Develop Reference

How to auto-resize a PySide6 app to the minimum size when decreasing a `pixmap`?

I use the following code to set a PySide6 app to the minimal possible size. This works fine when increasing the size of the widgets (set - to + in line 37), but not when decreasing it - in effect, the size of the windows does decrease, but it seems to be one step late.
I found a few workarounds, most notably in Qt Layout, resize to minimum after widget size changes, but none of what I tried seems to be working (and I have met other issues with app.processEvents(), which should be avoided anyway).
Edit: In the new code example below, I think the problem is the width of the QPushButton, which is calculated too late.
Interestingly, this width of the QPushButton is solved by the layout.setSizeConstraint(QLayout.SetFixedSize) workaround, but the window width is not.
app.processEvents() works for this example, but I see bad side effects on other signals when using it.
New code example:
from PySide6.QtCore import Qt
from PySide6.QtGui import QPixmap
from PySide6.QtWidgets import (QApplication, QLabel, QLayout, QMainWindow,
QPushButton, QVBoxLayout, QWidget)
class Window(QMainWindow):
def __init__(self):
super().__init__()
self.i = 0
self.button = QPushButton("push me!")
self.button.clicked.connect(self.clicked)
self.label = QLabel()
layout = QVBoxLayout()
layout.addWidget(self.button)
layout.addWidget(self.label)
# https://stackoverflow.com/a/21458822/880783
# layout.setSizeConstraint(QLayout.SetFixedSize) # (ineffective)
widget = QWidget()
widget.setLayout(layout)
self.setCentralWidget(widget)
self.setWindowFlag(Qt.MSWindowsFixedSizeDialogHint)
self.clicked()
self.show()
def clicked(self):
npix = 500 - 50 * self.i
self.label.setPixmap(QPixmap(npix, npix))
# app.processEvents() # (effective, but discouraged)
self.adjustSize()
self.i += 1
app = QApplication()
win = Window()
app.exec()
Original code example:
import threading
import time
from PySide6.QtCore import Qt
from PySide6.QtGui import QPixmap
from PySide6.QtWidgets import (
QApplication,
QHBoxLayout,
QLabel,
QLayout,
QMainWindow,
QWidget,
)
class Window(QMainWindow):
def __init__(self):
super().__init__()
self.label = QLabel()
layout = QHBoxLayout()
layout.addWidget(self.label)
# https://stackoverflow.com/a/21458822/880783
# layout.setSizeConstraint(QLayout.SetFixedSize) # (ineffective)
widget = QWidget()
widget.setLayout(layout)
self.setCentralWidget(widget)
self.setWindowFlag(Qt.MSWindowsFixedSizeDialogHint)
self.show()
def run(self):
for i in range(10):
npix = 500 - 50 * i
self.label.setPixmap(QPixmap(npix, npix))
# app.processEvents() # (ineffective)
self.adjustSize()
time.sleep(1)
app = QApplication()
threading.Thread(target=Window().run).start()
app.exec()

#musicamante has posted very helpful comments, which I now turn into an answer.
Basically, this code works great:
from PySide6.QtCore import QMetaObject, Qt, QTimer, Slot
from PySide6.QtGui import QPixmap
from PySide6.QtWidgets import (QApplication, QLabel, QMainWindow, QPushButton,
QVBoxLayout, QWidget)
class Window(QMainWindow):
def __init__(self):
super().__init__()
self.i = 0
self.button = QPushButton("push me!")
self.button.clicked.connect(self.clicked)
self.label = QLabel()
layout = QVBoxLayout()
layout.addWidget(self.button)
layout.addWidget(self.label)
widget = QWidget()
widget.setLayout(layout)
self.setCentralWidget(widget)
self.setWindowFlag(Qt.MSWindowsFixedSizeDialogHint)
self.clicked()
self.show()
# #Slot()
# def adjustSize(self):
# super().adjustSize()
def clicked(self):
npix = 500 - 50 * self.i
self.label.setPixmap(QPixmap(npix, npix))
self.i += 1
# # As in https://stackoverflow.com/a/23954088/880783 - does not work
# QMetaObject.invokeMethod(self, "adjustSize")
# This works!
QTimer.singleShot(0, self.adjustSize)
app = QApplication()
win = Window()
app.exec()
As one can see, I have also tried the approach put forward https://stackoverflow.com/a/23954088/880783 - without success, however.

Adding animation to QPushbutton enterEvent and exitEvent

I'm trying to add custom animation to QPushbutton without making a custom QPushbutton and overriding its enterEvent() and leaveEvent().
So far I've tried this,
#staticmethod
def addButtonHoverAnimation(button:QPushButton,currentPos:QPoint):
'''
Method to:
=> Add hover animation for provided button
'''
enterShift = QPropertyAnimation(button,b'pos',button)
exitShift = QPropertyAnimation(button,b'pos',button)
def enterEvent(e):
pos=button.pos()
enterShift.setStartValue(pos)
enterShift.setEndValue(QPoint(pos.x()+3,pos.y()+3))
enterShift.setDuration(100)
enterShift.start()
Effects.dropShadow(button,1,2)
def leaveEvent(e):
pos=button.pos()
exitShift.setStartValue(pos)
exitShift.setEndValue(QPoint(pos.x()-3,pos.y()-3))
exitShift.setDuration(100)
exitShift.start()
Effects.dropShadow(button)
button.enterEvent=enterEvent
button.leaveEvent=leaveEvent
But when I move the mouse very quickly in and out of the button before the animation finishes, The button starts to move wierdly towards the North-West direction.
Button Animation Using Dynamic Positions
I figured out this was due to the leaveEvent() being triggered before enterEvent() even finishes and also because the start and end values are dynamic. So, I tried providing currentPos as a static position and using it instead,
#staticmethod
def addButtonHoverAnimation(button:QPushButton,currentPos:QPoint):
'''
Method to:
=> Add hover animation for provided button
'''
enterShift = QPropertyAnimation(button,b'pos',button)
enterShift.setStartValue(currentPos)
enterShift.setEndValue(QPoint(currentPos.x()+3,currentPos.y()+3))
enterShift.setDuration(100)
exitShift = QPropertyAnimation(button,b'pos',button)
exitShift.setStartValue(QPoint(currentPos.x()-3,currentPos.y()-3))
exitShift.setEndValue(currentPos)
exitShift.setDuration(100)
def enterEvent(e):
button.setProperty(b'pos',exitShift.endValue())
enterShift.start()
Effects.dropShadow(button,1,2)
def leaveEvent(e):
exitShift.start()
Effects.dropShadow(button)
button.enterEvent=enterEvent
button.leaveEvent=leaveEvent
On running, as soon as the mouse enters the QPushbutton, it moves to the top-left of its parent widget and the animation starts working fine. I can't figure out why this is happening. But I was able to get that, it only happened when I used any static value in the animation.
Button Animation with Static Position:
Here is an example:
import sys
from PyQt5.QtCore import QEvent, QPoint, QObject, QPropertyAnimation
from PyQt5.QtWidgets import QApplication, QPushButton, QVBoxLayout, QWidget
# This is the same method mentioned above
from styling import addButtonHoverAnimation
class Widget(QWidget):
def __init__(self, parent=None):
super().__init__(parent)
layout=QVBoxLayout()
button1 = QPushButton("Proceed1", self)
layout.addWidget(button1)
button2 = QPushButton("Proceed2", self)
layout.addWidget(button2)
self.setLayout(layout)
self.resize(640, 480)
addButtonHoverAnimation(button1)
addButtonHoverAnimation(button2)
def main():
app = QApplication(sys.argv)
view = Widget()
view.show()
ret = app.exec_()
sys.exit(ret)
if __name__ == "__main__":
main()

The problem is that probably when the state is changed from enter to leave (or vice versa) the previous animation still does not end so the position of the widget is not the initial or final position, so when starting the new animation there is a deviation that accumulates. One possible solution is to initialize the position and keep it as a reference.
On the other hand you should not do x.fooMethod = foo_callable since many can fail, in this case it is better to use an eventfilter.
import sys
from dataclasses import dataclass
from functools import cached_property
from PyQt5.QtCore import QEvent, QPoint, QObject, QPropertyAnimation
from PyQt5.QtWidgets import QApplication, QPushButton, QWidget
#dataclass
class AnimationManager(QObject):
widget: QWidget
delta: QPoint = QPoint(3, 3)
duration: int = 100
def __post_init__(self):
super().__init__(self.widget)
self._start_value = QPoint()
self._end_value = QPoint()
self.widget.installEventFilter(self)
self.animation.setTargetObject(self.widget)
self.animation.setPropertyName(b"pos")
self.reset()
def reset(self):
self._start_value = self.widget.pos()
self._end_value = self._start_value + self.delta
self.animation.setDuration(self.duration)
#cached_property
def animation(self):
return QPropertyAnimation(self)
def eventFilter(self, obj, event):
if obj is self.widget:
if event.type() == QEvent.Enter:
self.start_enter_animation()
elif event.type() == QEvent.Leave:
self.start_leave_animation()
return super().eventFilter(obj, event)
def start_enter_animation(self):
self.animation.stop()
self.animation.setStartValue(self.widget.pos())
self.animation.setEndValue(self._end_value)
self.animation.start()
def start_leave_animation(self):
self.animation.stop()
self.animation.setStartValue(self.widget.pos())
self.animation.setEndValue(self._start_value)
self.animation.start()
class Widget(QWidget):
def __init__(self, parent=None):
super().__init__(parent)
button1 = QPushButton("Proceed1", self)
button1.move(100, 100)
button2 = QPushButton("Proceed2", self)
button2.move(200, 200)
self.resize(640, 480)
animation_manager1 = AnimationManager(widget=button1)
animation_manager2 = AnimationManager(widget=button2)
def main():
app = QApplication(sys.argv)
view = Widget()
view.show()
ret = app.exec_()
sys.exit(ret)
if __name__ == "__main__":
main()
184 / 5000
Resultados de traducción
If you are using a layout then you must reset the position since the layout does not apply the position change immediately but only when the parent widget applies the changes.
class Widget(QWidget):
def __init__(self, parent=None):
super().__init__(parent)
button1 = QPushButton("Proceed1")
button2 = QPushButton("Proceed2")
lay = QVBoxLayout(self)
lay.addWidget(button1)
lay.addWidget(button2)
self.resize(640, 480)
self.animation_manager1 = AnimationManager(widget=button1)
self.animation_manager2 = AnimationManager(widget=button2)
def resizeEvent(self, event):
super().resizeEvent(event)
self.animation_manager1.reset()
self.animation_manager2.reset()

How do I open an image in a separate window using a button click in PyQT5?

from PyQt5.QtWidgets import QApplication, QLabel, QWidget, QFileDialog, QPushButton, QLineEdit,QVBoxLayout, QHBoxLayout
from PyQt5.QtCore import *
from PyQt5.QtGui import QPixmap
from PyQt5.QtWidgets import QApplication, QWidget, QPushButton, QDialog, QVBoxLayout
import Updated_encrypt
import sys
class Window(QWidget):
def __init__(self):
super().__init__()
self.title = 'Encrypt/Decrypt'
self.top = 200
self.left = 500
self.width = 400
self.height = 300
self.InitWindow()
def InitWindow(self):
self.setWindowTitle(self.title)
self.setGeometry(self.left, self.top, self.width, self.height)
vbox = QVBoxLayout()
self.button1 = QPushButton('Encrypt')
self.button1.clicked.connect(self.openSecondDialog)
self.button2 = QPushButton('Decrypt')
vbox.addWidget(self.button1)
vbox.addWidget(self.button2)
self.setLayout(vbox)
self.show()
def openSecondDialog(self):
hbox = QVBoxLayout()
mydialog = QDialog(self)
mydialog.show()
self.button2 = QPushButton('Check Image')
self.button2.clicked.connect(self.getImage)
hbox.addWidget(self.button2)
self.setLayout(hbox)
self.show()
def getImage(self):
hbox = QHBoxLayout()
file_Name = QFileDialog.getOpenFileName(self,
'OpenFile',
'',
'')
image_path = file_Name[0]
updatedImage = Updated_encrypt.decrypt(image_path, 123)
pixmap = QPixmap(updatedImage)
self.label.setPixmap(QPixmap(pixmap))
self.resize(pixmap.width(), pixmap.height())
App = QApplication(sys.argv)
window = Window()
sys.exit(App.exec())
I have my code set up to implement an algorithm to modify an image when my I select it from my pop up dialogue. What I am trying to accomplish is for the image to pop up in a separate window when I click the encrypt button. I can't seem to get anything to pop up in the separate window aside from the window itself. Any help would be appreciated.

You have at least the following errors:
The "hbox" created is being added to the window and not to the QDialog: self.setLayout(hbox), it must be mydialog.setLayout(hbox).
Do not use the same name for 2 different objects as they can cause problems, in your case there are 2 QPushButton assigned to the variable "self.button2".
You try to use the variable "self.label" but never believe it.
Considering the above we can make the following improvements:
Use more descriptive names to easily distinguish their function.
If you are going to have a window that has a different objective, it is better to create a class.
The above avoid the indicated problems, considering the above the solution is:
import sys
from PyQt5.QtGui import QPixmap
from PyQt5.QtWidgets import (
QApplication,
QDialog,
QFileDialog,
QHBoxLayout,
QLabel,
QPushButton,
QVBoxLayout,
QWidget,
)
import Updated_encrypt
class Dialog(QDialog):
def __init__(self, parent=None):
super().__init__(parent)
self.load_image_btn = QPushButton("Check Image")
self.load_image_btn.clicked.connect(self.load_image)
self.image_lbl = QLabel()
lay = QVBoxLayout(self)
lay.addWidget(self.load_image_btn)
lay.addWidget(self.image_lbl)
def load_image(self):
image_path, _ = QFileDialog.getOpenFileName(self, "OpenFile", "", "")
if image_path:
updatedImage = Updated_encrypt.decrypt(image_path, 123)
pixmap = QPixmap(updatedImage)
self.image_lbl.setPixmap(QPixmap(pixmap))
class Window(QWidget):
def __init__(self, parent=None):
super().__init__(parent)
self.title = "Encrypt/Decrypt"
self.InitWindow()
def InitWindow(self):
self.setWindowTitle(self.title)
self.setGeometry(200, 500, 400, 300)
self.encrypt_btn = QPushButton("Encrypt")
self.encrypt_btn.clicked.connect(self.openSecondDialog)
self.decrypt_btn = QPushButton("Decrypt")
vbox = QVBoxLayout(self)
vbox.addWidget(self.encrypt_btn)
vbox.addWidget(self.decrypt_btn)
def openSecondDialog(self):
dialog = Dialog(self)
dialog.show()
if __name__ == "__main__":
app = QApplication(sys.argv)
window = Window()
window.show()
sys.exit(app.exec())

How to add a pixmap drawn in QGraphicsItem to QGraphicsScene? [duplicate]

This question already exists:
How to make the picture zoom (QGraphicsItem), and make scrollbars change their size accordingly (QGraphicsScene)? [duplicate]
Closed 4 years ago.
How to add a pixmap drawn in QGraphicsItem to QGraphicsScene in the following example?
#!/usr/bin/env python
from PyQt5.QtCore import QRectF, Qt
from PyQt5.QtGui import QPixmap
from PyQt5.QtWidgets import QApplication, QGraphicsItem, QGraphicsView, QGraphicsScene, QMainWindow
class TicTacToe(QGraphicsItem):
def __init__(self, helper):
super(TicTacToe, self).__init__()
self.mypixmap = QPixmap("exit.png")
def paint(self, painter, option, widget):
painter.setOpacity(1)
painter.drawPixmap(0,0, 300, 300, self.mypixmap)
def boundingRect(self):
return QRectF(0,0,300,300)
class MyGraphicsView(QGraphicsView):
def __init__(self):
super(MyGraphicsView, self).__init__()
scene = QGraphicsScene(self)
self.tic_tac_toe = TicTacToe(self)
scene.addItem(self.tic_tac_toe)
self.setScene(scene)
self.setHorizontalScrollBarPolicy(Qt.ScrollBarAlwaysOn)
self.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOn)
class Example(QMainWindow):
def __init__(self):
super(Example, self).__init__()
self.y = MyGraphicsView()
self.setCentralWidget(self.y)
if __name__ == '__main__':
import sys
app = QApplication(sys.argv)
w = Example()
w.show()
sys.exit(app.exec_())

Try it:
Drag and drop image,
Enlarge Image -> Qt.Key_Right,
Reduce image <- Qt.Key_Left.
from PyQt5.QtCore import (QLineF, QPointF, QRectF,
pyqtSignal, QStandardPaths, Qt)
from PyQt5.QtGui import (QIcon, QBrush, QColor, QPainter, QPixmap)
from PyQt5.QtWidgets import (QAction, QMainWindow, QApplication,
QGraphicsObject,
QGraphicsView, QGraphicsScene, QGraphicsItem,
QGridLayout, QVBoxLayout, QHBoxLayout,
QFileDialog, QLabel, QLineEdit, QPushButton)
from PyQt5.QtOpenGL import QGLFormat
class MyGraphicsView(QGraphicsView):
backgroundColor = QColor(28, 31, 34) # Background color
def __init__(self):
super(MyGraphicsView, self).__init__()
self.resize(800, 600)
self.setBackgroundBrush(self.backgroundColor)
self.setCacheMode(self.CacheBackground)
self.setRenderHints(
QPainter.Antialiasing | QPainter.TextAntialiasing | QPainter.SmoothPixmapTransform)
if QGLFormat.hasOpenGL():
self.setRenderHint(QPainter.HighQualityAntialiasing)
self.setViewportUpdateMode(self.SmartViewportUpdate)
self._scene = QGraphicsScene(-400, -300, 800, 600, self)
self.setScene(self._scene)
self._itemImage = None
def keyReleaseEvent(self, event):
""" Button processing event """
self._scaleImage(event)
super(MyGraphicsView, self).keyReleaseEvent(event)
def closeEvent(self, event):
""" Clear all items in the scene when the window is `closed` """
self._scene.clear()
self._itemImage = None
super(MyGraphicsView, self).closeEvent(event)
def _scaleImage(self, event):
""" Image zoom operation """
if not self._itemImage:
return
scale = self._itemImage.scale()
if event.key() == Qt.Key_Right:
# Enlarge Image -> Qt.Key_Right
if scale >= 0.91:
return
self._itemImage.setScale(scale + 0.1)
elif event.key() == Qt.Key_Left:
# Reduce image <- Qt.Key_Left
if scale <= 0.11:
return
self._itemImage.setScale(scale - 0.1)
def loadImage(self):
path, _ = QFileDialog.getOpenFileName(
self, 'Please select an image',
QStandardPaths.writableLocation(QStandardPaths.DesktopLocation),
'Image(*.jpg *.png)')
if not path:
return
if self._itemImage:
# Delete previous item
self._scene.removeItem(self._itemImage)
del self._itemImage
self._itemImage = self._scene.addPixmap(QPixmap(path))
self._itemImage.setFlag(QGraphicsItem.ItemIsMovable)
self._itemImage.setScale(0.1) # Default load factor
size = self._itemImage.pixmap().size()
# Adjust the image in the middle
self._itemImage.setPos(
-size.width() * self._itemImage.scale() / 2,
-size.height() * self._itemImage.scale() / 2
)
if __name__ == '__main__':
import sys
app = QApplication(sys.argv)
w = MyGraphicsView()
w.show()
ww = QPushButton('Select a file', clicked=w.loadImage)
ww.show()
sys.exit(app.exec_())

PyQt5: painting using events

I am new on PyQt I am working on a project on which I should implement a feature that make the user able to draw a digit using the mouse (digit recognition system). So what I want is when the mouse button is pressed the app will start to draw till the button is released. I made this source code but it is still not working (I think I am struggling with sending a signal to PaintEvent()).
import sys
from PyQt5 import QtCore
from PyQt5 import QtGui, QtWidgets
from PyQt5.QtWidgets import QApplication, QWidget, QInputDialog, QLineEdit, QFileDialog,QGraphicsView,QGraphicsScene,QVBoxLayout
from PyQt5.QtWidgets import (QApplication, QLabel, QWidget)
from PyQt5.QtGui import QPainter, QColor, QPen
from PyQt5.QtCore import Qt
from PyQt5.QtGui import QPainter
from PyQt5.QtCore import pyqtSignal, QObject
from PyQt5.QtWidgets import QMainWindow, QApplication
class Communicate(QObject):
drawApp = pyqtSignal()
class MyWidget(QWidget):
def __init__(self):
super().__init__()
self.initUI()
def initUI(self):
self.setGeometry(300, 300, 300, 220)
self.setWindowTitle('Simple')
self.setMouseTracking(True)
self.label = QLabel(self)
self.label.resize(500, 40)
self.c = Communicate()
self.c.drawApp.connect(self.PaintEvent())
self.show()
def mousePressEvent(self, event):
self.c.drawApp.emit()
self.startingposx = event.x()
self.startingposy = event.y()
#super().mousePressEvent(event)
print ("mouse pressed")
def mouseMoveEvent(self, event):
self.label.setText('Coordinates: ( %d : %d )' % (event.x(), event.y()) )
self.y = event.y()
self.x=event.x()
def PaintEvent(self,event):
qp = QPainter()
qp.begin(self)
#qp.setPen(Qt.red)
qp.drawPoints(self,qp)
qp.end()
self.update()
def mouseReleaseEvent(self,event):
self.endingposx = event.x()
self.endingposy = event.y()
super().mouseReleaseEvent(event)
print("starting point was",self.startingposx)
print("starting point y was ",self.startingposy)
print("ending point was ",self.endingposx)
print("ending point was y ",self.endingposy)
print("released")
def drawPoints(self,qp):
qp.setPen(Qt.red)
size = self.size()
x=self.x
y=self.y
qp.drawPoint(x,y)
app = QApplication(sys.argv)
widget = MyWidget()
widget.show()
app.exec_()

Python is sensitive to uppercase and lowercase so be more careful, the method is called paintEvent.
Also you should not call paintEvent directly, you must use the function update(), this method will internally call paintEvent().
But even correcting that error your problem is not solved, if you want to draw a path it is advisable to use QPainterPath as this stores the strokes.
class Drawer(QWidget):
newPoint = pyqtSignal(QPoint)
def __init__(self, parent=None):
QWidget.__init__(self, parent)
self.path = QPainterPath()
def paintEvent(self, event):
painter = QPainter(self)
painter.drawPath(self.path)
def mousePressEvent(self, event):
self.path.moveTo(event.pos())
self.update()
def mouseMoveEvent(self, event):
self.path.lineTo(event.pos())
self.newPoint.emit(event.pos())
self.update()
def sizeHint(self):
return QSize(400, 400)
class MyWidget(QWidget):
def __init__(self, parent=None):
QWidget.__init__(self, parent)
self.setLayout(QVBoxLayout())
label = QLabel(self)
drawer = Drawer(self)
drawer.newPoint.connect(lambda p: label.setText('Coordinates: ( %d : %d )' % (p.x(), p.y())))
self.layout().addWidget(label)
self.layout().addWidget(drawer)
if __name__ == '__main__':
app = QApplication(sys.argv)
w = MyWidget()
w.show()
sys.exit(app.exec_())
Screenshot:

I don't have the reputation to reply to eyllanesc's solution, but in case others are having issues, the imports were not complete. Here's is eyllanesc's solution with the imports. It will execute without error:
import sys
from PyQt5.QtWidgets import QVBoxLayout
from PyQt5.QtWidgets import (QLabel, QWidget)
from PyQt5.QtGui import QPainter, QPainterPath
from PyQt5.QtCore import pyqtSignal, QPoint, QSize
from PyQt5.QtWidgets import QApplication
class Drawer(QWidget):
newPoint = pyqtSignal(QPoint)
def __init__(self, parent=None):
QWidget.__init__(self, parent)
self.path = QPainterPath()
def paintEvent(self, event):
painter = QPainter(self)
painter.drawPath(self.path)
def mousePressEvent(self, event):
self.path.moveTo(event.pos())
self.update()
def mouseMoveEvent(self, event):
self.path.lineTo(event.pos())
self.newPoint.emit(event.pos())
self.update()
def sizeHint(self):
return QSize(400, 400)
class MyWidget(QWidget):
def __init__(self, parent=None):
QWidget.__init__(self, parent)
self.setLayout(QVBoxLayout())
label = QLabel(self)
drawer = Drawer(self)
drawer.newPoint.connect(lambda p: label.setText('Coordinates: ( %d : %d )' % (p.x(), p.y())))
self.layout().addWidget(label)
self.layout().addWidget(drawer)
if __name__ == '__main__':
app = QApplication(sys.argv)
w = MyWidget()
w.show()
sys.exit(app.exec_())