1 /* 2 * Copyright (C) 2007 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.Resources; 21 import android.content.res.Resources.Theme; 22 import android.content.res.TypedArray; 23 import android.util.AttributeSet; 24 25 import com.android.internal.R; 26 import com.android.internal.view.animation.HasNativeInterpolator; 27 import com.android.internal.view.animation.NativeInterpolatorFactory; 28 import com.android.internal.view.animation.NativeInterpolatorFactoryHelper; 29 30 /** 31 * An interpolator where the rate of change starts out quickly and 32 * and then decelerates. 33 * 34 */ 35 @HasNativeInterpolator 36 public class DecelerateInterpolator extends BaseInterpolator implements NativeInterpolatorFactory { DecelerateInterpolator()37 public DecelerateInterpolator() { 38 } 39 40 /** 41 * Constructor 42 * 43 * @param factor Degree to which the animation should be eased. Setting factor to 1.0f produces 44 * an upside-down y=x^2 parabola. Increasing factor above 1.0f exaggerates the 45 * ease-out effect (i.e., it starts even faster and ends evens slower). 46 */ DecelerateInterpolator(float factor)47 public DecelerateInterpolator(float factor) { 48 mFactor = factor; 49 } 50 DecelerateInterpolator(Context context, AttributeSet attrs)51 public DecelerateInterpolator(Context context, AttributeSet attrs) { 52 this(context.getResources(), context.getTheme(), attrs); 53 } 54 55 /** @hide */ DecelerateInterpolator(Resources res, Theme theme, AttributeSet attrs)56 public DecelerateInterpolator(Resources res, Theme theme, AttributeSet attrs) { 57 TypedArray a; 58 if (theme != null) { 59 a = theme.obtainStyledAttributes(attrs, R.styleable.DecelerateInterpolator, 0, 0); 60 } else { 61 a = res.obtainAttributes(attrs, R.styleable.DecelerateInterpolator); 62 } 63 64 mFactor = a.getFloat(R.styleable.DecelerateInterpolator_factor, 1.0f); 65 setChangingConfiguration(a.getChangingConfigurations()); 66 a.recycle(); 67 } 68 getInterpolation(float input)69 public float getInterpolation(float input) { 70 float result; 71 if (mFactor == 1.0f) { 72 result = (float)(1.0f - (1.0f - input) * (1.0f - input)); 73 } else { 74 result = (float)(1.0f - Math.pow((1.0f - input), 2 * mFactor)); 75 } 76 return result; 77 } 78 79 private float mFactor = 1.0f; 80 81 /** @hide */ 82 @Override createNativeInterpolator()83 public long createNativeInterpolator() { 84 return NativeInterpolatorFactoryHelper.createDecelerateInterpolator(mFactor); 85 } 86 } 87