display_utils.py

 
from typing import List, Optional
 
from visp.core import Display
 
VISP_DISPLAY_CLS_MAP = {
  'x': None,
  'opencv': None,
  'gtk': None,
  'win32': None,
  'gdi': None,
}
 
try:
  from visp.gui import DisplayX
  VISP_DISPLAY_CLS_MAP['x'] = DisplayX
except ImportError:
  pass
 
try:
  from visp.gui import DisplayOpenCV
  VISP_DISPLAY_CLS_MAP['opencv'] = DisplayOpenCV
except ImportError:
  pass
 
try:
  from visp.gui import DisplayGTK
  VISP_DISPLAY_CLS_MAP['gtk'] = DisplayGTK
except ImportError:
  pass
 
try:
  from visp.gui import DisplayWin32
  VISP_DISPLAY_CLS_MAP['win32'] = DisplayWin32
except ImportError:
  pass
 
try:
  from visp.gui import DisplayGDI
  VISP_DISPLAY_CLS_MAP['gdi'] = DisplayGDI
except ImportError:
  pass
 
VISP_DEFAULT_DISPLAY_PREFERENCE = ['x', 'opencv', 'gtk', 'win32', 'gdi']
 
 
def get_display(preferences: Optional[List[str]] = None) -> Optional[Display]:
  '''
  Get a new ViSP display instance, dependending on what display driver is available.
 
  :param preference: An optional list of preferred backends to use.
  The backends are tested in the order they are specified, and the first match is instanciated.
  If preference is None, a default list of display is used. This list contains all basic displays.
  The specified values are case insensitive and may include. See VISP_DEFAULT_DISPLAY_PREFERENCE for the available options
 
  :return: a new instance of a ViSP display if one of the requested backend has been found, None otherwise
  '''
 
  final_prefs: List[str] = preferences if preferences is not None else VISP_DEFAULT_DISPLAY_PREFERENCE
  for preference in final_prefs:
    pref_key = preference.lower()
    display_opt = VISP_DISPLAY_CLS_MAP.get(pref_key)
    if display_opt is not None:
      return display_opt()
  return None