NineOldAndroidsDemos 学习(3) PathAnimationActivity

sfshine

于 2013-10-31 21:07:23 发布

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分类专栏： Android

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本文介绍了一种使用ObjectAnimator实现视图沿预设路径运动的方法，这种方法常用于复杂动画效果的制作。通过定义路径并利用PathEvaluator更新视图位置，实现了按钮沿曲线平滑移动的动画效果。

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这个也很简单,其实就是为了让view 可以按照预设的路径运动,这个在很多变态的动画中非常有用

/*
 * Copyright (C) 2012 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.jakewharton.nineoldandroids.sample.pathanimation;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

import com.jakewharton.nineoldandroids.sample.R;
import com.nineoldandroids.animation.ObjectAnimator;
import com.nineoldandroids.view.animation.AnimatorProxy;

public class PathAnimationActivity extends Activity {
    Button mButton;
    AnimatorProxy mButtonProxy;
    PathEvaluator mEvaluator = new PathEvaluator();

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.pathanimator);

        mButton = (Button) findViewById(R.id.button);
        //
        mButtonProxy = AnimatorProxy.wrap(mButton);

        // Set up the path we're animating along
        AnimatorPath path = new AnimatorPath();
        path.moveTo(0, 0);
        path.lineTo(0, 300);
        path.curveTo(100, 0, 300, 900, 400, 500);

        // Set up the animation 其中buttonLoc是注册用来在后面调用getButtonLoc的,发现他们不区分大小写?
        final ObjectAnimator anim = ObjectAnimator.ofObject(this, "buttonLoc",
                new PathEvaluator(), path.getPoints().toArray());
        anim.setDuration(1000);

        mButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                anim.start();
            }
        });

    }

    /**
     * We need this setter to translate between the information the animator
     * produces (a new "PathPoint" describing the current animated location)
     * and the information that the button requires (an xy location). The
     * setter will be called by the ObjectAnimator given the 'buttonLoc'
     * property string.
     */
    public void setButtonLoc(PathPoint newLoc) {
        mButtonProxy.setTranslationX(newLoc.mX);
        mButtonProxy.setTranslationY(newLoc.mY);
    }

}

<?xml version="1.0" encoding="utf-8"?>
<!-- Copyright (C) 2011 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.
-->
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical"
    android:id="@+id/container" >

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Animate Me"
        android:id="@+id/button"/>

</LinearLayout>