关于python：Pyqt5 Qgraphicsview 在加载时适当缩放

Pyqt5 Qgraphicsview scaled appropriately on load

我有一些 QGraphicItems 在多个预定的 X 和 Y 坐标处加载。我有一个名为 fitInView 的函数，当用户单击按钮调用该函数时，视图的缩放效果很好，但是如果我在加载过程中尝试调用该函数，它不会按我想要的方式缩放。我相信这与我如何确定比例因子有关。当我在加载时打印出视口的宽度和高度值以及当用户单击按钮时，它们是非常不同的。

我的问题是如何让对象在加载时与用户单击按钮时的缩放比例相同。感谢您的帮助。

代码

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from PyQt5.QtCore import *
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
import sys
from math import sqrt

class Point(QGraphicsItem):
def __init__(self, x, y):
super(Point, self).__init__()
self.setFlag(QGraphicsItem.ItemIsSelectable, True)
self.rectF = QRectF(0, 0, 30, 30)
self.x=x
self.y=y
self._brush = QBrush(Qt.black)

def setBrush(self, brush):
self._brush = brush
self.update()

def boundingRect(self):
return self.rectF

def paint(self, painter=None, style=None, widget=None):
painter.fillRect(self.rectF, self._brush)

def hoverMoveEvent(self, event):
point = event.pos().toPoint()
print(point)
QGraphicsItem.hoverMoveEvent(self, event)

class Viewer(QGraphicsView):
photoClicked = pyqtSignal(QPoint)
rectChanged = pyqtSignal(QRect)

def __init__(self, parent):
super(Viewer, self).__init__(parent)
self.rubberBand = QRubberBand(QRubberBand.Rectangle, self)
self.setMouseTracking(True)
self.origin = QPoint()
self.changeRubberBand = False

self._zoom = 0
self._empty = True
self._scene = QGraphicsScene(self)

self.setTransformationAnchor(QGraphicsView.AnchorUnderMouse)
self.setResizeAnchor(QGraphicsView.AnchorUnderMouse)
self.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
self.setHorizontalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
self.setFrameShape(QFrame.NoFrame)
self.area = float()
self.setPoints()
self.fitInView()

def setItems(self):
self.data = {'x': [-2414943.8686, -2417160.6592, -2417160.6592, -2417856.1783, -2417054.7618, -2416009.9966, -2416012.5232, -2418160.8952, -2418160.8952, -2416012.5232, -2417094.7694, -2417094.7694], 'y': [10454269.7008,
10454147.2672, 10454147.2672, 10453285.2456, 10452556.8132, 10453240.2808, 10455255.8752, 10455183.1912, 10455183.1912, 10455255.8752, 10456212.5959, 10456212.5959]}
maxX = max(self.data['x'])
minX = min(self.data['x'])
maxY = max(self.data['y'])
minY = min(self.data['y'])
distance = sqrt((maxX-minX)**2+(maxY-minY)**2)

self.area = QRectF(minX, minY, distance, distance)
for i,x in enumerate(self.data['x']):
x = self.data['x'][i]
y = self.data['y'][i]
p = Point(x,y)
p.setPos(x,y)
self._scene.addItem(p)
self.setScene(self._scene)

def fitInView(self, scale=True):
rect = QRectF(self.area)
if not rect.isNull():
self.setSceneRect(rect)

unity = self.transform().mapRect(QRectF(0, 0, 1, 1))
self.scale(1 / unity.width(), 1 / unity.height())
viewrect = self.viewport().rect()
scenerect = self.transform().mapRect(rect)
factor = min(viewrect.width() / scenerect.width(),
viewrect.height() / scenerect.height())
self.scale(factor, factor)
self._zoom = 0

print('viewrect.width: '+str(viewrect.width()))
print('scenerect.width: '+str(scenerect.width()))
print('viewrect.height: '+str(viewrect.height()))
print('scenerect.height: '+str(scenerect.height()))

def setPoints(self):
self._zoom = 0
self.setItems()
self.setDragMode(self.ScrollHandDrag)
# self.fitInView()

def wheelEvent(self, event):
if event.angleDelta().y() > 0:
factor = 1.25
self._zoom += 1
else:
factor = 0.8
self._zoom -= 1
if self._zoom > 0:
self.scale(factor, factor)
elif self._zoom == 0:
self.fitInView()
else:
self._zoom = 0

def mousePressEvent(self, event):
if event.button() == Qt.LeftButton:

self.origin = event.pos()
self.rubberBand.setGeometry(QRect(self.origin, QSize()))
self.rectChanged.emit(self.rubberBand.geometry())
self.rubberBand.show()
self.changeRubberBand = True
return
#QGraphicsView.mousePressEvent(self,event)
elif event.button() == Qt.MidButton:
self.viewport().setCursor(Qt.ClosedHandCursor)
self.original_event = event
handmade_event = QMouseEvent(QEvent.MouseButtonPress,QPointF(event.pos()),Qt.LeftButton,event.buttons(),Qt.KeyboardModifiers())
QGraphicsView.mousePressEvent(self,handmade_event)

super(Viewer, self).mousePressEvent(event)

def mouseReleaseEvent(self, event):
if event.button() == Qt.LeftButton:
self.changeRubberBand = False
QGraphicsView.mouseReleaseEvent(self,event)
elif event.button() == Qt.MidButton:
self.viewport().setCursor(Qt.OpenHandCursor)
handmade_event = QMouseEvent(QEvent.MouseButtonRelease,QPointF(event.pos()),Qt.LeftButton,event.buttons(),Qt.KeyboardModifiers())
QGraphicsView.mouseReleaseEvent(self,handmade_event)
super(Viewer, self).mouseReleaseEvent(event)

def mouseMoveEvent(self, event):
if self.changeRubberBand:
self.rubberBand.setGeometry(QRect(self.origin, event.pos()).normalized())
self.rectChanged.emit(self.rubberBand.geometry())
QGraphicsView.mouseMoveEvent(self,event)
super(Viewer, self).mouseMoveEvent(event)

class Window(QWidget):
def __init__(self):
super(Window, self).__init__()
self.viewer = Viewer(self)
self.btnLoad = QToolButton(self)
self.btnLoad.setText('Fit Into View')
self.btnLoad.clicked.connect(self.fitPoints)

VBlayout = QVBoxLayout(self)
VBlayout.addWidget(self.viewer)
HBlayout = QHBoxLayout()
HBlayout.setAlignment(Qt.AlignLeft)
HBlayout.addWidget(self.btnLoad)

VBlayout.addLayout(HBlayout)
self.viewer.fitInView()

def fitPoints(self):
self.viewer.fitInView()

if __name__ == '__main__':
import sys
app = QApplication(sys.argv)
window = Window()
window.setGeometry(500, 300, 800, 600)
window.show()
sys.exit(app.exec_())

在 QGraphicsView 显示之前的瞬间，内部元素被重新计算，以便您观察到不同的行为，因此解决方案是在显示后立即应用该函数。为此，至少有 2 个选项：

1。 QTimer.singleShot(0, ...):

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# ...
self.setPoints()
QTimer.singleShot(0, self.fitInView)
# ...

1。覆盖 Viewer

的 showEvent 方法

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def showEvent(self, event):
self.fitInView()
super(Viewer, self).showEvent(event)