<?xml version="1.0" encoding="utf-8"?>

 
  
 
    
      
      
    
  
 
 

/**
   * 文本的颜色
   */
  private int mTitleTextColor;
  /**
   * 文本的大小
   */
  private float mTitleTextSize;
  private String mTitleText;//文字的内容
 
  /**
   * 背景图片
   */
  private int img;
  private Bitmap map;
  //bitmap对应的宽高
  private float img_width, img_height;
  Paint paint;
 
  private float numTextWidth;
  //测量seekbar的规格
  private Rect rect_seek;
  private Paint.FontMetrics fm;
 
  public static final int TEXT_ALIGN_LEFT = 0x00000001;
  public static final int TEXT_ALIGN_RIGHT = 0x00000010;
  public static final int TEXT_ALIGN_CENTER_VERTICAL = 0x00000100;
  public static final int TEXT_ALIGN_CENTER_HORIZONTAL = 0x00001000;
  public static final int TEXT_ALIGN_TOP = 0x00010000;
  public static final int TEXT_ALIGN_BOTTOM = 0x00100000;
  /**
   * 文本中轴线X坐标
   */
  private float textCenterX;
  /**
   * 文本baseline线Y坐标
   */
  private float textBaselineY;
  /**
   * 文字的方位
   */
  private int textAlign;
 
  public MySeekBar(Context context) {
    this(context, null);
  }
 
  public MySeekBar(Context context, AttributeSet attrs) {
    this(context, attrs, 0);
  }
 
  public MySeekBar(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    TypedArray array = context.getTheme().obtainStyledAttributes(attrs, R.styleable.MySeekBar, defStyleAttr, 0);
    int n = array.getIndexCount();
    for (int i = 0; i < n; i++) {
      int attr = array.getIndex(i);
      switch (attr) {
        case R.styleable.MySeekBar_textsize:
          mTitleTextSize = array.getDimension(attr, 15f);
          break;
        case R.styleable.MySeekBar_textcolor:
          mTitleTextColor = array.getColor(attr, Color.WHITE);
          break;
        case R.styleable.MySeekBar_img:
          img = array.getResourceId(attr, R.mipmap.ic_launcher);
          break;
      }
    }
    array.recycle();
    getImgWH();
    paint = new Paint();
    paint.setAntiAlias(true);//设置抗锯齿
    paint.setTextSize(mTitleTextSize);//设置文字大小
    paint.setColor(mTitleTextColor);//设置文字颜色
    //设置控件的padding 给提示文字留出位置
    setPadding((int) Math.ceil(img_width) / 2, 0, (int) Math.ceil(img_height) / 2, (int) Math.ceil(img_height) + 10);
    textAlign = TEXT_ALIGN_CENTER_HORIZONTAL | TEXT_ALIGN_CENTER_VERTICAL;
  }
 
  /**
   * 获取图片的宽高
   */
  private void getImgWH() {
    map = BitmapFactory.decodeResource(getResources(), img);
    img_width = map.getWidth();
    img_height = map.getHeight();
 
 
  }
 
  @Override
  protected synchronized void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    setTextLocation();//定位文本绘制的位置
    rect_seek = this.getProgressDrawable().getBounds();
    //定位文字背景图片的位置
    float bm_x = rect_seek.width() * getProgress() / getMax();
    float bm_y = rect_seek.height() + 20;
//    //计算文字的中心位置在bitmap
    float text_x = rect_seek.width() * getProgress() / getMax() + (img_width - numTextWidth) / 2;
    canvas.drawBitmap(map, bm_x, bm_y, paint);//画背景图
    // canvas.drawRoundRect();
    canvas.drawText(mTitleText, text_x, (float) (textBaselineY + bm_y + (0.16 * img_height / 2)), paint);//画文字
 
  }
 
  @Override
  public boolean onTouchEvent(MotionEvent event) {
    invalidate();//监听手势滑动，不断重绘文字和背景图的显示位置
    return super.onTouchEvent(event);
  }
 
  /**
   * 定位文本绘制的位置
   */
  private void setTextLocation() {
 
    fm = paint.getFontMetrics();
    //文本的宽度
    mTitleText = getProgress() + 10 + "℃";
 
    numTextWidth = paint.measureText(mTitleText);
 
    float textCenterVerticalBaselineY = img_height / 2 - fm.descent + (fm.descent - fm.ascent) / 2;
    switch (textAlign) {
      case TEXT_ALIGN_CENTER_HORIZONTAL | TEXT_ALIGN_CENTER_VERTICAL:
        textCenterX = img_width / 2;
        textBaselineY = textCenterVerticalBaselineY;
        break;
      case TEXT_ALIGN_LEFT | TEXT_ALIGN_CENTER_VERTICAL:
        textCenterX = numTextWidth / 2;
        textBaselineY = textCenterVerticalBaselineY;
        break;
      case TEXT_ALIGN_RIGHT | TEXT_ALIGN_CENTER_VERTICAL:
        textCenterX = img_width - numTextWidth / 2;
        textBaselineY = textCenterVerticalBaselineY;
        break;
      case TEXT_ALIGN_BOTTOM | TEXT_ALIGN_CENTER_HORIZONTAL:
        textCenterX = img_width / 2;
        textBaselineY = img_height - fm.bottom;
        break;
      case TEXT_ALIGN_TOP | TEXT_ALIGN_CENTER_HORIZONTAL:
        textCenterX = img_width / 2;
        textBaselineY = -fm.ascent;
        break;
      case TEXT_ALIGN_TOP | TEXT_ALIGN_LEFT:
        textCenterX = numTextWidth / 2;
        textBaselineY = -fm.ascent;
        break;
      case TEXT_ALIGN_BOTTOM | TEXT_ALIGN_LEFT:
        textCenterX = numTextWidth / 2;
        textBaselineY = img_height - fm.bottom;
        break;
      case TEXT_ALIGN_TOP | TEXT_ALIGN_RIGHT:
        textCenterX = img_width - numTextWidth / 2;
        textBaselineY = -fm.ascent;
        break;
      case TEXT_ALIGN_BOTTOM | TEXT_ALIGN_RIGHT:
        textCenterX = img_width - numTextWidth / 2;
        textBaselineY = img_height - fm.bottom;
        break;
    }
  }