Python code to change displayed image with pyqt4 on request - qt

I have the following code to display am image using pyQt:
app = QtGui.QApplication(sys.argv)
window = QtGui.QMainWindow()
window.setGeometry(opts.posx, opts.posy, opts.width, opts.height)
pic = QtGui.QLabel(window)
pic.setGeometry(5, 5, opts.width-10, opts.height-10)
pixmap = QtGui.QPixmap(opts.filename)
pixmap = pixmap.scaledToHeight(opts.height)
pic.setPixmap(pixmap)
window.show()
sys.exit(app.exec_())
I would like to wrap up this code possibly in the form of a class, and be able to set a different image during runtime, using signals, socket, threads I really do not know. I would imagine something like:
class MyImage(object):
def __init(self, args):
some setup code
self.pic = whatever
def set_image(self, filename):
pixmap = QtGui.QPixmap(opts.filename)
pixmap = pixmap.scaledToHeight(opts.height)
pic.setPixmap(pixmap)
With the original code I just call sys.exit(app.exec_()) which makes the code 'freeze'. But I want to send a signal (and a filename) from a different running python code. Any suggestion how this can be handled easily and straightforward? Maybe overwriting the app.exec_ method?

Something like this should work for you:
#!/usr/bin/env python
#-*- coding:utf-8 -*-
import sip
sip.setapi('QString', 2)
sip.setapi('QVariant', 2)
from PyQt4 import QtGui, QtCore
class ImageChanger(QtGui.QWidget):
def __init__(self, images, parent=None):
super(ImageChanger, self).__init__(parent)
self.comboBox = QtGui.QComboBox(self)
self.comboBox.addItems(images)
self.layout = QtGui.QVBoxLayout(self)
self.layout.addWidget(self.comboBox)
class MyWindow(QtGui.QWidget):
def __init__(self, images, parent=None):
super(MyWindow, self).__init__(parent)
self.label = QtGui.QLabel(self)
self.imageChanger = ImageChanger(images)
self.imageChanger.move(self.imageChanger.pos().y(), self.imageChanger.pos().x() + 100)
self.imageChanger.show()
self.imageChanger.comboBox.currentIndexChanged[str].connect(self.changeImage)
self.layout = QtGui.QVBoxLayout(self)
self.layout.addWidget(self.label)
#QtCore.pyqtSlot(str)
def changeImage(self, pathToImage):
pixmap = QtGui.QPixmap(pathToImage)
self.label.setPixmap(pixmap)
if __name__ == "__main__":
import sys
images = [ "/path/to/image/1",
"/path/to/image/2",
"/path/to/image/3",
]
app = QtGui.QApplication(sys.argv)
app.setApplicationName('MyWindow')
main = MyWindow(images)
main.show()
sys.exit(app.exec_())

Related

qt: qlayout do not correctly add widget

I want do dynamically change the layout in Qt. For example, I want to change the QHBoxLayout to QVBoxLayout through a button. My test code is:
from PyQt5.QtWidgets import *
import sys
class SubWidget(QWidget):
def __init__(self):
super().__init__()
self.lay = QHBoxLayout()
self.label1 = QLabel('left')
self.label2 = QLabel('right')
self.lay.addWidget(self.label1)
self.lay.addWidget(self.label2)
self.setLayout(self.lay)
def change(self):
self.lay.removeWidget(self.label1)
self.lay.removeWidget(self.label2)
self.lay = QVBoxLayout()
self.setLayout(self.lay)
self.lay.addWidget(self.label2)
self.lay.addWidget(self.label1)
class Widget(QWidget):
def __init__(self):
super().__init__()
lay = QVBoxLayout()
self.btn = QPushButton('change layout')
self.btn.clicked.connect(self.btnClick)
self.subWidget = SubWidget()
lay.addWidget(self.btn)
lay.addWidget(self.subWidget)
self.setLayout(lay)
def btnClick(self, check=False):
self.subWidget.change()
if __name__ == '__main__':
app = QApplication(sys.argv)
win = Widget()
win.show()
app.exec_()
The code output GUI is:
And I hope it change to the following picture after click change layout button:
Any suggestion is appreciated~~~
The point of the solution is
Make sure old layout is deleted, included both python wrapping reference and core Qt object, that's for deleteLater() is used.
Make sure new layout is assigned strictly after old was deleted, that's for need to use destroyed()-switchlayout() signal-slot chain.
I reproduced example with PySide6 (don't forget to switch on your version of PyQt or PySide package):
# from PyQt5.QtWidgets import *
from PySide6.QtWidgets import *
import sys
class SubWidget(QWidget):
def __init__(self):
super().__init__()
self.lay = QVBoxLayout()
self.label1 = QLabel('left')
self.label2 = QLabel('right')
self.lay.addWidget(self.label1)
self.lay.addWidget(self.label2)
self.setLayout(self.lay)
def change(self):
self.lay.removeWidget(self.label1)
self.lay.removeWidget(self.label2)
self.lay.deleteLater()
self.lay.destroyed.connect(self.switchlayout)
def switchlayout(self):
# print("***destroyed")
self.lay = QHBoxLayout()
self.lay.addWidget(self.label2)
self.lay.addWidget(self.label1)
self.setLayout(self.lay)
self.adjustSize()
class Widget(QWidget):
def __init__(self):
super().__init__()
lay = QVBoxLayout()
self.btn = QPushButton('change layout')
self.btn.clicked.connect(self.btnClick)
self.subWidget = SubWidget()
lay.addWidget(self.btn)
lay.addWidget(self.subWidget)
self.setLayout(lay)
def btnClick(self, check=False):
self.subWidget.change()
if __name__ == '__main__':
app = QApplication(sys.argv)
win = Widget()
win.show()
app.exec_()

I can't see QLabel and QLineEdit widgets in my QMainWindow in Python2

I wrote this code and I don't understand why widgets QLabel and QLineEdit don't show up? Do I have to put them in another class? It's Python2.7 and PySide.
This is how a window looks like when I run the code:
#!/usr/bin/env python
# coding: utf-8
import sys
import crypt
from PySide import QtGui
class MyApp(QtGui.QMainWindow):
def __init__(self, parent=None):
super(MyApp, self).__init__(parent)
self.initui()
def initui(self):
# main window size, title and icon
self.setMinimumSize(500, 350)
self.setWindowTitle("Calculate a password hash in Linux")
# lines for entering data
self.saltLabel = QtGui.QLabel("Salt:")
self.saltLine = QtGui.QLineEdit()
self.saltLine.setPlaceholderText("e.g. $6$xxxxxxxx")
# set layout
grid = QtGui.QGridLayout()
grid.addWidget(self.saltLabel, 0, 0)
grid.addWidget(self.saltLine, 1, 0)
self.setLayout(grid)
# show a widget
self.show()
def main():
app = QtGui.QApplication(sys.argv)
instance = MyApp()
instance.show()
sys.exit(app.exec_())
if __name__ == "__main__":
main()
How about using a QWidget as centralWidget
widget = QWidget()
widget.setLayout(grid)
#add your widgets and...
self.setCentralWidget(widget)
and you don't need to call show() since you do in your __main__
It's up to the owner but i would recommend sublassing a QWidget and leave your QMainWindow instance as concise as possible. An implementation could be:
class MyWidget(QtGui.QWidget):
def __init__(self, *args):
QtGui.QWidget.__init__(self, *args)
grid = QtGui.QGridLayout()
#and so on...
and use this as widget in your QMainWindow instance. This increases readability and maintainability and reusability a lot :)

Painting FocusRect with QStylePainter

I am trying to make my own widget that uses QStyle options in order to give it a "native" look and feel.
Step 1 would be drawing a simple FocusRect, which I tried to accomplish like that:
import sys
from PyQt5 import QtWidgets, QtGui
class MyWidget(QtWidgets.QWidget):
def __init__(self, parent=None):
super().__init__(parent)
def paintEvent(self, event):
painter = QtWidgets.QStylePainter(self)
option = QtWidgets.QStyleOptionFocusRect()
option.initFrom(self)
option.backgroundColor = self.palette().color(QtGui.QPalette.Background)
painter.drawPrimitive(QtWidgets.QStyle.PE_FrameFocusRect, option)
if __name__ == '__main__':
qApp = QtWidgets.QApplication(sys.argv)
qApp.setStyle('fusion')
window = QtWidgets.QMainWindow()
window.widget = MyWidget(window)
window.widget.resize(100, 100)
window.widget.move(50, 50)
window.setFixedSize(200, 200)
window.show()
sys.exit(qApp.exec_())
Unfortunately this only gives me an empty window. What am I missing?
Turns out that the FrameFocusRect is only painted, when it actually has the focus.
Adding option.state |= QtWidgets.QStyle.State_KeyboardFocusChange in the paintEvent method solves the problem.

QMovie setting filename second time wont work

I am setting the Initial Movie File like this:
self.movie = QMovie("dotGreenBlack.gif", QByteArray(), self)
At runtime, i want to change it by setting:
self.movie.setFileName("dotGreyStatic.gif")
But this leads to frame-freeze of the primarly set file "dotGreenBlack.gif"
Anything else i have to do to change the Gif-Animation on runtime?
Here is the fullcode:
from PyQt4 import QtCore, QtGui
from PyQt4.QtGui import *
from PyQt4.QtCore import *
import sys
class ImagePlayer(QWidget):
def __init__(self, filename, title, parent=None):
QWidget.__init__(self, parent)
# Load the file into a QMovie
self.movie = QMovie(filename, QByteArray(), self)
size = self.movie.scaledSize()
self.setGeometry(200, 200, size.width(), size.height())
self.setWindowTitle(title)
self.movie_screen = QLabel()
# Make label fit the gif
self.movie_screen.setSizePolicy(QSizePolicy.Expanding, QSizePolicy.Expanding)
self.movie_screen.setAlignment(Qt.AlignCenter)
# Create the layout
main_layout = QVBoxLayout()
main_layout.addWidget(self.movie_screen)
self.setLayout(main_layout)
# Add the QMovie object to the label
self.movie.setCacheMode(QMovie.CacheAll)
self.movie.setSpeed(100)
self.movie_screen.setMovie(self.movie)
self.movie.start()
self.movie.loopCount()
self.movie.setFileName("dotGreyStatic.gif")
self.movie_screen.setMovie(self.movie)
if __name__ == "__main__":
gif = "dotGreenBlack.gif"
app = QApplication(sys.argv)
app.setStyleSheet("QWidget { background-color: black }")
player = ImagePlayer(gif, "was")
player.show()
sys.exit(app.exec_())
Gif Icons used in this Example:
You just need to stop and restart the movie:
self.movie.stop()
self.movie.setFileName("dotGreyStatic.gif")
self.movie.start()

PySide crashing when replacing rows in QFormLayout

Using the following code example PySide segfaults when pushing "Add", "Add", "Remove", "Add" and due to some other sequences of interaction.
Python: 2.7.6
PySide: 1.2.1
QtCore: 4.8.5
Code:
from PySide.QtGui import *
from PySide.QtCore import *
class MainWindow(QMainWindow):
def __init__(self, parent=None):
super(MainWindow, self).__init__(parent)
self.setObjectName('MainWindow')
self.baseLayout = QWidget(self)
self.v_layout = QVBoxLayout(self.baseLayout)
self.setCentralWidget(self.baseLayout)
self.form_layout = QFormLayout(self.baseLayout)
self.v_layout.addLayout(self.form_layout)
self.button_add = QPushButton(self.baseLayout)
self.button_add.setText("Add")
self.v_layout.addWidget(self.button_add)
self.button_del = QPushButton(self.baseLayout)
self.button_del.setText("Remove")
self.v_layout.addWidget(self.button_del)
self.button_add.clicked.connect(self.add)
self.button_del.clicked.connect(self.remove)
self.fields = []
def add_item(self):
layout = QHBoxLayout(self.parent())
line = QLineEdit(self.parent())
slider = QSlider(self.parent())
layout.addWidget(line)
layout.addWidget(slider)
self.fields.append((layout, line, slider))
self.form_layout.addRow("Test", layout)
def add(self):
for i in range(15):
self.add_item()
def remove(self):
for (layout, line, slider) in self.fields:
line.deleteLater()
slider.deleteLater()
while self.form_layout.itemAt(0):
child = self.form_layout.takeAt(0)
if child.widget():
child.widget().deleteLater()
self.form_layout.update()
self.fields = []
def main():
import sys
app = QApplication(sys.argv)
frame = MainWindow()
frame.show()
app.exec_()
if __name__ == '__main__':
main()
Is this the correct way of adding compound widgets (in this case a QLineEdit and a QSlider within a QVBoxLayout) to a form layout? What am I doing wrong?
The correct way of adding "compound widgets" to a QFormLayout is to create a QWidget that will be the parent to that layout.
add_item() should rather look something like this:
def add_item(self):
widget = QWidget(self.parent())
layout = QHBoxLayout(widget)
line = QLineEdit(widget)
slider = QSlider(widget)
layout.addWidget(line)
layout.addWidget(slider)
self.fields.append((layout, widget, line, slider))
self.form_layout.addRow("Test", widget)
(And the widget also has to be removed when deleting the fields).
I think you are not creating the layouts in the right way, for example you are trying to set the layout of base_layout two times. Also you can check for count() on a QLayout to see if it has children:
from PySide.QtGui import *
from PySide.QtCore import *
class MainWindow(QMainWindow):
def __init__(self, parent=None):
super(MainWindow, self).__init__(parent)
self.baseLayout = QWidget(self)
self.v_layout = QVBoxLayout(self.baseLayout)
self.setCentralWidget(self.baseLayout)
self.form_layout = QFormLayout()
self.v_layout.addLayout(self.form_layout)
self.button_add = QPushButton()
self.button_add.setText("Add")
self.v_layout.addWidget(self.button_add)
self.button_del = QPushButton()
self.button_del.setText("Remove")
self.v_layout.addWidget(self.button_del)
self.button_add.clicked.connect(self.add)
self.button_del.clicked.connect(self.remove)
self.fields = []
def add_item(self):
layout = QHBoxLayout()
line = QLineEdit()
slider = QSlider()
layout.addWidget(line)
layout.addWidget(slider)
self.fields.append((layout, line, slider))
self.form_layout.addRow("Test", layout)
def add(self):
for i in range(15):
self.add_item()
def remove(self):
while self.form_layout.count() > 0:
child = self.form_layout.takeAt(0)
widget = child.widget()
if widget:
widget.deleteLater()
self.form_layout.update()
self.fields = []
def main():
import sys
app = QApplication(sys.argv)
frame = MainWindow()
frame.show()
app.exec_()
if __name__ == '__main__':
main()

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