Source code for enable.compass
# (C) Copyright 2005-2022 Enthought, Inc., Austin, TX
# All rights reserved.
#
# This software is provided without warranty under the terms of the BSD
# license included in LICENSE.txt and may be redistributed only under
# the conditions described in the aforementioned license. The license
# is also available online at http://www.enthought.com/licenses/BSD.txt
#
# Thanks for using Enthought open source!
from numpy import array, pi
# Enthought library imports
from traits.api import Bool, Enum, Float, Int
# Local, relative imports
from .component import Component
from .colors import ColorTrait
[docs]class Compass(Component):
""" A compass with triangles at the 4 cardinal directions. The center
of the compass of triangles is the center of the widget.
"""
# Which triangle was clicked
clicked = Enum(None, "n", "e", "s", "w", "c")
# Whether or not to allow clicks on the center
enable_center = Bool(False)
# ------------------------------------------------------------------------
# Shape and layout
# ------------------------------------------------------------------------
# The length of the triangle from tip to base
triangle_length = Int(11)
# The width of the base of the triangle
triangle_width = Int(8)
# Overall scaling factor for the triangle. Note that this also scales
# the outline width.
scale = Float(1.0)
# The distance from the center of the widget to the center of each triangle
# (halfway along its length, not the orthocenter).
spacing = Int(12)
# ------------------------------------------------------------------------
# Appearance Traits
# ------------------------------------------------------------------------
# The line color of the triangles
color = ColorTrait("black")
# The line width of the triangles
line_width = Int(2)
# The triangle fill color when the mouse has not been clicked
fill_color = ColorTrait("none")
# The fill color of the triangle that the user has clicked on
clicked_color = ColorTrait("lightgray")
# Override the inherited **event_state** attribute
event_state = Enum("normal", "clicked")
# ------------------------------------------------------------------------
# Stub methods for subclasses
# ------------------------------------------------------------------------
[docs] def mouse_down(self, arrow):
""" Called when the mouse is first pressed inside one of the
triangles. This gets called after self.clicked is set.
Parameters
==========
arrow: "n", "e", "s", "w"
indicates which arrow was pressed
"""
pass
[docs] def mouse_up(self):
""" Called when the mouse is released. This gets called after
self.clicked is unset.
"""
pass
# ------------------------------------------------------------------------
# Event handling methods
# ------------------------------------------------------------------------
[docs] def normal_left_down(self, event):
# Determine which arrow was clicked; use a rectangular approximation.
x = event.x - (self.x + self.width / 2)
y = event.y - (self.y + self.height / 2)
half_length = self.triangle_length / 2 * self.scale
half_width = self.triangle_width / 2 * self.scale
offset = self.spacing * self.scale
# Create dict mapping direction to (x, y, x2, y2)
near = offset - half_length
far = offset + half_length
rects = {
"n": array((-half_width, near, half_width, far)),
"e": array((near, -half_width, far, half_width)),
"s": array((-half_width, -far, half_width, -near)),
"w": array((-far, -half_width, -near, half_width)),
}
if self.enable_center:
rects["c"] = array((-near, -near, near, near))
for direction, rect in rects.items():
if (rect[0] <= x <= rect[2]) and (rect[1] <= y <= rect[3]):
self.event_state = "clicked"
self.clicked = direction
self.mouse_down(direction)
self.request_redraw()
break
event.handled = True
[docs] def clicked_left_up(self, event):
self.event_state = "normal"
self.clicked = None
event.handled = True
self.mouse_up()
self.request_redraw()
# ------------------------------------------------------------------------
# Rendering methods
# ------------------------------------------------------------------------
[docs] def get_preferred_size(self):
# Since we can compute our preferred size from the size of the
# arrows and the spacing, we can return a sensible preferred
# size, so override the default implementation in Component.
if self.fixed_preferred_size is not None:
return self.fixed_preferred_size
else:
extent = self.scale * 2 * (self.spacing + self.triangle_length / 2)
return [extent + self.hpadding, extent + self.vpadding]
def _draw_mainlayer(self, gc, view_bounds=None, mode="normal"):
with gc:
gc.set_stroke_color(self.color_)
gc.set_line_width(self.line_width)
gc.translate_ctm(self.x + self.width / 2, self.y + self.height / 2)
s = self.spacing
points_and_angles = [
("n", (0, s), 0),
("e", (s, 0), -pi / 2),
("s", (0, -s), pi),
("w", (-s, 0), pi / 2),
]
gc.scale_ctm(self.scale, self.scale)
for dir, (dx, dy), angle in points_and_angles:
if self.event_state == "clicked" and self.clicked == dir:
gc.set_fill_color(self.clicked_color_)
else:
gc.set_fill_color(self.fill_color_)
gc.translate_ctm(dx, dy)
gc.rotate_ctm(angle)
half_height = self.triangle_length / 2
half_width = self.triangle_width / 2
gc.begin_path()
gc.lines(
[
(-half_width, -half_height),
(0, half_height),
(half_width, -half_height),
(-half_width, -half_height),
(0, half_height),
]
)
gc.draw_path()
gc.rotate_ctm(-angle)
gc.translate_ctm(-dx, -dy)
if self.event_state == "clicked" and self.clicked == "c":
# Fill in the center
gc.set_fill_color(self.clicked_color_)
half_width = self.triangle_width / 2
gc.begin_path()
gc.lines(
[
(-half_width, -half_width),
(half_width, -half_height),
(half_width, half_width),
(-half_width, half_width),
(-half_width, -half_width),
]
)
gc.draw_path()
