package com.example.libingyuan.horizontallistview.ScrollViewGroup;

import android.content.Context;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.widget.Scroller;

/**
 * 自定義ViewGroup（橫向滾動(dòng)）
 */
public class ScrollViewGroup extends ViewGroup {
 //滾動(dòng)計(jì)算輔助類
 private Scroller mScroller;
 //屏幕寬度
 private int screenWidth;
 //可以移動(dòng)的最大距離
 private int mMaxDistance;
 //自定義手勢監(jiān)聽類
 private ScrollTouchLisener mTouchLisener;
 //手勢監(jiān)聽
 private GestureDetector mDetector;

 /**
  * 使用new關(guān)鍵字創(chuàng)建對(duì)象的時(shí)候調(diào)用
  */
 public ScrollViewGroup(Context context) {
  this(context, null);
 }

 /**
  * 在XML文件中使用的時(shí)候調(diào)用
  */
 public ScrollViewGroup(Context context, AttributeSet attrs) {
  this(context, attrs, 0);
 }

 /**
  * 在xml文件中調(diào)用，并且使用了自定義屬性的時(shí)候調(diào)用
  */
 public ScrollViewGroup(Context context, AttributeSet attrs, int defStyleAttr) {
  super(context, attrs, defStyleAttr);
  init(context);
 }

 /**
  * 初始化方法
  * 初始化滾動(dòng)輔助類Scroller以及計(jì)算出屏幕寬度
  */
 private void init(Context context) {
  //初始化輔助類
  mScroller = new Scroller(context);
  //獲取屏幕寬度
  WindowManager manager = (WindowManager) context
    .getSystemService(Context.WINDOW_SERVICE);
  DisplayMetrics outMetrics = new DisplayMetrics();
  manager.getDefaultDisplay().getMetrics(outMetrics);
  screenWidth = outMetrics.widthPixels;
  //手勢指示器初始化
  mTouchLisener = new ScrollTouchLisener();
  mDetector = new GestureDetector(context, mTouchLisener);
 }

 /**
  * 滾動(dòng)時(shí)需要重寫的方法，用于控制滾動(dòng)
  */
 @Override
 public void computeScroll() {
  //判斷滾動(dòng)時(shí)候停止
  if (mScroller.computeScrollOffset()) {
   //滾動(dòng)到指定的位置
   scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
   //這句話必須寫，否則不能實(shí)時(shí)刷新
   postInvalidate();
  }
 }

 /**
  * 手指觸屏事件監(jiān)聽
  */
 @Override
 public boolean onTouchEvent(MotionEvent event) {
  mDetector.onTouchEvent(event);
  if (event.getAction() == MotionEvent.ACTION_UP) {
   this.onUp(event);
  }
  return true;
 }

 /*
  *測量方法，測量父布局的寬度和高度
  */
 @Override
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
  //重新設(shè)置寬高
  this.setMeasuredDimension(measureWidth(widthMeasureSpec, heightMeasureSpec), measureHeight(widthMeasureSpec, heightMeasureSpec));
 }

 /**
  * 測量寬度
  */
 private int measureWidth(int widthMeasureSpec, int heightMeasureSpec) {
  // 寬度
  int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);
  int modeWidth = MeasureSpec.getMode(widthMeasureSpec);
  //父控件的寬（wrap_content）
  int width = 0;
  int childCount = getChildCount();

  //重新測量子view的寬度，以及最大高度
  for (int i = 0; i < childCount; i++) {
   View child = getChildAt(i);
   measureChild(child, widthMeasureSpec, heightMeasureSpec);
   MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
   int childWidth = child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;
   width += childWidth;
  }
  return modeWidth == MeasureSpec.EXACTLY ? sizeWidth : width;
 }

 /**
  * 測量高度
  */
 private int measureHeight(int widthMeasureSpec, int heightMeasureSpec) {
  //高度
  int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);
  int modeHeight = MeasureSpec.getMode(heightMeasureSpec);
  //父控件的高（wrap_content）
  int height = 0;
  int childCount = getChildCount();

  //重新測量子view的寬度，以及最大高度
  for (int i = 0; i < childCount; i++) {
   View child = getChildAt(i);
   measureChild(child, widthMeasureSpec, heightMeasureSpec);
   MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
   int childHeight = child.getMeasuredHeight() + lp.topMargin + lp.bottomMargin;
   height += childHeight;
  }
  height = height / childCount;
  return modeHeight == MeasureSpec.EXACTLY ? sizeHeight : height;
 }

 /**
  * 給子布局設(shè)定位置
  */
 @Override
 protected void onLayout(boolean changed, int l, int t, int r, int b) {
  int childLeft = 0;//子View左邊的間距
  int childWidth;//子View的寬度
  int height = getHeight();//屏幕的寬度
  int childCount = getChildCount();//子View的數(shù)量
  for (int i = 0; i < childCount; i++) {
   View child = getChildAt(i);
   MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
   childWidth = child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;
   child.layout(childLeft, 0, childLeft + childWidth, height);
   childLeft += childWidth;
  }
 }

 @Override
 public LayoutParams generateLayoutParams(AttributeSet attrs) {
  return new MarginLayoutParams(getContext(), attrs);
 }

 /*
  *按下事件 ACTION_DOWN
  */
 public boolean onDown(MotionEvent e) {
  //如果停止?jié)L動(dòng)則取消動(dòng)畫（即手指按下就停止?jié)L動(dòng)）
  if (!mScroller.isFinished()) {
   mScroller.abortAnimation();
  }
  return false;
 }
 /*
 *抬起事件 ACTION_UP
 */
 public boolean onUp(MotionEvent e) {
  //得到最后一個(gè)子View
  View lastChild = getChildAt(getChildCount() - 1);
  //獲取滑動(dòng)的最大滑動(dòng)距離（最后一個(gè)Child的右邊框的坐標(biāo)減去屏幕的寬度）
  int finalyChild = (int) (lastChild.getX() + lastChild.getWidth() - screenWidth);
  mMaxDistance = finalyChild;
  //如果滑動(dòng)的距離小于第一個(gè)控件的最左邊（0）則回彈至（0,0）點(diǎn)
  if (getScrollX() < 0) {
   scrollTo(0, 0);
  }
  //如果滑動(dòng)的距離大于最大可滑動(dòng)距離則滑動(dòng)到最后一個(gè)子View
  if (getScrollX() >= finalyChild)
   scrollTo(finalyChild, 0);
  //刷新界面
  invalidate();
  return false;
 }

 /*
  *ACTION_DOWN 、短按不移動(dòng)
  */
 public void onShowPress(MotionEvent e) {
 }

 /*
  *短按ACTION_DOWN、ACTION_UP
  */
 public boolean onSingleTapUp(MotionEvent e) {
  return false;
 }

 /*
  *ACTION_DOWN 、慢滑動(dòng)
  */
 public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
  //滾動(dòng)
  scrollBy((int) distanceX, 0);
  return false;
 }

 // ACTION_DOWN 、長按不滑動(dòng)
 public void onLongPress(MotionEvent e) {
 }

 /*
  *ACTION_DOWN 、快滑動(dòng)、 ACTION_UP
  */
 public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
  mScroller.fling(getScrollX(), 0, (int) -velocityX, 0, 0, mMaxDistance, 0, 0);
  return false;
 }

 /**
  * 自定義手勢監(jiān)聽類
  */
 private class ScrollTouchLisener implements GestureDetector.OnGestureListener {

  //按下事件
  @Override
  public boolean onDown(MotionEvent e) {
   return ScrollViewGroup.this.onDown(e);
  }

  //單擊事件
  @Override
  public void onShowPress(MotionEvent e) {
   ScrollViewGroup.this.onShowPress(e);
  }

  //手指抬起事件
  @Override
  public boolean onSingleTapUp(MotionEvent e) {
   return ScrollViewGroup.this.onSingleTapUp(e);
  }

  //滾動(dòng)事件
  @Override
  public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
   return ScrollViewGroup.this.onScroll(e1, e2, distanceX, distanceY);
  }

  //長按事件
  @Override
  public void onLongPress(MotionEvent e) {
   ScrollViewGroup.this.onLongPress(e);
  }

  //滑動(dòng)事件
  @Override
  public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
   return ScrollViewGroup.this.onFling(e1, e2, velocityX, velocityY);
  }
 }

}