Translating a PyQt4 code to PyQt5 is not a trivial task:
- PyQt4 and PyQt5 are wrappers of Qt4 and Qt5, respectively, so both are affected by the changes of that transition, and one of the transitions is that the QtGui sub-module of Qt4 was divided into the QtGui and QtWidgets sub-modules of Qt5.
- Some classes and methods are deprecated so you will have to find an equivalent if it exists.
In this case both things happen, the solution for the first case is simple: You must look in the Qt docs and check to which sub-module it belongs, for example QToolTip, at the top there is a table:

And the part of QT += widgets that indicates that it belongs to the QtWidgets sub-module is observed.
But the second case is somewhat more complicated since it involves looking for an equivalent that may or may not be in the same class, in this case it happens with the QPixmap.grabWindow() method which is deprecates (see here for more information). After doing a search you can replace that code with QApplication.primaryScreen().grabWindow(0).
Considering all of the above, the translation is:
import sys
from PyQt5.QtCore import QRectF, Qt
from PyQt5.QtGui import QColor, QFont, QPainter, QPixmap, QTextOption, QScreen
from PyQt5.QtWidgets import QApplication, QToolTip, QWidget
class AreaSelector(QWidget):
def __init__(self, parent=None):
QWidget.__init__(self, None, Qt.FramelessWindowHint)
self.setAttribute(Qt.WA_TranslucentBackground)
self.setAttribute(Qt.WA_DeleteOnClose)
self.setWindowState(Qt.WindowFullScreen)
self.setAutoFillBackground(False)
self.parent = parent
self.start_x = 0
self.start_y = 0
self.end_x = 0
self.end_y = 0
self.current_x = 0
self.current_y = 0
def showEvent(self, event):
self.bg = QApplication.primaryScreen().grabWindow(0)
self.screen_geometry = QApplication.primaryScreen().geometry()
def mousePressEvent(self, event):
self.start_x = event.globalX()
self.start_y = event.globalY()
def mouseReleaseEvent(self, event):
self.end_x = event.globalX()
self.end_y = event.globalY()
def mouseMoveEvent(self, event):
self.current_x = event.globalX()
self.current_y = event.globalY()
self.repaint()
text = "Start: %sx%s \nEnd: %sx%s" % (
self.start_x,
self.start_y,
self.current_x,
self.current_y,
)
QToolTip.showText(event.pos(), text)
def keyPressEvent(self, event):
if event.key() == Qt.Key_Return:
self._acceptSelection()
elif event.key() == Qt.Key_Escape:
self.close()
def _acceptSelection(self):
if self.parent is not None:
self.parent.areaSelectEvent(
self.start_x, self.start_y, self.end_x, self.end_y
)
self.close()
def paintEvent(self, event):
painter = QPainter()
painter.begin(self)
painter.fillRect(self.screen_geometry, QColor(10, 10, 10, 125))
self._paint_selection(painter)
self._paint_usage_text(painter)
painter.end()
def _paint_usage_text(self, painter):
font = QFont("Helvetica [Cronyx]", 26, QFont.Bold)
painter.setFont(font)
painter.setPen(QColor(255, 255, 255, 255))
screen_width = self.screen_geometry.width()
text_width = 800
text_start_x = screen_width / 2 - text_width / 2
screen_height = self.screen_geometry.height()
text_height = 200
text_start_y = screen_height / 2 - text_height / 2
textoption = QTextOption(Qt.AlignCenter)
textbox = QRectF(text_start_x, text_start_y, text_width, text_height)
painter.drawText(
textbox,
"Click & Drag to select an area\n" "ENTER to confirm or ESC to cancel",
textoption,
)
painter.drawRoundedRect(textbox, 20, 20)
def _paint_selection(self, painter):
"""Draws the current user selection"""
rectangle = QRectF()
if self.start_x > self.current_x:
rectangle.setLeft(self.current_x)
rectangle.setRight(self.start_x)
else:
rectangle.setLeft(self.start_x)
rectangle.setRight(self.current_x)
if self.start_y > self.current_y:
rectangle.setTop(self.current_y)
rectangle.setBottom(self.start_y)
else:
rectangle.setTop(self.start_y)
rectangle.setBottom(self.current_y)
painter.drawPixmap(rectangle, self.bg, rectangle)
painter.drawRect(rectangle)
if __name__ == "__main__":
app = QApplication(sys.argv)
main = AreaSelector()
main.show()
sys.exit(app.exec_())