| /* |
| * Copyright (C) 2009 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 android.view.animation; |
| |
| import static com.android.internal.R.styleable.AnticipateOvershootInterpolator; |
| import static com.android.internal.R.styleable.AnticipateOvershootInterpolator_extraTension; |
| import static com.android.internal.R.styleable.AnticipateOvershootInterpolator_tension; |
| |
| 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 com.android.internal.view.animation.HasNativeInterpolator; |
| import com.android.internal.view.animation.NativeInterpolatorFactory; |
| import com.android.internal.view.animation.NativeInterpolatorFactoryHelper; |
| |
| /** |
| * An interpolator where the change starts backward then flings forward and overshoots |
| * the target value and finally goes back to the final value. |
| */ |
| @HasNativeInterpolator |
| public class AnticipateOvershootInterpolator extends BaseInterpolator |
| implements NativeInterpolatorFactory { |
| private final float mTension; |
| |
| public AnticipateOvershootInterpolator() { |
| mTension = 2.0f * 1.5f; |
| } |
| |
| /** |
| * @param tension Amount of anticipation/overshoot. When tension equals 0.0f, |
| * there is no anticipation/overshoot and the interpolator becomes |
| * a simple acceleration/deceleration interpolator. |
| */ |
| public AnticipateOvershootInterpolator(float tension) { |
| mTension = tension * 1.5f; |
| } |
| |
| /** |
| * @param tension Amount of anticipation/overshoot. When tension equals 0.0f, |
| * there is no anticipation/overshoot and the interpolator becomes |
| * a simple acceleration/deceleration interpolator. |
| * @param extraTension Amount by which to multiply the tension. For instance, |
| * to get the same overshoot as an OvershootInterpolator with |
| * a tension of 2.0f, you would use an extraTension of 1.5f. |
| */ |
| public AnticipateOvershootInterpolator(float tension, float extraTension) { |
| mTension = tension * extraTension; |
| } |
| |
| public AnticipateOvershootInterpolator(Context context, AttributeSet attrs) { |
| this(context.getResources(), context.getTheme(), attrs); |
| } |
| |
| /** @hide */ |
| public AnticipateOvershootInterpolator(Resources res, Theme theme, AttributeSet attrs) { |
| TypedArray a; |
| if (theme != null) { |
| a = theme.obtainStyledAttributes(attrs, AnticipateOvershootInterpolator, 0, 0); |
| } else { |
| a = res.obtainAttributes(attrs, AnticipateOvershootInterpolator); |
| } |
| |
| mTension = a.getFloat(AnticipateOvershootInterpolator_tension, 2.0f) * |
| a.getFloat(AnticipateOvershootInterpolator_extraTension, 1.5f); |
| setChangingConfiguration(a.getChangingConfigurations()); |
| a.recycle(); |
| } |
| |
| private static float a(float t, float s) { |
| return t * t * ((s + 1) * t - s); |
| } |
| |
| private static float o(float t, float s) { |
| return t * t * ((s + 1) * t + s); |
| } |
| |
| public float getInterpolation(float t) { |
| // a(t, s) = t * t * ((s + 1) * t - s) |
| // o(t, s) = t * t * ((s + 1) * t + s) |
| // f(t) = 0.5 * a(t * 2, tension * extraTension), when t < 0.5 |
| // f(t) = 0.5 * (o(t * 2 - 2, tension * extraTension) + 2), when t <= 1.0 |
| if (t < 0.5f) return 0.5f * a(t * 2.0f, mTension); |
| else return 0.5f * (o(t * 2.0f - 2.0f, mTension) + 2.0f); |
| } |
| |
| /** @hide */ |
| @Override |
| public long createNativeInterpolator() { |
| return NativeInterpolatorFactoryHelper.createAnticipateOvershootInterpolator(mTension); |
| } |
| } |