Android自定义viewgroup 使用adapter适配数据（6）

package com.example.libingyuan.horizontallistview.ScrollViewGroup;

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

/**
 * 自定义ViewGroup（横向滚动）
 */
public class ScrollViewGroup extends ViewGroup {
  //滚动计算辅助类
  private Scroller mScroller;
  //屏幕宽度
  private int screenWidth;
  //可以移动的最大距离
  private int mMaxDistance;
  //自定义手势监听类
  private ScrollTouchLisener mTouchLisener;
  //手势监听
  private GestureDetector mDetector;

  private BaseAdapter mAdapter;

  /**
   * 使用new关键字创建对象的时候调用
   */
  public ScrollViewGroup(Context context) {
    this(context, null);
  }

  /**
   * 在XML文件中使用的时候调用
   */
  public ScrollViewGroup(Context context, AttributeSet attrs) {
    this(context, attrs, 0);
  }

  /**
   * 在xml文件中调用，并且使用了自定义属性的时候调用
   */
  public ScrollViewGroup(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    init(context);
  }

  /**
   * 初始化方法
   * 初始化滚动辅助类Scroller以及计算出屏幕宽度
   */
  private void init(Context context) {
    //初始化辅助类
    mScroller = new Scroller(context);
    //获取屏幕宽度
    WindowManager manager = (WindowManager) context
        .getSystemService(Context.WINDOW_SERVICE);
    DisplayMetrics outMetrics = new DisplayMetrics();
    manager.getDefaultDisplay().getMetrics(outMetrics);
    screenWidth = outMetrics.widthPixels;
    //手势指示器初始化
    mTouchLisener = new ScrollTouchLisener();
    mDetector = new GestureDetector(context, mTouchLisener);
  }

  /**
   * 滚动时需要重写的方法，用于控制滚动
   */
  @Override
  public void computeScroll() {
    //判断滚动时候停止
    if (mScroller.computeScrollOffset()) {
      //滚动到指定的位置
      scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
      //这句话必须写，否则不能实时刷新
      invalidate();
    }
  }

  /**
   * 手指触屏事件监听
   */
  @Override
  public boolean onTouchEvent(MotionEvent event) {
    mDetector.onTouchEvent(event);
    if (event.getAction() == MotionEvent.ACTION_UP) {
      this.onUp(event);
    }
    return true;
  }


  public void setAdapter(BaseAdapter adapter) {
    this.mAdapter = adapter;
    requestLayout();
  }

  /*
   *测量方法，测量父布局的宽度和高度
   */
  @Override
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    removeAllViews();
    for (int i = 0; i < mAdapter.getCount(); i++) {
      View child = mAdapter.getView(i, null, null);
      addView(child);
    }
    //重新设置宽高
    this.setMeasuredDimension(measureWidth(widthMeasureSpec, heightMeasureSpec), measureHeight(widthMeasureSpec, heightMeasureSpec));
  }

  /**
   * 测量宽度
   */
  private int measureWidth(int widthMeasureSpec, int heightMeasureSpec) {
    // 宽度
    int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);
    int modeWidth = MeasureSpec.getMode(widthMeasureSpec);
    //父控件的宽（wrap_content）
    int width = 0;
    int childCount = getChildCount();

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


  /**
   * 测量高度
   */
  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();

    //重新测量子view的宽度，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 += child.getMeasuredHeight();
    }
    height = height / childCount;
    return modeHeight == MeasureSpec.EXACTLY ? sizeHeight : height;
  }

  /**
   * 给子布局设定位置
   */
  @Override
  protected void onLayout(boolean changed, int l, int t, int r, int b) {
    int childLeft = 0;//子View左边的间距
    int childWidth;//子View的宽度
    int height = getHeight();//屏幕的宽度
    int childCount = getChildCount();//子View的数量
    for (int i = 0; i < childCount; i++) {
      View child = getChildAt(i);
     /*  MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
      childWidth = child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;*/
      childWidth = child.getMeasuredWidth();
      child.layout(childLeft, 0, childLeft + childWidth, height);
      childLayout(child);
      childLeft += childWidth;
    }
  }

  /**
   *让子View的子View和子View大小一样
   */
  private void childLayout(View child){
    if (child==null){
      throw new IllegalStateException("ScrollViewGroup must has one child");
    }
    if (child instanceof ViewGroup){
      if(((ViewGroup)child).getChildCount()>0)
        throw new IllegalStateException("view can host only one direct child");
      ((ViewGroup) child).getChildAt(0).layout(0,0,child.getWidth(),child.getHeight());
    }

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

  /*
   *按下事件 ACTION_DOWN
   */
  public boolean onDown(MotionEvent e) {
    //得到最后一个子View
    View lastChild = getChildAt(getChildCount() - 1);
    //获取滑动的最大滑动距离（最后一个Child的右边框的坐标减去屏幕的宽度）
    int finalyChild = (int) (lastChild.getX() + lastChild.getWidth() - screenWidth);
    mMaxDistance = finalyChild;
    //如果停止滚动则取消动画（即手指按下就停止滚动）
    if (!mScroller.isFinished()) {
      mScroller.abortAnimation();
    }
    return false;
  }

  /*
  *抬起事件 ACTION_UP
  */
  public boolean onUp(MotionEvent e) {
    //如果滑动的距离小于第一个控件的最左边（0）则回弹至（0,0）点
    if (getScrollX() <= 0) {
      scrollTo(0, 0);
    }
    //如果滑动的距离大于最大可滑动距离则滑动到最后一个子View
    if (getScrollX() >= mMaxDistance) {
      scrollTo(mMaxDistance, 0);
    }
    //刷新界面
    invalidate();
    return false;
  }

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

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

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

  // ACTION_DOWN 、长按不滑动
  public void onLongPress(MotionEvent e) {
  }

  /*
   *ACTION_DOWN 、快滑动、 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;
  }

  /**
   * 自定义手势监听类
   */
  private class ScrollTouchLisener implements GestureDetector.OnGestureListener {

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

    //单击事件
    @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);
    }

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

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

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

}