package com.example.libingyuan.horizontallistview.ScrollViewGroup;

import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;

/**
 * 自定義ViewGroup
 * 很簡單的橫向布局，把所有的子View都橫著排列起來，不可滾動(dòng)
 */
public class ScrollViewGroup extends ViewGroup{
  public ScrollViewGroup(Context context) {
    this(context,null);
  }

  public ScrollViewGroup(Context context, AttributeSet attrs) {
    this(context, attrs,0);
  }

  public ScrollViewGroup(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
  }

  @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);
    //寬度的類型
    int modeWidth = MeasureSpec.getMode(widthMeasureSpec);
    //父控件的寬（wrap_content）
    int width = 0;
    //子View的個(gè)數(shù)
    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++) {
      //獲取子View
      View child = getChildAt(i);
      //測量子View，無論什么模式，這句必須有否則界面不顯示子View（一片空白）
      measureChild(child, widthMeasureSpec, heightMeasureSpec);
      //得到子View的邊距
      MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
      //得到寬度
      int childWidth = child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;
      //寬度累加
      width += childWidth;
    }
    //返回寬度
    return modeWidth == MeasureSpec.EXACTLY ? sizeWidth : width;
  }

  /**
   * 測量高度
   */
  private int measureHeight(int widthMeasureSpec, int heightMeasureSpec) {
    //高度
    int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);
    //高度的模式
    int modeHeight = MeasureSpec.getMode(heightMeasureSpec);
    //父控件的高（wrap_content）
    int height = 0;
    //子View的個(gè)數(shù)
    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++) {
      //得到子View
      View child = getChildAt(i);
      //測量
      measureChild(child, widthMeasureSpec, heightMeasureSpec);
      //得到邊距
      MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
      //得到高度
      int childHeight = child.getMeasuredHeight() + lp.topMargin + lp.bottomMargin;
      //累加高度
      height += childHeight;
    }
    //求平均高度
    height = height / childCount;
    //返回高度
    return modeHeight == MeasureSpec.EXACTLY ? sizeHeight : height;
  }

  @Override
  protected void onLayout(boolean changed, int l, int t, int r, int b) {
    int childLeft=0;//子View左邊的距離
    int childWidth;//子View的寬度
    int height=getHeight();
    int childCount=getChildCount();
    for (int i = 0; i < childCount; i++) {
      View child=getChildAt(i);
      MarginLayoutParams lp= (MarginLayoutParams) child.getLayoutParams();
      childWidth=child.getMeasuredWidth()+lp.leftMargin+lp.rightMargin;
      //最主要的一句話
      child.layout(childLeft,0,childLeft+childWidth,height);
      childLeft+=childWidth;
    }
  }

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