I have a simple QWidget that contains a frame and two labels. I want to use eventFilter to change QFrame background color on label hover. Can someone please check the below code and tell me why I can't change the QFrame background and if it is the correct way for doing it?
import sys
from PyQt5.QtWidgets import QWidget, QHBoxLayout, \
QGraphicsDropShadowEffect, QPushButton, QApplication, QComboBox, QFrame, QLabel
from PyQt5 import QtCore
class MainWindow(QWidget):
def __init__(self, parent=None):
super(MainWindow, self).__init__(parent)
self.layout = QHBoxLayout(self)
self.frame = QFrame(self)
self.setObjectName("frame")
self.frame_lay = QHBoxLayout()
self.one_label = QLabel(self.frame)
self.one_label.setText("one")
self.one_label.setObjectName("one")
self.two_label = QLabel(self.frame)
self.two_label.setText("two")
self.two_label.setObjectName("two")
self.one_label.installEventFilter(self)
self.two_label.installEventFilter(self)
self.frame_lay.addWidget(self.one_label)
self.frame_lay.addWidget(self.two_label)
self.frame.setStyleSheet("""QFrame{background-color: red;}""")
self.frame.setLayout(self.frame_lay)
self.frame_lay.setContentsMargins(0, 0, 0, 0)
self.layout.addWidget(self.frame)
self.setLayout(self.layout)
def eventFilter(self, obj, event):
if event.type() == QtCore.QEvent.Enter:
if type(obj) == QLabel:
if obj.objectName() in ["one", "two"]:
print(obj.objectName())
self.frame.setStyleSheet("""QFrame#frame{background-color: blue;}""")
return super(QWidget, self).eventFilter(obj, event)
if __name__ == '__main__':
app = QApplication(sys.argv)
w = MainWindow()
w.show()
sys.exit(app.exec_())
Should the installEventFilter be applied to QWidget or QFrame? The labels are contained within the QFrame.
Thanks
You set the frame object name for the "MainWindow", but in the event filter you used the object name for a QFrame class.
Just set the object name for the frame instead:
self.frame.setObjectName("frame")
Note that QLabel inherits from QFrame, so, using QFrame{background-color: red;} technically applies the background for both the parent frame and any child label.
In case you want to be more specific, you either use the object name as you did in the event filter, or use the .ClassName selector, which applies the sheet only to the class and not its subclasses (note the full stop character before QFrame):
self.frame.setStyleSheet(""".QFrame{background-color: red;}""")
Related
There is no effect when I set the WA_TranslucentBackground attribute on a widget (derived from QOpenGLWidget). I have to set the attribute on the main window instead, which doesn't seem right: the documentation clearly states that the attribute applies to the widget itself:
Indicates that the widget should have a translucent background, i.e.,
any non-opaque regions of the widgets will be translucent because the
widget will have an alpha channel
What is the correct way to make the widget itself have a translucent background? Here is the code:
import sys
from PyQt5.QtWidgets import QApplication, QMainWindow, QOpenGLWidget
from PyQt5.QtCore import Qt, QPointF, QLineF
from PyQt5.QtGui import QColor, QPen, QPainter, QPaintEvent
class LineWidget(QOpenGLWidget):
def __init__(self, parent, start : QPointF, end : QPointF, colour : str = 'black'):
super(LineWidget, self).__init__(parent)
self.colour = colour
self.line = QLineF(start, end)
# self.setAttribute(Qt.WA_TranslucentBackground)
def paintEvent(self, a0: QPaintEvent) -> None:
painter = QPainter(self)
painter.begin(self)
painter.setPen(QPen(QColor(self.colour), 5))
painter.drawLine(self.line)
painter.end()
class MainWindow(QMainWindow):
def __init__(self):
super(MainWindow, self).__init__()
self.lineWidget = LineWidget(self, QPointF(0, 0), QPointF(400, 400), 'red')
self.setCentralWidget(self.lineWidget)
self.setWindowFlags(Qt.FramelessWindowHint)
self.setAttribute(Qt.WA_TranslucentBackground)
self.show()
if __name__ == "__main__":
app = QApplication(sys.argv)
window = MainWindow()
window.show()
sys.exit(app.exec())
I have a QTableView with QAbstractTableModel. I want to change row backgroundcolor when I click one cell. I know at least two methods that can change row backgroundcolor when clicking one cell. One is use delegate, and another is use setData method in QAbstractTable. But I have got none of them,,,oops. Here I tried using setData method in QAbstractTable to just change the selected cell backgroundcolor, but failed! Could you pls help me to correct my code in order to change a whole row color not just a cell. Anyway, changing cell color is not even ok! Much thanks! Code below
import sys
import typing
import numpy as np
import pandas as pd
from PyQt5 import QtCore
from PyQt5.QtWidgets import QApplication, QMainWindow, \
QWidget, QTableView, QVBoxLayout
from PyQt5.QtCore import QAbstractTableModel, Qt, QModelIndex
class MyTableModel(QAbstractTableModel):
def __init__(self, data:pd.DataFrame):
super().__init__()
self._data = data
def data(self, index: QModelIndex, role: int = ...) -> typing.Any:
if role==Qt.DisplayRole:
value = str(self._data.iloc[index.row()][index.column()])
return value
def setData(self, index: QModelIndex, value: typing.Any, role: int = ...) -> bool:
if not index.isValid():
return False
else:
if role==Qt.BackgroundColorRole:
self.dataChanged.emit(index, index, [role])
return True
def rowCount(self, parent: QModelIndex = ...) -> int:
return self._data.shape[0]
def columnCount(self, parent: QModelIndex = ...) -> int:
return self._data.shape[1]
class MainWindow(QMainWindow):
def __init__(self):
super().__init__()
self.myTable = QTableView()
df = self.get_DataFrame_Data()
self.model = MyTableModel(df)
self.myTable.setModel(self.model)
self.myTable.clicked.connect(self.change_row_bgcolor)
hlayout = QVBoxLayout()
hlayout.addWidget(self.myTable)
dummy_widget = QWidget()
dummy_widget.setLayout(hlayout)
self.setCentralWidget(dummy_widget)
self.setFixedSize(600, 600)
def get_DataFrame_Data(self):
ndarray = np.random.randint(10, 50, (7, 3))
df = pd.DataFrame(data=ndarray, columns=['col1','col2','col3'])
return df
def change_row_bgcolor(self, index):
self.model.setData(index,Qt.red,Qt.BackgroundColorRole)
app = QApplication(sys.argv)
window = MainWindow()
window.show()
app.exec_()
Solved! Two ways to changed QTableView Row background color when user mouse clicking.
Use QStyledItemDelegate.
Subclass QStyledItemDelegate. You should set a class property (etc tableview's currentindex) which can be reset value from outside the class, by this, the delegate's default loop will compare the tableview's currentindex.Code:
class TableDelegate(QStyledItemDelegate):
select_index = None
def paint(self, painter: QtGui.QPainter, option: 'QStyleOptionViewItem', index: QtCore.QModelIndex) -> None:
# option.state
row = index.row()
column = index.column()
select_row = self.select_index.row()
# self.initStyleOption(option,index)
if row == select_row:
# option.font.setItalic(True)
option.font.setStyle(QFont.StyleOblique)
bg = QColor(135, 206, 255)
painter.fillRect(option.rect, bg)
# painter.eraseRect(option.rect)
QStyledItemDelegate.paint(self, painter, option, index)
Use QAbstractTableModel.Also, you should set a class property, than the method data()'s default loop will compare with the class property(tableview's current index). and set backgroud color.Code:
class MyTableModel(QAbstractTableModel):
def __init__(self, data:pd.DataFrame):
super().__init__()
self._data = data
self.color_enabled = False
self.color_back = Qt.magenta
self.target_row = -1
def data(self, index: QModelIndex, role: int) -> typing.Any:
if role==Qt.DisplayRole:
# print(index.row())
value = str(self._data.iloc[index.row()][index.column()])
return value
if role == Qt.BackgroundRole and index.row()==self.target_row \
and self.color_enabled==True:
return QBrush(self.color_back)
And,,! there is another special problem that should emphasized here. When user click one cell, there is a default backgroud which I see in my computer is blue. If you want to whole row background color is same when clicking, you should do this after creating a QTableView:
self.myTable.setStyleSheet("QTableView::item:selected{"
"background:rgb(135, 206, 255)}")
This means,you set the selected cell bgcolor by QSS, and then, either when you use QAbstractTableModel' data() method or pain() method in QStyledItemDelege, you should set the same color. Then everything is ok!
How to change the following code to get the QLabel stretch to width of the window ?
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
from PyQt5.QtCore import *
class Window(QMainWindow):
def __init__(self):
super().__init__()
self.setGeometry(100, 100, 200, 100)
self.label = QLabel('Hello World!', self)
self.label.setAlignment(Qt.AlignCenter)
self.label.setStyleSheet('font-size: 12pt; background-color: red')
self.show()
app = QApplication([])
win = Window()
app.exec()
As the documentation about QMainWindow says, you must set a central widget for it:
Creating a main window without a central widget is not supported. You must have a central widget even if it is just a placeholder.
The problem is that you need a layout manager in order to properly adapt widget sizes inside a parent, and just manually setting widget geometries is generally discouraged.
You created the label as a direct child, so it will have no knowledge about its parents size changes.
Just set the label as central widget.
self.setCentralWidget(self.label)
Otherwise, you can use a container widget, set a layout and add the label to it, but you still must set the central widget.
central = QWidget()
layout = QVBoxLayout(central)
layout.addWidget(self.label)
self.setCentralWidget(central)
The alternative is to directly use a QWidget instead of QMainWindow as you did in your answer.
you can use sizePolicy
self.label.setSizePolicy(QSizePolicy.Expanding, QSizePolicy.Preferred)
Thank you very much for your answers. The problem is now solved by the following code changes
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
from PyQt5.QtCore import *
class Window(QWidget):
def __init__(self):
super().__init__()
self.setGeometry(100, 100, 200, 100)
self.label = QLabel('Hello World!', self)
self.label.setAlignment(Qt.AlignCenter)
self.label.setStyleSheet('font-size: 12pt; background-color: red')
self.box_layout = QHBoxLayout()
self.box_layout.addWidget(self.label)
self.setLayout(self.box_layout)
self.show()
app = QApplication([])
win = Window()
app.exec()
Edit: laytout -> box_layout
I need to move a QGraphicsPixmapItem through a circle that it is at the top left corner of the image. That is, when I grab with the mouse the circle, I need the top left corner of the image to follow the circle. I subclassed a QGraphicsEllipseItem and reimplemented the itemChange method but when I set the position of the image to that value, the image is not being positioned correctly. What should I modify in my code?
import sys
from PyQt5.QtWidgets import QMainWindow, QApplication, QGraphicsView
from PyQt5 import QtGui, QtWidgets
class MainWindow(QMainWindow):
def __init__(self, parent=None):
super(MainWindow, self).__init__(parent)
self.scene = Scene()
self.view = QGraphicsView(self)
self.setGeometry(10, 30, 850, 600)
self.view.setGeometry(20, 22, 800, 550)
self.view.setScene(self.scene)
class Scene(QtWidgets.QGraphicsScene):
def __init__(self, parent=None):
super(Scene, self).__init__(parent)
# other stuff here
self.set_image()
def set_image(self):
image = Image()
self.addItem(image)
image.set_pixmap()
class Image(QtWidgets.QGraphicsPixmapItem):
def __init__(self, parent=None):
super(Image, self).__init__(parent)
self.setFlag(QtWidgets.QGraphicsItem.ItemIsMovable, True)
def set_pixmap(self):
pixmap = QtGui.QPixmap("image.jpg")
self.setPixmap(pixmap)
self.pixmap_controller = PixmapController(self)
self.pixmap_controller.set_pixmap_controller()
self.pixmap_controller.setPos(self.boundingRect().topLeft())
self.pixmap_controller.setFlag(QtWidgets.QGraphicsItem.ItemSendsScenePositionChanges, True)
def change_image_position(self, position):
self.setPos(position)
class PixmapController(QtWidgets.QGraphicsEllipseItem):
def __init__(self, pixmap):
super(PixmapController, self).__init__(parent=pixmap)
self.pixmap = pixmap
self.setFlag(QtWidgets.QGraphicsItem.ItemIsMovable, True)
color = QtGui.QColor(0, 0, 0)
brush = QtGui.QBrush(color)
self.setBrush(brush)
def set_pixmap_controller(self):
self.setRect(-5, -5, 10, 10)
def itemChange(self, change, value):
if change == QtWidgets.QGraphicsItem.ItemPositionChange:
self.pixmap.change_image_position(value)
return super(PixmapController, self).itemChange(change, value)
if __name__ == "__main__":
app = QApplication(sys.argv)
window = MainWindow()
window.show()
sys.exit(app.exec_())
When a graphics item has a parent, its coordinate system is based on that parent, not on the scene.
The problem is that when you try to move the PixmapController, the movement is in parent coordinates (the pixmap item). When you check for the ItemPositionChange you are you're changing the parent position but the item position is changed anyway, based on the parent coordinate system.
While you could just return an empty QPoint (which will not change the item position), this wouldn't be a good choice: as soon as you release the mouse and start to move it again, the pixmap will reset its position.
The solution is not to set the movable item flag, but filter for mouse movements, compute a delta based on the click starting position, and use that delta to move the parent item based on its current position.
class PixmapController(QtWidgets.QGraphicsEllipseItem):
def __init__(self, pixmap):
super(PixmapController, self).__init__(parent=pixmap)
self.pixmap = pixmap
# the item should *NOT* move
# self.setFlag(QtWidgets.QGraphicsItem.ItemIsMovable, True)
color = QtGui.QColor(0, 0, 0)
brush = QtGui.QBrush(color)
self.setBrush(brush)
def set_pixmap_controller(self):
self.setRect(-5, -5, 10, 10)
def mousePressEvent(self, event):
if event.button() == QtCore.Qt.LeftButton:
self.startPos = event.pos()
def mouseMoveEvent(self, event):
if event.buttons() == QtCore.Qt.LeftButton:
delta = event.pos() - self.startPos
self.parentItem().setPos(self.parentItem().pos() + delta)
If you want to use your change_image_position function, you need to change those functions accordingly; the code below does the same thing as the last line in the example above:
class Image(QtWidgets.QGraphicsPixmapItem):
# ...
def change_image_position(self, delta):
self.setPos(self.pos() + delta)
class PixmapController(QtWidgets.QGraphicsEllipseItem):
# ...
def mouseMoveEvent(self, event):
if event.buttons() == QtCore.Qt.LeftButton:
delta = event.pos() - self.startPos
self.pixmap.change_image_position(delta)
Tip: do not add a child widget to a QMainWindow like that, as it will not resize correctly when the window is resized. Use self.setCentralWidget(self.view) instead; if you want to add margins, use a container QWidget, set that widget as the central widget, add a simple QHBoxLayout (or QVBoxLayout), add the view to that layout and then set the margins with layout.setContentsMargins(left, top, right, bottom)
I want to display an image and put a marker at the current mouse position for every left mouse click.
Below code does the job however, it works only if ("self.imglabel.setScaledContents(True)") is commented. Any reason?
I have to do this job on various images of different resolutions, I read to maintain the proper aspect ratio and display the image appropriately we need to use setScaledContents(True). But why enabling this is not allowing update() (PaintEvent)??
import sys
from PyQt5.QtCore import Qt, QPoint
from PyQt5.QtWidgets import QMainWindow, QApplication, QLabel, QSizePolicy, QMessageBox
from PyQt5.QtGui import QPixmap, QPainter, QPen, QColor, QImage, QPalette
class Menu(QMainWindow):
def __init__(self):
super().__init__()
self.central_widget = QWidget() # define central widget
self.setCentralWidget(self.central_widget)
self.vbox = QVBoxLayout(self.central_widget)
self.vbox.addWidget(self.imgWidget())
self.vbox.addWidget(QPushButton("test"))
def imgWidget(self):
self.imglabel = QLabel()
self.imglabel.setScaledContents(True)
self.image = QImage("calib.jpeg")
self.imagepix = QPixmap.fromImage(self.image)
self.imglabel.setPixmap(self.imagepix)
self.imglabel.mousePressEvent = self.imgMousePress
return self.imglabel
def imgMousePress(self, e):
painter = QPainter(self.imglabel.pixmap())
pen = QPen()
pen.setWidth(10)
pen.setColor(QColor('red'))
painter.setPen(pen)
painter.drawPoint(e.x(), e.y())
painter.end()
self.imglabel.update()
if __name__ == '__main__':
app = QApplication(sys.argv)
mainMenu = Menu()
mainMenu.show()
sys.exit(app.exec_())
To avoid unnecessary computation for each paintEvent of the QLabel, whenever the scaledContents property is True the scaled image is cached, and all the painting is automatically discarded.
To avoid that, you should create a new instance of QPixmap using the existing one, and then set the new painted pixmap again. Note that if the image is scaled, the widget coordinates won't reflect the actual position on the pixmap, so you need to use a transformation to get the actual point to paint at.
def imgMousePress(self, e):
pm = QPixmap(self.imglabel.pixmap())
painter = QPainter(pm)
pen = QPen()
pen.setWidth(10)
pen.setColor(QColor('red'))
painter.setPen(pen)
transform = QTransform().scale(
pm.width() / self.imglabel.width(),
pm.height() / self.imglabel.height())
painter.drawPoint(transform.map(e.pos()))
painter.end()
self.imglabel.setPixmap(pm)
Consider that all the "points" will become stretched rectangles if the width/height ratio is not the same of the source image, but this is only a problem of appearance: if you save the pixmap later, they will be squares again, since saving is based on the source pixmap.
If you want to keep their squared shape while displaying instead, you'll need to keep track of the points and overwrite paintEvent to paint them manually on the label.