colorWheel.py

This code demonstrates how to draw a color wheel into a RGBA ImageView.

This code demonstrates how to draw a color wheel into a RGBA ImageView. The part outside the wheel is transparent, using alpha channel.

import iolink
 
import math
from array import array
 
def hsvToRgb(h: float, s: float, v: float) -> iolink.Vector3u8:
    hp = h / 60.0
    c = s * v
    x = c * (1 - abs(math.fmod(hp, 2) - 1))
    m = v - c
    r = 0
    g = 0
    b = 0
 
    if hp <= 1:
        r = c
        g = x
    elif hp <= 2:
        r = x
        g = c
    elif hp <= 3:
        g = c
        b = x
    elif hp <= 4:
        g = x
        b = c
    elif hp <= 5:
        r = x
        b = c
    else:
        r = c
        b = x
 
    rgb_double = iolink.Vector3d(r, g, b)
    rgb_double += iolink.Vector3d.create_uniform(m)
    rgb_double *= 255.0
    return iolink.Vector3u8(int(rgb_double[0]), int(rgb_double[1]), int(rgb_double[2]))
 
 
 
def colorWheel(shape: iolink.VectorXu64):
 
    # first we can check if given shape has exactly 2 dimensions
    if shape.size() != 2:
        raise ValueError("Shape must have 2 dimensions ")
 
    # To create a RGBA ImageView, the datatype of the image must have 4 components, and so
    # should be be VEC4_XXX (with XXX: INT8, INT16, INT32, INT64, UINT8, ...)
    # We choose VEC4_UINT8 as the datatype for this example.
    dt = iolink.DataTypeId.VEC4_UINT8
    image = iolink.ImageViewFactory.allocate(shape, dt)
 
    # indicate the created image is a 2D IMAGE with RGB color interpretation and alpha channel
    image.axes_interpretation = iolink.AxesInterpretationId.IMAGE
    image.image_interpretation = iolink.ImageInterpretation.RGB
    image.has_alpha = True
 
    center = iolink.Vector2d(shape[0] / 2.0, shape[1] / 2.0)
 
    for y in range(0, shape[1]):
        for x in range(0, shape[0]):
            position = iolink.Vector2d(x, y)
            delta = position - center
            r = delta.length()
 
            if r > center[0]:
                # write transparent pixel
                pixVal = array('B', [0, 0, 0, 0])
                image.write([x, y], pixVal)
            else:
                # determine HSV value for current pixel position
                h = math.atan2(delta[1], delta[0]) * 180 / math.pi + 180
                s = r / (shape[0] / 2)
                v = 1
                # convert HSV to RGB
                rgb = hsvToRgb(h, s, v)
                # write RGBA pixel (with alpha = 255)
                pixVal = array('B', [*rgb, 255])
                image.write([x, y], pixVal)
 
    return image
 
 
image = colorWheel(iolink.VectorXu64([512, 512]))
 
print("Generated image:", str(image))
 
 
 
#import numpy as np
#from matplotlib import pyplot as plt
 
 
 
#plt.imshow(npy, interpolation='nearest')
#plt.show()
 
print("SUCCESS")