Retrieve x coordinate of left bound of upcoming stimulus sentence

Comments

• KarsLigtenberg

  August 23

  Found a temporary fix by calculating the width in pixels of each stimulus, and consequently using an in-line script to create a canvas with a fixdot element where I input the x coordinates as the negative width in pixels of the upcoming stimulus. For some reason this makes the fixdot appear slightly left of the upcoming sentence, but at least it is better than having a fixation dot in the middle.

  The code I used to make this work is as follows (in case anyone else would like to achieve something similar):

  import ctypes
  
  
  
  def GetTextDimensions(text, points, font):
  
  class SIZE(ctypes.Structure):
  
  _fields_ = [("cx", ctypes.c_long), ("cy", ctypes.c_long)]
  
  
  
  hdc = ctypes.windll.user32.GetDC(0)
  
  hfont = ctypes.windll.gdi32.CreateFontA(points, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, font)
  
  hfont_old = ctypes.windll.gdi32.SelectObject(hdc, hfont)
  
  
  
  size = SIZE(0, 0)
  
  ctypes.windll.gdi32.GetTextExtentPoint32A(hdc, text, len(text), ctypes.byref(size))
  
  
  
  ctypes.windll.gdi32.SelectObject(hdc, hfont_old)
  
  ctypes.windll.gdi32.DeleteObject(hfont)
  
  
  
  return (size.cx, size.cy)
  
  
  
  size = GetTextDimensions([Sentence][0], 20, "Droid Sans Mono")
  
• KarsLigtenberg

  August 23 edited August 23

  I have found a workaround using a code snippet to retrieve the pixel width of the upcoming stimulus, and then using the negative width as the x coordinate for the fixdot object. This makes the fixdot appear somewhat to the left of the upcoming sentence (not entirely sure why yet), but at least this is better than having it appear in the middle.

  The code I used for this is as follows:

  import ctypes
  
  
  def GetTextDimensions(text, points, font):
  
      class SIZE(ctypes.Structure):
  
          _fields_ = [("cx", ctypes.c_long), ("cy", ctypes.c_long)]
  
  
      hdc = ctypes.windll.user32.GetDC(0)
  
      hfont = ctypes.windll.gdi32.CreateFontA(points, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, font)
  
      hfont_old = ctypes.windll.gdi32.SelectObject(hdc, hfont)
  
  
      size = SIZE(0, 0)
  
      ctypes.windll.gdi32.GetTextExtentPoint32A(hdc, text, len(text), ctypes.byref(size))
  
  
      ctypes.windll.gdi32.SelectObject(hdc, hfont_old)
  
      ctypes.windll.gdi32.DeleteObject(hfont)
  
      
      return (size.cx, size.cy)
  
  
  size = GetTextDimensions([Sentence], 20, "Droid Sans Mono")
  
  xfix = size[0] * -1
  
  my_canvas = Canvas()
  my_canvas.fixdot(x = xfix, color = 'yellow')
  
  
  my_canvas.show()
  
  clock.sleep(1000)
  

  
  
• KarsLigtenberg

  August 23

  Managed to find a workaround in which I extract the width of the sentence stimulus in pixels, so that I can set that as the negative x coordinate of the fixdot. This allows the fixdot to appear slightly to the left of the upcoming sentence stimulus.

  The code for this is as follows (in case anyone else might need something similar in the future):

  import ctypes
  
  
  def GetTextDimensions(text, points, font):
  
      class SIZE(ctypes.Structure):
  
          _fields_ = [("cx", ctypes.c_long), ("cy", ctypes.c_long)]
  
  
      hdc = ctypes.windll.user32.GetDC(0)
  
      hfont = ctypes.windll.gdi32.CreateFontA(points, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, font)
  
      hfont_old = ctypes.windll.gdi32.SelectObject(hdc, hfont)
  
  
      size = SIZE(0, 0)
  
      ctypes.windll.gdi32.GetTextExtentPoint32A(hdc, text, len(text), ctypes.byref(size))
  
  
      ctypes.windll.gdi32.SelectObject(hdc, hfont_old)
  
      ctypes.windll.gdi32.DeleteObject(hfont)
  
  
      return (size.cx, size.cy)
  
  
  size = GetTextDimensions([Sentence], 20, "Droid Sans Mono")
  
  xfix = size[0] * -1
  
  my_canvas = Canvas()
  
  my_canvas.fixdot(x = xfix, color = 'yellow')
  
  
  my_canvas.show()
  
  clock.sleep(1000)
  
• eduard

  August 26

  Thanks for sharing!