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I am coding an app to solve electrical circuits and I need to model the circuit. To do so, I need to draw Resistors and other shapes on a scene, being able to move it and so on.
The thing is that I am tryng to show a resistor en the scene and I can't find the way. I am tryng by using QGraphicsPathItem but looking at the documentation I am not capable of doing it. I'll show a bit of the code I am writing to solve this part of the app:
1. The first code I show is the Resistor as it should be shown
2. The second part is the way I want to do it, but instead an ellipsis, I want to show a Resistor
### 1st Code
import sys
from PyQt5 import QtCore, QtGui, QtWidgets, uic
from PyQt5.QtCore import Qt
x0 = 100
y0 = 50
class MainWindow(QtWidgets.QMainWindow):
def __init__(self):
super().__init__()
self.x1 = 12
self.y1 = 33
self.y2 = 18
self.y3 = 15
self.y4 = 9
self.y5 = 3
self.p1 = QtCore.QPoint(0, 0 + self.y1)
self.p2 = QtCore.QPoint(0, 0 + self.y2)
self.p3 = QtCore.QPoint(self.x1, self.y3)
self.p4 = QtCore.QPoint(-self.x1, self.y4)
self.p5 = QtCore.QPoint(self.x1, self.y5)
self.p6 = QtCore.QPoint(-self.x1, -self.y5)
self.p7 = QtCore.QPoint(self.x1, -self.y4)
self.p8 = QtCore.QPoint(-self.x1, -self.y3)
self.p9 = QtCore.QPoint(0, 0 - self.y2)
self.p10 = QtCore.QPoint(0, 0 - self.y1)
def draw_resistor(self,angle=0, x0=0, y0=0):
self.x0 = x0
self.y0 = y0
self.label = QtWidgets.QLabel()
self.canvas = QtGui.QPixmap(200, 100) # This is to create the canvas
self.canvas.fill() # To set the canvas background color to white. If not, we will only see a black frame
self.label.setPixmap(self.canvas)
self.setCentralWidget(self.label)
self.painter = QtGui.QPainter(self.label.pixmap())
self.painter.translate(self.x0,self.y0) # To change the axis origin
self.painter.rotate(angle)
self.painter.drawLines(self.p1,self.p2,self.p2,self.p3,self.p3,self.p4,self.p4,self.p5,self.p5,
self.p6,self.p6,self.p7,self.p7,self.p8,self.p8,self.p9,self.p9,self.p10)
self.painter.end()
def rotate(self,angle=0):
self.painter.rotate(angle)
self.painter.drawLines(self.p1,self.p2,self.p2,self.p3,self.p3,self.p4,self.p4,self.p5,self.p5,
self.p6,self.p6,self.p7,self.p7,self.p8,self.p8,self.p9,self.p9,self.p10)
self.label.update() # Research about this, it could be the key
app = QtWidgets.QApplication(sys.argv)
window = MainWindow()
window.show()
window.draw_resistor(45,x0,y0)
app.exec_()
###################
###################
###################
###################
### 2nd Code
import sys
from PyQt5.QtWidgets import QApplication, QGraphicsItem, QGraphicsPathItem, QGraphicsView, QGraphicsScene, QGraphicsEllipseItem, QLabel
from PyQt5.QtCore import Qt, QPointF, QRectF, QPoint
from PyQt5.QtGui import QPixmap, QPainter
class MovingObject(QGraphicsEllipseItem):
def __init__(self, x, y, r):
super().__init__(0, 0, r, r)
self.setPos(x, y)
self.setBrush(Qt.blue)
self.setAcceptHoverEvents(True)
# Mouse hover events
def hoverEnterEvent(self, event):
app.instance().setOverrideCursor(Qt.OpenHandCursor)
def hoverLeaveEvent(self, event):
app.instance().restoreOverrideCursor()
# Mouse click events
def mousePressEvent(self, event):
pass
def mouseMoveEvent(self, event):
orig_cursor_position = event.lastScenePos()
updated_cursor_position = event.scenePos()
orig_position = self.scenePos()
updated_cursor_x = updated_cursor_position.x() - orig_cursor_position.x() + orig_position.x()
updated_cursor_y = updated_cursor_position.y() - orig_cursor_position.y() + orig_position.y()
self.setPos(QPointF(updated_cursor_x, updated_cursor_y))
def mouseReleaseEvent(self, event):
print("x: {0}, y: {1}".format(self.pos().x(), self.pos().y()))
class GraphicView(QGraphicsView):
def __init__(self):
super().__init__()
self.scene = QGraphicsScene()
self.setScene(self.scene)
self.setSceneRect(0, 0, 1200, 1000)
self.moveObject = MovingObject(50, 50, 40)
self.moveObject2 = MovingObject(100, 100, 100)
self.scene.addItem(self.moveObject)
self.scene.addItem(self.moveObject2)
app = QApplication(sys.argv)
view = GraphicView()
view.show()
sys.exit(app.exec_())
I solved it, this is the solution:
class Resistor(QGraphicsPathItem):
def __init__(self, x, y):
super(Resistor, self).__init__()
self.setFlag(QGraphicsItem.ItemIsSelectable, True)
self.setFlag(QGraphicsItem.ItemIsFocusable, True)
self.setAcceptHoverEvents(True)
self.isSelected = False
self.setPath(self.create_path())
self.setPos(x, y)
def create_path(self):
path = QPainterPath()
path.moveTo(0, 33)
path.lineTo(0, 18)
path.lineTo(12, 15)
path.lineTo(-12, 9)
path.lineTo(12, 3)
path.lineTo(-12, -3)
path.lineTo(12, -9)
path.lineTo(-12, -15)
path.lineTo(0, -18)
path.lineTo(0, -33)
return path
I'm trying to make fading looped rectangle area. I used base code from here
Just decided expand it.
Its just blinking rectangle, but I need smooth fade-in and fade-out effects. So I decided to make method which will calulate new opacity percent and set it to painter. But it doesnt work in cycle.
This is my class now
class HighlightRect(QFrame):
board_width = 400 # width of frame
board_height = 400 #height of frame
def __init__(self, parent, x, y, width=50, height=50, blink_speed=1000):
super().__init__(parent)
self.blink_speed = blink_speed
self.opacity_timer = self.blink_speed
self.board_height = self.parent().height()
self.board_width = self.parent().width()
self.square_height = height
self.square_width = width
self.highlight_x = x
self.highlight_y = y
#self.setFocusPolicy(QtCore.Qt.StrongFocus)
self.timer_draw = QtCore.QTimer(self)
self.timer_draw.timeout.connect(self.draw)
self.timer_draw.start(self.blink_speed)
self.color = QtCore.Qt.red
self.is_draw = False
self.x_apple = 0
self.y_apple = 0
self.draw()
def blink(self, painter):
self.color = QtCore.Qt.red
while self.opacity_timer >= 0:
self.opacity_timer -= 1 / 10 # просто подбор
percents = round(int(self.opacity_timer / self.blink_speed * 100)/100, 1)
print(percents)
painter.setOpacity(percents)
def paintEvent(self, event):
painter = QtGui.QPainter(self)
print ("Paint Event?")
if self.is_draw == True:
print ("Draw")
#self.color = QtCore.Qt.red
self.blink_thread = threading.Thread(name='background', target=lambda: self.blink(painter))
self.blink_thread.start()
else:
self.opacity_timer = self.blink_speed
print ("Do not draw")
self.color = QtCore.Qt.transparent
threading.SystemExit = SystemExit
painter.setPen(self.color)
painter.drawRect(self.rect)
def draw(self):
self.is_draw = not self.is_draw
self.rect = QRect(self.highlight_x, self.highlight_y, self.square_width, self.square_height)
self.update()
Changind of opacity inside blink function but outside while loop works as well, but its static. No changes. Changing opacity in loop isn't work.
Whats wrong?
Maybe somewhere here is another more correct way to get what I want?
One possible solution is to create a QProperty that handles opacity and then use QPropertyAnimation to make the change smooth.
import random
import sys
from PySide6.QtCore import Property, Signal, QPropertyAnimation, QRect, Qt
from PySide6.QtGui import QPainter
from PySide6.QtWidgets import QFrame, QApplication
class Board(QFrame):
rect_opacity_changed = Signal(name="rectOpacityChanged")
def __init__(self, parent=None):
super(Board, self).__init__(parent)
self._rect_opacity = 1.0
self._rect = QRect(0, 0, 50, 50)
self._opacity_animation = QPropertyAnimation(
targetObject=self, propertyName=b"rect_opacity", duration=3000
)
for p, v in ((0.0, 0.0), (0.3, 1.0), (0.7, 1.0), (1.0, 0.0)):
self._opacity_animation.setKeyValueAt(p, v)
self._opacity_animation.finished.connect(self.change)
self.change()
#Property(float, notify=rect_opacity_changed)
def rect_opacity(self):
return self._rect_opacity
#rect_opacity.setter
def rect_opacity(self, opacity):
self._rect_opacity = opacity
self.rect_opacity_changed.emit()
self.update()
def change(self):
x = random.randint(0, self.width() - self._rect.width())
y = random.randint(0, self.height() - self._rect.height())
self._rect.moveTo(x, y)
self._opacity_animation.start()
def paintEvent(self, event):
painter = QPainter(self)
painter.setOpacity(self.rect_opacity)
painter.setPen(Qt.red)
painter.drawRect(self._rect)
def main():
app = QApplication([])
board = Board()
board.show()
sys.exit(app.exec())
if __name__ == "__main__":
main()
I have a PyQt window built in Qt Designer and I am writing a custom paint method. The main window creates a label and sets it as the central widget. Then I override the paint method to draw a simple column chart.
The widget works well until it is resized. The widget calls the resize method and repaints as expected, but it uses the same size rectangle as before it was resized. There's a big black area -- the resized part -- that's not being painted on.
To test this out I grab the rectangle of the widget and draw a big rectangle with a light blue fill and red line outside. When the window is resized part of the outer rectangle is missing too.
Debugging statements show that the new rectangle is the correct size and the width and height values are fed properly into the paint event.
But when I resize, this is what I see. Why is paint not painting in the black area? I've checked my code and there are no hard coded limits on the paint. Is there some hidden clipping that occurs?
I couldn't find any questions with exactly this problem, so it would seem I'm missing something. This similar question says to invalidate the window before repaint, but that's for C++:
Graphics.DrawImage Doesn't Always Paint The Whole Bitmap?
Do I need to invalidate the widget somehow? I couldn't find the PyQt method to do that.
import sys
from PyQt5 import QtCore, QtGui, QtWidgets, uic
import PyQt5 as qt
import numpy as np
class MainWindow(QtWidgets.QMainWindow):
def __init__(self):
super().__init__()
self.label = QtWidgets.QLabel()
self.max_x = 600
self.max_y = 400
canvas = QtGui.QPixmap(self.max_x, self.max_y)
self.label.setPixmap(canvas)
self.setCentralWidget(self.label)
np.random.seed(777)
self.x_time = np.linspace(0, 12.56, 3000)
rand_data = np.random.uniform(0.0, 1.0, 3000)
self.data = np.sin(self.x_time) + rand_data
pal = self.palette()
pal.setColor(self.backgroundRole(), QtGui.QColor('black'))
self.setPalette(pal)
self.setAutoFillBackground(True)
def resizeEvent(self, a0: QtGui.QResizeEvent):
print("resizeEvent")
max_x = self.size().width()
max_y = self.size().height()
self.draw(max_x, max_y)
def mousePressEvent(self, a0: QtGui.QMouseEvent):
print("mousePressEvent")
def paintEvent(self, a0: QtGui.QPaintEvent):
print("New window size = ", self.size())
print("canvas size = ", self.label.size())
max_x = self.label.size().width()
max_y = self.label.size().height()
self.draw(max_x, max_y)
def draw(self, max_x, max_y):
x_final = self.x_time[-1]
data = self.data/np.max(np.abs(self.data))
data = [abs(int(k*max_y)) for k in self.data]
x_pos_all = [int(self.x_time[i]*max_x / x_final) for i in range(len(data))]
# Find and use only the max y value for each x pixel location
y_pos = []
x_pos = list(range(max_x))
cnt = 0
for x_pixel in range(max_x):
mx = 0.0
v = x_pos_all[cnt]
while cnt < len(x_pos_all) and x_pos_all[cnt] == x_pixel:
if data[cnt] > mx:
mx = data[cnt]
cnt += 1
y_pos.append(mx)
print("data = ")
dat = np.array(data)
print(dat[dat > 0].shape[0])
painter = QtGui.QPainter(self.label.pixmap()) # takes care of painter.begin(self)
pen = QtGui.QPen()
rect = self.label.rect()
print("rect = {}".format(rect))
painter.fillRect(rect, QtGui.QColor('lightblue'))
pen.setWidth(2)
pen.setColor(QtGui.QColor('green'))
for i in range(len(x_pos)):
painter.setPen(pen)
painter.drawLine(x_pos[i], max_y, x_pos[i], max_y - y_pos[i])
pen.setWidth(5)
pen.setColor(QtGui.QColor('red'))
painter.setPen(pen)
painter.drawRect(rect)
painter.end()
app = QtWidgets.QApplication(sys.argv)
window = MainWindow()
window.show()
app.exec_()
I expect that as the widget is resized, the paint event will repaint over the entire new size of the widget, not just the original size. Curiously, the graph part (green lines) looks like it is scaling as I resize, but everything's just cut off at the original widget size.
How do I fix this?
If you are using a QLabel then it is not necessary to override paintEvent since it is enough to create a new QPixmap and set it in the QLabel.
import sys
import numpy as np
from PyQt5 import QtCore, QtGui, QtWidgets
class MainWindow(QtWidgets.QMainWindow):
def __init__(self):
super().__init__()
self.label = QtWidgets.QLabel()
self.setCentralWidget(self.label)
np.random.seed(777)
self.x_time = np.linspace(0, 12.56, 3000)
rand_data = np.random.uniform(0.0, 1.0, 3000)
self.data = np.sin(self.x_time) + rand_data
pal = self.palette()
pal.setColor(self.backgroundRole(), QtGui.QColor("black"))
self.setPalette(pal)
self.setAutoFillBackground(True)
def resizeEvent(self, a0: QtGui.QResizeEvent):
self.draw()
super().resizeEvent(a0)
def draw(self):
max_x, max_y = self.label.width(), self.label.height()
x_final = self.x_time[-1]
data = self.data / np.max(np.abs(self.data))
data = [abs(int(k * max_y)) for k in self.data]
x_pos_all = [int(self.x_time[i] * max_x / x_final) for i in range(len(data))]
y_pos = []
x_pos = list(range(max_x))
cnt = 0
for x_pixel in range(max_x):
mx = 0.0
v = x_pos_all[cnt]
while cnt < len(x_pos_all) and x_pos_all[cnt] == x_pixel:
if data[cnt] > mx:
mx = data[cnt]
cnt += 1
y_pos.append(mx)
print("data = ")
dat = np.array(data)
print(dat[dat > 0].shape[0])
pixmap = QtGui.QPixmap(self.size())
painter = QtGui.QPainter(pixmap)
pen = QtGui.QPen()
rect = self.label.rect()
print("rect = {}".format(rect))
painter.fillRect(rect, QtGui.QColor("lightblue"))
pen.setWidth(2)
pen.setColor(QtGui.QColor("green"))
painter.setPen(pen)
for x, y in zip(x_pos, y_pos):
painter.drawLine(x, max_y, x, max_y - y)
pen.setWidth(5)
pen.setColor(QtGui.QColor("red"))
painter.setPen(pen)
painter.drawRect(rect)
painter.end()
self.label.setPixmap(pixmap)
app = QtWidgets.QApplication(sys.argv)
window = MainWindow()
window.show()
app.exec_()
Update:
Why can I not shrink the window after enlarging it? The layout of the QMainWindow takes as a reference the minimum size of the QMainWindow to the minimumSizeHint of the centralWidget, and in your case it is the QLabel that takes as minimumSizeHint the size of the QPixmap. If you want to be able to reduce the size you must override that method:
class Label(QtWidgets.QLabel):
def minimumSizeHint(self):
return QtCore.QSize(1, 1)
class MainWindow(QtWidgets.QMainWindow):
def __init__(self):
super().__init__()
self.label = Label()
self.setCentralWidget(self.label)
# ...
Why was the whole area not being painted before? Because you were painting a copy of the QPixmap: painter = QtGui.QPainter(self.label.pixmap()), not the stored QPixmap of the QLabel so nothing has been modified.
I'm working on a PyQt5 GUI, so far, I've just had experience with python scripts and did not delve into creating user interfaces.
The GUI will have to be used on different screens (maybe also some old 4:3 ratio screens) and will need to look nice in different sizes.
Now, my approach to make my life easier was to enforce a fixed aspect ratio of the window and resize the different elements according to window size.
from PyQt5 import QtCore, QtGui, QtWidgets
class MainWindow(QtWidgets.QMainWindow):
def __init__(self, parent= None):
super().__init__(parent)
self.form_widget = FormWidget(self)
self.setCentralWidget(self.form_widget)
self.resize(200, 400)
self.sizePolicy = QtWidgets.QSizePolicy(QtWidgets.QSizePolicy.Preferred, QtWidgets.QSizePolicy.Preferred)
self.sizePolicy.setHeightForWidth(True)
self.setSizePolicy(self.sizePolicy)
def heightForWidth(self, width):
return width * 2
class FormWidget(QtWidgets.QWidget):
def __init__(self, parent):
super().__init__(parent)
def resizeEvent(self, event):
f = self.font()
temp = event.size().height()
f.setPixelSize(temp / 16)
self.setFont(f)
return super().resizeEvent(event)
if __name__ == "__main__":
import sys
app = QtWidgets.QApplication(sys.argv)
w = MainWindow()
w.show()
sys.exit(app.exec_())
Resizing the elements according to window size works fine, but window aspect ratio is not kept at all.
I copied this approach with heightForWidth from old PyQt4 threads. Doesn't this approach work anymore in PyQt5? Am I missing something?
If I understood your question, you should try using a layout inside the main window.
I did this:
from PyQt5 import QtCore, QtGui, QtWidgets
class MainWindow(QtWidgets.QMainWindow):
def __init__(self, parent= None):
super().__init__(parent)
self.central_widget = QtWidgets.QWidget()
self.central_layout = QtWidgets.QVBoxLayout()
self.setCentralWidget(self.central_widget)
self.central_widget.setLayout(self.central_layout)
# Lets create some widgets inside
self.label = QtWidgets.QLabel()
self.list_view = QtWidgets.QListView()
self.push_button = QtWidgets.QPushButton()
self.label.setText('Hi, this is a label. And the next one is a List View :')
self.push_button.setText('Push Button Here')
# Lets add the widgets
self.central_layout.addWidget(self.label)
self.central_layout.addWidget(self.list_view)
self.central_layout.addWidget(self.push_button)
if __name__ == "__main__":
import sys
app = QtWidgets.QApplication(sys.argv)
w = MainWindow()
w.show()
sys.exit(app.exec_())
If you resize the window, the widgets inside it get resized.
First, answered by Marc and codeling in this question, heightForWidth is only supported for QGraphicsLayout's subclasses.
Second, how to make a fixed aspect ratio window (or top-level widget) in qt (or pyqt) is a question that have been asked for years. However, as far as I know, there is no standard way of doing so, and it is something surprisingly hard to achieve. In short, my way of doing this is use Qt.FramelessWindowHint to create a frameless window without system move and resize function, and implement custom move and resize.
Explain important mechanism:
move:
In mousePressEvent, keep the place where we last clicked on the widget(the draggable area).
In mouseMoveEvent, calculate the distance between the last clicked point and the current mouse location. Move the window according to this distance.
resize:
Find the increase or decrease step size of width and height by dividing the minimum width and height of the window by their highest common factor.
Use the step size to increase or decrease the window size to keep the aspect ratio.
A screenshot to show that it can resize according to the aspect ratio.
The following code should works with both PyQt5 and Pyside2.
from PyQt5.QtCore import Qt, QRect, QPoint, QEvent
from PyQt5.QtWidgets import (QLabel, QMainWindow, QApplication, QSizePolicy,
QVBoxLayout, QWidget, QHBoxLayout, QPushButton)
from enum import Enum
class MainWindow(QMainWindow):
def __init__(self, parent=None):
super(MainWindow, self).__init__(parent)
self.setWindowFlags(Qt.FramelessWindowHint)
self.createCostumTitleBar()
self.setContentsMargins(0, 0, 0, 0)
self.central = QWidget()
self.central.setStyleSheet("background-color: #f8ecdf")
self.centralLayout = QVBoxLayout()
self.central.setLayout(self.centralLayout)
self.centralLayout.addWidget(
self.costumsystemmenu, alignment=Qt.AlignTop)
self.centralLayout.setContentsMargins(0, 0, 0, 0)
self.setCentralWidget(self.central)
# Set the minimum size to avoid window being resized too small.
self.setMinimumSize(300, 400)
self.minheight = self.minimumHeight()
self.minwidth = self.minimumWidth()
self.resize(300, 400)
# make sure your minium size have the same aspect ratio as the step.
self.stepY = 4
self.stepX = 3
# install the event filter on this window.
self.installEventFilter(self)
self.grabarea.installEventFilter(self)
self.cursorpos = CursorPos.DEFAULT
self.iswindowpress = False
def createCostumTitleBar(self):
self.costumsystemmenu = QWidget()
self.costumsystemmenu.setStyleSheet("background-color: #ccc")
self.costumsystemmenu.setContentsMargins(0, 0, 0, 0)
self.costumsystemmenu.setMinimumHeight(30)
self.grabarea = QLabel("")
self.grabarea.setStyleSheet("background-color: #ccc")
self.grabarea.setSizePolicy(
QSizePolicy.Expanding, QSizePolicy.Preferred)
titlebarlayout = QHBoxLayout()
titlebarlayout.setContentsMargins(11, 11, 11, 11)
titlebarlayout.setSpacing(0)
self.closeButton = QPushButton("X")
self.closeButton.setSizePolicy(
QSizePolicy.Minimum, QSizePolicy.Preferred)
self.closeButton.clicked.connect(self.close)
self.costumsystemmenu.setLayout(titlebarlayout)
titlebarlayout.addWidget(self.grabarea)
titlebarlayout.addWidget(self.closeButton, alignment=Qt.AlignRight)
self.istitlebarpress = False
def eventFilter(self, object, event):
# The eventFilter() function must return true if the event
# should be filtered, (i.e. stopped); otherwise it must return false.
# https://doc.qt.io/qt-5/qobject.html#eventFilter
# check if the object is the mainwindow.
if object == self:
if event.type() == QEvent.HoverMove:
if not self.iswindowpress:
self.setCursorShape(event)
return True
elif event.type() == QEvent.MouseButtonPress:
self.iswindowpress = True
# Get the position of the cursor and map to the global coordinate of the widget.
self.globalpos = self.mapToGlobal(event.pos())
self.origingeometry = self.geometry()
return True
elif event.type() == QEvent.MouseButtonRelease:
self.iswindowpress = False
return True
elif event.type() == QEvent.MouseMove:
if self.cursorpos != CursorPos.DEFAULT and self.iswindowpress:
self.resizing(self.globalpos, event,
self.origingeometry, self.cursorpos)
return True
else:
return False
elif object == self.grabarea:
if event.type() == QEvent.MouseButtonPress:
if event.button() == Qt.LeftButton and self.iswindowpress == False:
self.oldpos = event.globalPos()
self.oldwindowpos = self.pos()
self.istitlebarpress = True
return True
elif event.type() == QEvent.MouseButtonRelease:
self.istitlebarpress = False
return True
elif event.type() == QEvent.MouseMove:
if (self.istitlebarpress):
distance = event.globalPos()-self.oldpos
newwindowpos = self.oldwindowpos + distance
self.move(newwindowpos)
return True
else:
return False
else:
return False
# Change the cursor shape when the cursor is over different part of the window.
def setCursorShape(self, event, handlersize=11):
rect = self.rect()
topLeft = rect.topLeft()
topRight = rect.topRight()
bottomLeft = rect.bottomLeft()
bottomRight = rect.bottomRight()
# get the position of the cursor
pos = event.pos()
# make the resize handle include some space outside the window,
# can avoid user move too fast and loss the handle.
# top handle
if pos in QRect(QPoint(topLeft.x()+handlersize, topLeft.y()-2*handlersize),
QPoint(topRight.x()-handlersize, topRight.y()+handlersize)):
self.setCursor(Qt.SizeVerCursor)
self.cursorpos = CursorPos.TOP
# bottom handle
elif pos in QRect(QPoint(bottomLeft.x()+handlersize, bottomLeft.y()-handlersize),
QPoint(bottomRight.x()-handlersize, bottomRight.y()+2*handlersize)):
self.setCursor(Qt.SizeVerCursor)
self.cursorpos = CursorPos.BOTTOM
# right handle
elif pos in QRect(QPoint(topRight.x()-handlersize, topRight.y()+handlersize),
QPoint(bottomRight.x()+2*handlersize, bottomRight.y()-handlersize)):
self.setCursor(Qt.SizeHorCursor)
self.cursorpos = CursorPos.RIGHT
# left handle
elif pos in QRect(QPoint(topLeft.x()-2*handlersize, topLeft.y()+handlersize),
QPoint(bottomLeft.x()+handlersize, bottomLeft.y()-handlersize)):
self.setCursor(Qt.SizeHorCursor)
self.cursorpos = CursorPos.LEFT
# topRight handle
elif pos in QRect(QPoint(topRight.x()-handlersize, topRight.y()-2*handlersize),
QPoint(topRight.x()+2*handlersize, topRight.y()+handlersize)):
self.setCursor(Qt.SizeBDiagCursor)
self.cursorpos = CursorPos.TOPRIGHT
# topLeft handle
elif pos in QRect(QPoint(topLeft.x()-2*handlersize, topLeft.y()-2*handlersize),
QPoint(topLeft.x()+handlersize, topLeft.y()+handlersize)):
self.setCursor(Qt.SizeFDiagCursor)
self.cursorpos = CursorPos.TOPLEFT
# bottomRight handle
elif pos in QRect(QPoint(bottomRight.x()-handlersize, bottomRight.y()-handlersize),
QPoint(bottomRight.x()+2*handlersize, bottomRight.y()+2*handlersize)):
self.setCursor(Qt.SizeFDiagCursor)
self.cursorpos = CursorPos.BOTTOMRIGHT
# bottomLeft handle
elif pos in QRect(QPoint(bottomLeft.x()-2*handlersize, bottomLeft.y()-handlersize),
QPoint(bottomLeft.x()+handlersize, bottomLeft.y()+2*handlersize)):
self.setCursor(Qt.SizeBDiagCursor)
self.cursorpos = CursorPos.BOTTOMLEFT
# Default is the arrow cursor.
else:
self.setCursor(Qt.ArrowCursor)
self.cursorpos = CursorPos.DEFAULT
def resizing(self, originpos, event, geo, cursorpos):
newpos = self.mapToGlobal(event.pos())
# find the distance between new and old cursor position.
dist = newpos - originpos
# calculate the steps to grow or srink.
if cursorpos in [CursorPos.TOP, CursorPos.BOTTOM,
CursorPos.TOPRIGHT,
CursorPos.BOTTOMLEFT, CursorPos.BOTTOMRIGHT]:
steps = dist.y()//self.stepY
elif cursorpos in [CursorPos.LEFT, CursorPos.TOPLEFT, CursorPos.RIGHT]:
steps = dist.x()//self.stepX
# if the distance moved is too stort, grow or srink by 1 step.
if steps == 0:
steps = -1 if dist.y() < 0 or dist.x() < 0 else 1
oldwidth = geo.width()
oldheight = geo.height()
oldX = geo.x()
oldY = geo.y()
if cursorpos in [CursorPos.TOP, CursorPos.TOPRIGHT]:
width = oldwidth - steps * self.stepX
height = oldheight - steps * self.stepY
newX = oldX
newY = oldY + (steps * self.stepY)
# check if the new size is within the size limit.
if height >= self.minheight and width >= self.minwidth:
self.setGeometry(newX, newY, width, height)
elif cursorpos in [CursorPos.BOTTOM, CursorPos.RIGHT, CursorPos.BOTTOMRIGHT]:
width = oldwidth + steps * self.stepX
height = oldheight + steps * self.stepY
self.resize(width, height)
elif cursorpos in [CursorPos.LEFT, CursorPos.BOTTOMLEFT]:
width = oldwidth - steps * self.stepX
height = oldheight - steps * self.stepY
newX = oldX + steps * self.stepX
newY = oldY
# check if the new size is within the size limit.
if height >= self.minheight and width >= self.minwidth:
self.setGeometry(newX, newY, width, height)
elif cursorpos == CursorPos.TOPLEFT:
width = oldwidth - steps * self.stepX
height = oldheight - steps * self.stepY
newX = oldX + steps * self.stepX
newY = oldY + steps * self.stepY
# check if the new size is within the size limit.
if height >= self.minheight and width >= self.minwidth:
self.setGeometry(newX, newY, width, height)
else:
pass
# cursor position
class CursorPos(Enum):
TOP = 1
BOTTOM = 2
RIGHT = 3
LEFT = 4
TOPRIGHT = 5
TOPLEFT = 6
BOTTOMRIGHT = 7
BOTTOMLEFT = 8
DEFAULT = 9
if __name__ == "__main__":
import sys
app = QApplication(sys.argv)
w = MainWindow()
w.show()
sys.exit(app.exec_())
Finally, I'd like to give special thanks to the authors and editors of this question, GLHF, DRPK, Elad Joseph, and SimoN SavioR. Without their contribution to the community, it wouldn't be possible to come up with this answer.
I am making a custom QWidget in which I have a QGridLayout, and draw a rectangle on a particular element in the grid. I also manually draw lines to delineate the location of the grid elements (with QPainter.DrawLines).
After drawing the lines, I then paint the rectangle within one of the grid elements, with its location specified using the QGridLayout coordinate system .
The problem is, the rectangle does not stay confined to its grid element. For instance, in the example below, the blue rectangle and black grid lines get out of alignment, so I end up with a blue box floating around in space.
I have not found explicit discussion of this issue via Google or SO.
Edit:
Note as pointed out in the accepted answer, the mistake was using grid coordinates to draw on the grid, when I should have been using point coordinates (i.e., column, row). That is, the mistake in the code below is that the element in the grid has its x- and y- coordinates reversed.
from PySide import QtGui, QtCore
class HighlightSquare(QtGui.QWidget):
def __init__(self, parent = None):
QtGui.QWidget.__init__(self, parent=None)
self.setSizePolicy(QtGui.QSizePolicy(QtGui.QSizePolicy.Expanding,
QtGui.QSizePolicy.Expanding))
self.setMinimumSize(self.minimumSizeHint())
layout = QtGui.QGridLayout()
layout.addItem(QtGui.QSpacerItem(10,10), 0, 0)
layout.addItem(QtGui.QSpacerItem(10,10), 0, 1)
layout.addItem(QtGui.QSpacerItem(10,10), 1, 0)
layout.addItem(QtGui.QSpacerItem(10,10), 1, 1)
self.setLayout(layout)
self.resize(150, 150)
self.update()
def paintEvent(self, event = None):
painter = QtGui.QPainter(self)
painter.setRenderHint(QtGui.QPainter.Antialiasing)
winHeight=self.size().height(); heightStep=winHeight/2
winWidth=self.size().width(); widthStep=winWidth/2
#Draw lines
painter.setPen(QtCore.Qt.black)
for i in range(4):
#vertical lines
painter.drawLine(QtCore.QPoint(i*widthStep,0), QtCore.QPoint(i*widthStep, winHeight))
#horizontal lines
painter.drawLine(QtCore.QPoint(0,heightStep*i), QtCore.QPoint(winWidth, heightStep*i))
#Draw blue outline around box 1,1
highlightCoordinate=(1,1)
pen=QtGui.QPen(QtCore.Qt.blue, 3)
painter.setPen(pen)
coordHighlight=[QtCore.QPoint(highlightCoordinate[1]*heightStep, highlightCoordinate[0]*widthStep),\
QtCore.QPoint(highlightCoordinate[1]*heightStep, (highlightCoordinate[0]+1)*widthStep),\
QtCore.QPoint((highlightCoordinate[1]+1)*heightStep, (highlightCoordinate[0]+1)*widthStep),\
QtCore.QPoint((highlightCoordinate[1]+1)*heightStep, highlightCoordinate[0]*widthStep),\
QtCore.QPoint(highlightCoordinate[1]*heightStep, highlightCoordinate[0]*widthStep)]
#print coordHighlight
painter.drawPolyline(coordHighlight)
def minimumSizeHint(self):
return QtCore.QSize(120,120)
if __name__=="__main__":
import sys
app=QtGui.QApplication(sys.argv)
myLight = HighlightSquare()
myLight.show()
sys.exit(app.exec_())
Have you read the definition of the constructor of class QtCore.QPoint? At method QPoint.__init__ (self, int xpos, int ypos) your code is reversed (ypos, xpos). I fixed it.
import sys
from PyQt4 import QtGui, QtCore
class QHighlightSquareWidget (QtGui.QWidget):
def __init__ (self, parent = None):
QtGui.QWidget.__init__(self, parent = None)
self.setSizePolicy (
QtGui.QSizePolicy (
QtGui.QSizePolicy.Expanding,
QtGui.QSizePolicy.Expanding))
self.setMinimumSize(self.minimumSizeHint())
allQGridLayout = QtGui.QGridLayout()
allQGridLayout.addItem(QtGui.QSpacerItem(10,10), 0, 0)
allQGridLayout.addItem(QtGui.QSpacerItem(10,10), 0, 1)
allQGridLayout.addItem(QtGui.QSpacerItem(10,10), 1, 0)
allQGridLayout.addItem(QtGui.QSpacerItem(10,10), 1, 1)
self.setLayout(allQGridLayout)
self.resize(150, 150)
self.update()
def paintEvent (self, eventQPaintEvent):
myQPainter = QtGui.QPainter(self)
myQPainter.setRenderHint(QtGui.QPainter.Antialiasing)
winHeight = self.size().height()
heightStep = winHeight / 2
winWidth = self.size().width()
widthStep = winWidth / 2
myQPainter.setPen(QtCore.Qt.black)
for i in range(4):
myQPainter.drawLine(QtCore.QPoint(i * widthStep, 0 ), QtCore.QPoint(i * widthStep, winHeight ))
myQPainter.drawLine(QtCore.QPoint(0, heightStep * i), QtCore.QPoint(winWidth, heightStep * i))
highlightCoordinate = (1, 1)
myQPen = QtGui.QPen(QtCore.Qt.blue, 3)
myQPainter.setPen(myQPen)
coordHighlight = [
QtCore.QPoint( highlightCoordinate[0] * widthStep, highlightCoordinate[1] * heightStep),
QtCore.QPoint((highlightCoordinate[0] + 1) * widthStep, highlightCoordinate[1] * heightStep),
QtCore.QPoint((highlightCoordinate[0] + 1) * widthStep, (highlightCoordinate[1] + 1) * heightStep),
QtCore.QPoint( highlightCoordinate[0] * widthStep, (highlightCoordinate[1] + 1) * heightStep),
QtCore.QPoint( highlightCoordinate[0] * widthStep, highlightCoordinate[1] * heightStep)]
myQPainter.drawPolyline(*coordHighlight)
def minimumSizeHint (self):
return QtCore.QSize(120, 120)
if __name__=="__main__":
myQApplication = QtGui.QApplication(sys.argv)
myQHighlightSquareWidget = QHighlightSquareWidget()
myQHighlightSquareWidget.show()
sys.exit(myQApplication.exec_())