"""
Qt.AA_EnableHighDpiScaling scaling behavior broken if all screens have a scale factor
of < 150% on startup

Repro steps:
1) Set all screens to 100% or 125% scaling.
2) Launch this app.
3) Press the button. Note the geometry, scale factors, etc. that are printed.
4) Change the scaling on the screen with the app.
Expected: the app and its contents scales appropriately.
Actual: it doesn't.

Notice the debug output for the screens. If the ratios are reported as 1.0 initially,
they will remain that way regardless of changes to scaling factors on any screen. The
argument to the logicalDotsPerInchChanged will be 96.0 * whatever the scale factor is
set to--this is the same behavior as when the Qt.AA_EnableHighDpiScaling is NOT set.

If at least one of the ratios was reported as > 1.0, then the reported ratios will
change with scaling changes. The argument to the logicalDotsPerInchChanged will always
be 96.0.
"""

import sys

# Must pip install PySide2

from PySide2.QtCore import (
    QCoreApplication,
    QEvent,
    QRect,
    QSize,
    Qt,
    Slot,
)

from PySide2.QtGui import (
    QFont,
)

from PySide2.QtWidgets import (
    QApplication,
    QMainWindow,
    QPushButton,
    QVBoxLayout,
    QWidget,
)

import win32gui


class MainWindow(QWidget):

    def __init__(self, parent=None):
        super().__init__(parent)

        # Create button
        self.button = QPushButton("Show Greetings")
        font = QFont("Segoe UI")
        font.setPointSizeF(24)
        self.button.setFont(font)

        # Create layout and add button
        layout = QVBoxLayout()
        layout.addWidget(self.button)
        layout.setAlignment(self.button, Qt.AlignHCenter | Qt.AlignCenter)

        # Set layout
        self.setLayout(layout)

        # Add button signal to greetings slot
        self.button.clicked.connect(self.on_click)

        for screen in QApplication.screens():
            screen.logicalDotsPerInchChanged.connect(self.on_dpi_changed)

        self.dump('__init__')

    def on_dpi_changed(self, dpi: float) -> None:
        self.dump('on_dpi_changed ' + str(dpi))

    def dump_screens(self):
        for index, screen in enumerate(QApplication.instance().screens()):
            print('screen {} ratio {} geometry {},{},{},{} size {},{}'.format(
                index,
                screen.devicePixelRatio(),
                screen.geometry().left(),
                screen.geometry().top(),
                screen.geometry().right(),
                screen.geometry().bottom(),
                screen.size().width(),
                screen.size().height(),
                ))

    def dump_widget(self, widget, name):
        left, top, right, bottom = win32gui.GetWindowRect(widget.winId())
        actual_width = right - left
        actual_height = bottom - top
        ratio = widget.devicePixelRatio()

        if actual_width == ratio * widget.width() and actual_height == ratio * widget.height():
            status = 'consistent'
        else:
            status = 'INCONSISTENT'

        print("{}: virtual px {},{} ratio {} actual px {},{} {}".format(
            name,
            widget.width(),
            widget.height(),
            ratio,
            actual_width,
            actual_height,
            status,
            )
        )


    def on_click(self):
        self.dump('click')

    def dump(self, caption=None):
        if caption:
            print(caption)

        self.dump_widget(self, 'window')
        self.dump_widget(self.button, 'button')
        self.dump_screens()
        print()

if __name__ == '__main__':

    QCoreApplication.setAttribute(Qt.AA_EnableHighDpiScaling)
    QCoreApplication.setAttribute(Qt.AA_UseHighDpiPixmaps)

    # Create the Qt Application
    app = QApplication(sys.argv)
    # Create and show the MainWindow
    main = MainWindow()
    main.show()
    # Run the main Qt loop
    sys.exit(app.exec_())