安卓项目实战之布局隐藏与展开效果的属性动画

效果如下：

点击箭头显示隐藏的布局，再次点击则又关闭，为了能有更好的用户体验，展开与收起伴随有动画效果，所以单纯的设置visibility属性值为gone和visible并不能体现出动画效果，因此我们选择使用属性动画来实现。

代码实现

1.布局代码如下

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com.ltl.mpiggybank.MainActivity" >

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#458EFD"
        android:padding="10dip" >

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerInParent="true"
            android:gravity="center_vertical"
            android:text="下拉展开动画"
            android:textColor="#ffffff"
            android:textSize="20sp" />
    </RelativeLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#548AEA"
        android:gravity="center"
        android:orientation="vertical" >

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="20dip"
            android:text="昨日收益(元)"
            android:textColor="#ffffff"
            android:textSize="16sp" />

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="0.00"
            android:textColor="#ffffff"
            android:textSize="45sp" />
    </LinearLayout>

    <LinearLayout
        android:id="@+id/linear_hidden"
        android:layout_width="match_parent"
        android:layout_height="120dip"
        android:background="#548AEA"
        android:gravity="center"
        android:orientation="vertical" >

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="20dip"
            android:text="显示的View"
            android:textColor="#ffffff"
            android:textSize="16sp" />

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="0.00"
            android:textColor="#ffffff"
            android:textSize="35sp" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#548AEA"
        android:gravity="center"
        android:onClick="onClick"
        android:orientation="vertical" >

        <ImageView
            android:id="@+id/my_iv"
            android:layout_width="25dip"
            android:layout_height="25dip"
            android:layout_margin="20dip"
            android:src="@drawable/scroll" />
    </LinearLayout>

</LinearLayout>

这里面代码并不多，也很简单，三个线性布局，里面装载着各自的控件，并且还设置了ID。按钮是一个线性布局，采用了onClick自身的点击事件。接下来，当点击了这个线性布局的时候，需要隐藏的控件最终到达一个高度，这个就是我们的目标值，只需要通过布局中的dp转换成像素就行了。

mDensity = getResources().getDisplayMetrics().density;
mHiddenViewMeasuredHeight = (int) (mDensity * 120 + 0.5);

这里是120就是我们布局里面定义的高度。

2.完整的Activity代码如下：

public class MainActivity extends ActionBarActivity {
    private LinearLayout mHiddenLayout;

    private float mDensity;

    private int mHiddenViewMeasuredHeight;

    private ImageView mIv;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.activity_main);

        mHiddenLayout = (LinearLayout) findViewById(R.id.linear_hidden);
        mIv = (ImageView) findViewById(R.id.my_iv);
       // 隐藏部分布局的高度
        mDensity = getResources().getDisplayMetrics().density;
        mHiddenViewMeasuredHeight = (int) (mDensity * 120 + 0.5);

    }

    public void onClick(View v) {
        if (mHiddenLayout.getVisibility() == View.GONE) {
            animateOpen(mHiddenLayout);
            animationIvOpen();
        } else {
            animateClose(mHiddenLayout);
            animationIvClose();
        }
    }

    private void animateOpen(View v) {
        v.setVisibility(View.VISIBLE);
        ValueAnimator animator = createDropAnimator(v, 0,
                mHiddenViewMeasuredHeight);
        animator.start();

    }

    private void animationIvOpen() {
        RotateAnimation animation = new RotateAnimation(0, 180,
                Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF,
                0.5f);
        animation.setFillAfter(true);
        animation.setDuration(100);
        mIv.startAnimation(animation);
    }

    private void animationIvClose() {
        RotateAnimation animation = new RotateAnimation(180, 0,
                Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF,
                0.5f);
        animation.setFillAfter(true);
        animation.setDuration(100);
        mIv.startAnimation(animation);
    }

    private void animateClose(final View view) {
        int origHeight = view.getHeight();
        ValueAnimator animator = createDropAnimator(view, origHeight, 0);
        animator.addListener(new AnimatorListenerAdapter() {
            @Override
            public void onAnimationEnd(Animator animation) {
                view.setVisibility(View.GONE);
            }

        });
        animator.start();
    }

    private ValueAnimator createDropAnimator(final View v, int start, int end) {
        ValueAnimator animator = ValueAnimator.ofInt(start, end);
        animator.addUpdateListener(new AnimatorUpdateListener() {

            @Override
            public void onAnimationUpdate(ValueAnimator arg0) {
                int value = (int) arg0.getAnimatedValue();
                ViewGroup.LayoutParams layoutParams = v.getLayoutParams();
                layoutParams.height = value;
                v.setLayoutParams(layoutParams);

            }
        });
        return animator;
    }

}

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https://blog.youkuaiyun.com/jarchie520/article/details/79009017