流式布局FlowLayout

package extra.view;

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

import java.util.ArrayList;
import java.util.List;

public class FlowLayout extends ViewGroup
{

   private static final String TAG = "FlowLayout";


   public FlowLayout(Context context, AttributeSet attrs)
   {
      super(context, attrs);
   }

   @Override
   protected LayoutParams generateLayoutParams(
         LayoutParams p)
   {
      return new MarginLayoutParams(p);
   }

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

   @Override
   protected LayoutParams generateDefaultLayoutParams()
   {
      return new MarginLayoutParams(LayoutParams.MATCH_PARENT,
            LayoutParams.MATCH_PARENT);
   }

   /**
    * 负责设置子控件的测量模式和大小 根据所有子控件设置自己的宽和高
    */
   @Override
   protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
   {
      super.onMeasure(widthMeasureSpec, heightMeasureSpec);
      // 获得它的父容器为它设置的测量模式和大小
      int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);
      int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);
      int modeWidth = MeasureSpec.getMode(widthMeasureSpec);
      int modeHeight = MeasureSpec.getMode(heightMeasureSpec);

      Log.e(TAG, sizeWidth + "," + sizeHeight);

      // 如果是warp_content情况下,记录宽和高
      int width = 0;
      int height = 0;
      /**
       * 记录每一行的宽度,width不断取最大宽度
       */
      int lineWidth = 0;
      /**
       * 每一行的高度,累加至height
       */
      int lineHeight = 0;

      int cCount = getChildCount();

      // 遍历每个子元素
      for (int i = 0; i < cCount; i++)
      {
         View child = getChildAt(i);
         // 测量每一个child的宽和高
         measureChild(child, widthMeasureSpec, heightMeasureSpec);
         // 得到child的lp
         MarginLayoutParams lp = (MarginLayoutParams) child
               .getLayoutParams();
         // 当前子空间实际占据的宽度
         int childWidth = child.getMeasuredWidth() + lp.leftMargin
               + lp.rightMargin;
         // 当前子空间实际占据的高度
         int childHeight = child.getMeasuredHeight() + lp.topMargin
               + lp.bottomMargin;
         /**
          * 如果加入当前child,则超出最大宽度,则的到目前最大宽度给width,类加height 然后开启新行
          */
         if (lineWidth + childWidth > sizeWidth)
         {
            width = Math.max(lineWidth, childWidth);// 取最大的
            lineWidth = childWidth; // 重新开启新行,开始记录
            // 叠加当前高度,
            height += lineHeight;
            // 开启记录下一行的高度
            lineHeight = childHeight;
         } else
         // 否则累加值lineWidth,lineHeight取最大高度
         {
            lineWidth += childWidth;
            lineHeight = Math.max(lineHeight, childHeight);
         }
         // 如果是最后一个,则将当前记录的最大宽度和当前lineWidth做比较
         if (i == cCount - 1)
         {
            width = Math.max(width, lineWidth);
            height += lineHeight;
         }

      }
      setMeasuredDimension((modeWidth == MeasureSpec.EXACTLY) ? sizeWidth
            : width, (modeHeight == MeasureSpec.EXACTLY) ? sizeHeight
            : height);

   }
   /**
    * 存储所有的View,按行记录
    */
   private List<List<View>> mAllViews = new ArrayList<List<View>>();
   /**
    * 记录每一行的最大高度
    */
   private List<Integer> mLineHeight = new ArrayList<Integer>();
   @Override
   protected void onLayout(boolean changed, int l, int t, int r, int b)
   {
      mAllViews.clear();
      mLineHeight.clear();

      int width = getWidth();

      int lineWidth = 0;
      int lineHeight = 0;
      // 存储每一行所有的childView
      List<View> lineViews = new ArrayList<View>();
      int cCount = getChildCount();
      // 遍历所有的孩子
      for (int i = 0; i < cCount; i++)
      {
         View child = getChildAt(i);
         MarginLayoutParams lp = (MarginLayoutParams) child
               .getLayoutParams();
         int childWidth = child.getMeasuredWidth();
         int childHeight = child.getMeasuredHeight();

         // 如果已经需要换行
         if (childWidth + lp.leftMargin + lp.rightMargin + lineWidth > width)
         {
            // 记录这一行所有的View以及最大高度
            mLineHeight.add(lineHeight);
            // 将当前行的childView保存,然后开启新的ArrayList保存下一行的childView
            mAllViews.add(lineViews);
            lineWidth = 0;// 重置行宽
            lineViews = new ArrayList<View>();
         }
         /**
          * 如果不需要换行,则累加
          */
         lineWidth += childWidth + lp.leftMargin + lp.rightMargin;
         lineHeight = Math.max(lineHeight, childHeight + lp.topMargin
               + lp.bottomMargin);
         lineViews.add(child);
      }
      // 记录最后一行
      mLineHeight.add(lineHeight);
      mAllViews.add(lineViews);

      int left = 0;
      int top = 0;
      // 得到总行数
      int lineNums = mAllViews.size();
      for (int i = 0; i < lineNums; i++)
      {
         // 每一行的所有的views
         lineViews = mAllViews.get(i);
         // 当前行的最大高度
         lineHeight = mLineHeight.get(i);

         Log.e(TAG, "第" + i + "行 :" + lineViews.size() + " , " + lineViews);
         Log.e(TAG, "第" + i + "行, :" + lineHeight);

         // 遍历当前行所有的View
         for (int j = 0; j < lineViews.size(); j++)
         {
            View child = lineViews.get(j);
            if (child.getVisibility() == View.GONE)
            {
               continue;
            }
            MarginLayoutParams lp = (MarginLayoutParams) child
                  .getLayoutParams();

            //计算childView的left,top,right,bottom
            int lc = left + lp.leftMargin;
            int tc = top + lp.topMargin;
            int rc =lc + child.getMeasuredWidth();
            int bc = tc + child.getMeasuredHeight();

            Log.e(TAG, child + " , l = " + lc + " , t = " + t + " , r ="
                  + rc + " , b = " + bc);

            child.layout(lc, tc, rc, bc);

            left += child.getMeasuredWidth() + lp.rightMargin
                  + lp.leftMargin;
         }
         left = 0;
         top += lineHeight;
      }

   }
}
2016-10-29 11:125