canvas.drawText() 文本画图

/**
     * 在给定的图片的右上角加上联系人数量。数量用红色表示
     * @param icon 给定的图片
     * @return 带联系人数量的图片
     */
    private Bitmap generatorContactCountIcon(Bitmap icon){
        //初始化画布
        int iconSize=(int)getResources().getDimension(android.R.dimen.app_icon_size);
        Log.d(TAG, "the icon size is "+iconSize);
        Bitmap contactIcon=Bitmap.createBitmap(iconSize, iconSize, Config.ARGB_8888);
        Canvas canvas=new Canvas(contactIcon);

        //拷贝图片
        Paint iconPaint=new Paint();
        iconPaint.setDither(true);//防抖动
        iconPaint.setFilterBitmap(true);//用来对Bitmap进行滤波处理，这样，当你选择Drawable时，会有抗锯齿的效果
        Rect src=new Rect(0, 0, icon.getWidth(), icon.getHeight());
        Rect dst=new Rect(0, 0, iconSize, iconSize);
        canvas.drawBitmap(icon, src, dst, iconPaint);

        //在图片上创建一个覆盖的联系人个数
        int contacyCount=getContactCount();
        //启用抗锯齿和使用设备的文本字距
        Paint countPaint=new Paint(Paint.ANTI_ALIAS_FLAG|Paint.DEV_KERN_TEXT_FLAG);
        countPaint.setColor(Color.RED);
        countPaint.setTextSize(20f);
        countPaint.setTypeface(Typeface.DEFAULT_BOLD);
        canvas.drawText(String.valueOf(contacyCount), iconSize-18, 25, countPaint);
        return contactIcon;
    }