江阴网站开发招聘,托管网站是什么意思,网站构建培训,图盛网站建设一般进入APP都有欢迎界面#xff0c;基本都是水平滚动的#xff0c;今天和大家分享一个垂直滚动的例子。 先来看看效果把#xff1a; 首先是布局文件#xff1a; com.example.verticallinearlayout.VerticalLinearLayout xmlns:androidhttp://schemas.android.…一般进入APP都有欢迎界面基本都是水平滚动的今天和大家分享一个垂直滚动的例子。 先来看看效果把 首先是布局文件 com.example.verticallinearlayout.VerticalLinearLayout xmlns:androidhttp://schemas.android.com/apk/res/android xmlns:toolshttp://schemas.android.com/tools android:idid/id_main_ly android:layout_widthmatch_parent android:layout_heightfill_parent android:orientationvertical android:background#fff RelativeLayout android:layout_widthfill_parent android:layout_heightfill_parent android:backgrounddrawable/w02 Button android:layout_widthwrap_content android:layout_heightwrap_content android:texthello / /RelativeLayout RelativeLayout android:layout_widthfill_parent android:layout_heightfill_parent android:backgrounddrawable/w03 Button android:layout_widthwrap_content android:layout_heightwrap_content android:layout_centerInParenttrue android:background#fff android:texthello / /RelativeLayout RelativeLayout android:layout_widthfill_parent android:layout_heightfill_parent android:backgrounddrawable/w04 Button android:layout_widthwrap_content android:layout_heightwrap_content android:layout_centerInParenttrue android:texthello / /RelativeLayout RelativeLayout android:layout_widthfill_parent android:layout_heightfill_parent android:backgrounddrawable/w05 Button android:layout_widthwrap_content android:layout_heightwrap_content android:layout_centerInParenttrue android:texthello / /RelativeLayout /com.example.verticallinearlayout.VerticalLinearLayout 自定义的Layout了 package com.example.verticallinearlayout;import android.content.Context; import android.util.AttributeSet; import android.util.DisplayMetrics; import android.util.Log; import android.view.MotionEvent; import android.view.VelocityTracker; import android.view.View; import android.view.ViewGroup; import android.view.WindowManager; import android.widget.Scroller;public class VerticalLinearLayout extends ViewGroup {/*** 屏幕的高度*/private int mScreenHeight;/*** 手指按下时的getScrollY*/private int mScrollStart;/*** 手指抬起时的getScrollY*/private int mScrollEnd;/*** 记录移动时的Y*/private int mLastY;/*** 滚动的辅助类*/private Scroller mScroller;/*** 是否正在滚动*/private boolean isScrolling;/*** 加速度检测*/private VelocityTracker mVelocityTracker;/*** 记录当前页*/private int currentPage 0;private OnPageChangeListener mOnPageChangeListener;public VerticalLinearLayout(Context context, AttributeSet attrs){super(context, attrs);/*** 获得屏幕的高度*/WindowManager wm (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);DisplayMetrics outMetrics new DisplayMetrics();wm.getDefaultDisplay().getMetrics(outMetrics);mScreenHeight outMetrics.heightPixels;// 初始化mScroller new Scroller(context);}Overrideprotected void onMeasure(int widthMeasureSpec, int heightMeasureSpec){super.onMeasure(widthMeasureSpec, heightMeasureSpec);int count getChildCount();for (int i 0; i count; i){View childView getChildAt(i);measureChild(childView, widthMeasureSpec, heightMeasureSpec);}}Overrideprotected void onLayout(boolean changed, int l, int t, int r, int b){if (changed){int childCount getChildCount();// 设置主布局的高度MarginLayoutParams lp (MarginLayoutParams) getLayoutParams();lp.height mScreenHeight * childCount;setLayoutParams(lp);for (int i 0; i childCount; i){View child getChildAt(i);if (child.getVisibility() ! View.GONE){child.layout(l, i * mScreenHeight, r, (i 1) * mScreenHeight);// 调用每个自布局的layout}}}}Overridepublic boolean onTouchEvent(MotionEvent event){// 如果当前正在滚动调用父类的onTouchEventif (isScrolling)return super.onTouchEvent(event);int action event.getAction();int y (int) event.getY();obtainVelocity(event);switch (action){case MotionEvent.ACTION_DOWN:mScrollStart getScrollY();mLastY y;break;case MotionEvent.ACTION_MOVE:if (!mScroller.isFinished()){mScroller.abortAnimation();}int dy mLastY - y;// 边界值检查int scrollY getScrollY();// 已经到达顶端下拉多少就往上滚动多少if (dy 0 scrollY dy 0){dy -scrollY;Log.i(test, 已经到达顶端下拉多少就往上滚动多少scrollYscrollY);}// 已经到达底部上拉多少就往下滚动多少if (dy 0 scrollY dy getHeight() - mScreenHeight){dy getHeight() - mScreenHeight - scrollY;Log.i(test, 已经到达顶端下拉多少就往上滚动多少scrollYscrollY);}Log.i(test, dydy,scrollYscrollY);scrollBy(0, dy);mLastY y;break;case MotionEvent.ACTION_UP:mScrollEnd getScrollY();int dScrollY mScrollEnd - mScrollStart;if (wantScrollToNext())// 往上滑动{if (shouldScrollToNext()){mScroller.startScroll(0, getScrollY(), 0, mScreenHeight - dScrollY);} else{mScroller.startScroll(0, getScrollY(), 0, -dScrollY);}}if (wantScrollToPre())// 往下滑动{if (shouldScrollToPre()){mScroller.startScroll(0, getScrollY(), 0, -mScreenHeight - dScrollY);} else{mScroller.startScroll(0, getScrollY(), 0, -dScrollY);}}isScrolling true;postInvalidate();recycleVelocity();break;}return true;}/*** 根据滚动距离判断是否能够滚动到下一页* * return*/private boolean shouldScrollToNext(){return mScrollEnd - mScrollStart mScreenHeight / 2 || Math.abs(getVelocity()) 600;}/*** 根据用户滑动判断用户的意图是否是滚动到下一页* * return*/private boolean wantScrollToNext(){return mScrollEnd mScrollStart;}/*** 根据滚动距离判断是否能够滚动到上一页* * return*/private boolean shouldScrollToPre(){return -mScrollEnd mScrollStart mScreenHeight / 2 || Math.abs(getVelocity()) 600;}/*** 根据用户滑动判断用户的意图是否是滚动到上一页* * return*/private boolean wantScrollToPre(){return mScrollEnd mScrollStart;}Overridepublic void computeScroll(){super.computeScroll();if (mScroller.computeScrollOffset()){scrollTo(0, mScroller.getCurrY());postInvalidate();} else{int position getScrollY() / mScreenHeight;Log.e(xxx, position , currentPage);if (position ! currentPage){if (mOnPageChangeListener ! null){currentPage position;mOnPageChangeListener.onPageChange(currentPage);}}isScrolling false;}}/*** 获取y方向的加速度* * return*/private int getVelocity(){mVelocityTracker.computeCurrentVelocity(1000);return (int) mVelocityTracker.getYVelocity();}/*** 释放资源*/private void recycleVelocity(){if (mVelocityTracker ! null){mVelocityTracker.recycle();mVelocityTracker null;}}/*** 初始化加速度检测器* * param event*/private void obtainVelocity(MotionEvent event){if (mVelocityTracker null){mVelocityTracker VelocityTracker.obtain();}mVelocityTracker.addMovement(event);}/*** 设置回调接口* * param onPageChangeListener*/public void setOnPageChangeListener(OnPageChangeListener onPageChangeListener){mOnPageChangeListener onPageChangeListener;}/*** 回调接口* * author zhy* */public interface OnPageChangeListener{void onPageChange(int currentPage);} } 释还是相当详细的我简单描述一下Action_down时获得当前的scrollY,然后Action_move时根据移动的距离不断scrollby就行了当前处理了一下边界判断在Action_up中再次获得scrollY两个的scrollY进行对比然后根据移动的距离与方向决定最后的动作 MainActivity package com.example.verticallinearlayout;import android.app.Activity; import android.os.Bundle; import android.widget.Toast;import com.example.verticallinearlayout.VerticalLinearLayout.OnPageChangeListener;public class MainActivity extends Activity {private VerticalLinearLayout mMianLayout;Overrideprotected void onCreate(Bundle savedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);mMianLayout (VerticalLinearLayout) findViewById(R.id.id_main_ly);mMianLayout.setOnPageChangeListener(new OnPageChangeListener(){Overridepublic void onPageChange(int currentPage){ // mMianLayout.getChildAt(currentPage);Toast.makeText(MainActivity.this, 第(currentPage1)页, Toast.LENGTH_SHORT).show();}});}}为了提供可扩展性还是定义了回调接口完全可以把这个当成一个垂直的ViewPager使用。 总结下 Scroller这个辅助类还是相当好用的原理我简单说一下每次滚动时让Scroller进行滚动然后调用postInvalidate方法这个方法会引发调用onDraw方法onDraw方法中会去调用computeScroll方法然后我们在computScroll中判断Scroller的滚动是否结束没有的话把当前的View滚动到现在Scroller的位置然后继续调用postInvalidate这样一个循环的过程。 画张图方便大家理解ps:没找到什么好的画图工具那rose随便画了莫计较。 源码 源码点击此处下载 完成