1 files changed, 78 insertions, 0 deletions
diff --git a/android/view/animation/AnticipateInterpolator.java b/android/view/animation/AnticipateInterpolator.java
new file mode 100644
index 00000000..7a837c37
--- /dev/null
+++ b/android/view/animation/AnticipateInterpolator.java
@@ -0,0 +1,78 @@
+/*
+ * 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 starts backward then flings forward.
+ */
+@HasNativeInterpolator
+public class AnticipateInterpolator extends BaseInterpolator implements NativeInterpolatorFactory {
+    private final float mTension;
+
+    public AnticipateInterpolator() {
+        mTension = 2.0f;
+    }
+
+    /**
+     * @param tension Amount of anticipation. When tension equals 0.0f, there is
+     *                no anticipation and the interpolator becomes a simple
+     *                acceleration interpolator.
+     */
+    public AnticipateInterpolator(float tension) {
+        mTension = tension;
+    }
+
+    public AnticipateInterpolator(Context context, AttributeSet attrs) {
+        this(context.getResources(), context.getTheme(), attrs);
+    }
+
+    /** @hide */
+    public AnticipateInterpolator(Resources res, Theme theme, AttributeSet attrs) {
+        TypedArray a;
+        if (theme != null) {
+            a = theme.obtainStyledAttributes(attrs, R.styleable.AnticipateInterpolator, 0, 0);
+        } else {
+            a = res.obtainAttributes(attrs, R.styleable.AnticipateInterpolator);
+        }
+
+        mTension = a.getFloat(R.styleable.AnticipateInterpolator_tension, 2.0f);
+        setChangingConfiguration(a.getChangingConfigurations());
+        a.recycle();
+    }
+
+    public float getInterpolation(float t) {
+        // a(t) = t * t * ((tension + 1) * t - tension)
+        return t * t * ((mTension + 1) * t - mTension);
+    }
+
+    /** @hide */
+    @Override
+    public long createNativeInterpolator() {
+        return NativeInterpolatorFactoryHelper.createAnticipateInterpolator(mTension);
+    }
+}