流式布局

package com.example.dell.text;


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


/**
 * Created by DELL on 2018/6/8.
 */


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


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


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


    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        measureChildren(widthMeasureSpec, heightMeasureSpec);
        int widthSize = MeasureSpec.getSize(widthMeasureSpec);
        int widthMode = MeasureSpec.getMode(widthMeasureSpec);
        int heightSize = MeasureSpec.getSize(heightMeasureSpec);
        int heightMode = MeasureSpec.getMode(heightMeasureSpec);


        int width = 0;
        int height = 0;
        int lineWidth = 0;
        int lineHeight = 0;
        int totalHeight = 0;
        View childView;
        int childWidth = 0;
        int childHeight = 0;
        for (int i=0; i< getChildCount(); i++){
            childView =getChildAt(i);
            childWidth =childView.getMeasuredWidth();
            if (childWidth>widthSize){
                throw new IllegalArgumentException("子布局宽不能大于FlowLayout宽度");
            }
            childHeight=childView.getMeasuredHeight();
            if (lineWidth+childWidth>widthSize){
                width = widthSize;
                int prelineHeight = lineHeight;
                totalHeight += prelineHeight;
                lineHeight = childHeight;
                lineWidth = childWidth;
            }else{
                lineWidth += childWidth;
                lineHeight = Math.max(lineHeight,childHeight);


                width = Math.max(width,lineWidth);
            }


            if (i == getChildCount()-1 ){
                totalHeight += lineHeight;
                height=totalHeight;
            }
        }
        width = widthMode == MeasureSpec.EXACTLY ? widthSize:width;
        height = heightMode == MeasureSpec.EXACTLY ? heightSize:height;
        setMeasuredDimension(width,height);
    }


    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        int lineWidth = 0;
        int lineHeight = 0;
        int totalHeight = 0;
        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 (lineWidth + childWidth>getMeasuredWidth()){
                totalHeight += childHeight;
                lineWidth = 0;
                LayoutChildView(childView, lineWidth,totalHeight,lineWidth + childWidth, totalHeight + childHeight);
                lineHeight = childHeight;
                lineWidth = childWidth;
            }else{
                LayoutChildView(childView, lineWidth,totalHeight,lineWidth + childWidth, totalHeight + childHeight);
                lineWidth += childWidth;
                lineHeight=Math.max(lineHeight,childHeight);
            }
        }
    }


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