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目录

前置：

代码

演示

视频

---

前置：

1 pyqtgraph默认的缩放功能经常让K线不消失在可视区域，与通达信等软件的缩放体验差别巨大

2 pyqtgraph的缩放策略是以鼠标所在位置为中心进行x轴和y轴的缩放。当鼠标所在位置偏离K线主体很远时，K线主体经常消失，或者K线显示不全

3 修改思想，不管放大还是缩小，计算缩放后K线主体的x轴y轴范围，将缩放后的可视区域设置为缩放后K线主体的x轴和y轴范围，这样就能保证可视区域内总是完整的K线图。

4 在 pyqtgraph 里面，鼠标滚轮事件wheelEvent有一个delta可以表征滚轮的向上和向下
向上，放大，delta大于1，显示的内容减少（显示的K线个数减少）
向下，缩小，delta小于1，显示的内容增多（显示的K线个数增多）
根据以上逻辑，重写pg.PlotWidget()里面的wheelEvent

代码

from PyQt6.QtCore import (
QSize
)
from PyQt6.QtWidgets import (
QApplication,
QMainWindow,
QVBoxLayout,
QWidget
)
import pyqtgraph as pg
from pyqtgraph import QtCore, QtGui
import pandas as pd
import numpy as np## Create a subclass of GraphicsObject.
## The only required methods are paint() and boundingRect()
## (see QGraphicsItem documentation)
class CandlestickItem(pg.GraphicsObject):def __init__(self, data):pg.GraphicsObject.__init__(self)self.data = data  ## data must have fields: time, open, close, min, maxself.generatePicture()def generatePicture(self):## pre-computing a QPicture object allows paint() to run much more quickly,## rather than re-drawing the shapes every time.self.picture = QtGui.QPicture()p = QtGui.QPainter(self.picture)p.setPen(pg.mkPen('w'))w = (self.data[1][0] - self.data[0][0]) / 3.for (t, open, close, min, max) in self.data:p.drawLine(QtCore.QPointF(t, min), QtCore.QPointF(t, max))if open > close:p.setBrush(pg.mkBrush('r'))else:p.setBrush(pg.mkBrush('g'))p.drawRect(QtCore.QRectF(t - w, open, w * 2, close - open))p.end()def paint(self, p, *args):p.drawPicture(0, 0, self.picture)def boundingRect(self):## boundingRect _must_ indicate the entire area that will be drawn on## or else we will get artifacts and possibly crashing.## (in this case, QPicture does all the work of computing the bouning rect for us)return QtCore.QRectF(self.picture.boundingRect())class StrAxisItem(pg.AxisItem):def __init__(self,ticks,*args,**kwargs):pg.AxisItem.__init__(self,*args,**kwargs)self.x_values = [x[0] for x in ticks]self.x_strings = [x[1] for x in ticks]passdef tickStrings(self, values, scale, spacing):strings = []for v in values:vs = v*scaleif vs in self.x_values:vstr = self.x_strings[self.x_values.index(vs)]else:vstr = ''strings.append(vstr)return stringsclass KPlotWidget(pg.PlotWidget):def __init__(self,*args,**kwargs):super().__init__(*args,**kwargs)self.df_data:pd.DataFrame = pd.DataFrame()passdef setDfData(self,data:pd.DataFrame):self.df_data = datapassdef wheelEvent(self, ev):if len(self.df_data) <= 0:super().wheelEvent(ev)else:delta = ev.angleDelta().x()if delta == 0:delta = ev.angleDelta().y()s = 1.001 ** deltabefore_xmin, before_xmax = self.viewRange()[0]val_x = self.getViewBox().mapSceneToView(ev.position()).x()after_xmin = val_x - (val_x - before_xmin) // safter_xmax = val_x + (before_xmax - val_x) // sif after_xmin < 0:after_xmin = 0if after_xmax >= len(self.df_data):after_xmax = len(self.df_data) - 1df00 = self.df_data.loc[(self.df_data['a00'] >= after_xmin) & (self.df_data['a00'] <= after_xmax)].copy()after_ymin = df00['lowestPrice'].min()after_ymax = df00['highestPrice'].max()self.setXRange(after_xmin, after_xmax)self.setYRange(after_ymin, after_ymax)passclass MainWindow(QMainWindow):def __init__(self):super().__init__()self.setWindowTitle('pyqtgragh实例')self.setMinimumSize(QSize(800,600))self.pw = KPlotWidget()self.pw.setMouseEnabled(x=True,y=True)layout = QVBoxLayout()layout.addWidget(self.pw)widget = QWidget()widget.setLayout(layout)self.setCentralWidget(widget)self.open_init()passdef open_init(self):df = pd.read_excel(r'E:/temp003/600584_adj.xlsx',engine='openpyxl')df = df.loc[df['turnoverValue']!=0].copy()df['a00'] = np.arange(0,len(df))data = df.loc[:,['a00','openPrice','closePrice','lowestPrice','highestPrice']].valuesitem = CandlestickItem(data)# ticks = [(i,j) for i,j in zip(df['a00'].to_list(),df['tradeDate'].to_list())]# print(ticks)ticks = df.loc[:,['a00','tradeDate']].valueshorAxis = StrAxisItem(ticks=ticks,orientation='bottom')# text_item = pg.TextItem(angle=-45,#                         html='<div style="transform: rotate(-45deg)">X Axis Label</div>')  # 创建文本项并设置旋转角度# horAxis.setLabel(text=text_item, angle=0)self.pw.setAxisItems({'bottom':horAxis})self.pw.addItem(item)self.pw.setDfData(df)passif __name__ == '__main__':app = QApplication([])mw = MainWindow()mw.show()app.exec()pass

演示

视频

PyQt6基础_pyqtgraph_k线图缩放_哔哩哔哩_bilibili