无缝连接可循环滚动布局

package com.drw.myapplication.custom; import android.content.Context; import android.graphics.Canvas; import android.util.AttributeSet; import android.util.Log; import android.view.Gravity; import android.view.MotionEvent; import android.view.View; import android.view.ViewGroup; import android.view.animation.BounceInterpolator; import android.widget.Scroller; /** * Created by Administrator on 2018/2/22. */ public class ForeverLayout extends ViewGroup{ private int front=0;//代表前面还有几个页面的变量 private int mWidth;//存储屏幕宽度 private float mXDownPos;//存储点击时的x坐标 private float mXLastMovePos;//存储上一次滑动时保存的x坐标 private float mXMovePos;//存储滑动所到位置的x坐标 private int mTotalNum;//存储子元素个数 private Scroller mScroller;//操控滚动效果的实例 public ForeverLayout(Context context) { super(context); Init(context); } public ForeverLayout(Context context, AttributeSet attrs) { super(context, attrs); Init(context); } public ForeverLayout(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); Init(context); } /** * 初始化函数 * @param context 上下文对象 */ private void Init(Context context){ if(mScroller==null) mScroller = new Scroller(context); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); final int count = getChildCount(); for (int i = 0; i < count; i++) { View child = getChildAt(i); child.measure(widthMeasureSpec,heightMeasureSpec); } mTotalNum=getChildCount(); mWidth = getMeasuredWidth(); } @Override protected void onLayout(boolean changed, int l, int t, int r, int b) { final int count = getChildCount(); int left=0; for (int i = 0; i < count; i++) { final View child = getChildAt(i); if (child.getVisibility() != GONE) { child.layout(left, 0, left+mWidth, child.getMeasuredHeight()); left=left+mWidth; } } } @Override public boolean onInterceptTouchEvent(MotionEvent ev) { switch (ev.getAction()) { case MotionEvent.ACTION_DOWN://点击时获得x,y坐标 mXDownPos = ev.getRawX(); mXLastMovePos = mXDownPos; break; case MotionEvent.ACTION_MOVE://判断手指移动的距离有没有达到定性为滑动的最小距离 float distance; mXMovePos = ev.getRawX(); distance= Math.abs(mXMovePos - mXDownPos); mXLastMovePos = mXMovePos; if (distance > 100) { return true; } break; } return super.onInterceptTouchEvent(ev); } @Override public boolean onTouchEvent(MotionEvent event) { switch (event.getAction()) { case MotionEvent.ACTION_MOVE: mXMovePos = event.getRawX(); int scrolledX = (int) (mXLastMovePos - mXMovePos); scrollBy(scrolledX, 0); mXLastMovePos = mXMovePos; break; case MotionEvent.ACTION_UP: mXMovePos = event.getRawX(); if((mXMovePos-mXDownPos)>mWidth/3){ if(front==0) { int temp2=Math.abs(getScrollX()); temp2=mWidth-temp2; View temp=getChildAt(mTotalNum-1); removeViewAt(mTotalNum-1); addView(temp,0); invalidate(); setScrollX(temp2); mScroller.startScroll(getScrollX(), 0, -temp2, 0); } else{ front--; mScroller.startScroll(getScrollX(), 0, -getScrollX() + front * mWidth, 0); } invalidate(); }else if((mXMovePos-mXDownPos)<-mWidth/3){ if(front==mTotalNum-1) { int temp2=Math.abs(getScrollX()); int temp3=temp2/mWidth; temp2=(temp3+1)*mWidth-temp2; View temp = getChildAt(0); removeViewAt(0); addView(temp, mTotalNum - 1); invalidate(); setScrollX(-temp2); mScroller.startScroll(getScrollX(), 0, temp2, 0); }else{ front++; mScroller.startScroll(getScrollX(), 0, -getScrollX() + front * mWidth, 0); } invalidate(); }else{ mScroller.startScroll(getScrollX(),0,-getScrollX()+front*mWidth,0); invalidate(); } } return super.onTouchEvent(event); } @Override protected void dispatchDraw(Canvas canvas) { super.dispatchDraw(canvas); canvas.save(); canvas.translate(mWidth * getChildCount(), 0); super.dispatchDraw(canvas); canvas.restore(); canvas.save(); canvas.translate(-mWidth * getChildCount(), 0); super.dispatchDraw(canvas); canvas.restore(); } @Override public void computeScroll() { if (mScroller.computeScrollOffset()) { scrollTo(mScroller.getCurrX(), mScroller.getCurrY()); invalidate(); } } }