Book a Demo!
CoCalc Logo Icon
StoreFeaturesDocsShareSupportNewsAboutPoliciesSign UpSign In
REMitchell
GitHub Repository: REMitchell/python-crawling
 Path: blob/master/6-Selenium/phantomjs/examples/colorwheel.js
164 views
1
var page = require('webpage').create();

2
page.viewportSize = { width: 400, height : 400 };

3
page.content = '<html><body><canvas id="surface"></canvas></body></html>';

4
page.evaluate(function() {

5
    var el = document.getElementById('surface'),

6
        context = el.getContext('2d'),

7
        width = window.innerWidth,

8
        height = window.innerHeight,

9
        cx = width / 2,

10
        cy = height / 2,

11
        radius = width  / 2.3,

12
        imageData,

13
        pixels,

14
        hue, sat, value,

15
        i = 0, x, y, rx, ry, d,

16
        f, g, p, u, v, w, rgb;

17


18
    el.width = width;

19
    el.height = height;

20
    imageData = context.createImageData(width, height);

21
    pixels = imageData.data;

22


23
    for (y = 0; y < height; y = y + 1) {

24
        for (x = 0; x < width; x = x + 1, i = i + 4) {

25
            rx = x - cx;

26
            ry = y - cy;

27
            d = rx * rx + ry * ry;

28
            if (d < radius * radius) {

29
                hue = 6 * (Math.atan2(ry, rx) + Math.PI) / (2 * Math.PI);

30
                sat = Math.sqrt(d) / radius;

31
                g = Math.floor(hue);

32
                f = hue - g;

33
                u = 255 * (1 - sat);

34
                v = 255 * (1 - sat * f);

35
                w = 255 * (1 - sat * (1 - f));

36
                pixels[i] = [255, v, u, u, w, 255, 255][g];

37
                pixels[i + 1] = [w, 255, 255, v, u, u, w][g];

38
                pixels[i + 2] = [u, u, w, 255, 255, v, u][g];

39
                pixels[i + 3] = 255;

40
            }

41
        }

42
    }

43


44
    context.putImageData(imageData, 0, 0);

45
    document.body.style.backgroundColor = 'white';

46
    document.body.style.margin = '0px';

47
});

48


49
page.render('colorwheel.png');

50


51
phantom.exit();

52


53