Hi,
I don't know exactly why that would be happening, but seems like a rounding
error somewhere. Your bounding box function is returning a y-axis range of
0 to 1 (which I assume is from the minimum size of the picture object
maybe?) even though the data is a million times smaller than that.
If I change the bounding box method to:
# import numpy as np
def boundingRect(self):
data = np.array(self.data)
xmin = data[:,0].min()
xmax = data[:,0].max()
ymin = data[:,1:].min()
ymax = data[:,1:].max()
return QtCore.QRectF(xmin, ymin, xmax-xmin, ymax-ymin)
then it seems to work better.
Also needed to change this for python3:
request_data = json.loads(data.decode('utf8'))
Patrick
On Monday, 29 April 2019 04:23:40 UTC+9:30, [email protected] wrote:
>
> I use pyqtgraph to draw the candles, but if I zoom graph very much, image
> hide.
>
> I noticed that when zoom very much, “paint” method stops being called.
> Code with http request to exchange below.
>
> import pyqtgraph as pgfrom pyqtgraph import QtCore, QtGuifrom PyQt5 import
> QtWidgets
> class CandlestickItem(QtWidgets.QGraphicsRectItem):
> def __init__(self, data):
> super(CandlestickItem, self).__init__()
> self.data = data
> self.generatePicture()
>
> def generatePicture(self):
> 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:
> if max != min:
> 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):
> print('paint call')
> p.drawPicture(0, 0, self.picture)
>
> def boundingRect(self):
> return QtCore.QRectF(self.picture.boundingRect())
>
> if __name__ == '__main__':
> import sys
> import urllib.request
> import json
>
> get_symbols_url =
> 'https://api.hitbtc.com/api/2/public/candles/BCNBTC?period=M30&limit=1000'
> response = urllib.request.urlopen(get_symbols_url)
> request_data = json.loads(response.read())
> data_list = []
> for i in range(0, len(request_data)):
> data_list.append((float(i), float(request_data[i]['open']),
> float(request_data[i]['close']),
> float(request_data[i]['min']),
> float(request_data[i]['max'])))
>
> item = CandlestickItem(data_list)
> plt = pg.plot()
> plt.addItem(item)
>
> if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
> QtGui.QApplication.instance().exec_()
>
> I need to display very small values, for example, 0.0000001-0.00000015.
> What can I do to prevent image hidden at high zoom?
>
>
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