/* * 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 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.R; 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 flings forward and overshoots the last value * then comes back. */ @HasNativeInterpolator public class OvershootInterpolator extends BaseInterpolator implements NativeInterpolatorFactory { private final float mTension; public OvershootInterpolator() { mTension = 2.0f; } /** * @param tension Amount of overshoot. When tension equals 0.0f, there is * no overshoot and the interpolator becomes a simple * deceleration interpolator. */ public OvershootInterpolator(float tension) { mTension = tension; } public OvershootInterpolator(Context context, AttributeSet attrs) { this(context.getResources(), context.getTheme(), attrs); } /** @hide */ public OvershootInterpolator(Resources res, Theme theme, AttributeSet attrs) { TypedArray a; if (theme != null) { a = theme.obtainStyledAttributes(attrs, R.styleable.OvershootInterpolator, 0, 0); } else { a = res.obtainAttributes(attrs, R.styleable.OvershootInterpolator); } mTension = a.getFloat(R.styleable.OvershootInterpolator_tension, 2.0f); setChangingConfiguration(a.getChangingConfigurations()); a.recycle(); } public float getInterpolation(float t) { // _o(t) = t * t * ((tension + 1) * t + tension) // o(t) = _o(t - 1) + 1 t -= 1.0f; return t * t * ((mTension + 1) * t + mTension) + 1.0f; } /** @hide */ @Override public long createNativeInterpolator() { return NativeInterpolatorFactoryHelper.createOvershootInterpolator(mTension); } }