import param
import numpy as np
import holoviews as hv
hv.extension('bokeh', 'matplotlib')

from holoviews import streams
listing = ', '.join(sorted([str(s.name) for s in param.descendents(streams.LinkedStream)]))
print('The linked stream classes supported by HoloViews are:\n\n{listing}'.format(listing=listing))

pointer = streams.PointerXY()
print(pointer.source)

print('The %s stream has contents %r' % (pointer, pointer.contents))

pointer_dmap = hv.DynamicMap(lambda x, y: hv.Points([(x, y)]), streams=[pointer])
print(pointer.source is pointer_dmap)

pointer_dmap.options(size=10)

pointer.contents

%%opts Area (color='#fff8dc' line_width=2) Curve (color='black') VLine (color='red')
xs = np.linspace(-3, 3, 400)

def function(xs, time):
    "Some time varying function"
    return np.exp(np.sin(xs+np.pi/time))

def integral(limit, time):
    limit = -3 if limit is None else np.clip(limit,-3,3)
    curve = hv.Curve((xs, function(xs, time)))[limit:]
    area  = hv.Area ((xs, function(xs, time)))[:limit]
    summed = area.dimension_values('y').sum() * 0.015  # Numeric approximation
    return (area * curve * hv.VLine(limit) * hv.Text(limit + 0.8, 2.0, '%.2f' % summed))

hv.DynamicMap(integral, streams=[streams.Stream.define('Time', time=1.0)(), 
                                 streams.PointerX().rename(x='limit')])

xvals = np.linspace(0,4,202)
ys,xs = np.meshgrid(xvals, -xvals[::-1])
img = hv.Image(np.sin(((ys)**3)*xs))

pointer = streams.PointerXY(x=0,y=0, source=img)
pointer_dmap = hv.DynamicMap(lambda x, y: hv.Points([(x, y)]), streams=[pointer])

img + pointer_dmap.options(size=10)

%%opts Curve {+framewise}
hv.DynamicMap(lambda x, y: img.sample(y=np.clip(y,-.49,.49)), streams=[pointer]) +\
hv.DynamicMap(lambda x, y: img.sample(x=np.clip(x,-.49,.49)), streams=[pointer])

pointer = streams.PointerXY(x=0, y=0)
cross_dmap = hv.DynamicMap(lambda x, y: (hv.VLine(x) * hv.HLine(y)), streams=[pointer])

cross_dmap + cross_dmap.clone(link_inputs=False)

tap = streams.SingleTap(transient=True)
double_tap = streams.DoubleTap(rename={'x': 'x2', 'y': 'y2'}, transient=True)

taps = []

def record_taps(x, y, x2, y2):
    if None not in [x,y]:
        taps.append((x, y, 1))
    elif None not in [x2, y2]:
        taps.append((x2, y2, 2))
    return hv.Points(taps, vdims='Taps')

%%opts Points [color_index='Taps' tools=['hover']] (size=10 cmap='Set1')
hv.DynamicMap(record_taps, streams=[tap, double_tap])

taps