# -*- coding: utf-8 -*-

"""

This example shows how to insert text into a scene using TextItem. This class 

is for displaying text that is anchored to a particular location in the data

coordinate system, but which is always displayed unscaled. 

For text that scales with the data, use QTextItem. 

For text that can be placed in a layout, use LabelItem.

"""

 ## Add path to library (just for examples; you do not need this)

import pyqtgraph as pg

from pyqtgraph.Qt import QtCore, QtGui

import numpy as np

x = np.linspace(-20, 20, 1000)

y = np.sin(x) / x

plot = pg.plot()   ## create an empty plot widget

plot.setYRange(-1, 2)

plot.setWindowTitle('pyqtgraph example: text')

curve = plot.plot(x,y)  ## add a single curve

## Create text object, use HTML tags to specify color/size

text = pg.TextItem(html='<div style="text-align: center"><span style="color: #FFF;">This is the</span><br><span style="color: #FF0; font-size: 16pt;">PEAK</span></div>', anchor=(-0.3,0.5), angle=45, border='w', fill=(0, 0, 255, 100))

plot.addItem(text)

text.setPos(0, y.max())

## Draw an arrowhead next to the text box

arrow = pg.ArrowItem(pos=(0, y.max()), angle=-45)

plot.addItem(arrow)

## Set up an animated arrow and text that track the curve

curvePoint = pg.CurvePoint(curve)

plot.addItem(curvePoint)

text2 = pg.TextItem("test", anchor=(0.5, -1.0))

text2.setParentItem(curvePoint)

arrow2 = pg.ArrowItem(angle=90)

arrow2.setParentItem(curvePoint)

## update position every 10ms

index = 0

def update():

    global curvePoint, index

    index = (index + 1) % len(x)

    print(float(index)/(len(x)-1))

    curvePoint.setPos(float(index)/(len(x)-1))

    text2.setText('[%0.1f, %0.1f]' % (x[index], y[index]))

timer = QtCore.QTimer()

timer.timeout.connect(update)

timer.start(10)

## Start Qt event loop unless running in interactive mode or using pyside.

if __name__ == '__main__':

    import sys

    if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):

        QtGui.QApplication.instance().exec_()