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# -*- coding: utf-8 -*-
# -----------------------------------------------------------------------------
# Copyright (c) Vispy Development Team. All Rights Reserved.
# Distributed under the (new) BSD License. See LICENSE.txt for more info.
# -----------------------------------------------------------------------------
from ...ext.gdi32plus import (gdi32, user32, HORZSIZE, VERTSIZE,
HORZRES, VERTRES)
def get_dpi(raise_error=True):
"""Get screen DPI from the OS
Parameters
----------
raise_error : bool
If True, raise an error if DPI could not be determined.
Returns
-------
dpi : float
Dots per inch of the primary screen.
"""
try:
user32.SetProcessDPIAware()
except AttributeError:
pass # not present on XP
dc = user32.GetDC(0)
h_size = gdi32.GetDeviceCaps(dc, HORZSIZE)
v_size = gdi32.GetDeviceCaps(dc, VERTSIZE)
h_res = gdi32.GetDeviceCaps(dc, HORZRES)
v_res = gdi32.GetDeviceCaps(dc, VERTRES)
user32.ReleaseDC(None, dc)
return (h_res/float(h_size) + v_res/float(v_size)) * 0.5 * 25.4
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