WordGridView not a ViewGroup

WordGridView.java

package com.meituan.android.widget;

import android.content.Context;
import android.content.res.Resources;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.View;

/**
 * Created with IntelliJ IDEA.
 * User: dingzhihu
 * Date: 13-3-13
 * Time: 下午5:58
 */
public class WordGridView extends View {
    private String[] mWords;
    private OnWordClickListener mListener;
    private int mNumRows, mNumColumns;
    private float mCellPadding;
    private int mLineWidth;
    private Paint mPaintText;
    private Paint mPaintLine;
    private boolean mIsTouching;
    private float mTouchX, mTouchY;

    public WordGridView(Context context) {
        this(context, null);

    }

    public WordGridView(Context context, AttributeSet attrs) {
        this(context, attrs, R.attr.mtWordGridViewStyle);

    }

    public WordGridView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        final Resources res = context.getResources();
        final int defaultNumRows = res.getInteger(R.integer.default_word_grid_view_num_rows);
        final int defaultNumColumns = res.getColor(R.integer.default_word_grid_view_num_columns);
        final float defaultCellPadding = res.getDimension(R.dimen.default_word_grid_view_cell_padding);
        final int defaultLineColor = res.getColor(R.color.default_word_grid_view_line_color);
        final int defaultTextColor = res.getColor(R.color.default_word_grid_view_text_color);
        final float defaultTextSize = res.getDimension(R.dimen.default_word_grid_view_text_size);
        final int defaultLineWidth = res.getInteger(R.integer.default_word_grid_view_line_width);

        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.WordGridView, defStyle, 0);
        mNumRows = a.getInteger(R.styleable.WordGridView_numRows, defaultNumRows);
        mNumColumns = a.getInteger(R.styleable.WordGridView_numColumns, defaultNumColumns);
        mCellPadding = a.getDimension(R.styleable.WordGridView_cellPadding, defaultCellPadding);

        mPaintText = new Paint();
        mPaintText.setAntiAlias(true);
        mPaintText.setTextSize(a.getDimension(R.styleable.WordGridView_android_textSize,
                defaultTextSize));
        mPaintText.setColor(a.getColor(R.styleable.WordGridView_android_textColor,
                defaultTextColor));

        mPaintLine = new Paint();
        mLineWidth = a.getInteger(R.styleable.WordGridView_lineWidth, defaultLineWidth);
        mPaintLine.setStrokeWidth(mLineWidth);
        mPaintLine.setColor(a.getColor(R.styleable.WordGridView_lineColor, defaultLineColor));

        a.recycle();
    }

    public void setNumRows(int rows) {
        if (mNumRows != rows) {
            mNumRows = rows;
            requestLayout();
            invalidate();
        }

    }

    public void setNumColumns(int columns) {
        if (mNumColumns != columns) {
            mNumColumns = columns;
            invalidate();
        }

    }

    public void setOnWordClickListener(OnWordClickListener listener) {
        mListener = listener;
    }

    public void setWords(String[] words) {
        if (words == null) {
            clearWords();
            return;
        }

        //remove useless words
        final int cells = mNumRows * mNumColumns;
        if (words.length > cells) {
            mWords = new String[cells];
            System.arraycopy(words, 0, mWords, 0, cells);
        } else {
            mWords = words;
        }
        invalidate();
    }

    public void clearWords() {
        mWords = null;
        invalidate();
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        final int measuredWidth = MeasureSpec.getSize(widthMeasureSpec);

        final float textHeight = getTextHeight();

        float height = getPaddingTop();
        height += mLineWidth;    //line
        for (int i = 0; i < mNumRows; i++) {
            height += textHeight;
            height += mCellPadding * 2;
            height += mLineWidth;    //row line
        }
        height += getPaddingBottom();

        final int measuredHeight = (int) height;
        setMeasuredDimension(measuredWidth, measuredHeight);
    }

    private float getTextHeight() {
        final Paint.FontMetrics metrics = mPaintText.getFontMetrics();
        return metrics.descent - metrics.ascent;
    }

    @Override
    protected void onDraw(Canvas canvas) {
        final int measuredWidth = getMeasuredWidth();
        final int measuredHeight = getMeasuredHeight();
        final int paddingLeft = getPaddingLeft();
        final int paddingTop = getPaddingTop();
        final int paddingRight = getPaddingRight();
        final int paddingBottom = getPaddingBottom();

        // draw horizontal lines
        final int horizontalLines = mNumRows + 1;
        final float cellHeight = (measuredHeight - paddingTop - paddingBottom - horizontalLines * mLineWidth) / (mNumRows * 1.0f);
        canvas.drawLine(paddingLeft, paddingTop, measuredWidth - paddingRight, paddingTop, mPaintLine);
        float h = paddingTop;
        h += mLineWidth;
        for (int i = 0; i < mNumRows; i++) {
            h += mCellPadding * 2;
            h += getTextHeight();
            canvas.drawLine(paddingLeft, h, measuredWidth - paddingRight, h, mPaintLine);
            h += mLineWidth;
        }

        // draw vertical lines
        final int verticalLines = mNumColumns - 1;
        final float cellWidth = (measuredWidth - paddingLeft - paddingRight - verticalLines * mLineWidth) / (mNumColumns * 1.0f);
        float w = paddingLeft;
        for (int i = 1; i <= verticalLines; i++) {
            w += cellWidth;
            canvas.drawLine(w, paddingTop, w, measuredHeight - paddingBottom, mPaintLine);
            w += mLineWidth;
        }

        if (mWords == null) {
            return;
        }

        // draw texts
        for (int i = 0; i < mWords.length; i++) {
            final String word = mWords[i];
            Paint.FontMetrics metrics = mPaintText.getFontMetrics();
            final float wordWidth = mPaintText.measureText(word);

            int cellX = i % mNumColumns;
            int cellY = i / mNumColumns;

            float restrictedWordWidth = wordWidth;
            if (wordWidth > cellWidth) {
                restrictedWordWidth = cellWidth;
            }
            float x = paddingLeft + cellX * mLineWidth + cellX * cellWidth + (cellWidth - restrictedWordWidth) / 2;
            float y = paddingTop + (1 + cellY) * mLineWidth + cellY * cellHeight + mCellPadding - metrics.ascent;

            canvas.drawText(word, x, y, mPaintText);
        }
    }

    public static interface OnWordClickListener {
        void onClick(String word);
    }
}