如何解决如何在PyQt5 Python中显示QDial上的标记
我正在qt-desginer
中设计一个用户界面,在其中添加了dial
。如下图所示:
它没有任何标记。是否可以添加一些标记以更好地理解它。如下所示:
解决方法
不幸的是,QDial是一个从未真正关心过的小部件,主要是因为它很少使用,而且还因为许多功能需求可能会以不一致的方式改变其行为。无论如何,Designer都无法做到这一点。
可以通过对QDial进行子类化并在设计器中进行推广来部分完成 ,但是最终您会在 槽口或表盘本身上绘制数字,这将看起来很丑。
为了实现所需的功能,您需要使用包含表盘 的自定义小部件,并最终升级那个小部件,但是您将无法在Designer中查看它或设置其属性(除非您创建Designer插件,这不是一件容易的事)。这是通过设置容器布局边距来实现的,以便始终有足够的空间将值显示为文本。
这是可能的实现。出于显而易见的原因,请考虑一下,如果您的值范围较大且表盘较小,则数字将重叠。
class ValueDial(QtWidgets.QWidget):
_dialProperties = ('minimum','maximum','value','singleStep','pageStep','notchesVisible','tracking','wrapping','invertedAppearance','invertedControls','orientation')
_inPadding = 3
_outPadding = 2
valueChanged = QtCore.pyqtSignal(int)
def __init__(self,*args,**kwargs):
# remove properties used as keyword arguments for the dial
dialArgs = {k:v for k,v in kwargs.items() if k in self._dialProperties}
for k in dialArgs.keys():
kwargs.pop(k)
super().__init__(*args,**kwargs)
layout = QtWidgets.QVBoxLayout(self)
self.dial = QtWidgets.QDial(self,**dialArgs)
layout.addWidget(self.dial)
self.dial.valueChanged.connect(self.valueChanged)
# make the dial the focus proxy (so that it captures focus *and* key events)
self.setFocusProxy(self.dial)
# simple "monkey patching" to access dial functions
self.value = self.dial.value
self.setValue = self.dial.setValue
self.minimum = self.dial.minimum
self.maximum = self.dial.maximum
self.wrapping = self.dial.wrapping
self.notchesVisible = self.dial.notchesVisible
self.setNotchesVisible = self.dial.setNotchesVisible
self.setNotchTarget = self.dial.setNotchTarget
self.notchSize = self.dial.notchSize
self.invertedAppearance = self.dial.invertedAppearance
self.setInvertedAppearance = self.dial.setInvertedAppearance
self.updateSize()
def inPadding(self):
return self._inPadding
def setInPadding(self,padding):
self._inPadding = max(0,padding)
self.updateSize()
def outPadding(self):
return self._outPadding
def setOutPadding(self,padding):
self._outPadding = max(0,padding)
self.updateSize()
# the following functions are required to correctly update the layout
def setMinimum(self,minimum):
self.dial.setMinimum(minimum)
self.updateSize()
def setMaximum(self,maximum):
self.dial.setMaximum(maximum)
self.updateSize()
def setWrapping(self,wrapping):
self.dial.setWrapping(wrapping)
self.updateSize()
def updateSize(self):
# a function that sets the margins to ensure that the value strings always
# have enough space
fm = self.fontMetrics()
minWidth = max(fm.width(str(v)) for v in range(self.minimum(),self.maximum() + 1))
self.offset = max(minWidth,fm.height()) / 2
margin = self.offset + self._inPadding + self._outPadding
self.layout().setContentsMargins(margin,margin,margin)
def translateMouseEvent(self,event):
# a helper function to translate mouse events to the dial
return QtGui.QMouseEvent(event.type(),self.dial.mapFrom(self,event.pos()),event.button(),event.buttons(),event.modifiers())
def changeEvent(self,event):
if event.type() == QtCore.QEvent.FontChange:
self.updateSize()
def mousePressEvent(self,event):
self.dial.mousePressEvent(self.translateMouseEvent(event))
def mouseMoveEvent(self,event):
self.dial.mouseMoveEvent(self.translateMouseEvent(event))
def mouseReleaseEvent(self,event):
self.dial.mouseReleaseEvent(self.translateMouseEvent(event))
def paintEvent(self,event):
radius = min(self.width(),self.height()) / 2
radius -= (self.offset / 2 + self._outPadding)
invert = -1 if self.invertedAppearance() else 1
if self.wrapping():
angleRange = 360
startAngle = 270
rangeOffset = 0
else:
angleRange = 300
startAngle = 240 if invert > 0 else 300
rangeOffset = 1
fm = self.fontMetrics()
# a reference line used for the target of the text rectangle
reference = QtCore.QLineF.fromPolar(radius,0).translated(self.rect().center())
fullRange = self.maximum() - self.minimum()
textRect = QtCore.QRect()
qp = QtGui.QPainter(self)
qp.setRenderHints(qp.Antialiasing)
for p in range(0,fullRange + rangeOffset,self.notchSize()):
value = self.minimum() + p
if invert < 0:
value -= 1
if value < self.minimum():
continue
angle = p / fullRange * angleRange * invert
reference.setAngle(startAngle - angle)
textRect.setSize(fm.size(QtCore.Qt.TextSingleLine,str(value)))
textRect.moveCenter(reference.p2().toPoint())
qp.drawText(textRect,QtCore.Qt.AlignCenter,str(value))
if __name__ == '__main__':
import sys
app = QtWidgets.QApplication(sys.argv)
dial = ValueDial(minimum=1,maximum=11)
dial.setNotchesVisible(True)
dial.show()
sys.exit(app.exec_())
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