Question

我想用QPainter画一些线，然后将线的开始(x1,y1)坐标移到centerpoint上，而另一些想从中心偏移的线。这些线应基于椭圆值或其他值以编程方式运行。我尝试了各种方法来解决此问题，但是没有用。

QRect可以使用

之类的代码

moveCenter, moveTopLeft, etc...

但是对于Qline，没有这样的方法。根据 PyQt文档，可以由此绘制一条线：

QLine(int x1, int y1, int x2, int y2)
QLine(const QPoint &p1, const QPoint &p2)

也许应该使用此行来抵消它。但是没有知识去做。

translated(const QPoint &offset)

另一方面，我们想绘制一些文本并以与Qline类似的方式来补偿它们。

看看下面的数字，看看我到底想做什么？

可视化

到目前为止我所取得的成就。

我想实现的目标。

代码：

import sys
from PyQt5 import QtCore, QtGui, QtWidgets

class Foo(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super(Foo, self).__init__(parent)
        self.setGeometry(QtCore.QRect(200, 100, 700, 600))        
        self.paint = Paint()
        self.sizeHint()
        self.lay = QtWidgets.QVBoxLayout()
        self.lay.addWidget(self.paint)
        self.setLayout(self.lay)

class Paint(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super(Paint, self).__init__(parent)
        self.setBackgroundRole(QtGui.QPalette.Base)     
        self.setAutoFillBackground(True)

        xl = self.rect().center().x()
        yl = self.rect().center().y()

        self.e = QtCore.QRect(QtCore.QPoint(), QtCore.QSize(250, 250))
        self.l = QtCore.QLine(QtCore.QPoint(xl, yl) , QtCore.QPoint(self.width(), self.height()/2))



    def paintEvent(self, event):
        pen = QtGui.QPen()
        brush = QtGui.QBrush( QtCore.Qt.darkCyan, QtCore.Qt.Dense7Pattern)
        painter = QtGui.QPainter(self)
        painter.setBrush(brush)
        painter.setPen(pen)
        painter.setRenderHint(QtGui.QPainter.Antialiasing)

        self.e.moveCenter(self.rect().center())

        painter.drawEllipse(self.e)
        painter.drawLine(self.l)
#        painter.drawText('D')

if __name__ == '__main__':
    app = QtWidgets.QApplication(sys.argv)
    w = Foo()
    w.show()
    sys.exit(app.exec_())

更新问题：

我已经更新了代码，我设法画出我想要的东西。但是还有另一个挑战。您可以在下图看到。

代码运行并显示时

当Widget最小化或最大化时，某些行消失了吗？

更新代码：

import sys
from PyQt5 import QtCore, QtGui, QtWidgets

class Foo(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super(Foo, self).__init__(parent)
        self.setGeometry(QtCore.QRect(200, 100, 700, 600))        
        self.paint = Paint()
        self.sizeHint()
        self.lay = QtWidgets.QVBoxLayout()
        self.lay.addWidget(self.paint)
        self.setLayout(self.lay)

class Paint(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super(Paint, self).__init__(parent)
        self.setBackgroundRole(QtGui.QPalette.Base)     
        self.setAutoFillBackground(True)


        self.e = QtCore.QRect(QtCore.QPoint(), QtCore.QSize(250, 250))
        self.l1 = QtCore.QLine(QtCore.QPoint(), QtCore.QPoint(200, 0))
        self.l2 = QtCore.QLine(QtCore.QPoint(), QtCore.QPoint(0, -200))

        self.vl = QtCore.QLine(QtCore.QPoint(), QtCore.QPoint(0, -125))
        delta = QtCore.QPoint(20, 0)
        self.hl = QtCore.QLine(-delta, self.e.topRight() + delta)
        self.al = QtCore.QLine(QtCore.QPoint(), QtCore.QPoint(-20, -20))
        self.a2 = QtCore.QLine(QtCore.QPoint(), QtCore.QPoint(-20, 20))
        self.a3 = QtCore.QLine(QtCore.QPoint(), QtCore.QPoint(20, 20))
        self.a4 = QtCore.QLine(QtCore.QPoint(), QtCore.QPoint(-20, 20))
        self._factor = 1.0

    def paintEvent(self, event):
        pen = QtGui.QPen()
        brush = QtGui.QBrush( QtCore.Qt.darkCyan, QtCore.Qt.Dense7Pattern)
        painter = QtGui.QPainter(self)
        painter.setBrush(brush)
        painter.setPen(pen)
        painter.setRenderHint(QtGui.QPainter.Antialiasing)

        self.e.moveCenter(self.rect().center())
        self.l1.translate(self.rect().center() - self.l1.p1())
        self.l2.translate(self.rect().center() - self.l2.p1())

        self.al.translate(self.l1.p2())
        self.a2.translate(self.l1.p2())

        painter.translate(self.rect().center())
        painter.scale(self._factor, self._factor)
        painter.translate(-self.rect().center())

        painter.drawEllipse(self.e)
        painter.drawLine(self.l1)
        painter.drawLine(self.l2)

        fnt = painter.font() 
        fnt.setPointSize(20) 
        painter.setFont(fnt) 
        h = QtGui.QFontMetrics(painter.font()).height() 
        p = QtCore.QPoint(self.rect().center().x(), self.e.top() - 3*h) 
        u = QtCore.QPoint(self.e.right() + 3*h, self.rect().center().y()) 
        painter.drawText(p, "y")
        painter.drawText(u, "x")

        r = QtCore.QRect(QtCore.QPoint(self.e.x(), self.e.bottom()), QtCore.QSize(self.e.width(), h)) 
        painter.drawText(r, QtCore.Qt.AlignCenter, "D = 350mm")
        offset = QtCore.QPoint(0, 1.5*h)

        self.vl.translate(self.e.bottomLeft() - self.vl.p1() + offset)
        painter.drawLine(self.vl)
        self.vl.translate(self.e.width(), 0)
        painter.drawLine(self.vl)
        self.hl.translate(self.e.bottomLeft() +  offset - QtCore.QPoint(0, 0.4*h))

        self.a3.translate(self.l2.p2())
        self.a4.translate(self.l2.p2())

        painter.drawLine(self.hl)
        painter.drawLine(self.al)
        painter.drawLine(self.a2)
        painter.drawLine(self.a3)
        painter.drawLine(self.a4)       


    def wheelEvent(self, event):
        self._factor *= 1.01**(event.angleDelta().y()/15.0)
        self.update()
        super(Paint, self).wheelEvent(event)

if __name__ == '__main__':
    app = QtWidgets.QApplication(sys.argv)
    w = Foo()
    w.show()
    sys.exit(app.exec_())

我不知道为什么会这样？任何意见或帮助，我非常感谢。

Answer 1

Qt不知道小部件开始时的大小，因此self.rect()将具有任何大小，例如在我的测试self.rect()中的__init__中返回PyQt5.QtCore.QRect(0, 0, 640, 480)，但是在paintEvent()中返回PyQt5.QtCore.QRect(0, 0, 678, 578)，这就是计算不正确的原因。

解决方案是使用translate()移动行（不要使用translated()，因为这会创建新的QLine，而这正是我所不希望的）

import sys
from PyQt5 import QtCore, QtGui, QtWidgets

class Foo(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super(Foo, self).__init__(parent)
        self.setGeometry(QtCore.QRect(200, 100, 700, 600))        
        self.paint = Paint()
        self.sizeHint()
        self.lay = QtWidgets.QVBoxLayout()
        self.lay.addWidget(self.paint)
        self.setLayout(self.lay)

class Paint(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super(Paint, self).__init__(parent)
        self.setBackgroundRole(QtGui.QPalette.Base)     
        self.setAutoFillBackground(True)

        self.e = QtCore.QRect(QtCore.QPoint(), QtCore.QSize(250, 250))
        self.l1 = QtCore.QLine(QtCore.QPoint(), QtCore.QPoint(200, 0))
        self.l2 = QtCore.QLine(QtCore.QPoint(), QtCore.QPoint(0, -200))

    def paintEvent(self, event):
        pen = QtGui.QPen()
        brush = QtGui.QBrush( QtCore.Qt.darkCyan, QtCore.Qt.Dense7Pattern)
        painter = QtGui.QPainter(self)
        painter.setBrush(brush)
        painter.setPen(pen)
        painter.setRenderHint(QtGui.QPainter.Antialiasing)

        self.e.moveCenter(self.rect().center())
        self.l1.translate(self.rect().center() - self.l1.p1())
        self.l2.translate(self.rect().center() - self.l2.p1())
        painter.drawEllipse(self.e)
        painter.drawLine(self.l1)
        painter.drawLine(self.l2)

if __name__ == '__main__':
    app = QtWidgets.QApplication(sys.argv)
    w = Foo()
    w.show()
    sys.exit(app.exec_())

更新：

class Paint(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super(Paint, self).__init__(parent)
        self.setBackgroundRole(QtGui.QPalette.Base)     
        self.setAutoFillBackground(True)

        self.e = QtCore.QRect(QtCore.QPoint(), QtCore.QSize(250, 250))
        self.l1 = QtCore.QLine(QtCore.QPoint(), QtCore.QPoint(200, 0))
        self.l2 = QtCore.QLine(QtCore.QPoint(), QtCore.QPoint(0, -200))

        self.vl = QtCore.QLine(QtCore.QPoint(), QtCore.QPoint(0, -125))
        delta = QtCore.QPoint(20, 0)
        self.hl = QtCore.QLine(-delta, self.e.topRight() + delta)

    def paintEvent(self, event):
        pen = QtGui.QPen()
        brush = QtGui.QBrush( QtCore.Qt.darkCyan, QtCore.Qt.Dense7Pattern)
        painter = QtGui.QPainter(self)
        painter.setBrush(brush)
        painter.setPen(pen)
        painter.setRenderHint(QtGui.QPainter.Antialiasing)

        self.e.moveCenter(self.rect().center())
        self.l1.translate(self.rect().center() - self.l1.p1())
        self.l2.translate(self.rect().center() - self.l2.p1())

        painter.drawEllipse(self.e)
        painter.drawLine(self.l1)
        painter.drawLine(self.l2)

        fnt = painter.font() 
        fnt.setPointSize(25) 
        painter.setFont(fnt) 
        h = QtGui.QFontMetrics(painter.font()).height() 
        p = QtCore.QPoint(self.rect().center().x(), self.e.bottom() + 0.8*h)

        r = QtCore.QRect(QtCore.QPoint(self.e.x(), self.e.bottom()), QtCore.QSize(self.e.width(), h)) 
        painter.drawText(r, QtCore.Qt.AlignCenter, "D")
        offset = QtCore.QPoint(0, 1.5*h)

        self.vl.translate(self.e.bottomLeft() - self.vl.p1() + offset)
        painter.drawLine(self.vl)
        self.vl.translate(self.e.width(), 0)
        painter.drawLine(self.vl)
        self.hl.translate(self.e.bottomLeft() +  offset - QtCore.QPoint(0, 20))
        painter.drawLine(self.hl)

QPaint绘制具有偏移的线

1 个答案: