打造一个无数据显示无数据提示信息的ListView

package com.tianjs.tianjinsuop2p.widgets;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.widget.Adapter;
import android.widget.ListView;

import com.tianjs.tianjinsuop2p.R;

/**
 * Created by xiaolei on 2017/4/28.
 */

public class NoDataListView extends ListView
{
    private int height = 0;
    private int width = 0;
    private Bitmap noDataBitmap = null;
    private Paint mPaint;

    private int minItem = 0;
    private int noDataImgInt = 0;

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

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

    public NoDataListView(Context context, AttributeSet attrs, int defStyleAttr)
    {
        super(context, attrs, defStyleAttr);
        TypedArray array = context.obtainStyledAttributes(attrs, R.styleable.NoDataListView);

        noDataImgInt = array.getResourceId(R.styleable.NoDataListView_noDataImg, 0);
        minItem = array.getInt(R.styleable.NoDataListView_minItem, 0);

        if (noDataImgInt != 0)
        {
            noDataBitmap = BitmapFactory.decodeResource(getResources(), noDataImgInt);
        } else
        {
            noDataBitmap = Bitmap.createBitmap(1, 1, Bitmap.Config.ARGB_8888);
        }
        mPaint = new Paint();

        array.recycle();
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
    {
        height = MeasureSpec.getSize(heightMeasureSpec);
        width = MeasureSpec.getSize(widthMeasureSpec);
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }

    @Override
    protected void onDraw(Canvas canvas)
    {
        Adapter adapter = getAdapter();
        super.onDraw(canvas);
        if (adapter == null || adapter.getCount() <= minItem)
        {
            canvas.drawBitmap(noDataBitmap, width / 2 - noDataBitmap.getWidth() / 2, height / 2 - noDataBitmap.getHeight() / 2, mPaint);
        }
    }
}

<declare-styleable name="NoDataListView">
    <!--最低Item数-->
    <attr name="minItem" format="integer"/>
    <!--没有数据时，显示的图片资源-->
    <attr name="noDataImg" format="reference"/>
</declare-styleable>

<com.tianjs.tianjinsuop2p.widgets.NoDataListView
            android:id="@+id/listview"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:divider="#00000000"
            android:dividerHeight="0dp"
            android:overScrollMode="never"
            android:scrollbars="none"
            app:minItem="0"
            app:noDataImg="@drawable/icon_wushuju"/>