have mkQApp configure QApplication such that it handles HIDPI displays on Windows (#1509)

* set environment variables before starting QApp

* fix-422

* Better support of hidpi

* Fix Typo in App-Name

* Remove fontScaleFactor bits

* Add documenation for hidpi displays

doc/source/how_to_use.rst

@@ -54,6 +54,28 @@ For the serious application developer, all of the functionality in pyqtgraph is
 See the designer documentation for more information on promoting widgets. The "VideoSpeedTest" and "ScatterPlotSpeedTest" examples both demonstrate the use of .ui files that are compiled to .py modules using pyuic5 or pyside-uic. The "designerExample" example demonstrates dynamically generating python classes from .ui files (no pyuic5 / pyside-uic needed).
 
 
+HiDPI Displays
+--------------
+
+PyQtGraph has a method :func:`mkQApp <pyqtgraph.Qt.mkQApp>` that by default sets what we have tested to be the best combination of options to support hidpi displays, when in combination with non-hidpi secondary displays.  For your application, you may have instantiated ``QApplication`` yourself, in which case we advise setting these options *before* runing ``QApplication.exec_()``.  
+
+For Qt6 bindings, this functionally "just works" without having to set any attributes.
+
+On Versions of Qt >= 5.14 and < 6; you can get ideal behavior with the following lines::
+
+    os.environ["QT_ENABLE_HIDPI_SCALING"] = "1" 
+    QApplication.setHighDpiScaleFactorRoundingPolicy(QtCore.Qt.HighDpiScaleFactorRoundingPolicy.PassThrough)
+
+If you are on Qt >= 5.6 and < 5.14; you can get near ideal behavior with the following lines::
+
+    QApplication.setAttribute(QtCore.Qt.AA_EnableHighDpiScaling)
+    QApplication.setAttribute(QtCore.Qt.AA_UseHighDpiPixmaps)
+
+With the later, ideal behavior was not achieved.
+
+.. autofunction:: pyqtgraph.Qt.mkQApp
+
+
 PyQt and PySide
 ---------------
 
@@ -63,8 +85,9 @@ pyqtgraph is first imported, it automatically determines which library to use by
     
 #. If PyQt5 is already imported, use that
 #. Else, if PySide2 is already imported, use that
-#. Else, attempt to import PyQt5
-#. If that import fails, attempt to import PySide2. 
+#. Else, if PySide6 is already imported, use that
+#. Else, if PyQt6 is already imported, use that
+#. Else, attempt to import PyQt5, PySide2, PySide6, PyQt6, in that order.
 
 If you have both libraries installed on your system and you wish to force pyqtgraph to use one or the other, simply
 make sure it is imported before pyqtgraph::

examples/Arrow.py

@@ -15,7 +15,7 @@ from pyqtgraph.Qt import QtGui, QtCore
 import pyqtgraph as pg
 
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("Arrow Example")
 
 w = QtGui.QMainWindow()
 cw = pg.GraphicsLayoutWidget()

examples/ColorButton.py

@@ -11,7 +11,7 @@ import pyqtgraph as pg
 from pyqtgraph.Qt import QtCore, QtGui
 import numpy as np
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("ColorButton Example")
 win = QtGui.QMainWindow()
 btn = pg.ColorButton()
 win.setCentralWidget(btn)

examples/DataSlicing.py

@@ -14,7 +14,7 @@ import numpy as np
 from pyqtgraph.Qt import QtCore, QtGui
 import pyqtgraph as pg
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("Data Slicing Example")
 
 ## Create window with two ImageView widgets
 win = QtGui.QMainWindow()

examples/DataTreeWidget.py

@@ -22,7 +22,7 @@ def some_func2():
         return sys.exc_info()[2]
 
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("DataTreeWidget Example")
 d = {
     'a list': [1,2,3,4,5,6, {'nested1': 'aaaaa', 'nested2': 'bbbbb'}, "seven"],
     'a dict': {

examples/DateAxisItem.py

@@ -12,7 +12,7 @@ import numpy as np
 import pyqtgraph as pg
 from pyqtgraph.Qt import QtGui
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("DateAxisItem Example")
 
 # Create a plot with a date-time axis
 w = pg.PlotWidget(axisItems = {'bottom': pg.DateAxisItem()})

examples/DiffTreeWidget.py

@@ -12,7 +12,7 @@ from pyqtgraph.Qt import QtCore, QtGui
 import numpy as np
 
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("DiffTreeWidget Example")
 A = {
     'a list': [1,2,2,4,5,6, {'nested1': 'aaaa', 'nested2': 'bbbbb'}, "seven"],
     'a dict': {

examples/Draw.py

@@ -12,7 +12,7 @@ from pyqtgraph.Qt import QtCore, QtGui
 import numpy as np
 import pyqtgraph as pg
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("Draw Example")
 
 ## Create window with GraphicsView widget
 w = pg.GraphicsView()

examples/Flowchart.py

@@ -19,7 +19,7 @@ import pyqtgraph as pg
 import numpy as np
 import pyqtgraph.metaarray as metaarray
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("Flowchart Example")
 
 ## Create main window with grid layout
 win = QtGui.QMainWindow()

examples/FlowchartCustomNode.py

@@ -13,7 +13,7 @@ from pyqtgraph.Qt import QtGui, QtCore
 import pyqtgraph as pg
 import numpy as np
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("Flowchart Custom Node Example")
 
 ## Create main window with a grid layout inside
 win = QtGui.QMainWindow()

examples/GLBarGraphItem.py

@@ -11,7 +11,7 @@ import pyqtgraph.opengl as gl
 import pyqtgraph as pg
 import numpy as np
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("GLBarGraphItem Example")
 w = gl.GLViewWidget()
 w.opts['distance'] = 40
 w.show()

examples/GLImageItem.py

@@ -13,7 +13,7 @@ import pyqtgraph.opengl as gl
 import pyqtgraph as pg
 import numpy as np
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("GLImageItem Example")
 w = gl.GLViewWidget()
 w.opts['distance'] = 200
 w.show()

examples/GLIsosurface.py

@@ -11,7 +11,7 @@ from pyqtgraph.Qt import QtCore, QtGui
 import pyqtgraph as pg
 import pyqtgraph.opengl as gl
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("GLIsosurface Example")
 w = gl.GLViewWidget()
 w.show()
 w.setWindowTitle('pyqtgraph example: GLIsosurface')

examples/GLLinePlotItem.py

@@ -11,7 +11,7 @@ import pyqtgraph.opengl as gl
 import pyqtgraph as pg
 import numpy as np
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("GLLinePlotItem Example")
 w = gl.GLViewWidget()
 w.opts['distance'] = 40
 w.show()

examples/GLMeshItem.py

@@ -11,7 +11,7 @@ from pyqtgraph.Qt import QtCore, QtGui
 import pyqtgraph as pg
 import pyqtgraph.opengl as gl
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("GLMeshItem Example")
 w = gl.GLViewWidget()
 w.show()
 w.setWindowTitle('pyqtgraph example: GLMeshItem')

examples/GLScatterPlotItem.py

@@ -7,11 +7,12 @@ Demonstrates use of GLScatterPlotItem with rapidly-updating plots.
 ## Add path to library (just for examples; you do not need this)
 import initExample
 
+import pyqtgraph as pg
 from pyqtgraph.Qt import QtCore, QtGui
 import pyqtgraph.opengl as gl
 import numpy as np
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("GLScatterPlotItem Example")
 w = gl.GLViewWidget()
 w.opts['distance'] = 20
 w.show()

examples/GLSurfacePlot.py

@@ -13,7 +13,7 @@ import pyqtgraph.opengl as gl
 import numpy as np
 
 ## Create a GL View widget to display data
-app = QtGui.QApplication([])
+app = pg.mkQApp("GLSurfacePlot Example")
 w = gl.GLViewWidget()
 w.show()
 w.setWindowTitle('pyqtgraph example: GLSurfacePlot')

examples/GLViewWidget.py

@@ -9,7 +9,7 @@ import initExample
 from pyqtgraph.Qt import QtCore, QtGui
 import pyqtgraph.opengl as gl
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("GLViewWidget Example")
 w = gl.GLViewWidget()
 w.opts['distance'] = 20
 w.show()

examples/GLVolumeItem.py

@@ -7,10 +7,11 @@ Demonstrates GLVolumeItem for displaying volumetric data.
 ## Add path to library (just for examples; you do not need this)
 import initExample
 
+import pyqtgraph as pg
 from pyqtgraph.Qt import QtCore, QtGui
 import pyqtgraph.opengl as gl
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("GLVolumeItem Example")
 w = gl.GLViewWidget()
 w.opts['distance'] = 200
 w.show()

examples/GLshaders.py

@@ -13,7 +13,7 @@ from pyqtgraph.Qt import QtCore, QtGui
 import pyqtgraph as pg
 import pyqtgraph.opengl as gl
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("GLShaders Example")
 w = gl.GLViewWidget()
 w.show()
 w.setWindowTitle('pyqtgraph example: GL Shaders')

examples/GradientEditor.py

@@ -7,7 +7,7 @@ from pyqtgraph.Qt import QtGui, QtCore
 import pyqtgraph as pg
 
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("Gradiant Editor Example")
 mw = pg.GraphicsView()
 mw.resize(800,800)
 mw.show()

examples/GradientWidget.py

@@ -12,7 +12,7 @@ import numpy as np
 
 
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("Gradiant Widget Example")
 w = QtGui.QMainWindow()
 w.show()
 w.setWindowTitle('pyqtgraph example: GradientWidget')

examples/GraphicsLayout.py

@@ -12,7 +12,7 @@ from pyqtgraph.Qt import QtGui, QtCore
 import pyqtgraph as pg
 import numpy as np
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("Gradiant Layout Example")
 view = pg.GraphicsView()
 l = pg.GraphicsLayout(border=(100,100,100))
 view.setCentralItem(l)

examples/GraphicsScene.py

@@ -6,7 +6,7 @@ from pyqtgraph.Qt import QtCore, QtGui
 import pyqtgraph as pg
 from pyqtgraph.GraphicsScene import GraphicsScene
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("GraphicsScene Example")
 win = pg.GraphicsView()
 win.show()
 

examples/HistogramLUT.py

@@ -11,7 +11,7 @@ from pyqtgraph.Qt import QtGui, QtCore
 import pyqtgraph as pg
 
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("Histogram Lookup Table Example")
 win = QtGui.QMainWindow()
 win.resize(800,600)
 win.show()

examples/ImageItem.py

@@ -11,7 +11,7 @@ import numpy as np
 import pyqtgraph as pg
 import pyqtgraph.ptime as ptime
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("ImageItem Example")
 
 ## Create window with GraphicsView widget
 win = pg.GraphicsLayoutWidget()

examples/ImageView.py

@@ -20,7 +20,7 @@ import pyqtgraph as pg
 # Interpret image data as row-major instead of col-major
 pg.setConfigOptions(imageAxisOrder='row-major')
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("ImageView Example")
 
 ## Create window with ImageView widget
 win = QtGui.QMainWindow()

examples/InfiniteLine.py

@@ -9,7 +9,7 @@ import numpy as np
 import pyqtgraph as pg
 
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("InfiniteLine Example")
 win = pg.GraphicsLayoutWidget(show=True, title="Plotting items examples")
 win.resize(1000,600)
 

examples/JoystickButton.py

@@ -12,7 +12,7 @@ from pyqtgraph.Qt import QtGui, QtCore
 import pyqtgraph as pg
 
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("Joystick Button Example")
 mw = QtGui.QMainWindow()
 mw.resize(300,50)
 mw.setWindowTitle('pyqtgraph example: JoystickButton')

examples/LogPlotTest.py

@@ -10,7 +10,7 @@ from pyqtgraph.Qt import QtGui, QtCore
 import numpy as np
 import pyqtgraph as pg
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("Log Plot Example")
 
 win = pg.GraphicsLayoutWidget(show=True, title="Basic plotting examples")
 win.resize(1000,600)

examples/MultiPlotSpeedTest.py

@@ -12,7 +12,7 @@ from pyqtgraph.Qt import QtGui, QtCore
 import numpy as np
 import pyqtgraph as pg
 from pyqtgraph.ptime import time
-app = QtGui.QApplication([])
+app = pg.mkQApp("MultiPlot Speed Test")
 
 plot = pg.plot()
 plot.setWindowTitle('pyqtgraph example: MultiPlotSpeedTest')

examples/MultiPlotWidget.py

@@ -14,7 +14,7 @@ except:
     print("MultiPlot is only used with MetaArray for now (and you do not have the metaarray package)")
     exit()
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("MultiPlot Widget Example")
 mw = QtGui.QMainWindow()
 mw.resize(800,800)
 pw = MultiPlotWidget()

examples/NonUniformImage.py

@@ -41,7 +41,7 @@ P_loss[P_mech > 1.5e5] = np.NaN
 # green - orange - red
 Gradients['gor'] = {'ticks': [(0.0, (74, 158, 71)), (0.5, (255, 230, 0)), (1, (191, 79, 76))], 'mode': 'rgb'}
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("NonUniform Image Example")
 
 win = QtGui.QMainWindow()
 cw = pg.GraphicsLayoutWidget()

examples/PColorMeshItem.py

@@ -11,7 +11,7 @@ import numpy as np
 import pyqtgraph as pg
 import pyqtgraph.ptime as ptime
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("PColorMesh Example")
 
 ## Create window with GraphicsView widget
 win = pg.GraphicsLayoutWidget()

examples/PlotAutoRange.py

@@ -12,7 +12,7 @@ import numpy as np
 import pyqtgraph as pg
 
 #QtGui.QApplication.setGraphicsSystem('raster')
-app = QtGui.QApplication([])
+app = pg.mkQApp("Plot Auto Range Example")
 #mw = QtGui.QMainWindow()
 #mw.resize(800,800)
 

examples/PlotSpeedTest.py

@@ -12,7 +12,7 @@ from pyqtgraph.Qt import QtGui, QtCore
 import numpy as np
 import pyqtgraph as pg
 from pyqtgraph.ptime import time
-app = QtGui.QApplication([])
+app = pg.mkQApp("Plot Speed Test")
 
 p = pg.plot()
 p.setWindowTitle('pyqtgraph example: PlotSpeedTest')

examples/Plotting.py

@@ -13,7 +13,7 @@ import numpy as np
 import pyqtgraph as pg
 
 #QtGui.QApplication.setGraphicsSystem('raster')
-app = QtGui.QApplication([])
+app = pg.mkQApp("Plotting Example")
 #mw = QtGui.QMainWindow()
 #mw.resize(800,800)
 

examples/ProgressDialog.py

@@ -9,7 +9,7 @@ import time
 import pyqtgraph as pg
 from pyqtgraph.Qt import QtCore, QtGui
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("Progress Dialog Example")
 
 
 def runStage(i):

examples/ROIExamples.py

@@ -32,7 +32,7 @@ arr[8:13, 44:46] = 10
 
 
 ## create GUI
-app = QtGui.QApplication([])
+app = pg.mkQApp("ROI Examples")
 w = pg.GraphicsLayoutWidget(show=True, size=(1000,800), border=True)
 w.setWindowTitle('pyqtgraph example: ROI Examples')
 

examples/ROItypes.py

@@ -11,7 +11,7 @@ import pyqtgraph as pg
 pg.setConfigOptions(imageAxisOrder='row-major')
 
 ## create GUI
-app = QtGui.QApplication([])
+app = pg.mkQApp("ROI Types Examples")
 
 w = pg.GraphicsLayoutWidget(show=True, size=(800,800), border=True)
 v = w.addViewBox(colspan=2)

examples/ScatterPlot.py

@@ -14,7 +14,7 @@ import numpy as np
 from collections import namedtuple
 from itertools import chain
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("Scatter Plot Item Example") 
 mw = QtGui.QMainWindow()
 mw.resize(800,800)
 view = pg.GraphicsLayoutWidget()  ## GraphicsView with GraphicsLayout inserted by default

examples/ScatterPlotSpeedTest.py

@@ -17,7 +17,7 @@ import numpy as np
 import pyqtgraph as pg
 from pyqtgraph.ptime import time
 #QtGui.QApplication.setGraphicsSystem('raster')
-app = QtGui.QApplication([])
+app = pg.mkQApp("Scatter Plot Speed Test")
 #mw = QtGui.QMainWindow()
 #mw.resize(800,800)
 import importlib

examples/SpinBox.py

@@ -15,7 +15,7 @@ from pyqtgraph.Qt import QtCore, QtGui
 import numpy as np
 import ast
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("SpinBox Example")
 
 
 spins = [

examples/Symbols.py

@@ -10,7 +10,7 @@ import initExample ## Add path to library (just for examples; you do not need th
 from pyqtgraph.Qt import QtGui, QtCore
 import pyqtgraph as pg
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("Symbols Examples")
 win = pg.GraphicsLayoutWidget(show=True, title="Scatter Plot Symbols")
 win.resize(1000,600)
 

examples/TableWidget.py

@@ -9,7 +9,7 @@ import pyqtgraph as pg
 from pyqtgraph.Qt import QtCore, QtGui
 import numpy as np
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("Table Widget Example")
 
 w = pg.TableWidget()
 w.show()

examples/TreeWidget.py

@@ -10,7 +10,7 @@ from pyqtgraph.Qt import QtCore, QtGui
 import numpy as np
 
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("TreeWidget Example")
 
 w = pg.TreeWidget()
 w.setColumnCount(2)

examples/VideoSpeedTest.py

@@ -38,7 +38,7 @@ parser.add_argument('--size', default='512x512', type=lambda s: tuple([int(x) fo
 args = parser.parse_args(sys.argv[1:])
 
 #QtGui.QApplication.setGraphicsSystem('raster')
-app = QtGui.QApplication([])
+app = pg.mkQApp("Video Speed Test Example")
 
 win = QtGui.QMainWindow()
 win.setWindowTitle('pyqtgraph example: VideoSpeedTest')

examples/ViewBox.py

@@ -18,7 +18,7 @@ import numpy as np
 from pyqtgraph.Qt import QtGui, QtCore
 import pyqtgraph as pg
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("ViewBox Example")
 mw = QtGui.QMainWindow()
 mw.setWindowTitle('pyqtgraph example: ViewBox')
 mw.show()

examples/crosshair.py

@@ -12,7 +12,7 @@ from pyqtgraph.Qt import QtGui, QtCore
 from pyqtgraph.Point import Point
 
 #generate layout
-app = QtGui.QApplication([])
+app = pg.mkQApp("Crosshair Example")
 win = pg.GraphicsLayoutWidget(show=True)
 win.setWindowTitle('pyqtgraph example: crosshair')
 label = pg.LabelItem(justify='right')

examples/dockarea.py

@@ -24,7 +24,7 @@ import numpy as np
 
 from pyqtgraph.dockarea import *
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("DockArea Example")
 win = QtGui.QMainWindow()
 area = DockArea()
 win.setCentralWidget(area)

examples/fractal.py

@@ -9,7 +9,7 @@ import pyqtgraph as pg
 from pyqtgraph.Qt import QtCore, QtGui
 import numpy as np
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("Fractal Example")
 
 # Set up UI widgets
 win = pg.QtGui.QWidget()

examples/infiniteline_performance.py

@@ -5,7 +5,7 @@ from pyqtgraph.Qt import QtGui, QtCore
 import numpy as np
 import pyqtgraph as pg
 from pyqtgraph.ptime import time
-app = QtGui.QApplication([])
+app = pg.mkQApp("Infinite Line Performance")
 
 p = pg.plot()
 p.setWindowTitle('pyqtgraph performance: InfiniteLine')

examples/isocurve.py

@@ -11,7 +11,7 @@ from pyqtgraph.Qt import QtGui, QtCore
 import numpy as np
 import pyqtgraph as pg
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("Isocurve Example")
 
 ## make pretty looping data
 frames = 200

examples/linkedViews.py

@@ -13,7 +13,7 @@ import numpy as np
 import pyqtgraph as pg
 
 #QtGui.QApplication.setGraphicsSystem('raster')
-app = QtGui.QApplication([])
+app = pg.mkQApp("Linked Views Example")
 #mw = QtGui.QMainWindow()
 #mw.resize(800,800)
 

examples/logAxis.py

@@ -9,7 +9,7 @@ from pyqtgraph.Qt import QtGui, QtCore
 import pyqtgraph as pg
 
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("Log Axis Example")
 
 w = pg.GraphicsLayoutWidget(show=True)
 w.setWindowTitle('pyqtgraph example: logAxis')

examples/multiprocess.py

@@ -40,7 +40,7 @@ print( "process finished")
 
 import pyqtgraph as pg
 from pyqtgraph.Qt import QtCore, QtGui
-app = pg.QtGui.QApplication([])
+app = pg.mkQApp("Multiprocess Example")
 
 print( "\n=================\nStart QtProcess")
 import sys

examples/optics_demos.py

@@ -15,7 +15,7 @@ import pyqtgraph as pg
 import numpy as np
 from pyqtgraph import Point
 
-app = pg.QtGui.QApplication([])
+app = pg.mkQApp("Optics Demo")
 
 w = pg.GraphicsLayoutWidget(show=True, border=0.5)
 w.resize(1000, 900)

examples/parametertree.py

@@ -14,7 +14,7 @@ import pyqtgraph as pg
 from pyqtgraph.Qt import QtCore, QtGui
 
 
-app = QtGui.QApplication([])
+app = pg.mkQApp("Parameter Tree Example")
 import pyqtgraph.parametertree.parameterTypes as pTypes
 from pyqtgraph.parametertree import Parameter, ParameterTree, ParameterItem, registerParameterType
 

examples/template.py

@@ -8,10 +8,10 @@ Description of example
 import initExample ## Add path to library (just for examples; you do not need this)
 
 import pyqtgraph as pg
-from pyqtgraph.Qt import QtCore, QtGui
+from pyqtgraph.Qt import QtCore, QtGui, mkQApp
 import numpy as np
 
-app = QtGui.QApplication([])
+app = mkQApp()
 
 # win.setWindowTitle('pyqtgraph example: ____')
 

pyqtgraph/Qt.py

@@ -457,8 +457,8 @@ USE_PYQT4 = QT_LIB == PYQT4
 USE_PYQT5 = QT_LIB == PYQT5
 
     
-## Make sure we have Qt >= 4.7
-versionReq = [4, 7]
+## Make sure we have Qt >= 5.12
+versionReq = [5, 12]
 m = re.match(r'(\d+)\.(\d+).*', QtVersion)
 if m is not None and list(map(int, m.groups())) < versionReq:
     print(list(map(int, m.groups())))
@@ -482,7 +482,6 @@ class App(QtGui.QApplication):
             color = palette.base().color().name()
         self.dark_mode = color.lower() != "#ffffff"
 
-
 QAPP = None
 def mkQApp(name=None):
     """
@@ -494,8 +493,20 @@ def mkQApp(name=None):
     ============== ========================================================
     """
     global QAPP
+    
     QAPP = QtGui.QApplication.instance()
     if QAPP is None:
+        # hidpi handling
+        qtVersionCompare = tuple(map(int, QtVersion.split(".")))
+        if qtVersionCompare > (6, 0):
+            # Qt6 seems to support hidpi without needing to do anything so continue
+            pass
+        elif qtVersionCompare > (5, 14):
+            os.environ["QT_ENABLE_HIGHDPI_SCALING"] = "1"
+            QtGui.QApplication.setHighDpiScaleFactorRoundingPolicy(QtCore.Qt.HighDpiScaleFactorRoundingPolicy.PassThrough)
+        else:  # qt 5.12 and 5.13
+            QtGui.QApplication.setAttribute(QtCore.Qt.AA_EnableHighDpiScaling)
+            QtGui.QApplication.setAttribute(QtCore.Qt.AA_UseHighDpiPixmaps)
         QAPP = App(sys.argv or ["pyqtgraph"])
 
     if name is not None:

pyqtgraph/SRTTransform.py

@@ -172,7 +172,7 @@ if __name__ == '__main__':
     from . import widgets
     import GraphicsView
     from .functions import *
-    app = QtGui.QApplication([])
+    app = pg.mkQApp()
     win = QtGui.QMainWindow()
     win.show()
     cw = GraphicsView.GraphicsView()

pyqtgraph/SRTTransform3D.py

@@ -227,7 +227,7 @@ if __name__ == '__main__':
     from . import widgets
     import GraphicsView
     from .functions import *
-    app = QtGui.QApplication([])
+    app = pg.mkQApp()
     win = QtGui.QMainWindow()
     win.show()
     cw = GraphicsView.GraphicsView()

pyqtgraph/graphicsItems/DateAxisItem.py

@@ -269,10 +269,10 @@ class DateAxisItem(AxisItem):
         # Size in pixels a specific tick label will take
         if self.orientation in ['bottom', 'top']:
             def sizeOf(text):
-                return self.fontMetrics.boundingRect(text).width() + padding*self.fontScaleFactor
+                return self.fontMetrics.boundingRect(text).width() + padding
         else:
             def sizeOf(text):
-                return self.fontMetrics.boundingRect(text).height() + padding*self.fontScaleFactor
+                return self.fontMetrics.boundingRect(text).height() + padding
         
         # Fallback zoom level: Years/Months
         self.zoomLevel = YEAR_MONTH_ZOOM_LEVEL
@@ -314,6 +314,5 @@ class DateAxisItem(AxisItem):
         self.fontMetrics = p.fontMetrics()
         
         # Get font scale factor by current window resolution
-        self.fontScaleFactor = p.device().logicalDpiX() / 96
         
         return super(DateAxisItem, self).generateDrawSpecs(p)

pyqtgraph/multiprocess/processes.py

@@ -451,7 +451,7 @@ def startQtEventLoop(name, port, authkey, ppid, debug=False):
     app = QtGui.QApplication.instance()
     #print app
     if app is None:
-        app = QtGui.QApplication([])
+        app = pg.mkQApp()
         app.setQuitOnLastWindowClosed(False)  ## generally we want the event loop to stay open 
                                               ## until it is explicitly closed by the parent process.
     

pyqtgraph/opengl/GLViewWidget.py

@@ -56,9 +56,41 @@ class GLViewWidget(QtWidgets.QOpenGLWidget):
         self.keysPressed = {}
         self.keyTimer = QtCore.QTimer()
         self.keyTimer.timeout.connect(self.evalKeyState)
-        
         self.makeCurrent()
+
+
+    @property
+    def _dpiRatio(self):
+        return self.devicePixelRatioF() or 1
+
+    def _updateScreen(self, screen):
+        self._updatePixelRatio()
+        if screen is not None:
+            screen.physicalDotsPerInchChanged.connect(self._updatePixelRatio)
+            screen.logicalDotsPerInchChanged.connect(self._updatePixelRatio)
+    
+    def _updatePixelRatio(self):
+        event = QtGui.QResizeEvent(self.size(), self.size())
+        self.resizeEvent(event)
+    
+    def showEvent(self, event):
+        window = self.window().windowHandle()
+        window.screenChanged.connect(self._updateScreen)
+        self._updateScreen(window.screen())
         
+    def width(self):
+        if self._dpiRatio.is_integer():
+            return super().width()
+        else:
+            return int(super().width() * self._dpiRatio)
+    
+    def height(self):
+        if self._dpiRatio.is_integer():
+            return super().height()
+        else:
+            return int(super().height() * self._dpiRatio)
+
+
     def reset(self):
         """
         Initialize the widget state or reset the current state to the original state.