package com.allen.view;

import com.allen.mygridlayout.R;

import android.content.Context;

import android.content.res.TypedArray;

import android.util.AttributeSet;

import android.view.View;

import android.view.ViewGroup;

import android.view.View.MeasureSpec;

/**

 * @package：com.fumei.letao.views

 * @author：Allen

 * @email：jaylong1302@163.com

 * @data：2013年11月26日 下午8:39:51

 * @description：瀑布流视图

 */

public class WaterfullLayout extends ViewGroup {

    final String tag = "balance";

    // 列数

    int columns = 2;

    // 行数

    int rows = 0;

    // 边距

    int margin = 10;

    // 子视图数量

    int count = 0;

    private int mMaxChildWidth = 0;

    private int mMaxChildHeight = 0;

    public WaterfullLayout(Context context, AttributeSet attrs, int defStyle) {

        super(context, attrs, defStyle);

        if (attrs != null) {

            TypedArray a = getContext().obtainStyledAttributes(attrs,

                    R.styleable.MyGridLayout);

            columns = a.getInteger(R.styleable.MyGridLayout_numColumns, 2);

            margin = (int) a.getInteger(R.styleable.MyGridLayout_itemMargin, 2);

        }

    }

    public WaterfullLayout(Context context, AttributeSet attrs) {

        super(context, attrs, 0);

        // TODO Auto-generated constructor stub

    }

    public WaterfullLayout(Context context) {

        super(context);

        // TODO Auto-generated constructor stub

    }

    @Override

    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

        mMaxChildWidth = 0;

        mMaxChildHeight = 0;

        count = getChildCount();

        if (count == 0) {

            super.onMeasure(widthMeasureSpec, heightMeasureSpec);

            return;

        }

        rows = count % columns == 0 ? count / columns : count / columns + 1;// 行数

        int top[] = new int[columns];

        for (int i = 0; i < rows; i++) {// 遍历行

            for (int j = 0; j < columns; j++) {// 遍历每一行的元素

                View child = this.getChildAt(i * columns + j);

                if (child == null)

                    break;

                ViewGroup.LayoutParams lp = child.getLayoutParams();

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

                    continue;

                }

                child.measure(MeasureSpec.makeMeasureSpec(

                        MeasureSpec.getSize(widthMeasureSpec),

                        MeasureSpec.EXACTLY), MeasureSpec.makeMeasureSpec(

                        lp.height, MeasureSpec.AT_MOST));

                top[j] += lp.height + margin;

                mMaxChildWidth = Math.max(mMaxChildWidth,

                        child.getMeasuredWidth());

            }

        }

        setMeasuredDimension(resolveSize(mMaxChildWidth, widthMeasureSpec),

                resolveSize(getMax(top) + margin, heightMeasureSpec));

    }

    @Override

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

        // TODO Auto-generated method stub

        int height = b - t;// 布局区域高度

        int width = r - l;// 布局区域宽度

        if (count == 0)

            return;

        int gridW = (width - margin * (columns + 1)) / columns;// 格子宽度

        int gridH = 0;// 格子高度

        int left = 0;

        int top[] = new int[columns];

        for (int i = 0; i < rows; i++) {// 遍历行

            for (int j = 0; j < columns; j++) {// 遍历每一行的元素

                View child = this.getChildAt(i * columns + j);

                if (child == null)

                    return;

                ViewGroup.LayoutParams lp = child.getLayoutParams();

                child.measure(MeasureSpec.makeMeasureSpec(gridW,

                        MeasureSpec.EXACTLY), MeasureSpec.makeMeasureSpec(

                        lp.height, MeasureSpec.AT_MOST));

                // 如果最后有一个对其的标志，为了底部对其

                if (child.getTag() != null && child.getTag().equals(tag)) {

                    child.measure(MeasureSpec.makeMeasureSpec(gridW,

                            MeasureSpec.EXACTLY), MeasureSpec.makeMeasureSpec(

                            getMax(top) - top[j], MeasureSpec.EXACTLY));

                    gridH = getMax(top) - top[j];

                    left = j * gridW + margin * (j + 1);

                    child.layout(left, top[j] + margin, left + gridW, top[j]

                            + gridH);

                    break;

                }

                gridH = lp.height;

                left = j * gridW + margin * (j + 1);

                top[j] += margin;

                child.layout(left, top[j], left + gridW, top[j] + gridH);

                top[j] += gridH;

            }

        }

    }

    /** 计算整体布局高度，为了在嵌套在scrollview中能显示出来 */

    private int getMax(int array[]) {

        int max = array[0];

        for (int i = 0; i < array.length; i++) {

            if (max < array[i])

                max = array[i];

        }

        return max;

    }

}