docs: def write(self, text="", xy=(0,0), align="left", font=None, fontName=None, fontSize = 10, fill = 1, spacing = 0, screenCenter = False):
          """!
          \~english 
          Print one line text or multi-line text on the screen
          @param text: Text to be drawn. eg. "Hello World!" or "Hello/nWorld!"
          @param xy: Top left corner of the text. defaule: (0,0)
          @param align: "left", "center" or "right". defaule: "left"
          @param fontName: Name of font or font instance. defaule: None (use default font) 
          @param fontSize: Font size. default: 10
          @param fill: Color to use for the text. default: 1 (white)
          @param spacing: The number of pixels between lines. default: 0
          @param screenCenter： Keep the text center of screen. default: False
          
          @note
          How to use screenCenter?
          1. align="left"; screenCenter=False
          <pre>
          +---------------------------------+
          |  Simple text line1              |
          |  Simple line2                   |
          |  Simple                         |
          |                                 |
          +---------------------------------+
          </pre>
          
          2. align="left"; screenCenter=True
          <pre>
          +---------------------------------+
          |        Simple text line1        |
          |        Simple line2             |
          |        Simple                   |
          |                                 |
          +---------------------------------+
          </pre>
  
          \~chinese
          在屏幕上打印一行文字或多行文字        
          @param text: 要输出的文字，可以单行也可以多行。例如： "Hello World!"  或 "Hello/nWorld!"
          @param xy: 文字输出的坐标点。默认： (0,0)
          @param align: 多行文字对齐方式，可选： "left", "center" 或 "right". 默认： "left"
          @param fontName: 字体名或字体对象实例。默认：None（使用系统默认的字体） 
          @param fontSize: 字体大小。默认：10
          @param fill: 文字颜色。默认： 1 （白色）
          @param spacing: 行间距。默认：0
          @param screenCenter： 让文本居中屏幕。
          
          @note
          screenCenter 效果示例：
          1. align="left"; screenCenter=False
          <pre>
          +---------------------------------+
          |  Simple text line1              |
          |  Simple line2                   |
          |  Simple                         |
          |                                 |
          +---------------------------------+
          </pre>
          
          2. align="left"; screenCenter=True
          <pre>
          +---------------------------------+
          |        Simple text line1        |
          |        Simple line2             |
          |        Simple                   |
          |                                 |
          +---------------------------------+
          </pre>
          """
          tx = xy[0]
          
          try:
              dwFont = font if font != None else DEF_SCR_FRONT if fontName==None else ImageFont.truetype(fontName, fontSize)
          except:
              dwFont = DEF_SCR_FRONT
  
          try:
              if screenCenter == True:
                  (fw, fh) = self.Canvas.multiline_textsize( text, font )
                  tx = xy[0] + (self._display_size[0]-fw)/2
              self.Canvas.multiline_text( (tx, xy[1]) , text, font = dwFont, align=align, fill=fill, spacing=spacing)
          except:
              print("ERROR: canvas write error")