流式布局FlowLayout控件

package com.shuijiaosuidao.user.v.view;

import android.content.Context;
import android.content.res.TypedArray;
import android.database.DataSetObserver;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;

import com.shuijiaosuidao.user.R;

/**
 * @author: xiaolijuan
 * @description: 流式布局-标签流容器
 * @projectName: FlowLayoutDome
 * @date: 2016-06-16
 * @time: 16:21
 */
public class FlowLayout extends ViewGroup {
    /**
     * 每个item纵向间距
     */
    private int mVerticalSpacing;
    /**
     * 每个item横向间距
     */
    private int mHorizontalSpacing;
    private BaseAdapter mAdapter;
    private OnItemClickListener mListener;
    private DataChangeObserver mObserver;

    public FlowLayout(Context context) {
        this(context, null);
    }

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

    public FlowLayout(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        /**
         * 获得我们所定义的自定义样式属性
         */
        TypedArray a = context.getTheme().obtainStyledAttributes(attrs, R.styleable.FlowLayout, defStyle, 0);
        for (int i = 0; i < a.getIndexCount(); i++) {
            int attr = a.getIndex(i);
            switch (attr) {
                case R.styleable.FlowLayout_verticalSpacing:
                    mVerticalSpacing = a.getDimensionPixelSize(R.styleable.FlowLayout_verticalSpacing, 5);
                    break;
                case R.styleable.FlowLayout_horizontalSpacing:
                    mHorizontalSpacing = a.getDimensionPixelSize(R.styleable.FlowLayout_horizontalSpacing, 10);
                    break;
            }
        }
        a.recycle();
    }

    //wxm:设置子View的间距
    public void setSpacing(int verticalSpacing, int horizontalSpacing) {
        mVerticalSpacing = verticalSpacing;
        mHorizontalSpacing = horizontalSpacing;
    }

    /**
     * 负责设置子控件的测量模式和大小 根据所有子控件设置自己的宽和高
     */
    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

        final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
        final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
        final int widthSize = MeasureSpec.getSize(widthMeasureSpec);
        final int heightSize = MeasureSpec.getSize(heightMeasureSpec);

        measureChildren(widthMeasureSpec, heightMeasureSpec);

        int width = 0;
        int height = 0;

        int row = 0; // The row counter.
        int rowWidth = 0; // Calc the current row width.
        int rowMaxHeight = 0; // Calc the max tag height, in current row.

        final int count = getChildCount();
        for (int i = 0; i < count; i++) {
            final View child = getChildAt(i);
            final int childWidth = child.getMeasuredWidth();
            final int childHeight = child.getMeasuredHeight();

            if (child.getVisibility() != GONE) {
                rowWidth += childWidth;
                if (rowWidth > widthSize) { // Next line.
                    rowWidth = childWidth; // The next row width.
                    height += rowMaxHeight + mVerticalSpacing;
                    rowMaxHeight = childHeight; // The next row max height.
                    row++;
                } else { // This line.
                    rowMaxHeight = Math.max(rowMaxHeight, childHeight);
                }
                rowWidth += mHorizontalSpacing;
            }
        }
        // Account for the last row height.
        height += rowMaxHeight;

        // Account for the padding too.
        height += getPaddingTop() + getPaddingBottom();

        // If the tags grouped in one row, set the width to wrap the tags.
        if (row == 0) {
            width = rowWidth;
            width += getPaddingLeft() + getPaddingRight();
        } else {// If the tags grouped exceed one line, set the width to match the parent.
            width = widthSize;
        }

        setMeasuredDimension(widthMode == MeasureSpec.EXACTLY ? widthSize : width,
                heightMode == MeasureSpec.EXACTLY ? heightSize : height);
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        final int parentLeft = getPaddingLeft();
        final int parentRight = r - l - getPaddingRight();
        final int parentTop = getPaddingTop();
        final int parentBottom = b - t - getPaddingBottom();

        int childLeft = parentLeft;
        int childTop = parentTop;

        int rowMaxHeight = 0;

        final int count = getChildCount();
        for (int i = 0; i < count; i++) {
            final View child = getChildAt(i);
            final int width = child.getMeasuredWidth();
            final int height = child.getMeasuredHeight();

            if (child.getVisibility() != GONE) {
                if (childLeft + width > parentRight) { // Next line
                    childLeft = parentLeft;
                    childTop += rowMaxHeight + mVerticalSpacing;
                    rowMaxHeight = height;
                } else {
                    rowMaxHeight = Math.max(rowMaxHeight, height);
                }
                child.layout(childLeft, childTop, childLeft + width, childTop + height);

                childLeft += width + mHorizontalSpacing;
            }
        }
    }

    private void drawLayout() {
        if (mAdapter == null || mAdapter.getCount() == 0) {
            return;
        }
        removeAllViews();
        for (int i = 0; i < mAdapter.getCount(); i++) {
            View view = mAdapter.getView(i, null, null);
            final int position = i;
            view.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    if (mListener != null) {
                        mListener.itemClick(position);
                    }
                }
            });
            addView(view);
        }
    }

    public void setAdapter(BaseAdapter adapter) {

        if(mAdapter!=null && mObserver!=null){
            mAdapter.unregisterDataSetObserver(mObserver);
        }

        mAdapter = adapter;

        if(mAdapter!=null){

            if (mObserver == null) {
                mObserver = new DataChangeObserver();
            }

            mAdapter.registerDataSetObserver(mObserver);

            drawLayout();

        }
    }

    public void setItemClickListener(OnItemClickListener mListener) {
        this.mListener = mListener;
    }

    public interface OnItemClickListener {
        void itemClick(int position);
    }

    class DataChangeObserver extends DataSetObserver {
        @Override
        public void onChanged() {
            drawLayout();
        }

        @Override
        public void onInvalidated() {
            super.onInvalidated();
        }
    }
}