From d283f7e661e14d6ae1881fe803e5b4f1ed0689ff Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson2@worcester.edu>
Date: Mon, 24 Jun 2024 13:49:08 -0400
Subject: Add 2024 Guix social talk.

---
 2024-06-18-guix-social/reveal.js/js/utils/color.js | 77 ++++++++++++++++++++++
 1 file changed, 77 insertions(+)
 create mode 100644 2024-06-18-guix-social/reveal.js/js/utils/color.js

(limited to '2024-06-18-guix-social/reveal.js/js/utils/color.js')

diff --git a/2024-06-18-guix-social/reveal.js/js/utils/color.js b/2024-06-18-guix-social/reveal.js/js/utils/color.js
new file mode 100644
index 0000000..e28a2b1
--- /dev/null
+++ b/2024-06-18-guix-social/reveal.js/js/utils/color.js
@@ -0,0 +1,77 @@
+/**
+ * Converts various color input formats to an {r:0,g:0,b:0} object.
+ *
+ * @param {string} color The string representation of a color
+ * @example
+ * colorToRgb('#000');
+ * @example
+ * colorToRgb('#000000');
+ * @example
+ * colorToRgb('rgb(0,0,0)');
+ * @example
+ * colorToRgb('rgba(0,0,0)');
+ *
+ * @return {{r: number, g: number, b: number, [a]: number}|null}
+ */
+export const colorToRgb = ( color ) => {
+
+	let hex3 = color.match( /^#([0-9a-f]{3})$/i );
+	if( hex3 && hex3[1] ) {
+		hex3 = hex3[1];
+		return {
+			r: parseInt( hex3.charAt( 0 ), 16 ) * 0x11,
+			g: parseInt( hex3.charAt( 1 ), 16 ) * 0x11,
+			b: parseInt( hex3.charAt( 2 ), 16 ) * 0x11
+		};
+	}
+
+	let hex6 = color.match( /^#([0-9a-f]{6})$/i );
+	if( hex6 && hex6[1] ) {
+		hex6 = hex6[1];
+		return {
+			r: parseInt( hex6.slice( 0, 2 ), 16 ),
+			g: parseInt( hex6.slice( 2, 4 ), 16 ),
+			b: parseInt( hex6.slice( 4, 6 ), 16 )
+		};
+	}
+
+	let rgb = color.match( /^rgb\s*\(\s*(\d+)\s*,\s*(\d+)\s*,\s*(\d+)\s*\)$/i );
+	if( rgb ) {
+		return {
+			r: parseInt( rgb[1], 10 ),
+			g: parseInt( rgb[2], 10 ),
+			b: parseInt( rgb[3], 10 )
+		};
+	}
+
+	let rgba = color.match( /^rgba\s*\(\s*(\d+)\s*,\s*(\d+)\s*,\s*(\d+)\s*,\s*([\d]+|[\d]*.[\d]+)\s*\)$/i );
+	if( rgba ) {
+		return {
+			r: parseInt( rgba[1], 10 ),
+			g: parseInt( rgba[2], 10 ),
+			b: parseInt( rgba[3], 10 ),
+			a: parseFloat( rgba[4] )
+		};
+	}
+
+	return null;
+
+}
+
+/**
+ * Calculates brightness on a scale of 0-255.
+ *
+ * @param {string} color See colorToRgb for supported formats.
+ * @see {@link colorToRgb}
+ */
+export const colorBrightness = ( color ) => {
+
+	if( typeof color === 'string' ) color = colorToRgb( color );
+
+	if( color ) {
+		return ( color.r * 299 + color.g * 587 + color.b * 114 ) / 1000;
+	}
+
+	return null;
+
+}
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