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rozek/Bangle_ColorStripe.js

Last active December 6, 2019 08:49
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Bangle.js: fills the display with a color stripe
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Bangle_ColorStripe.js
// fills the display of a Bangle.js with a color stripe
Bangle.setLCDMode(); // use normal display mode
g.clear();
/**** HSVtoRGB ****/
// see https://en.wikipedia.org/wiki/HSL_and_HSV#HSV_to_RGB
function HSVtoRGB (h, s, v) {
let c = v*s;
let k = h/60;
let x = c*(1 - Math.abs(k%2 - 1));
let r, g, b;
switch (true) {
case (k >=0) && (k <= 1): r = c; g = x; b = 0; break;
case (k > 1) && (k <= 2): r = x; g = c; b = 0; break;
case (k > 2) && (k <= 3): r = 0; g = c; b = x; break;
case (k > 3) && (k <= 4): r = 0; g = x; b = c; break;
case (k > 4) && (k <= 5): r = x; g = 0; b = c; break;
case (k > 5) && (k <= 6): r = c; g = 0; b = x; break;
}
let m = v-c;
return [
Math.round(255*(r+m)), Math.round(255*(g+m)), Math.round(255*(b+m))
];
}
/**** draw color stripe ****/
const Width = g.getWidth();
const Height = g.getHeight();
const Saturation = 1.0;
const Value = 1.0;
for (let x = 0; x < Width; x++) {
let Hue = Math.round(360*x/Width);
let RGB = HSVtoRGB(Hue, Saturation, Value);
g.setColor(RGB[0]/255,RGB[1]/255,RGB[2]/255);
g.drawLine(x,0, x,Height-1);
}
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