Styles, colors and color maps

Main author: Maël Godard

Style

By default, the drawn shapes will have a black edge and no fill. a StyleProperties object can be passed as an additionnal argument to change it.

Predefined styles are available in the StyleProperties class:

• inside() : black edge, green fill

• outside() : black edge, cyan fill

• boundary() : black edge, yellow fill

A StyleProperties object is composed of two Color objects, one for the edge and one for the fill. Three constructors are available:

PythonC++

default_style = StyleProperties() # default
edge_style = StyleProperties(Color.red()) # edge only
edge_fill_style = StyleProperties([Color.blue(),Color.green()]) # edge and fill

It can also be deduced from one or two Color objects.

PythonC++

fig.draw_box([[2.2,2.5],[2.2,2.5]]) # Default style
fig.draw_box([[2.2,2.5],[2.2,2.5]],StyleProperties.inside()) # black edge, green fill
fig.draw_box([[2.2,2.5],[2.2,2.5]],Color.red()) # red edge, no fill
fig.draw_box([[2.2,2.5],[2.2,2.5]],[Color.blue(),Color.green()]) # blue edge, green fill

In addition, a line style and/or a layer can be added to the StyleProperties object. The line style is defined by a string, and the layer is defined by its name (string).

Available line styles are:

• “-” (solid)

• “--” (dashed)

• “..” (dotted)

• “-.” (dash-dotted)

• “-..” (dash-dot-dotted)

These two arguments are optional, only one can be added and they can be added in any order.

PythonC++

fig.draw_box([[2.2,2.5],[2.2,2.5]], StyleProperties(Color.red(), "..", "layer1")) # Red edge, dotted line and layer1

Colors

Predefined colors are available in the Color class. Each of the static methods can take an argument to define the transparency of the color between 0 (full transparency) and 1 (full opacity).

PythonC++

Color.none() # transparent
Color.black() # black
Color.white() # white
Color.green() # green
Color.blue() # blue
Color.cyan() # cyan
Color.yellow() # yellow
Color.red() # red
Color.dark_gray() # dark gray
Color.purple() # purple
Color.dark_green() # dark green

Custom colors can be defined in the RGB or HSV color spaces. An enumaration Model is used to make the distinction between the two.

PythonC++

Model.RGB # RGB color space
Model.HSV # HSV color space

A getter model() is available, and the methods rgb() and hsv() are used to do the conversion between the two color spaces.

If the color is in RGB the red, green, blue and alpha values are between 0 and 255. If the color is in HSV the hue value is between 0 and 360 while the saturation, value and alpha values are between 0 and 100.

The Color class constructor can take different arguments:

• No argument : black color

• An array of 3 floats and a Model (default is RGB): the RGB or HSV values

• An array of 4 floats and a Model (default is RGB): the RGBA or HSVA values and the transparency

• A list of 3 or 4 floats and a Model (default is RGB): the RGB, HSV, RGBA or HSVA values

• A string : the html representation of the color (e.g. “#FF0000” for red)

Additionnal methods are available for any useful purpose:

• hex_str() : the html representation of the color

• vec() : the RGBA or HSVA values in a vector

Color creation example :

PythonC++

# predefined colors without and with opacity
fig.draw_point([2,2], [Color.red(),Color.yellow(0.5)])
# HTML color without and with opacity
fig.draw_box([[2.4,2.9],[2.4,2.9]],[Color("#da3907"),Color("#da390755")])
# HSV color without and with opacity
fig.draw_box([[2.6,3.1],[2.6,3.1]],[Color([108,90,78],Model.HSV),Color([108,90,78,20],Model.HSV)])
# RGB color auto cast from list without and with opacity
fig.draw_box([[2.,2.3],[2.6,2.9]],[[255,0,255],[255,0,255,100]])

Color maps

Color maps are used to convert a scalar value (between 0 and 1) to a color. The ColorMap class provides a set of predefined color maps:

PythonC++

ColorMap.basic() # default color map
ColorMap.haxby() # Haxby color map
ColorMap.rainbow() # rainbow color map
ColorMap.blue_tube() # blue color map, used mainly for tubes
ColorMap.red_tube() # red color map, used mainly for tubes

These five color maps are displayed below:

The method color() is used to get the color corresponding to a scalar value. The argument is a float between 0 and 1.

As for the Color class, the ColorMap also has a Model (RGB or HSV) and an associated getter model(). The default Model is RGB.

You can also create your own color map :

PythonC++

# Create a custom color map
custom_map = ColorMap(Model.RGB)
custom_map[0] = Color([255,0,0])
custom_map[0.5] = Color([0,255,0])
custom_map[1] = Color([0,0,255])

Note that you can add RGB and HSV colors to the same color map. The model of the color map will define the interpolation space.