"""
Range Selection tool

Displays a line plot, on which you can select an arbitrary range of x-values.

Left-drag will create a horizontal range selection; 
this selection can then be dragged
around, or resized by dragging its edges.
"""

# Major library imports
from numpy import arange
from scipy.special import jn

# Enthought library imports
from enable.api import Component, ComponentEditor
from traits.api import HasTraits, Instance
from traitsui.api import Item, Group, View

# Chaco imports
from chaco.api import create_line_plot, add_default_axes, add_default_grids
from chaco.tools.api import RangeSelection, RangeSelectionOverlay


# ===============================================================================
# # Create the Chaco plot.
# ===============================================================================
def _create_plot_component():

    numpoints = 100
    low = -5
    high = 15.001
    x = arange(low, high, (high - low) / numpoints)

    # Plot a bessel function
    y = jn(0, x)
    plot = create_line_plot(
        (x, y), color=(0, 0, 1, 1), width=2.0, index_sort="ascending"
    )
    value_range = plot.value_mapper.range
    plot.active_tool = RangeSelection(plot, left_button_selects=True)
    plot.overlays.append(RangeSelectionOverlay(component=plot))
    plot.bgcolor = "white"
    plot.padding = 50
    add_default_grids(plot)
    add_default_axes(plot)

    return plot


# ===============================================================================
# Attributes to use for the plot view.
size = (600, 500)
title = "Simple line plot"

# ===============================================================================
# # Demo class that is used by the demo.py application.
# ===============================================================================
class Demo(HasTraits):
    plot = Instance(Component)

    traits_view = View(
        Group(
            Item("plot", editor=ComponentEditor(size=size), show_label=False),
            orientation="vertical",
        ),
        resizable=True,
        title=title,
        width=size[0],
        height=size[1],
    )

    def _plot_default(self):
        return _create_plot_component()


demo = Demo()

if __name__ == "__main__":
    demo.configure_traits()