Android 仿百度手机助手首页滑动效果

朴灿烈づ我的快乐病毒、 2022-08-01 16:34 210阅读 0赞

今天看到百度手机助手首页上的滑动效果非常nice，主要功能归结为：

> 1、当手指上划时，顶部搜索栏随手指移动距离而缩小到隐藏，隐藏后内容还是可以继续移动  
> 2、手指下滑时，当显示内容达到第一个时，顶部搜索栏逐渐变大显示

自己实现用到的知识：

> 1、android事件传递机制：捕获到手指移动事件后，根据移动的方向与功能栏的高度对功能栏大小进行修改 。由于listview与功能栏高度要同时移动，需要重写了dispatchTouchEvent方法，直接调用this.onTouchEvent(ev);进行所有事件的捕捉分析  
> 2、自定义viewgroup：测量view高度

额外添加的功能：

> 功能栏高度<=1/2时，会自动隐藏  
> 功能栏高度>1/2时，会自动改变到最大值  
> 代码实现在MotionEvent.ACTION\_UP

效果展示，录像工具太卡，将就着看吧：  
![这里写图片描述][20150701121815382]![这里写图片描述][20150701121833681]

本来想做成一个通用的工具类，工作比较忙就偷懒了，在ScrollHideLayout类中定义了两个常量，直接写死了需要被捕获滑动事件与改变大小的viewID，使用时可以自己再次封装，或者直接修改ID，虽然不推荐，但是省事哈！！！

> private int scrollViewId = R.id.scrollView; //滑动后变化功能栏的viewid  
> private int changeViewId = R.id.changeView;// 大小随之变化的viewid

完整代码：  
1、自定义的viewgroup

package com.example.materialtest.widget;
    
    import android.animation.ObjectAnimator;
    import android.animation.ValueAnimator;
    import android.animation.ValueAnimator.AnimatorUpdateListener;
    import android.content.Context;
    import android.graphics.PointF;
    import android.graphics.RectF;
    import android.support.v4.view.ViewCompat;
    import android.util.AttributeSet;
    import android.util.Log;
    import android.view.MotionEvent;
    import android.view.View;
    import android.widget.AbsListView;
    import android.widget.AbsListView.OnScrollListener;
    import android.widget.LinearLayout;
    
    import com.example.materialtest.R;
    
    /** * 滑动隐藏控件 * * */
    public class ScrollHideLayout extends LinearLayout implements OnScrollListener { 
    
        private static final String TAG = ScrollHideLayout.class.getSimpleName();
    
        private int scrollViewId = R.id.scrollView;
        private int changeViewId = R.id.changeView;
    
        private int changeViewMaxHeight;
        private PointF touchPoint = new PointF();
    
        private View changeView;
        private AbsListView scrollView;
    
        private RectF scrollViewRect = new RectF();
    
        public ScrollHideLayout(Context context, AttributeSet attrs) {
            this(context, attrs, 0);
        }
    
        public ScrollHideLayout(Context context) {
            this(context, null);
        }
    
        public ScrollHideLayout(Context context, AttributeSet attrs, int defStyleAttr) {
            super(context, attrs, defStyleAttr);
        }
    
        @Override
        protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
            super.onMeasure(widthMeasureSpec, heightMeasureSpec);
            int len = getChildCount();
    
            if (null == changeView || null == scrollView) {
                for (int i = 0; i < len; i++) {
                    View child = getChildAt(i);
                    // 滑动控件
                    if (child.getId() == scrollViewId && child instanceof AbsListView) {
                        scrollView = (AbsListView) child;
                        setScrollViewRect();
                    }
                    if (child.getId() == changeViewId) {
                        changeView = child;
                        changeView.setMinimumHeight(0);
    
                        changeViewMaxHeight = changeView.getMeasuredHeight();
                    }
    
                }
            } else {
                // 重新计算滚动控件的位置
                setScrollViewRect();
            }
    
            Log.i(TAG, "find scrollview and changeView :" + scrollViewId + "," + changeViewId);
            Log.i(TAG, "scrollview rect:" + changeView.getLayoutParams().getClass().getCanonicalName());
    
            if (null == changeView || null == scrollView) {
                throw new IllegalArgumentException("could not foud changeView or scrollView");
            }
        }
    
        private void setScrollViewRect() {
            // 获取滚动控件的范围
            float left = ViewCompat.getX(scrollView);
            float top = ViewCompat.getY(scrollView);
            float right = left + scrollView.getMeasuredWidth();
            float bottom = top + scrollView.getMeasuredHeight();
    
            scrollViewRect.left = left;
            scrollViewRect.top = top;
            scrollViewRect.right = right;
            scrollViewRect.bottom = bottom;
        }
    
        @Override
        public boolean onTouchEvent(MotionEvent ev) {
    
            if (!isScrollViewTouch(ev)) {
                return false;
            }
    
            final android.view.ViewGroup.LayoutParams params = changeView.getLayoutParams();
    
            switch (ev.getAction()) {
    
            case MotionEvent.ACTION_DOWN:
                touchPoint.x = ev.getX();
                touchPoint.y = ev.getY();
                break;
    
            case MotionEvent.ACTION_MOVE:
    
                int height = params.height;
    
                // 滑动控件移动事件
                float distance = ev.getY() - touchPoint.y;
    
                // 最大高度，不能向下拖动
                if (height >= changeViewMaxHeight && distance > 0) {
                    touchPoint.y = ev.getY();
                    break;
                }
                // 已经隐藏 不能向上滑动
                if (height <= 0 && distance < 0) {
                    touchPoint.y = ev.getY();
                    break;
                }
    
                // listview到达顶部才可以向下拖动
                if (distance > 0 && scrollView.getFirstVisiblePosition() != 0) {
                    touchPoint.y = ev.getY();
                    break;
                }
    
                height = Math.round(height + distance);
    
                if (height > changeViewMaxHeight) {
                    height = changeViewMaxHeight;
                }
    
                if (height <= 0 && distance < 0) {
                    height = 0;
                    // TODO onhide
                }
    
                params.height = height;
    
                changeView.requestLayout();
    
                touchPoint.x = ev.getX();
                touchPoint.y = ev.getY();
    
                break;
    
            case MotionEvent.ACTION_CANCEL:
            case MotionEvent.ACTION_UP:
    
                // 高度超过一半，自动隐藏
                int[] values = null;
                // 向上滑动,剩余位置不足一半
                if (params.height <= changeViewMaxHeight / 2) {
                    values = new int[] { params.height, 0 };
                } else {
                    values = new int[] { params.height, changeViewMaxHeight };
                }
    
                if (null != values) {
                    ValueAnimator anim = ObjectAnimator.ofInt(changeView, "translationY", values);
                    anim.addUpdateListener(new AnimatorUpdateListener() {
    
                        @Override
                        public void onAnimationUpdate(ValueAnimator animation) {
                            int value = (int) animation.getAnimatedValue();
                            params.height = value;
                            changeView.requestLayout();
                        }
                    });
                    anim.setDuration(250);
                    anim.setTarget(changeView);
                    anim.start();
                }
    
                break;
            }
    
            return true;
        }
    
        @Override
        public boolean dispatchTouchEvent(MotionEvent ev) {
            // 直接拦截事件
            this.onTouchEvent(ev);
            return super.dispatchTouchEvent(ev);
        }
    
        private boolean isScrollViewTouch(MotionEvent ev) {
    
            float x = ev.getX();
            float y = ev.getY();
            return (x >= scrollViewRect.left && x <= scrollViewRect.right) && (y >= scrollViewRect.top && y <= scrollViewRect.bottom);
        }
    
        /** * @return Whether it is possible for the child view of this layout to * scroll up. Override this if the child view is a custom view. */
        public boolean canChildScrollUp() {
            if (android.os.Build.VERSION.SDK_INT < 14) {
                if (scrollView instanceof AbsListView) {
                    final AbsListView absListView = (AbsListView) scrollView;
                    return absListView.getChildCount() > 0
                            && (absListView.getFirstVisiblePosition() > 0 || absListView.getChildAt(0).getTop() < absListView.getPaddingTop());
                } else {
                    return ViewCompat.canScrollVertically(scrollView, -1) || scrollView.getScrollY() > 0;
                }
            } else {
                return ViewCompat.canScrollVertically(scrollView, -1);
            }
        }
    
        @Override
        public void onScrollStateChanged(AbsListView view, int scrollState) {
            // TODO Auto-generated method stub
    
        }
    
        @Override
        public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
            // TODO Auto-generated method stub
    
        }
    }

[20150701121815382]: https://img-blog.csdn.net/20150701121815382
[20150701121833681]: /images/20220731/57ba6dcaf5d54fc38f2d70672bb3a0c7.png