package zhangyf.vir56k.flowframelayout;

import android.content.Context;

import android.util.AttributeSet;

import android.view.View;

import android.view.ViewGroup;

/**

 * name: android 简单的流布局自定义view

 * 作者：张云飞

 * 特点：可以不断添加多个子view，计算位置，自动换行。

 * 适用： 热门标签

 * Created by zhangyunfei on 15/12/4.

 */

public class SimpleFlowLayout extends ViewGroup {

    public SimpleFlowLayout(Context context) {

        super(context);

    }

    public SimpleFlowLayout(Context context, AttributeSet attrs) {

        super(context, attrs);

    }

    public SimpleFlowLayout(Context context, AttributeSet attrs, int defStyleAttr) {

        super(context, attrs, defStyleAttr);

    }

    @Override

    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

        int widthMax = MeasureSpec.getSize(widthMeasureSpec);

        int widthMode = MeasureSpec.getMode(widthMeasureSpec);

        int heightMax = MeasureSpec.getSize(heightMeasureSpec);

        int heightMode = MeasureSpec.getMode(heightMeasureSpec);

        int widthNeed = 0;

        int heightNeed = 0;

        int x = 0;

        int y = 0;

        int currentLineHeight = 0;

        View child;

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

            child = getChildAt(i);

            if (child.getVisibility() == View.GONE) {

                continue;

            }

            child.measure(widthMeasureSpec, heightMeasureSpec);

            MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();//获得子view的 外边距

            //测算子view宽度，本行这句代码有问题，不能计算子view的自动换行 int childWidth = child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;

            //使用viewGroup的measureChildWithMargins测算宽度，在这个方法里处理了 LayoutParams的match_parent等方式的处理

            int childHeight = child.getMeasuredHeight() + lp.topMargin + lp.bottomMargin;

            measureChildWithMargins(child, widthMeasureSpec, 0, heightMeasureSpec, 0);

            int childWidth = child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;

            if (x + childWidth > widthMax) {//换行处理，本行高度和x轴都清零，y轴下移（加上上次的行高）

                y += currentLineHeight;

                currentLineHeight = 0;

                x = 0;

            }

            x += childWidth;

            currentLineHeight = Math.max(currentLineHeight, childHeight);

            widthNeed = Math.max(widthNeed, x);//加入了这个 子view后，留下最大宽度

            heightNeed = Math.max(heightNeed, y + currentLineHeight);//对比上次的，留下最大的高度

        }

        setMeasuredDimension(widthMode == MeasureSpec.EXACTLY ? widthMax : widthNeed,

                heightMode == MeasureSpec.EXACTLY ? heightMax : heightNeed);

    }

    @Override

    protected void onLayout(boolean changed, int l, int t, int r, int b) {

        int widthMax = getWidth();

        int x, y;

        x = 0;

        y = 0;

        View child;

        int left = 0;

        int top = 0;

        int currentLineHeight = 0;

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

            child = getChildAt(i);

            if (child.getVisibility() == View.GONE) {

                continue;

            }

            MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();

            int childWidth = child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin;

            int childHeight = child.getMeasuredHeight() + lp.topMargin + lp.bottomMargin;

            if (x + childWidth > widthMax) {//换行处理

                y += currentLineHeight;

                x = 0;

                currentLineHeight = 0;

            }

            left = x + lp.leftMargin;

            top = y + lp.topMargin;

            //定位子view的位置

            child.layout(left, top, left + child.getMeasuredWidth(), top + child.getMeasuredHeight());

            x += childWidth;

            currentLineHeight = Math.max(currentLineHeight, childHeight);

        }

    }

    @Override

    public LayoutParams generateLayoutParams(AttributeSet attrs) {

        return new MarginLayoutParams(getContext(), attrs);

    }

}