util.AttributeSet; 22 23 /** 24 * An interpolator where the rate of change starts out slowly and 25 * and then accelerates. 26 * 27 */ 28 public class AccelerateInterpolator implements Interpolator { 29 private final float mFactor; 30 private final double mDoubleFactor; 31 AccelerateInterpolator()32 public AccelerateInterpolator() { 33 mFactor = 1.0f; 34 mDoubleFactor = 2.0; 35 } 36 37 /** 38 * Constructor 39 * 40 * @param factor Degree to which the animation should be eased. Seting 41 * factor to 1.0f produces a y=x^2 parabola. Increasing factor above 42 * 1.0f exaggerates the ease-in effect (i.e., it starts even 43 * slower and ends evens faster) 44 */ AccelerateInterpolator(float factor)45 public AccelerateInterpolator(float factor) { 46 mFactor = factor; 47 mDoubleFactor = 2 * mFactor; 48 } 49 AccelerateInterpolator(Context context, AttributeSet attrs)50 public AccelerateInterpolator(Context context, AttributeSet attrs) { 51 TypedArray a = 52 context.obtainStyledAttributes(attrs, com.android.internal.R.styleable.AccelerateInterpolator); 53 54 mFactor = a.getFloat(com.android.internal.R.styleable.AccelerateInterpolator_factor, 1.0f); 55 mDoubleFactor = 2 * mFactor; 56 57 a.recycle(); 58 } 59 getInterpolation(float input)60 public float getInterpolation(float input) { 61 if (mFactor == 1.0f) { 62 return input * input; 63 } else { 64 return (float)Math.pow(input, mDoubleFactor); 65 } 66 } 67 } 68