PyQt: eventFilter to get mouse position in a semi-transparent window - qt

Question

I want to make:
a semi-transparent fullscreen window (rgba(0,0,0,180)).
while moving mouse, display absolute position on label.
user can press on it to get the absolute position of the mouse.
However I cannot achieve the second one. When moving mouse on it, label won't update mouse's position. But I found when moving out of label (after removing layout.setMargin(0) and layout.setSpacing(0)), it works.
# -*- coding: utf-8 -*-
import sys, os, math
from PyQt4 import QtCore, QtGui
class ScreenPositionLabel(QtGui.QWidget):
def __init__(self):
super(ScreenPositionLabel, self).__init__()
self.setStyleSheet("background-color:rgba(0, 0, 0, 180); color:#fff;")
self.setAttribute(QtCore.Qt.WA_TranslucentBackground)
#self.setAttribute(QtCore.Qt.WA_OpaquePaintEvent, False)
#self.setStyleSheet("QMainWindow{opacity:0.5;}")
self.label = QtGui.QLabel("Please click on screen")
self.label.setAlignment(QtCore.Qt.AlignCenter)
layout = QtGui.QHBoxLayout()
layout.addWidget(self.label)
# remove margin and padding
layout.setMargin(0)
layout.setSpacing(0)
self.setLayout(layout)
self.setMouseTracking(True)
self.installEventFilter(self)
self.label.show()
self.show()
def eventFilter(self, source, event):
if (event.type() == QtCore.QEvent.MouseMove and
event.buttons() == QtCore.Qt.NoButton):
pos = event.pos()
self.label.setText('Please click on screen. ( %d : %d )' % (pos.x(), pos.y()))
elif event.type() == QtCore.QEvent.MouseButtonPress:
pos = event.pos()
print('( %d : %d )' % (pos.x(), pos.y()))
self.close()
return QtGui.QWidget.eventFilter(self, source, event)
app = QtGui.QApplication(sys.argv)
main_window = ScreenPositionLabel()
app.exec_()
Any way to solve this problem? Thanks!

Answer 1

Your 4 questions:
1) I want to make: a semi-transparent fullscreen window (rgba(0,0,0,180)).
Yes, you can. Please use QWidget.setWindowOpacity (self, float level).
2) I want to make: while moving mouse, display absolute position on label.
I recommend using QWidget.mouseMoveEvent (self, QMouseEvent) to get current position your mouse and enable QWidget.setMouseTracking (self, bool enable) for track all mouse movement.
QWidget.setMouseTracking (self, bool enable)
QWidget.mouseMoveEvent (self, QMouseEvent)
3) I want to make: user can press on it to get the absolute position of the mouse.
Using QWidget.mousePressEvent (self, QMouseEvent) to track when mouse press.
4) However I cannot achieve the second one. When moving mouse on it, label won't update mouse's position. But I found when moving out of label (after removing layout.setMargin(0) and layout.setSpacing(0)), it works.
Because in default layout height of QLabel has spacing & margin, then real area isn't all area widget solve it is your solution is OK.
Full example for your solution:
import sys
from PyQt4 import QtGui, QtCore
class QCustomLabel (QtGui.QLabel):
def __init__ (self, parent = None):
super(QCustomLabel, self).__init__(parent)
self.setMouseTracking(True)
self.setTextLabelPosition(0, 0)
self.setAlignment(QtCore.Qt.AlignCenter)
def mouseMoveEvent (self, eventQMouseEvent):
self.setTextLabelPosition(eventQMouseEvent.x(), eventQMouseEvent.y())
QtGui.QWidget.mouseMoveEvent(self, eventQMouseEvent)
def mousePressEvent (self, eventQMouseEvent):
if eventQMouseEvent.button() == QtCore.Qt.LeftButton:
QtGui.QMessageBox.information(self, 'Position', '( %d : %d )' % (self.x, self.y))
QtGui.QWidget.mousePressEvent(self, eventQMouseEvent)
def setTextLabelPosition (self, x, y):
self.x, self.y = x, y
self.setText('Please click on screen ( %d : %d )' % (self.x, self.y))
class QCustomWidget (QtGui.QWidget):
def __init__ (self, parent = None):
super(QCustomWidget, self).__init__(parent)
self.setWindowOpacity(0.7)
# Init QLabel
self.positionQLabel = QCustomLabel(self)
# Init QLayout
layoutQHBoxLayout = QtGui.QHBoxLayout()
layoutQHBoxLayout.addWidget(self.positionQLabel)
layoutQHBoxLayout.setMargin(0)
layoutQHBoxLayout.setSpacing(0)
self.setLayout(layoutQHBoxLayout)
self.showFullScreen()
myQApplication = QtGui.QApplication(sys.argv)
myQTestWidget = QCustomWidget()
myQTestWidget.show()
myQApplication.exec_()