1 files changed, 36 insertions, 0 deletions
diff --git a/web/js/labitrack.d/05-utils.js b/web/js/labitrack.d/05-utils.js
new file mode 100644
index 0000000..12822da
--- /dev/null
+++ b/web/js/labitrack.d/05-utils.js
@@ -0,0 +1,36 @@
+(function(labitrack){
+
+labitrack.utils = {};
+labitrack.utils.new_context = function(w, h){
+	var canvas = document.createElement('canvas');
+	canvas.width = w;
+	canvas.height = h;
+	return canvas.getContext('2d');
+};
+
+// Color quantization using Euclidean distance
+// https://en.wikipedia.org/wiki/Euclidean_distance
+// We don't do any alpha blending for now
+labitrack.utils.convert_to_monochrome = function(data){
+	var p = data.data;
+	for(var i = 0, l = p.length; i < l; i+=4) {
+		var v = (p[i+3] === 0 // handle alpha
+		         ||
+		           (Math.pow(p[i], 2) + Math.pow(p[i+1], 2) + Math.pow(p[i+2], 2))
+		           >
+		           (Math.pow(255-p[i], 2) + Math.pow(255-p[i+1], 2) + Math.pow(255-p[i+2], 2))
+		        ) * 255;
+		p[i] = p[i+1] = p[i+2] = v;
+		p[i+3] = 255;
+	}
+};
+
+labitrack.utils.time = function(callback){
+	var start = Date.now();
+	var end = start;
+	callback();
+	end = Date.now();
+	return end - start;
+};
+
+}(labitrack));