自定义控件--垂直滑动布局

野性酷女 2022-08-12 12:59 175阅读 0赞

![20140925141607109][]

自定义一个垂直的布局

package com.zyh.verticalscrollview;
    
    import android.content.Context;
    import android.util.AttributeSet;
    import android.view.GestureDetector;
    import android.view.GestureDetector.OnGestureListener;
    import android.view.MotionEvent;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.Scroller;
    
    public class VerticalSrcollView extends ViewGroup {
    
    	public VerticalSrcollView(Context context, AttributeSet attrs, int defStyle) {
    		super(context, attrs, defStyle);
    	}
    
    	private Context cx;
    
    	public VerticalSrcollView(Context context) {
    		super(context);
    		this.cx = context;
    		init();
    	}
    
    	public VerticalSrcollView(Context context, AttributeSet attrs) {
    		super(context, attrs);
    		this.cx = context;
    		init();
    	}
    
    	private void init() {
    		scroller = new Scroller(cx);
    		detector = new GestureDetector(cx, new OnGestureListener() {
    			public boolean onSingleTapUp(MotionEvent e) {
    				return false;
    			}
    
    			public void onShowPress(MotionEvent e) {
    			}
    
    			/**
    			 * 当手指正常滑动时回调
    			 */
    			public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
    				if ((distanceY < 0 && curId == 0) || (distanceY > 0 && curId == getChildCount() - 1)) {// 首页跟末尾页超出边界
    					return false;
    				}
    				scrollBy(0, (int) distanceY);
    				return false;
    			}
    
    			public void onLongPress(MotionEvent e) {
    			}
    
    			/**
    			 * 当快速滑动式回调
    			 */
    			public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
    				System.out.println("vY：" + velocityY);
    				System.out.println("cr：" + curId);
    				if (velocityY > 0 && curId > 0) {
    					moveToDest(curId - 1);
    				} else if (velocityY < 0 && curId < getChildCount() - 1) {
    					moveToDest(curId + 1);
    				} else {
    					moveToDest(curId);
    				}
    				isFling = true;
    				return false;
    			}
    
    			public boolean onDown(MotionEvent e) {
    				return false;
    			}
    		});
    	}
    
    	/**
    	 * 对子view进行排列布局
    	 */
    	@Override
    	protected void onLayout(boolean changed, int l, int t, int r, int b) {
    
    		for (int i = 0; i < getChildCount(); i++) {
    			View view = this.getChildAt(i);
    			view.layout(0, i * getHeight(), getWidth(), (i + 1) * getHeight());
    		}
    	}
    
    	/**
    	 * 必须对子View进行measure
    	 */
    	@Override
    	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    		super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    
    		for (int i = 0; i < getChildCount(); i++) {
    			View view = getChildAt(i);
    			view.measure(widthMeasureSpec, heightMeasureSpec);
    		}
    	}
    
    	private GestureDetector detector;
    	private Scroller scroller;
    	private int curId;// 当前子View的Id
    	private boolean isFling = false; // 是否发生快速滑动
    
    	@Override
    	public boolean onTouchEvent(MotionEvent event) {
    
    		detector.onTouchEvent(event);// 交给手势识别器
    
    		switch (event.getAction()) {
    			case MotionEvent.ACTION_UP:// 手指抬起
    				if (!isFling) moveToDest();
    				isFling = false;
    				break;
    			default:
    				break;
    		}
    		return true;
    	}
    
    	/**
    	 * ViewGroup的内容移动到合适位置
    	 */
    	private void moveToDest() {
    		// 计算当前子view的id
    		int destId = (getHeight() / 2 + getScrollY()) / getHeight();
    		moveToDest(destId);
    	}
    
    	/**
    	 * 将指定下标destId的控件移到屏幕
    	 * @param destId
    	 */
    	private void moveToDest(int destId) {
    		curId = destId;
    		if (destId > getChildCount() - 1) destId = getChildCount() - 1;
    		int distance = destId * getHeight() - getScrollY();// 需要移动的距离
    		// scrollBy(0, distance);
    		scroller.startScroll(0, getScrollY(), 0, distance);
    		invalidate();// 刷新视图,执行computeScroll()
    	}
    
    	@Override
    	public void computeScroll() {
    		if (scroller.computeScrollOffset()) {
    			scrollTo(0, scroller.getCurrY());
    			invalidate();
    		}
    	}
    
    	public void setOnPageScrollListener(IPageChangeListener changeListener) {
    		this.pageChangeListener = changeListener;
    	}
    
    	private IPageChangeListener pageChangeListener;
    
    	/**
    	 * 页面滑动监听器
    	 * @author zyh
    	 */
    	public interface IPageChangeListener {
    		public void changeTo(int pageId);
    	}
    }

[20140925141607109]: /images/20220810/11b1bebf751d40f0af44b93620dd2b4f.png