""" Demonstration of how to register event callbacks using an adaptation
of the color_scatter example from the Bokeh gallery
"""
import numpy as np

from bokeh import events
from bokeh.io import output_file, show
from bokeh.layouts import column, row
from bokeh.models import Button, CustomJS, Div
from bokeh.plotting import figure


def display_event(div, attributes=[], style = 'float:left;clear:left;font_size=13px'):
    "Build a suitable CustomJS to display the current event in the div model."
    return CustomJS(args=dict(div=div), code="""
        var attrs = %s; var args = [];
        for (var i = 0; i<attrs.length; i++) {
            args.push(attrs[i] + '=' + Number(cb_obj[attrs[i]]).toFixed(2));
        }
        var line = "<span style=%r><b>" + cb_obj.event_name + "</b>(" + args.join(", ") + ")</span>\\n";
        var text = div.text.concat(line);
        var lines = text.split("\\n")
        if (lines.length > 35)
            lines.shift();
        div.text = lines.join("\\n");
    """ % (attributes, style))

x = np.random.random(size=4000) * 100
y = np.random.random(size=4000) * 100
radii = np.random.random(size=4000) * 1.5
colors = ["#%02x%02x%02x" % (int(r), int(g), 150) for r, g in zip(50+2*x, 30+2*y)]

p = figure(tools="pan,wheel_zoom,zoom_in,zoom_out,reset")
p.scatter(x, y, radius=np.random.random(size=4000) * 1.5,
          fill_color=colors, fill_alpha=0.6, line_color=None)

div = Div(width=400, height=p.plot_height, height_policy="fixed")
button = Button(label="Button", button_type="success")
layout = column(button, row(p, div))

## Events with no attributes
button.js_on_event(events.ButtonClick, display_event(div)) # Button click
p.js_on_event(events.LODStart, display_event(div))         # Start of LOD display
p.js_on_event(events.LODEnd, display_event(div))           # End of LOD display

## Events with attributes
point_attributes = ['x', 'y', 'sx', 'sy']                  # Point events
wheel_attributes = point_attributes + ['delta']            # Mouse wheel event
pan_attributes = point_attributes + ['delta_x', 'delta_y'] # Pan event
pinch_attributes = point_attributes + ['scale']            # Pinch event

point_events = [
    events.Tap, events.DoubleTap, events.Press, events.PressUp,
    events.MouseMove, events.MouseEnter, events.MouseLeave,
    events.PanStart, events.PanEnd, events.PinchStart, events.PinchEnd,
]

for event in point_events:
    p.js_on_event(event, display_event(div, attributes=point_attributes))

p.js_on_event(events.MouseWheel, display_event(div, attributes=wheel_attributes))
p.js_on_event(events.Pan,        display_event(div, attributes=pan_attributes))
p.js_on_event(events.Pinch,      display_event(div, attributes=pinch_attributes))

output_file("js_events.html", title="JS Events Example")
show(layout)
