| /* |
| * Copyright 2013 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 com.example.android.interactivechart; |
| |
| import android.content.Context; |
| import android.os.SystemClock; |
| import android.view.animation.DecelerateInterpolator; |
| import android.view.animation.Interpolator; |
| |
| /** |
| * A simple class that animates double-touch zoom gestures. Functionally similar to a {@link |
| * android.widget.Scroller}. |
| */ |
| public class Zoomer { |
| /** |
| * The interpolator, used for making zooms animate 'naturally.' |
| */ |
| private Interpolator mInterpolator; |
| |
| /** |
| * The total animation duration for a zoom. |
| */ |
| private int mAnimationDurationMillis; |
| |
| /** |
| * Whether or not the current zoom has finished. |
| */ |
| private boolean mFinished = true; |
| |
| /** |
| * The current zoom value; computed by {@link #computeZoom()}. |
| */ |
| private float mCurrentZoom; |
| |
| /** |
| * The time the zoom started, computed using {@link android.os.SystemClock#elapsedRealtime()}. |
| */ |
| private long mStartRTC; |
| |
| /** |
| * The destination zoom factor. |
| */ |
| private float mEndZoom; |
| |
| public Zoomer(Context context) { |
| mInterpolator = new DecelerateInterpolator(); |
| mAnimationDurationMillis = context.getResources().getInteger( |
| android.R.integer.config_shortAnimTime); |
| } |
| |
| /** |
| * Forces the zoom finished state to the given value. Unlike {@link #abortAnimation()}, the |
| * current zoom value isn't set to the ending value. |
| * |
| * @see android.widget.Scroller#forceFinished(boolean) |
| */ |
| public void forceFinished(boolean finished) { |
| mFinished = finished; |
| } |
| |
| /** |
| * Aborts the animation, setting the current zoom value to the ending value. |
| * |
| * @see android.widget.Scroller#abortAnimation() |
| */ |
| public void abortAnimation() { |
| mFinished = true; |
| mCurrentZoom = mEndZoom; |
| } |
| |
| /** |
| * Starts a zoom from 1.0 to (1.0 + endZoom). That is, to zoom from 100% to 125%, endZoom should |
| * by 0.25f. |
| * |
| * @see android.widget.Scroller#startScroll(int, int, int, int) |
| */ |
| public void startZoom(float endZoom) { |
| mStartRTC = SystemClock.elapsedRealtime(); |
| mEndZoom = endZoom; |
| |
| mFinished = false; |
| mCurrentZoom = 1f; |
| } |
| |
| /** |
| * Computes the current zoom level, returning true if the zoom is still active and false if the |
| * zoom has finished. |
| * |
| * @see android.widget.Scroller#computeScrollOffset() |
| */ |
| public boolean computeZoom() { |
| if (mFinished) { |
| return false; |
| } |
| |
| long tRTC = SystemClock.elapsedRealtime() - mStartRTC; |
| if (tRTC >= mAnimationDurationMillis) { |
| mFinished = true; |
| mCurrentZoom = mEndZoom; |
| return false; |
| } |
| |
| float t = tRTC * 1f / mAnimationDurationMillis; |
| mCurrentZoom = mEndZoom * mInterpolator.getInterpolation(t); |
| return true; |
| } |
| |
| /** |
| * Returns the current zoom level. |
| * |
| * @see android.widget.Scroller#getCurrX() |
| */ |
| public float getCurrZoom() { |
| return mCurrentZoom; |
| } |
| } |