Develop Reference

PyQt5 drawing lines that have mouse events

I have an application where I draw 2 custom widgets and then draw a line between them. I want to add a mousePressEvent to the line.
What would be the best way to do this?
I suppose I could create a QWidget of x pixel thickness and y length and then fill in the whole widget with the colour I want the line to have. Then the QWidget has the mousePressEvent that I can override. This doesn't seem like the most elegant solution and feels more like a workaround. Is there a better way?
import sys
from PyQt5.QtCore import Qt
from PyQt5.QtGui import QPaintEvent, QPainter, QPen, QFont
from PyQt5.QtWidgets import QApplication, QMainWindow, QWidget, QLabel
class MyWidget(QWidget):
def __init__(self, name, parent):
super().__init__(parent)
self.setAutoFillBackground(True)
self.setFixedSize(300, 100)
p = self.palette()
p.setColor(self.backgroundRole(), Qt.white)
self.setPalette(p)
lbl_name = QLabel(name, self)
lbl_name.setFont(QFont('Arial', 16))
lbl_name.move((self.width() - lbl_name.width()) / 2, self.height()/2 - lbl_name.height()/2)
class MainWindow(QMainWindow):
def __init__(self, parent=None):
super().__init__(parent)
self.main_widget = QWidget(self)
self.widget_1 = MyWidget("Widget 1", self)
self.widget_1.move(50, 50)
self.widget_2 = MyWidget("Widget 2", self)
self.widget_2.move(700, 600)
self.resize(1200, 800)
self.setCentralWidget(self.main_widget)
def paintEvent(self, a0: QPaintEvent) -> None:
super().paintEvent(a0)
painter = QPainter(self)
painter.setPen(QPen(Qt.red, 3, Qt.SolidLine))
widget_1_x = self.widget_1.pos().x() + self.widget_1.size().width()
widget_1_y = self.widget_1.pos().y() + self.widget_1.size().height() / 2
widget_2_x = self.widget_2.pos().x()
widget_2_y = self.widget_2.pos().y() + self.widget_2.size().height() / 2
halfway_x = widget_1_x + (widget_2_x - widget_1_x) / 2
# add mousePressEvents to these lines:
painter.drawLine(widget_1_x, widget_1_y, halfway_x, widget_1_y)
painter.drawLine(halfway_x, widget_1_y, halfway_x, widget_2_y)
painter.drawLine(halfway_x, widget_2_y, widget_2_x, widget_2_y)
if __name__ == "__main__":
app = QApplication(sys.argv)
myapp = MainWindow()
myapp.show()
sys.exit(app.exec_())
How the above code looks like when run

PyQT5 Add a label and icon in a rectangle

I've a list of rectangle make in this way:
import sys
from PyQt5.QtCore import Qt, QRect, QRectF
from PyQt5.QtGui import *
from PyQt5.QtWidgets import ( QGridLayout, QWidget, QApplication, QGraphicsScene,
QGraphicsView, QGraphicsProxyWidget, QGraphicsRectItem
)
class WidRect(QWidget):
def __init__(self, mIntMeasureId,mStrLabel=None):
super().__init__()
self.aIntMeasureId=mIntMeasureId
self.aStrLabel=mStrLabel
#self.setWidget(QLabel(mStrLabel))
def mousePressEvent(self, QMouseEvent):
if QMouseEvent.button() == Qt.LeftButton:
print("Left Button Clicked on measure "+ str(self.aIntMeasureId))
elif QMouseEvent.button() == Qt.RightButton:
#do what you want here
print("Right Button Clicked on measure "+ str(self.aIntMeasureId))
class MeasureGrid(QWidget):
#grid = None
#scene = None
def __init__(self, geometry, parent=None):
super(MeasureGrid, self).__init__(parent=parent)
#super().onclick.connec(self.click)
self.aLayMeasureGrid = QGridLayout(self)
self.aGsMeasureScene = QGraphicsScene(self)
self.aGsMeasureScene .setSceneRect(geometry.x(), geometry.y(), geometry.width(), geometry.height())
self.aGsMeasureScene .setBackgroundBrush(Qt.white)
self.aGvMeasureView = QGraphicsView()
self.aGvMeasureView.setScene(self.aGsMeasureScene )
self.aLayMeasureGrid.addWidget(self.aGvMeasureView)
for i in range(1,5):
rect = QRectF(100*i, 20, 80, 140)
self.addRect(rect,i)
def addRect(self, mRecMeasureBox,mIntMeasureNum):
#label = QLabel("World")
#label.setAlignment(Qt.AlignCenter | Qt.AlignCenter)
wrRectBox = WidRect(mIntMeasureNum,"Meas #" + str(mIntMeasureNum))
### CREA IL PROXY ###
gpqProxMeasure = QGraphicsProxyWidget()
gpqProxMeasure.setWidget(wrRectBox)
gpqProxMeasure.setGeometry(mRecMeasureBox)
self.aGsMeasureScene.addItem(gpqProxMeasure)
### CREA L'OGGETTO GENITORE ###
griMeasure = QGraphicsRectItem(mRecMeasureBox)
#rectangle.setFlag(QGraphicsItem.ItemIsMovable, True)
self.aGsMeasureScene.addItem(griMeasure)
gpqProxMeasure.setParentItem(griMeasure)
if __name__ == "__main__":
app = QApplication(sys.argv)
mgMeasureList = MeasureGrid(QRect(10, 10, 550, 280))
mgMeasureList.show()
app.exec_()
I would like to add:
a text into every rectangle
an icon into every rectangle
change the icon with another if I click with right button.
I try to add a QLabel but I cannot add a widget to a widget.
Can you tell me where is my error?
I create the rectangle using a proxy object because in the final version of the application they will be from 100 to 300 objects.

How to properly scale GraphicsScene

I've created a small app and I'm trying to make it so that when the main window is resized (and the GraphicsView and scene are too) that the whole scene (pixmap and rectangles) scale vertically to fit completely inside the GraphicsView. I don't want a vertical scrollbar and I don't want it to scale horizontally.
I can't figure out how to scale the scene properly. I use a GraphicsScene to contain a graph and a couple vertical rectangle "markers". When I can scale the graph to fit by redrawing the pixmap and then reattach it, the z-order is wrong AND the rectangle widgets are not scaled with it.
I need to keep track of the rectangle widgets, so I can't just keep deleting and re-adding them as there's meta data along with each one.
I know about fitInView (from here: Issue with fitInView of QGraphicsView when ItemIgnoresTransformations is on) that applies to the containing GraphicsView, but I don't understand why it needs a parameter. I just want the scene to fit in the GraphicsView (vertically but not horizontally) so why doesn't GraphicsView just scale everything in the scene to fit inside it's current size? What should the parameter look like to get the scene to fit vertically?
In the resizeEvent I can redraw the pixmap and re-add, but then it covers the rectangles as the z-order is messed up. Also, it doesn't stay centered vertically in the scene and I would need to copy over the meta data.
import sys
import os
from PyQt5 import QtCore, QtGui, QtWidgets
import PyQt5 as qt
from PyQt5.QtGui import QColor
from PyQt5.QtCore import Qt, QPoint
from PyQt5.QtWidgets import QApplication, QWidget, QPushButton, QHBoxLayout, QGroupBox, QDialog, QVBoxLayout
from PyQt5.QtWidgets import QVBoxLayout, QGridLayout, QStackedWidget, QTabWidget
import numpy as np
class GraphicsScene(QtWidgets.QGraphicsScene):
def __init__(self, parent=None):
super(GraphicsScene, self).__init__(parent)
def minimumSizeHint(self):
return QtCore.QSize(300, 200)
def dragMoveEvent(self, event):
print("dragMoveEvent", event)
class MainWindow(QtWidgets.QMainWindow):
def __init__(self, parent=None):
super(MainWindow, self).__init__(parent)
#super(MainWindow).__init__()
layout = QVBoxLayout()
layout.setContentsMargins(0, 0, 0, 0)
max_x, max_y = 2400, 700
max_x_view = 1200
self.max_x = max_x
self.max_y = max_y
self.first = True
self.setGeometry(200, 200, max_x_view, self.max_y)
self.gv = QtWidgets.QGraphicsView(self)
self.gv.setGeometry(0, 0, max_x_view, self.max_y)
self.gv2 = QtWidgets.QGraphicsView(self)
layout.addWidget(self.gv)
layout.addWidget(self.gv2)
scene = GraphicsScene()
self.scene = scene
self.gv.setScene(scene)
tab_widget = QTabWidget()
tab_widget.setTabPosition(QTabWidget.West)
widget = QWidget()
widget.setLayout(layout)
tab_widget.addTab(widget, "main")
self.setCentralWidget(tab_widget)
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 = .45*(np.sin(2*self.x_time) + rand_data) - .25*(np.sin(3*self.x_time))
self.first = True
pixmap_height = max_y//2 - 2*22 # 22 to take care of scrollbar height
pixmap = self.draw_graph()
pen = QtGui.QPen()
pen.setWidth(2)
pen.setColor(QtGui.QColor("red"))
self.gv1_pixmap = scene.addPixmap(pixmap)
rect = scene.sceneRect()
print("scene rect = {}".format(rect))
scene.setSceneRect(rect)
side, offset = 50, 200
for i in range(2):
r = QtCore.QRectF(QtCore.QPointF((i + 1)*offset + i * 2 * side, 2), QtCore.QSizeF(side, pixmap_height - 4))
rect_ref = scene.addRect(r, pen, QColor(255, 0, 0, 127))
rect_ref.setFlag(QtWidgets.QGraphicsItem.ItemIsMovable)
all_items = scene.items()
print(all_items)
def draw_graph(self):
print("draw_graph: main Window size {}:".format(self.size()))
pixmap_height = self.height()//2 - 2*22 # 22 to take care of scrollbar height
x_final = self.x_time[-1]
data = self.data / np.max(np.abs(self.data))
data = [abs(int(k * pixmap_height)) for k in self.data]
x_pos = [int(self.x_time[i] * self.max_x / x_final) for i in range(len(data))]
pixmap = QtGui.QPixmap(self.max_x, pixmap_height)
painter = QtGui.QPainter(pixmap)
pen = QtGui.QPen()
pen.setWidth(2)
rect = pixmap.rect()
pen.setColor(QtGui.QColor("red"))
painter.drawRect(rect)
print("pixmap 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, data):
painter.drawLine(x, pixmap_height, x, pixmap_height - y)
painter.end()
return pixmap
def resizeEvent(self, a0: QtGui.QResizeEvent):
#print("main Window resizeEvent")
print("main Window size {}:".format(a0.size()))
redraw = False
if redraw:
pixmap = self.draw_graph()
self.scene.removeItem(self.gv1_pixmap)
self.gv1_pixmap = self.scene.addPixmap(pixmap)
self.gv1_pixmap.moveBy(0, 30)
else:
#rect = QtCore.QRect(self.gv.startPos, self.gv.endPos)
#sceneRect = self.gv.mapToScene(rect).boundingRect()
#print 'Selected area: viewport coordinate:', rect,', scene coordinate:', sceneRect
#self.gv.fitInView(sceneRect)
pass
app = QtWidgets.QApplication(sys.argv)
window = MainWindow()
window.show()
app.exec_()

My solution will fit the height of the smallest rectangle that encapsulates all the items (sceneRect) to the viewport of the QGraphicsView. So set the height of the items a value not so small so that the image quality is not lost. I have also scaled the items using the QTransforms. In addition, the QGraphicsView coordinate system was inverted since by default the vertical axis is top-bottom and I have inverted it so that the painting is more consistent with the data.
I have refactored the OP code to make it more scalable, there is a GraphItem that takes the data (x, y) and the image dimensions.
Considering the above, the solution is:
import numpy as np
from PyQt5 import QtCore, QtGui, QtWidgets
class GraphItem(QtWidgets.QGraphicsPixmapItem):
def __init__(self, xdata, ydata, width, height, parent=None):
super(GraphItem, self).__init__(parent)
self._xdata = xdata
self._ydata = ydata
self._size = QtCore.QSize(width, height)
self.redraw()
def redraw(self):
x_final = self._xdata[-1]
pixmap = QtGui.QPixmap(self._size)
pixmap_height = pixmap.height()
pixmap.fill(QtGui.QColor("lightblue"))
painter = QtGui.QPainter(pixmap)
pen = QtGui.QPen(QtGui.QColor("green"))
pen.setWidth(2)
painter.setPen(pen)
for i, (x, y) in enumerate(
zip(self._xdata, self._ydata / np.max(np.abs(self._ydata)))
):
x_pos = int(x * self._size.width() / x_final)
y_pos = abs(int(y * pixmap_height))
painter.drawLine(x_pos, 0, x_pos, y_pos)
painter.end()
self.setPixmap(pixmap)
class HorizontalRectItem(QtWidgets.QGraphicsRectItem):
def itemChange(self, change, value):
if change == QtWidgets.QGraphicsItem.ItemPositionChange and self.scene():
newPos = self.pos()
newPos.setX(value.x())
return newPos
return super(HorizontalRectItem, self).itemChange(change, value)
class GraphicsView(QtWidgets.QGraphicsView):
def __init__(self, parent=None):
super(GraphicsView, self).__init__(parent)
scene = QtWidgets.QGraphicsScene(self)
self.setScene(scene)
self.scale(1, -1)
def resizeEvent(self, event):
h = self.mapToScene(self.viewport().rect()).boundingRect().height()
r = self.sceneRect()
r.setHeight(h)
self.setSceneRect(r)
height = self.viewport().height()
for item in self.items():
item_height = item.boundingRect().height()
tr = QtGui.QTransform()
tr.scale(1, height / item_height)
item.setTransform(tr)
super(GraphicsView, self).resizeEvent(event)
class MainWindow(QtWidgets.QMainWindow):
def __init__(self, parent=None):
super(MainWindow, self).__init__(parent)
tab_widget = QtWidgets.QTabWidget(tabPosition=QtWidgets.QTabWidget.West)
self.setCentralWidget(tab_widget)
self.graphics_view_top = GraphicsView()
self.graphics_view_bottom = QtWidgets.QGraphicsView()
container = QtWidgets.QWidget()
lay = QtWidgets.QVBoxLayout(container)
lay.addWidget(self.graphics_view_top)
lay.addWidget(self.graphics_view_bottom)
tab_widget.addTab(container, "main")
self.resize(640, 480)
side, offset, height = 50, 200, 400
np.random.seed(777)
x_time = np.linspace(0, 12.56, 3000)
rand_data = np.random.uniform(0.0, 1.0, 3000)
data = 0.45 * (np.sin(2 * x_time) + rand_data) - 0.25 * (np.sin(3 * x_time))
graph_item = GraphItem(x_time, data, 3000, height)
self.graphics_view_top.scene().addItem(graph_item)
for i in range(2):
r = QtCore.QRectF(
QtCore.QPointF((i + 1) * offset + i * 2 * side, 2),
QtCore.QSizeF(side, height),
)
it = HorizontalRectItem(r)
it.setPen(QtGui.QPen(QtGui.QColor("red"), 2))
it.setBrush(QtGui.QColor(255, 0, 0, 127))
self.graphics_view_top.scene().addItem(it)
it.setFlags(
it.flags()
| QtWidgets.QGraphicsItem.ItemIsMovable
| QtWidgets.QGraphicsItem.ItemSendsGeometryChanges
)
def main():
import sys
app = QtWidgets.QApplication(sys.argv)
w = MainWindow()
w.show()
ret = app.exec_()
sys.exit(ret)
if __name__ == "__main__":
main()

How to set QGraphicsView 's background Image? [duplicate]

This question already has answers here:
Painting background on QGraphicsView using drawBackground
(1 answer)
How to enable Pan and Zoom in a QGraphicsView
(3 answers)
How to put an image in QGraphicsView's scrollbar area?
(1 answer)
Closed 3 years ago.
I'm wondering how to set QgraphicsView's background Image.
In this painter program, the background is just white color.
I want to load some image(jpg, png, .. whatever) and set it as painter's background.
and after painting it, I want to just save painting (not include background, just what i painted.)
how can i do this? please help me.
import sys
from PyQt5.QtCore import *
from PyQt5.QtCore import Qt
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
from PyQt5.QtWidgets import (QApplication, QCheckBox, QGridLayout, QGroupBox,
QPushButton, QVBoxLayout, QWidget, QSlider)
QApplication.setAttribute(Qt.AA_EnableHighDpiScaling, True)
class CWidget(QWidget):
def __init__(self):
super().__init__()
# 전체 폼 박스
formbox = QHBoxLayout()
self.setLayout(formbox)
# 좌, 우 레이아웃박스
left = QVBoxLayout()
right = QVBoxLayout()
# 그룹박스2
gb = QGroupBox('펜 설정')
left.addWidget(gb)
grid = QGridLayout()
gb.setLayout(grid)
label = QLabel('펜 색상')
grid.addWidget(label, 1, 0)
self.pencolor = QColor(0, 0, 0)
self.penbtn = QPushButton()
self.penbtn.setStyleSheet('background-color: rgb(0,0,0)')
self.penbtn.clicked.connect(self.showColorDlg)
grid.addWidget(self.penbtn, 1, 1)
label = QLabel('펜 굵기')
grid.addWidget(label, 2, 0)
self.slider = QSlider(Qt.Horizontal)
self.slider.setMinimum(3)
self.slider.setMaximum(21)
self.slider.setValue(5)
self.slider.setFocusPolicy(Qt.StrongFocus)
self.slider.setTickPosition(QSlider.TicksBothSides)
self.slider.setTickInterval(1)
self.slider.setSingleStep(1)
grid.addWidget(self.slider)
# 그룹박스4
gb = QGroupBox('지우개')
left.addWidget(gb)
hbox = QHBoxLayout()
gb.setLayout(hbox)
self.checkbox = QCheckBox('지우개')
self.checkbox.stateChanged.connect(self.checkClicked)
hbox.addWidget(self.checkbox)
left.addStretch(1)
# 우 레이아웃 박스에 그래픽 뷰 추가
self.view = CView(self)
right.addWidget(self.view)
# 전체 폼박스에 좌우 박스 배치
formbox.addLayout(left)
formbox.addLayout(right)
formbox.setStretchFactor(left, 0)
formbox.setStretchFactor(right, 1)
self.setGeometry(100, 100, 800, 500)
def checkClicked(self):
pass
def createExampleGroup(self):
groupBox = QGroupBox("Slider Example")
slider = QSlider(Qt.Horizontal)
slider.setFocusPolicy(Qt.StrongFocus)
slider.setTickPosition(QSlider.TicksBothSides)
slider.setTickInterval(10)
slider.setSingleStep(1)
vbox = QVBoxLayout()
vbox.addWidget(slider)
vbox.addStretch(1)
groupBox.setLayout(vbox)
return groupBox
def showColorDlg(self):
# 색상 대화상자 생성
color = QColorDialog.getColor()
sender = self.sender()
# 색상이 유효한 값이면 참, QFrame에 색 적용
self.pencolor = color
self.penbtn.setStyleSheet('background-color: {}'.format(color.name()))
# QGraphicsView display QGraphicsScene
class CView(QGraphicsView):
def __init__(self, parent):
super().__init__(parent)
self.scene = QGraphicsScene()
self.setScene(self.scene)
self.items = []
self.start = QPointF()
self.end = QPointF()
self.setRenderHint(QPainter.HighQualityAntialiasing)
def moveEvent(self, e):
rect = QRectF(self.rect())
rect.adjust(0, 0, -2, -2)
self.scene.setSceneRect(rect)
def mousePressEvent(self, e):
if e.button() == Qt.LeftButton:
# 시작점 저장
self.start = e.pos()
self.end = e.pos()
def mouseMoveEvent(self, e):
# e.buttons()는 정수형 값을 리턴, e.button()은 move시 Qt.Nobutton 리턴
if e.buttons() & Qt.LeftButton:
self.end = e.pos()
if self.parent().checkbox.isChecked():
pen = QPen(QColor(255, 255, 255), 10)
path = QPainterPath()
path.moveTo(self.start)
path.lineTo(self.end)
self.scene.addPath(path, pen)
self.start = e.pos()
return None
pen = QPen(self.parent().pencolor, self.parent().slider.value())
# Path 이용
path = QPainterPath()
path.moveTo(self.start)
path.lineTo(self.end)
self.scene.addPath(path, pen)
# 시작점을 다시 기존 끝점으로
self.start = e.pos()
def open(self):
fileName, _ = QFileDialog.getOpenFileName(self, "Open File",
QDir.currentPath())
if fileName:
image = QImage(fileName)
if image.isNull():
QMessageBox.information(self, "Image Viewer",
"Cannot load %s." % fileName)
return
self.imageLabel.setPixmap(QPixmap.fromImage(image))
self.scaleFactor = 1.0
self.printAct.setEnabled(True)
self.fitToWindowAct.setEnabled(True)
self.updateActions()
if not self.fitToWindowAct.isChecked():
self.imageLabel.adjustSize()
if __name__ == '__main__':
app = QApplication(sys.argv)
w = CWidget()
w.show()
sys.exit(app.exec_())

You can create an instance of QGraphicsPixmapItem and add it to the scene, here is an example:
import sys
from PyQt5.QtCore import *
from PyQt5.QtCore import Qt
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
from PyQt5.QtWidgets import (QApplication, QCheckBox, QGridLayout, QGroupBox,
QPushButton, QVBoxLayout, QWidget, QSlider)
QApplication.setAttribute(Qt.AA_EnableHighDpiScaling, True)
class CWidget(QWidget):
def __init__(self):
super().__init__()
# 전체 폼 박스
formbox = QHBoxLayout()
self.setLayout(formbox)
# 좌, 우 레이아웃박스
left = QVBoxLayout()
right = QVBoxLayout()
# 그룹박스2
gb = QGroupBox('펜 설정')
left.addWidget(gb)
grid = QGridLayout()
gb.setLayout(grid)
label = QLabel('펜 색상')
grid.addWidget(label, 1, 0)
self.pencolor = QColor(0, 0, 0)
self.penbtn = QPushButton()
self.penbtn.setStyleSheet('background-color: rgb(0,0,0)')
self.penbtn.clicked.connect(self.showColorDlg)
grid.addWidget(self.penbtn, 1, 1)
label = QLabel('펜 굵기')
grid.addWidget(label, 2, 0)
self.slider = QSlider(Qt.Horizontal)
self.slider.setMinimum(3)
self.slider.setMaximum(21)
self.slider.setValue(5)
self.slider.setFocusPolicy(Qt.StrongFocus)
self.slider.setTickPosition(QSlider.TicksBothSides)
self.slider.setTickInterval(1)
self.slider.setSingleStep(1)
grid.addWidget(self.slider)
# 그룹박스4
gb = QGroupBox('지우개')
left.addWidget(gb)
hbox = QHBoxLayout()
gb.setLayout(hbox)
self.checkbox = QCheckBox('지우개')
self.checkbox.stateChanged.connect(self.checkClicked)
hbox.addWidget(self.checkbox)
left.addStretch(1)
# 우 레이아웃 박스에 그래픽 뷰 추가
self.view = CView(self)
right.addWidget(self.view)
# 전체 폼박스에 좌우 박스 배치
formbox.addLayout(left)
formbox.addLayout(right)
formbox.setStretchFactor(left, 0)
formbox.setStretchFactor(right, 1)
self.setGeometry(100, 100, 800, 500)
def checkClicked(self, state):
self.view.stretch(state)
def createExampleGroup(self):
groupBox = QGroupBox("Slider Example")
slider = QSlider(Qt.Horizontal)
slider.setFocusPolicy(Qt.StrongFocus)
slider.setTickPosition(QSlider.TicksBothSides)
slider.setTickInterval(10)
slider.setSingleStep(1)
vbox = QVBoxLayout()
vbox.addWidget(slider)
vbox.addStretch(1)
groupBox.setLayout(vbox)
return groupBox
def showColorDlg(self):
# 색상 대화상자 생성
color = QColorDialog.getColor()
sender = self.sender()
# 색상이 유효한 값이면 참, QFrame에 색 적용
self.pencolor = color
self.penbtn.setStyleSheet('background-color: {}'.format(color.name()))
# QGraphicsView display QGraphicsScene
class CView(QGraphicsView):
def __init__(self, parent):
super().__init__(parent)
self.scene = QGraphicsScene()
self.setScene(self.scene)
self.items = []
self.start = QPointF()
self.end = QPointF()
self.backgroundImage = None
self.graphicsPixmapItem = None
self.setRenderHint(QPainter.HighQualityAntialiasing)
self.open()
def moveEvent(self, e):
rect = QRectF(self.rect())
rect.adjust(0, 0, -2, -2)
self.scene.setSceneRect(rect)
def mousePressEvent(self, e):
if e.button() == Qt.LeftButton:
# 시작점 저장
self.start = e.pos()
self.end = e.pos()
def mouseMoveEvent(self, e):
# e.buttons()는 정수형 값을 리턴, e.button()은 move시 Qt.Nobutton 리턴
if e.buttons() & Qt.LeftButton:
self.end = e.pos()
if self.parent().checkbox.isChecked():
pen = QPen(QColor(255, 255, 255), 10)
path = QPainterPath()
path.moveTo(self.start)
path.lineTo(self.end)
self.scene.addPath(path, pen)
self.start = e.pos()
return None
pen = QPen(self.parent().pencolor, self.parent().slider.value())
# Path 이용
path = QPainterPath()
path.moveTo(self.start)
path.lineTo(self.end)
self.scene.addPath(path, pen)
# 시작점을 다시 기존 끝점으로
self.start = e.pos()
def stretch(self, state):
self._set_image(state == 2)
def open(self):
fileName, _ = QFileDialog.getOpenFileName(self, "Open File", QDir.currentPath(), filter='Images (*.png *.xpm *.jpg)')
if fileName:
image = QImage(fileName)
if image.isNull():
QMessageBox.information(self, "Image Viewer",
"Cannot load %s." % fileName)
return
self.backgroundImage = fileName
self._set_image(False)
def _set_image(self, stretch: bool):
tempImg = QPixmap(self.backgroundImage)
if stretch:
tempImg = tempImg.scaled(self.scene.width(), self.scene.height())
if self.graphicsPixmapItem is not None:
self.scene.removeItem(self.graphicsPixmapItem)
self.graphicsPixmapItem = QGraphicsPixmapItem(tempImg)
self.scene.addItem(self.graphicsPixmapItem)
if __name__ == '__main__':
app = QApplication(sys.argv)
w = CWidget()
w.show()
sys.exit(app.exec_())

How to subtract QPainterPaths, QPolygon?

I'm trying to understand how path1.subtracted(path2) works.
I have path1 and path2:
And I'm getting path3 using path3=path1.subtracted(path2).
Why I'm not getting a path I want? Image:
Here is the code:
from PyQt5.QtCore import QPointF
from PyQt5.QtCore import QRectF, Qt
from PyQt5.QtGui import QPainterPath, QPen
from PyQt5.QtGui import QPolygonF
from PyQt5.QtWidgets import QApplication, QGraphicsScene, \
QGraphicsView, QPushButton, QWidget, \
QVBoxLayout, QGraphicsItem, QGraphicsPathItem, QGraphicsRectItem
class Window(QWidget):
scene = None
def __init__(self):
QWidget.__init__(self)
self.view = View(self)
self.button = QPushButton('Clear View', self)
self.button.clicked.connect(self.handleClearView)
layout = QVBoxLayout(self)
layout.addWidget(self.view)
layout.addWidget(self.button)
def handleClearView(self):
self.view.scene.clear()
class View(QGraphicsView):
def __init__(self, parent):
self.scribing = False
self.erasing = False
QGraphicsView.__init__(self, parent)
self.scene = QGraphicsScene()
self.setScene(self.scene)
def resizeEvent(self, QResizeEvent):
self.setSceneRect(QRectF(self.viewport().rect()))
def mousePressEvent(self, event):
if event.buttons() == Qt.LeftButton:
self.scribing = True
self.path1 = QPainterPath()
self.path2 = QPainterPath()
self.polygon1 = QPolygonF()
self.polygon1.append(QPointF(100,100))
self.polygon1.append(QPointF(100, 300))
self.polygon1.append(QPointF(300, 300))
self.polygon1.append(QPointF(300, 100))
self.polygon2 = QPolygonF()
self.polygon2.append(QPointF(300,100))
self.polygon2.append(QPointF(300, 300))
self.polygon2.append(QPointF(100, 300))
self.path1.addPolygon(self.polygon1)
self.path2.addPolygon(self.polygon2)
path3 = self.path1.subtracted(self.path2)
# self.scene.addPath(self.path1, QPen(Qt.blue))
# self.scene.addPath(self.path2, QPen(Qt.green))
self.scene.addPath(path3, QPen(Qt.red))
if event.buttons() == Qt.RightButton:
self.erasing = True
def mouseMoveEvent(self, event):
if (event.buttons() & Qt.LeftButton) and self.scribing:
if self.free_draw_item:
pass
if event.buttons() & Qt.RightButton and self.erasing:
pass
def mouseReleaseEvent(self, event):
self.scribing = False
self.erasing = False
# if self.eraser_item != None:
# self.scene.removeItem(self.eraser_item)
# if self.free_draw_item != None:
# self.free_draw_item.setSelected(True)
if __name__ == '__main__':
import sys
app = QApplication(sys.argv)
window = Window()
window.resize(640, 480)
window.show()
sys.exit(app.exec_())
In this sample I'm working with QPolygonF. Also I've tried to create p1=QPainterPath(), p2=QPainterPath() and subtracted to get p3. But, without success, getting the same result.

QpainterPath.subtracted() doesn't subtract path elements but path areas,
see documentation
same effect if QpainterPath::operator-() is used:
# path3 = self.path1.subtracted(self.path2)
path3 = self.path1 – self.path2
You can identify the elements of a path by something like this
c = path3.elementCount()
for i in range(c):
e = path3.elementAt(i)
print('Element-nr.: ', i, 'Type: ', e.type, 'x: ', e.x, 'y: ', e.y) # type: 0 = MoveTo, 1 = LineTo
I think, you have to write an own method, which creates path3 from the elements of path1 and path2.