自定义流式布局

package com.example.liushibuju;

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

/**  * 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 onLayout(boolean b, int i, int i1, int i2, int i3) {

        int lineWidth = 0;
        int lineHeight = 0;
        int totalHeight = 0;
        View childView;
        int childWidth = 0;
        int childHeight = 0;
        MarginLayoutParams layoutParams;
        int leftMargin;
        int rightMargin;
        int topMargin;
        int bottomMargin;


        for (int j = 0; j < getChildCount(); j++) {
            childView = getChildAt(j);

            childWidth = childView.getMeasuredWidth();
            childHeight = childView.getMeasuredHeight();

            layoutParams = (MarginLayoutParams) childView.getLayoutParams();
            leftMargin = layoutParams.leftMargin;
            rightMargin = layoutParams.rightMargin;
            topMargin = layoutParams.topMargin;
            bottomMargin = layoutParams.bottomMargin;

            if (lineWidth + childWidth + leftMargin + rightMargin > getMeasuredWidth() - getPaddingLeft() - getPaddingRight()) {
                //换行  totalHeight += childHeight + topMargin + bottomMargin;
                lineWidth = 0 + leftMargin;
                layoutChildView(childView, lineWidth + leftMargin, totalHeight + topMargin, lineWidth + childWidth + leftMargin, totalHeight + childHeight + topMargin);
                lineHeight = childHeight + topMargin + bottomMargin;
                lineWidth = childWidth + leftMargin + rightMargin;
            } else {
                //不换行  layoutChildView(childView, lineWidth + leftMargin, totalHeight + topMargin, lineWidth + childWidth + leftMargin, totalHeight + childHeight + topMargin);
                lineWidth += childWidth + leftMargin + rightMargin;
                lineHeight = Math.max(lineHeight, childHeight + topMargin + bottomMargin);
            }
        }
    }

    @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 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;
        int childWidth = 0;
        int childHeight = 0;
        View childView;
        MarginLayoutParams layoutParams;
        int leftMargin;
        int rightMargin;
        int topMargin;
        int bottomMargin;

        for (int i = 0; i < getChildCount(); i++) {
            childView = getChildAt(i);

            childWidth = childView.getMeasuredWidth();
            childHeight = childView.getMeasuredHeight();

            layoutParams = (MarginLayoutParams) childView.getLayoutParams();
            leftMargin = layoutParams.leftMargin;
            rightMargin = layoutParams.rightMargin;
            topMargin = layoutParams.topMargin;
            bottomMargin = layoutParams.bottomMargin;

            if (childWidth + leftMargin + rightMargin > widthsize - getPaddingLeft() - getPaddingRight()) {
                throw new IllegalArgumentException("子view的宽度不能大于父布局的宽度");
            }

            if (lineWidth + childWidth + leftMargin + rightMargin > widthsize - getPaddingLeft() - getPaddingRight()) {
                //换行  width = widthsize;
                totalHeight += lineHeight;
                lineWidth = childWidth + leftMargin + rightMargin;
                lineHeight = childHeight + topMargin + bottomMargin;
            } else {
                //不换行  lineWidth += childWidth + leftMargin + rightMargin;

                //比较当前行的高度  lineHeight = Math.max(lineHeight, childHeight + topMargin + bottomMargin);

                //比较当前宽度，如果没有换行那么宽度就是当前的行宽，否则就是最大宽  width = Math.max(width, lineWidth + getPaddingLeft() + getPaddingRight());

            }

            //当结束遍历的时候要加上最后一行的高  if (i == getChildCount() - 1) {
                totalHeight += lineHeight;
                height = totalHeight;
            }
        }

        width = widthmode == MeasureSpec.EXACTLY ? widthsize : width;
        height = heightmode == MeasureSpec.EXACTLY ? heightsize : height + getPaddingTop() + getPaddingBottom();

        setMeasuredDimension(width, height);
    }

    public void layoutChildView(View child, int l, int t, int r, int b) {
        //统一根据flowlayout设置的padding进行整体的平移  l += getPaddingLeft();
        t += getPaddingTop();
        r += getPaddingLeft();
        b += getPaddingLeft();
        child.layout(l, t, r, b);
    }

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

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

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