ObjectAnimator详解

ObjectAnimator继承自ValueAnimator，所以ValueAnimator所能使用的方法，ObjectAnimator都可以使用，ObjectAnimator同时也重写了几个方法，比如：ofInt() ofFloat()等

基本使用

//第一个参数：指定执行动画的控件，第二个参数：指定控件的属性，第三个参数是可变长参数
public static ObjectAnimator ofFloat(Object target, String propertyName, float... values) 

//透明度动画
ObjectAnimator animator = ObjectAnimator.ofFloat(view,"alpha",1,0,1);  
animator.setDuration(2000);  
animator.start(); 

//旋转动画：围绕x轴旋转
ObjectAnimator animator = ObjectAnimator.ofFloat(tv,"rotationX",0,270,0);  
animator.setDuration(2000);  
animator.start();

//旋转动画：围绕y轴旋转
ObjectAnimator animator = ObjectAnimator.ofFloat(tv,"rotationY",0,180,0);  
animator.setDuration(2000);  
animator.start();

//旋转动画:围绕z轴旋转
ObjectAnimator animator = ObjectAnimator.ofFloat(tv,"rotation",0,270,0);  
animator.setDuration(2000);  
animator.start();  

//平移动画:在x轴上平移
ObjectAnimator animator = ObjectAnimator.ofFloat(tv, "translationX", 0, 200, -200,0);  
animator.setDuration(2000);  
animator.start(); 

//平移动画:在y轴上平移
ObjectAnimator animator = ObjectAnimator.ofFloat(tv, "translationY", 0, 200, -100,0);  
animator.setDuration(2000);  
animator.start(); 

//缩放动画：在x轴缩放
ObjectAnimator animator = ObjectAnimator.ofFloat(tv, "scaleX", 0, 3, 1);  
animator.setDuration(2000);  
animator.start();

//缩放动画：在y轴上缩放
ObjectAnimator animator = ObjectAnimator.ofFloat(tv, "scaleY", 0, 3, 1);  
animator.setDuration(2000);  
animator.start(); 

ObjectAnimator动画原理

ObjectAnimator动画原理：如上图最后一步，根据属性值拼装成对应的set函数的名字，比如”scaleY”的拼接方法就是将属性的第一个字母强制大写后，与set拼接，也就是setScaleY,然后通过反射找到对应控件的setScaleY(float scaleY)函数，将当前数字值作为setScaleY(float scale)的参数将其传入。属性值得首字母大小写都可以，最终都会被强转成大写。View中都已经实现了相关的alpha rotation translate scale相关的set方法。

自定义ObjectAnimator属性

   ObjectAnimator objectAnimator = ObjectAnimator.ofInt(mCircleView,"pointRadius",0,200,100,200,50);
        objectAnimator.setDuration(1000);
        objectAnimator.start();

自定义Point

public class Ponit {
    private int mRadius;

    public Ponit() {
    }

    public Ponit(int mRadius) {
        this.mRadius = mRadius;
    }

    public int getRadius() {
        return mRadius;
    }

    public void setRadius(int mRadius) {
        this.mRadius = mRadius;
    }
}

自定义view

public class CircleView extends View {
    private Ponit mCurrentPoint = new Ponit();
    private Paint mPiant ;
    private int mScreenWidth;//屏幕宽度
    public CircleView(Context context) {
        this(context,null);
    }

    public CircleView(Context context, @Nullable AttributeSet attrs) {
        this(context, attrs,0);
    }

    public CircleView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        mPiant = new Paint(Paint.ANTI_ALIAS_FLAG);
        mPiant.setColor(Color.RED);
        mPiant.setStyle(Paint.Style.FILL);
        mScreenWidth = ((WindowManager)getContext().getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay().getWidth();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        if (mCurrentPoint != null){
            canvas.drawCircle(mScreenWidth/2,getY()+getPaddingTop(),mCurrentPoint.getRadius(),mPiant);
        }
    }
    public int getPointRadius(){  //这个get方法只作为默认值出现在这里的
        return 50;  
    }  
    public void setPointRadius(int radius){//这里set方法必须和ObjectAnimator中的属性值对应
        mCurrentPoint.setRadius(radius);
        invalidate();
    }
}

ObjectAnimator改变控件背景颜色

以TextView为类，改变其背景颜色，关键方法是继承View的控件都实现了这个方法

public void setBackgroundColor(int color); 

 ObjectAnimator objectAnimator = ObjectAnimator.ofInt(tv,"backgroundColor",0xfff10f0f,0xff0f94f1,0xffeaf804,0xfff92a0f);
        objectAnimator.setDuration(2000);
        objectAnimator.setEvaluator(new ArgbEvaluator());
        objectAnimator.start();