Andriod 通用按钮文本点击效果

按钮点击效果，背景透明度变化。

继承Button，Button有点击效果。

继承LinearLayout，LinearLayout有点击效果。

```

import android.animation.AnimatorSet;

import android.animation.ObjectAnimator;

import android.annotation.SuppressLint;

import android.content.Context;

import android.util.AttributeSet;

import android.view.MotionEvent;

import android.view.View;

import android.widget.Button;

import android.widget.LinearLayout;

import androidx.annotation.Nullable;

@SuppressLint("AppCompatCustomView")

public class AnimButton extends Button {

private static final float FROM_VALUE =1.0f;

    private static final float TO_VALUE =0.94f;

    private static final float ALPHA_VALUE =0.8f;

    private AnimatorSetanimatorSet =new AnimatorSet();

    public AnimButton(Context context) {

super(context);

        init();

    }

public AnimButton(Context context, @Nullable AttributeSet attrs) {

super(context, attrs);

        init();

    }

public AnimButton(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {

super(context, attrs, defStyleAttr);

        init();

    }

public AnimButton(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {

super(context, attrs, defStyleAttr, defStyleRes);

        init();

    }

private void init() {

setClickable(true);

    }

@Override

    protected void onWindowVisibilityChanged(int visibility) {

super.onWindowVisibilityChanged(visibility);

        if (visibility ==0) {

setAlpha(FROM_VALUE);

            setScaleX(FROM_VALUE);

            setScaleY(FROM_VALUE);

        }

}

@Override

    public boolean onTouchEvent(MotionEvent event) {

if (isClickable() && isEnabled()) {

if (event.getAction() == MotionEvent.ACTION_DOWN) {

animOne(this);

            }else if (event.getAction() == MotionEvent.ACTION_UP) {

animNormal(this);

            }else if (event.getAction() == MotionEvent.ACTION_CANCEL) {

animNormal(this);

            }

}

return super.onTouchEvent(event);

    }

private void animNormal(View view) {

animatorSet.setDuration(250);

        ObjectAnimator scaleX = ObjectAnimator.ofFloat(view, "scaleX", TO_VALUE, FROM_VALUE);

        ObjectAnimator scaleY = ObjectAnimator.ofFloat(view, "scaleY", TO_VALUE, FROM_VALUE);

        ObjectAnimator alpha = ObjectAnimator.ofFloat(view, "alpha", ALPHA_VALUE, FROM_VALUE);

        animatorSet.play(scaleX).with(scaleY).with(alpha);

        animatorSet.start();

    }

private void animOne(View view) {

animatorSet.setDuration(200);

        ObjectAnimator scaleX = ObjectAnimator.ofFloat(view, "scaleX", FROM_VALUE, TO_VALUE);

        ObjectAnimator scaleY = ObjectAnimator.ofFloat(view, "scaleY", FROM_VALUE, TO_VALUE);

        ObjectAnimator alpha = ObjectAnimator.ofFloat(view, "alpha", FROM_VALUE, ALPHA_VALUE);

        animatorSet.play(scaleX).with(scaleY).with(alpha);

        animatorSet.start();

    }

}

```