我正在尝试获取一个蓝色和绿色 QPolygons 的交集,并计算这个交集在蓝色 QPolygon 中所占的百分比(见下图)。
我已按以下方式创建多边形:
import PyQt5
from PyQt5 import QtWidgets,QtGui,QtCore
from PyQt5.QtWidgets import *
from PyQt5.QtGui import *
from PyQt5.QtCore import *
import sys, math
class MyWidget(QtWidgets.QWidget):
def __init__(self, parent=None):
QtWidgets.QWidget.__init__(self, parent)
self.pen1 = QtGui.QPen(QtGui.QColor(20,0,250)) # set lineColor
self.pen = QtGui.QPen(QtGui.QColor(0,0,0)) # set lineColor
self.pen2 = QtGui.QPen(QtGui.QColor(0,250,0)) # set lineColor
self.pen.setWidth(3) # set lineWidth
self.brush = QtGui.QBrush(QtGui.QColor(255,255,255,10)) # set fillColor
coords = [PyQt5.QtCore.QPointF(640.0, 334.0), PyQt5.QtCore.QPointF(626.0, 462.0), PyQt5.QtCore.QPointF(782.0, 509.0), PyQt5.QtCore.QPointF(807.0, 373.0), PyQt5.QtCore.QPointF(807.0, 333.0)]
greenpolygoncoords = [PyQt5.QtCore.QPointF(698.0, 373.0), PyQt5.QtCore.QPointF(690.0, 433.0), PyQt5.QtCore.QPointF(757.0, 376.0), PyQt5.QtCore.QPointF(713.0, 351.0), PyQt5.QtCore.QPointF(713.0, 351.0), PyQt5.QtCore.QPointF(698.0, 373.0)]
self.bluepolygon = QPolygonF(coords)
self.greenpolygon =QPolygonF(greenpolygoncoords)
self.intersection = self.bluepolygon.intersected(self.greenpolygon)
print("overlap = "+str(self.intersection.size()/self.bluepolygon.size()))
def paintEvent(self, event):
painter = QtGui.QPainter(self)
painter.setPen(self.pen1)
painter.setBrush(self.brush)
painter.drawPolygon(self.bluepolygon) #bluepolygon = Blue
painter.setPen(self.pen)
painter.drawPolygon(self.intersection) #Intersection = black
painter.setPen(self.pen2)
painter.drawPolygon(self.greenpolygon) # greenpolygon = Green
app = QtWidgets.QApplication(sys.argv)
widget = MyWidget()
widget.show()
sys.exit(app.exec_())
然而,当我尝试计算两个多边形之间的重叠部分占蓝色多边形的百分比时,我得到了错误的答案(它显示重叠部分等于1,但是绿色多边形明显并没有占据蓝色多边形的100%)。
overlap = self.intersection.size()/self.bluepolygon.size()
当查看由QPolygon.size()计算出的大小时,很明显QPolygon.size()返回了多边形的错误大小。
print("size of blue polygon = "+str(self.bluepolygon.size()))
print("size of greenpolygon = "+str(self.greenpolygon.size()))
print("size of intersection = "+str(self.intersection.size()))
返回值:
size of blue polygon = 5
size of greenpolygon = 6
size of intersection = 5
显然,由于某种原因,在PyQt5中,蓝色多边形比绿色多边形小。这是怎么回事?
我做错了什么?
QPolygonF.size()
返回边数(或顶点数)的原因是它实际上是一个QVector<QPointF>
加上一些方法。 - olepinto