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API categories | API index

DpiAware (class)

Available only on Windows. All methods of this class are static, access them through cefpython.WindowUtils.

Example usage of High DPI support is in the wxpython.py example.

Table of contents:

Introduction

By default if DPI awareness is not enabled in application, then OS performs display scaling. That causes text to look blurry on high DPI displays. To resolve this you have to call cef.DpiAware.EnableHighDpiSupport method. High DPI support is available only on Windows.

Enabling High DPI support in app can be done by embedding a DPI awareness xml manifest in both main executable and subprocess executable (see Issue #112 comment #2), or by calling the cef.DpiAware.EnableHighDpiSupport method.

Static methods

CalculateWindowSize

Parameter Type
width int
height int
Return tuple

Deprecated. Use Scale() method instead which can handle non standard DPI settings such as '132%' on Windows 10.

This utility function will adjust width/height using OS DPI settings. For 800/600 with Win7 DPI settings being set to "Larger 150%" will return 1200/900.

EnableHighDpiSupport
Return void

Calling this function will set current process and subprocesses to be DPI aware.

Description from upstream CEF:

Call during process startup to enable High-DPI support on Windows 7 or newer. Older versions of Windows should be left DPI-unaware because they do not support DirectWrite and GDI fonts are kerned very badly.

GetSystemDpi
Return tuple

Returns tuple(int dpix, int dpiy).

Returns Windows DPI settings ("Custom scaling" on Win10).

Win7 DPI (Control Panel > Appearance and Personalization > Display):

  • text size Larger 150% => dpix/dpiy 144
  • text size Medium 125% => dpix/dpiy 120
  • text size Smaller 100% => dpix/dpiy 96

Example zoom levels based on DPI. For use with the ApplicationSettings.auto_zooming option.

  • dpix=96 zoomlevel=0.0
  • dpix=120 zoomlevel=1.0
  • dpix=144 zoomlevel=2.0
  • dpix=72 zoomlevel=-1.0

If DPI awareness wasn't yet enabled, then GetSystemDpi will always return a default 96 DPI.

DPI settings should not be cached. When SetProcessDpiAware is not yet called, then OS returns 96 DPI, even though it is set to 144 DPI. After DPI Awareness is enabled for the running process it will return the correct 144 DPI.

IsProcessDpiAware
Return bool

To check whether OS display scaling on high DPI settings was disabled. DPI awareness may be enabled by calling SetProcessDpiAware. It may also be enabled manually by user by changing options in .exe properties > Compatibility tab.

On Win8 this will return True if DPI awareness is set to either "System DPI aware" or "Per monitor DPI aware".

SetProcessDpiAware
Return void

Calling this method is deprecated, call instead EnableHighDpiSupport(). See Issue #358 for how the behavior changed in latest CEF. This method now internally calls EnableHighDpiSupport().

Enables DPI awareness for the running process. Embedding a DPI manifest in .exe is the prefered way, as it gives more reliable results, otherwise some display bugs may appear (discussed in the "Introduction" section on this page).

Scale

Parameter Type
size int/tuple/list
Return tuple

Scale units for high DPI devices.