Android 流式布局之自动换行

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

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

/**
 * Created by lpq on 2017/7/13.
 */

public class FlowLayout extends ViewGroup {
    /**
     * 用来保存每行views的列表
     */
    private List> mViewLinesList = new ArrayList<>();
    /**
     * 用来保存行高的列表
     */
    private List mLineHeights = new ArrayList<>();

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

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

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
//        获取父容器给设置的测量模式和大小
        int iWidthMode = MeasureSpec.getMode(widthMeasureSpec);
        int iHeightMode = MeasureSpec.getMode(heightMeasureSpec);
        int iWidthSpecSize = MeasureSpec.getSize(widthMeasureSpec);
        int iHeightSpecSize = MeasureSpec.getSize(heightMeasureSpec);

        int measuredWith = 0;//总的行宽
        int measuredHeight = 0;//总的行高

        int iCurLineW = 0;//当前行宽
        int iCurLineH = 0;//当前行高

        if (iWidthMode == MeasureSpec.EXACTLY && iHeightMode == MeasureSpec.EXACTLY) {
            measuredWith = iWidthSpecSize;
            measuredHeight = iHeightSpecSize;
        } else {
            int childCount = getChildCount();
            int iChildWidth;
            int iChildHeight;
            List viewList = new ArrayList<>();
            for (int i = 0; i < childCount; i++) {
                View childView = getChildAt(i);
                measureChild(childView, widthMeasureSpec, heightMeasureSpec);
                MarginLayoutParams layoutParams = (MarginLayoutParams) childView.getLayoutParams();
                iChildWidth = childView.getMeasuredWidth() + layoutParams.leftMargin + layoutParams.rightMargin;
                iChildHeight = childView.getMeasuredHeight() + layoutParams.topMargin + layoutParams.bottomMargin;
                if (iChildWidth + iCurLineW > iWidthSpecSize) { //换行

                    measuredWith = Math.max(iCurLineW, measuredWith);
                    measuredHeight += iCurLineH;
                    mViewLinesList.add(viewList);
                    mLineHeights.add(iCurLineH);

                    //重新设置当前行宽行高
                    iCurLineH = iChildHeight;
                    iCurLineW = iChildWidth;
                    viewList = new ArrayList<>();
                    viewList.add(childView);
                } else {
                    //不换行，记录当前行宽和行高
                    iCurLineW += iChildWidth;
                    iCurLineH = Math.max(iCurLineH, iChildHeight);
                    viewList.add(childView);
                }

                if(i == childCount - 1){
                    measuredWith = Math.max(measuredWith,iCurLineW);
                    measuredHeight += iCurLineH;

                    mViewLinesList.add(viewList);
                    mLineHeights.add(iCurLineH);

                }
            }
        }
        //测量最后必须调用
        setMeasuredDimension(measuredWith, measuredHeight);
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        int left, top, right, bottom;
        int curTop = 0;
        int curLeft = 0;
        int lineCount = mViewLinesList.size();
        for (int i = 0; i < lineCount; i++) {
            List viewList = mViewLinesList.get(i);
            int lineViewSize = viewList.size();
            for (int j = 0; j < lineViewSize; j++) {
                View childView = viewList.get(j);
                MarginLayoutParams layoutParams = (MarginLayoutParams) childView.getLayoutParams();

                left = curLeft + layoutParams.leftMargin;
                top = curTop + layoutParams.topMargin;
                right = left + childView.getMeasuredWidth();
                bottom = top + childView.getMeasuredHeight();
                childView.layout(left, top, right, bottom);
                curLeft += childView.getMeasuredWidth() + layoutParams.leftMargin + layoutParams.rightMargin;
            }
            curLeft = 0;
            curTop += mLineHeights.get(i);
        }
        mViewLinesList.clear();
        mLineHeights.clear();

    }


    public interface OnItemClickListener{
        void onItemClick (View v, int index);
    }

    public void setOnItemClickListener(final OnItemClickListener listener){

        int childCount = getChildCount();
        for(int i = 0 ; i < childCount ; i++){
            View childView = getChildAt(i);
            final int finalI = i;
            childView.setOnClickListener(new OnClickListener() {

                @Override
                public void onClick(View v) {
                    listener.onItemClick(v, finalI);
                }
            });
        }

    }
}