流式布局的简单实现

public class MyFlow extends ViewGroup {
    public MyFlow(Context context) {
        super(context);
    }

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

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

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);

        //测量所有孩子的宽高
        measureChildren(widthMeasureSpec, heightMeasureSpec);

        int widthMode = MeasureSpec.getMode(widthMeasureSpec);
        int widthSize = MeasureSpec.getSize(widthMeasureSpec);//AT-MOST
        int heightMode = MeasureSpec.getMode(heightMeasureSpec);
        int heightSize = MeasureSpec.getSize(heightMeasureSpec);

        int width = 0;
        int height = 0;
        int lineWidth = 0;
        //int lineHeight = 0;
        int totalHeight = 0;//累加的高度
        View childView;
        int childWidth = 0;
        int childHeight = 0;


        for (int i = 0; i < getChildCount(); i++) {
            childView = getChildAt(i);
            childWidth = childView.getMeasuredWidth();
            childHeight = childView.getMeasuredHeight();

            //
            if (childWidth > widthSize) {
                //Log.d(TAG, "onMeasure: 太大了");
            }

            //测量布局的宽
            //换行/不换行
            if (childWidth + lineWidth > widthSize) {
                //换行
                width = widthSize;
                totalHeight += childHeight;

                //第一个
                //lineHeight = childHeight;
                lineWidth = childWidth;
            } else {
                //不换行

                lineWidth += childWidth;

                //lineHeight = Math.max(lineHeight, childHeight);

                width = Math.max(width, lineWidth);
            }
            //测量高度
            if (i == getChildCount() - 1) {
                totalHeight += childHeight;
                height = totalHeight;
            }
        }

        width = widthMode == MeasureSpec.EXACTLY ? widthSize : width;
        height = heightMode == MeasureSpec.EXACTLY ? heightSize : height;

        setMeasuredDimension(widthSize, heightSize);
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        int lineWidth = 0;
        //int lineHeight = 0;
        int totalHeight = 0;//累加的高度
        View childView;
        int childWidth = 0;
        int childHeight = 0;


        for (int i = 0; i < getChildCount(); i++) {
            childView = getChildAt(i);
            childWidth = childView.getMeasuredWidth();
            childHeight = childView.getMeasuredHeight();


            //测量布局的宽
            //换行/不换行
            if (childWidth + lineWidth > getMeasuredWidth()) {
                //换行
                totalHeight += childHeight;
                lineWidth = 0;
                childViewLayout(childView, lineWidth, totalHeight, lineWidth + childWidth, totalHeight + childHeight);
                //第一个
                //lineHeight = childHeight;
                lineWidth = childWidth;
            } else {
                //不换行
                childViewLayout(childView, lineWidth, totalHeight, lineWidth + childWidth, totalHeight + childHeight);

                lineWidth += childWidth;

                //lineHeight = Math.max(lineHeight, childHeight);

            }
        }
    }

    public void childViewLayout(View childView, int l, int t, int r, int b) {
        childView.layout(l, t, r, b);
    }
}