在 PyQtGraph 上放大/缩小时从 PyQt 更新滑块

Question

我想将 PyQtGraph 鼠标滚轮缩放功能连接到 QSlider 小部件。所以当我放大/缩小图表时，我会得到视图框的范围，滑块窗口应该在滑动范围内。在这个 PyQtGraph 示例中可以找到最接近的示例：http://www.pyqtgraph.org/downloads/0.10.0/pyqtgraph-0.10.0-deb/pyqtgraph-0.10.0/examples/crosshair.py

所以我想以某种方式连接以下定义。

def update_plot(self):
    self.axX = self.p6.getAxis('bottom')
    self.xmin = self.axX.range[0]
    self.xmax = self.axX.range[0]
    print(self.axX.range)
    return xmin, xmax

def update_slider(self, xmin, xmax):
    self.size = self.w1.slider.value()
    self.p6.setXRange(self.xmin+self.size,self.xmax+self.size)
    print(self.size)

但是，我似乎无法让它工作。我在下面附上了我的示例的完整代码。你能帮我什么忙吗？

import sys
from PyQt5.QtCore import Qt
from PyQt5.QtWidgets import QApplication, QHBoxLayout, QLabel, QSizePolicy, QSlider, QSpacerItem, \
    QVBoxLayout, QWidget

import pyqtgraph as pg
import numpy as np


class Slider(QWidget):
    def __init__(self, minimum, maximum, parent=None):
        super(Slider, self).__init__(parent=parent)
        self.verticalLayout = QVBoxLayout(self)
        self.label = QLabel(self)
        self.verticalLayout.addWidget(self.label)
        self.horizontalLayout = QHBoxLayout()
        spacerItem = QSpacerItem(0, 20, QSizePolicy.Expanding, QSizePolicy.Minimum)
        self.horizontalLayout.addItem(spacerItem)
        self.slider = QSlider(self)
        self.slider.setOrientation(Qt.Vertical)
        self.horizontalLayout.addWidget(self.slider)
        spacerItem1 = QSpacerItem(0, 20, QSizePolicy.Expanding, QSizePolicy.Minimum)
        self.horizontalLayout.addItem(spacerItem1)
        self.verticalLayout.addLayout(self.horizontalLayout)
        self.resize(self.sizeHint())

        self.minimum = minimum
        self.maximum = maximum
        self.slider.valueChanged.connect(self.setLabelValue)
        self.x = None
        self.setLabelValue(self.slider.value())

    def setLabelValue(self, value):
        self.x = self.minimum + (float(value) / (self.slider.maximum() - self.slider.minimum())) * (
        self.maximum - self.minimum)
        self.label.setText("{0:.4g}".format(self.x))

class Widget(QWidget):
    def __init__(self, parent=None):
        super(Widget, self).__init__(parent=parent)
        self.horizontalLayout = QHBoxLayout(self)

        # plot (p6)
        self.win = pg.GraphicsWindow(title="Basic plotting examples")
        self.horizontalLayout.addWidget(self.win)
        self.p6 = self.win.addPlot(title="My Plot")
        x = np.arange(1e5)
        self.y1 = np.random.randn(x.size)
        self.p6.plot(self.y1, pen="r")
        self.p6.setMouseEnabled(x=True, y=False)
        self.p6.setXRange(0,300)
        self.p6.setLimits(xMin=0, xMax=len(self.y1))

        self.p6.sigRangeChanged.connect(self.update_plot)

        # slider (w1)
        self.w1 = Slider(0, len(self.y1))
        self.horizontalLayout.addWidget(self.w1)        
        self.w1.slider.setMinimum(0)
        self.w1.slider.setMaximum(len(self.y1))

        self.w1.slider.valueChanged.connect(self.update_slider)

    def update_plot(self):
        self.axX = self.p6.getAxis('bottom')
        self.xmin = self.axX.range[0]
        self.xmax = self.axX.range[0]
        print(self.axX.range)
        return self.xmin, self.xmax


    def update_slider(self, xmin, xmax):
        self.size = self.w1.slider.value()
        self.p6.setXRange(self.xmin+self.size,self.xmax+self.size)
        print(self.size)



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

Answer 1

首先，您首先提出的问题实际上对 StackOverflow 的“行为”更有用。编辑后，您只是从 pyqtgraph 示例中留下了 useless 纯副本/粘贴。

不要那样做。

人们很少进行编辑，并且看到您问题的当前状态，他们会认为您根本没有为解决您的问题付出任何努力（导致他们只是忽略你的问题）。我建议您撤消您的编辑，或者至少恢复原始问题示例代码。

---

您的问题的主要问题是缩放不是线性。从普通用户的角度来看，缩放滑块的每一步都应该增加或减少一个缩放因子（实际上，pyqtgraph 就是这样做的）。

滑块通常是一个线性界面，这意味着它的每一步都应该与其上一步或下一步成比例。
简而言之，如果滑块的“中间步骤”等于图像的原始尺寸，并且“下一步”等于双倍尺寸，则用户期望接下来的步骤将导致再次将尺寸翻倍。很明显，同样的情况也适用。

将它想象成一个旋转框，甚至是几个+/- 按钮。

    size = 2
    print(size)
Out[1]: 2

    def doZoom(size, step):
        zoomFactor = 2
        if step > 0:
            size *= zoomFactor
        else:
            size /= zoomFactor
        return size

    size = doZoom(size, +1)
    print(size)
Out[2]: 4

    size = doZoom(size, +1)
    print(size)
Out[3]: 8

    size = doZoom(size, -1)
    print(size)
Out[4]: 4

一个可能的解决方案是实现一个考虑所有这些的滑块。

import sys
from math import log
from PyQt5.QtCore import Qt
from PyQt5.QtWidgets import (QApplication, QLabel, QSlider, QWidget, 
    QHBoxLayout, QVBoxLayout)

import pyqtgraph as pg
import numpy as np

class LabelSlider(QWidget):
    def __init__(self, *args, **kwargs):
        super(LabelSlider, self).__init__(*args, **kwargs)
        layout = QVBoxLayout(self)
        # IMPORTANT! QStyles sometimes create *huge* margins (6-10 pixels) around
        # layout contents; we don't really need those in here
        layout.setContentsMargins(0, 0, 0, 0)

        self.label = QLabel()
        layout.addWidget(self.label, alignment=Qt.AlignHCenter)
        # use an arbitrary text for the minimum width to minimize size flickering
        # on value changes
        self.label.setMinimumWidth(self.fontMetrics().width("8.8888e+88"))
        self.label.setAlignment(Qt.AlignCenter)

        layout.addSpacing(10)

        self.slider = QSlider()
        # when adding a QSlider to a QLayout and specifying an alignment, the
        # opposite of the orientation *has* to be omitted to ensure that it's
        # centered in the other direction
        layout.addWidget(self.slider, alignment=Qt.AlignHCenter)
        # set the slider "transparent" for mouse events, so that the user will
        # still see it as enabled but won't be able to interact with it
        self.slider.setAttribute(Qt.WA_TransparentForMouseEvents)

        #set a range high enough to limit rounding errors
        self.slider.setMaximum(100000)

        # expose the basic slider signal/methods for transparency, so that
        # this LabelSlider will have a similar interface to that of a QSlider
        self.value = self.slider.value
        self.valueChanged = self.slider.valueChanged

    def setValue(self, value, xLimit):
        sliderValue = self.slider.maximum() - value * self.slider.maximum()
        self.slider.setValue(sliderValue)

        xLimitMin, xLimitMax = xLimit
        limitRange = xLimitMax - xLimitMin
        floatValue = xLimitMin + (value * limitRange / (limitRange)) * (
            limitRange)
        self.label.setText("{0:.4g}".format(floatValue))
        # ensure that the widget is resized to fit the label contents too;
        # sizeHint will be called afterwards
        self.updateGeometry()

    def sizeHint(self):
        hint = super(LabelSlider, self).sizeHint()
        # adjust the minimum hint width to accomodate the label contents
        if hint.width() < self.label.width():
            hint.setWidth(self.label.width())
        return hint


class Widget(QWidget):
    def __init__(self, parent=None):
        super(Widget, self).__init__(parent=parent)
        self.horizontalLayout = QHBoxLayout(self)

        self.win = pg.GraphicsWindow(title="Basic plotting examples")
        self.horizontalLayout.addWidget(self.win)
        self.p6 = self.win.addPlot(title="My Plot")
        x = np.arange(1e5)
        self.y1 = np.random.randn(x.size)
        self.p6.plot(self.y1, pen="r")
        self.p6.setMouseEnabled(x=True, y=False)
        self.p6.setXRange(0,300)
        # set a minimum x range for the plot
        # this value *HAS* to be > 0
        self.p6.setLimits(xMin=0, xMax=len(self.y1), minXRange=1)

        self.p6.sigRangeChanged.connect(self.update_plot)

        self.slider = LabelSlider()
        self.horizontalLayout.addWidget(self.slider)

    def update_plot(self):
        state = self.p6.getViewBox().state

        # get the limits of the plot's ViewBox
        limits = state["limits"]
        minZoom, maxZoom = xLimit = limits["xLimits"]
        xRangeMin, xRangeMax = limits["xRange"]

        # if the minimum x range is set, use that instead
        if xRangeMin is not None:
            minZoom = xRangeMin
        # ensure that the minimum x range is > 0
        minZoom = max(1, minZoom)
        if xRangeMax is not None:
            maxZoom = xRangeMax
        xMin, xMax = self.p6.getAxis("bottom").range
        diff = xMax - xMin

        # get the possible minimum and maximum values based on the wheel factor
        factor = abs(state["wheelScaleFactor"])
        minimum = log(maxZoom / 100000., factor)
        maximum = log(minZoom / 100000., factor)
        value = log(diff / 100000., factor)

        # adjust the factor to a 0.0-1.0 range according to the possible zoom
        realValue = (value - minimum) / (maximum - minimum)

        # set the slider value according to the above value
        self.slider.setValue(realValue, xLimit)


if __name__ == "__main__":
    app = QApplication(sys.argv)
    w = Widget()
    w.show()
    sys.exit(app.exec_())