layout里动态添加控件，并自动换行

来源：互联网发布：ghost添加预装软件编辑：程序博客网时间：2024/06/02 05:03

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

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

public class FlowLayout extends ViewGroup
{

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

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

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

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

   /**
   * 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);

       // 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);
           // 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();

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

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

   }
}

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