/
knob.py
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/
knob.py
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import math
from kivy import Config
"""
Knob
====
The :class:`Knob` widget creates a component that looks like a
control Knob or Dial (from Wikipedia : "A control knob is a rotary
control used to provide input to a device when grasped by an
operator and turned, so that the degree of rotation corresponds to
the desired input." http://en.wikipedia.org/wiki/Control_knob).
To configure a knob a max/min, slope and step values should be provided.
Additionally, knobimg_source could be set to load
a texture that visually represents the knob.
"""
__all__ = ('Knob',)
__version__ = '0.2'
Config.set('graphics', 'multisamples', '0')
from kivy.lang import Builder
from kivy.uix.widget import Widget
from kivy.properties import NumericProperty, ObjectProperty, StringProperty,\
BooleanProperty, ReferenceListProperty, BoundedNumericProperty,\
ListProperty
Builder.load_string('''
#
# Knob
# ====
# To create a basic knob (in a kv file):
#
# Knob:
# size: 100, 100
# min: 0
# max: 100
# step: 1
# slope: 1
# value: 0 # Default position of knob.
# knobimg_source: "img/knob_metal.png" # Knob texture
# show_marker: False # Do not show surrounding marker
#
# To create a knob with a surrounding marker:
#
# Knob:
# size: 100, 100
# min: 0
# max: 100
# step: 1
# slope: 1
# value: 0 # Default position of knob.
# knobimg_source: "img/knob_metal.png" # Knob texture
# show_marker: True # Show surrounding marker
# marker_img: "img/bline.png" # Marker texture image
# knob_size: 0.9 # Scales knob size to leave space for marker
# markeroff_color: 0, 0, 0, 0
<Knob>
size_hint: None, None
canvas.before:
Color:
rgba: self.markeroff_color
Ellipse:
pos: self.pos
size: self.size[0], self.size[1]
angle_start: 0
angle_end: 360
source: self.markeroff_img
Color:
rgba: self.marker_color
Ellipse:
pos: self.pos
size: self.size[0], self.size[1]
angle_start: self.marker_startangle
angle_end: self._angle + self.marker_ahead if self._angle > self.marker_startangle else self.marker_startangle
source: self.marker_img
Color:
rgba: self.knobimg_bgcolor
Ellipse:
pos: self.pos[0] + (self.size[0] * (1 - self.knobimg_size))/2, self.pos[1] + (self.size[1] * (1 - self.knobimg_size)) / 2
size: self.size[0] * (self.knobimg_size), self.size[1] * (self.knobimg_size)
Color:
rgba: self.knobimg_color
PushMatrix
Rotate:
angle: 360 - self._angle
origin: self.center
Rectangle:
pos: self.pos[0] + (self.size[0] * (1 - self.knobimg_size)) /2, self.pos[1] + (self.size[1] * (1 - self.knobimg_size)) / 2
size: self.size[0] * (self.knobimg_size), self.size[1] * (self.knobimg_size)
source: self.knobimg_source
canvas:
PopMatrix
''')
class Knob(Widget):
"""Class for creating a Knob widget."""
min = NumericProperty(0)
'''Minimum value for value :attr:`value`.
:attr:`min` is a :class:`~kivy.properties.NumericProperty` and defaults
to 0.
'''
max = NumericProperty(100)
'''Maximum value for value :attr:`value`.
:attr:`max` is a :class:`~kivy.properties.NumericProperty` and defaults
to 100.
'''
range = ReferenceListProperty(min, max)
''' Range of the values for Knob.
:attr:`range` is a :class:`~kivy.properties.ReferenceListProperty` of
(:attr:`min`, :attr:`max`).
'''
value = NumericProperty(0)
'''Current value of the knob. Set :attr:`value` when creating a knob to
set its initial position. An internal :attr:`_angle` is calculated to set
the position of the knob.
:attr:`value` is a :class:`~kivy.properties.NumericProperty` and defaults
to 0.
'''
step = BoundedNumericProperty(1, min=0)
'''Step interval of knob to go from min to max. An internal
:attr:`_angle_step` is calculated to set knob step in degrees.
:attr:`step` is a :class:`~kivy.properties.BoundedNumericProperty`
and defaults to 1 (min=0).
'''
curve = BoundedNumericProperty(1, min=1)
'''This parameter determines the shape of the map function. It represent the
reciprocal of a power function's exponent used to map the input value.
So, for higher values of curve the contol is more reactive, and conversely.
'''
knobimg_source = StringProperty("")
'''Path of texture image that visually represents the knob. Use PNG for
transparency support. The texture is rendered on a centered rectangle of
size = :attr:`size` * :attr:`knobimg_size`.
:attr:`knobimg_source` is a :class:`~kivy.properties.StringProperty`
and defaults to empty string.
'''
knobimg_color = ListProperty([1, 1, 1, 1])
'''Color to apply to :attr:`knobimg_source` texture when loaded.
:attr:`knobimg_color` is a :class:`~kivy.properties.ListProperty`
and defaults to [1,1,1,1].
'''
knobimg_size = BoundedNumericProperty(1.0, max=1.0, min=0.1)
''' Internal proportional size of rectangle that holds
:attr:`knobimg_source` texture.
:attr:`knobimg_size` is a :class:`~kivy.properties.BoundedNumericProperty`
and defaults to 0.9.
'''
show_marker = BooleanProperty(True)
''' Shows/hides marker surrounding knob. use :attr:`knob_size` < 1.0 to
leave space to marker.
:attr:`show_marker` is a :class:`~kivy.properties.BooleanProperty`
and defaults to True.
'''
marker_img = StringProperty("")
'''Path of texture image that visually represents the knob marker. The
marker is rendered in a centered Ellipse (Circle) with the same size of
the widget and goes from angle_start=:attr:`marker_startangle` to
angle_end=:attr:`_angle`.
:attr:`marker_img` is a :class:`~kivy.properties.StringProperty` and
defaults to "".
'''
marker_color = ListProperty([1, 1, 1, 1])
'''Color to apply to :attr:`marker_img` texture when loaded.
:attr:`marker_color` is a :class:`~kivy.properties.ListProperty`
and defaults to [1,1,1,1].
'''
knobimg_bgcolor = ListProperty([0, 0, 0, 1])
''' Background color behind :attr:`knobimg_source` texture.
:attr:`value` is a :class:`~kivy.properties.ListProperty` and defaults
to [0,0,0,1].
'''
markeroff_img = StringProperty("")
'''Path of texture image that visually represents the knob marker where
it's off, that is, parts of the marker that haven't been reached yet by
the knob (:attr:`value`).
:attr:`markeroff_img` is a :class:`~kivy.properties.StringProperty`
and defaults to "".
'''
markeroff_color = ListProperty([0, 0, 0, 0])
'''Color applied to :attr:`markeroff_img` int the Canvas.
:attr:`markeroff_color` is a :class:`~kivy.properties.ListProperty`
and defaults to [0,0,0,0].
'''
marker_startangle = NumericProperty(0)
'''Starting angle of Ellipse where :attr:`marker_img` is rendered.
:attr:`value` is a :class:`~kivy.properties.NumericProperty` and defaults
to 0.
'''
marker_ahead = NumericProperty(0)
''' Adds degrees to angle_end of marker (except when :attr:`value` == 0).
:attr:`marker_ahead` is a :class:`~kivy.properties.NumericProperty`
and defaults to 0.
'''
_angle = NumericProperty(0) # Internal angle calculated from value.
_angle_step = NumericProperty(0) # Internal angle_step calculated from step.
def __init__(self, *args, **kwargs):
super(Knob, self).__init__(*args, **kwargs)
self.bind(show_marker = self._show_marker)
self.bind(value = self._value)
def _value(self, instance, value):
self._angle = pow( (value - self.min)/(self.max - self.min), 1./self.curve) * 360.
self.on_knob(value)
def _show_marker(self, instance, flag):
# "show/hide" marker.
if flag:
self.knobimg_bgcolor[3] = 1
self.marker_color[3] = 1
self.markeroff_color[3] = 1
else:
self.knobimg_bgcolor[3] = 0
self.marker_color[3] = 0
self.markeroff_color[3] = 0
def on_touch_down(self, touch):
if self.collide_point(*touch.pos):
self.update_angle(touch)
def on_touch_move(self, touch):
if self.collide_point(*touch.pos):
self.update_angle(touch)
def update_angle(self, touch):
posx, posy = touch.pos
cx, cy = self.center
rx, ry = posx - cx, posy - cy
if ry >= 0: # Quadrants are clockwise.
quadrant = 1 if rx >= 0 else 4
else:
quadrant = 3 if rx <= 0 else 2
try:
angle = math.atan(rx / ry) * (180./math.pi)
if quadrant == 2 or quadrant == 3:
angle = 180 + angle
elif quadrant == 4:
angle = 360 + angle
except: # atan not def for angle 90 and 270
angle = 90 if quadrant <= 2 else 270
self._angle_step = (self.step*360)/(self.max - self.min)
self._angle = self._angle_step
while self._angle < angle:
self._angle = self._angle + self._angle_step
relativeValue = pow((angle/360.), 1./self.curve)
self.value = (relativeValue * (self.max - self.min)) + self.min
#TO OVERRIDE
def on_knob(self, value):
pass