1 files changed, 43 insertions, 0 deletions
diff --git a/src/Utils.ts b/src/Utils.ts
index daacca51d..1a00c0bfb 100644
--- a/src/Utils.ts
+++ b/src/Utils.ts
@@ -549,6 +549,49 @@ export function simulateMouseClick(element: Element | null | undefined, x: numbe
         }));
 }
 
+export function lightOrDark(color: any) {
+
+    // Variables for red, green, blue values
+    var r, g, b, hsp;
+
+    // Check the format of the color, HEX or RGB?
+    if (color.match(/^rgb/)) {
+
+        // If RGB --> store the red, green, blue values in separate variables
+        color = color.match(/^rgba?\((\d+),\s*(\d+),\s*(\d+)(?:,\s*(\d+(?:\.\d+)?))?\)$/);
+
+        r = color[1];
+        g = color[2];
+        b = color[3];
+    }
+    else {
+
+        // If hex --> Convert it to RGB: http://gist.github.com/983661
+        color = +("0x" + color.slice(1).replace(
+            color.length < 5 && /./g, '$&$&'));
+
+        r = color >> 16;
+        g = color >> 8 & 255;
+        b = color & 255;
+    }
+
+    // HSP (Highly Sensitive Poo) equation from http://alienryderflex.com/hsp.html
+    hsp = Math.sqrt(
+        0.299 * (r * r) +
+        0.587 * (g * g) +
+        0.114 * (b * b)
+    );
+
+    // Using the HSP value, determine whether the color is light or dark
+    if (hsp > 127.5) {
+        return 'light';
+    }
+    else {
+
+        return 'dark';
+    }
+}
+
 export function setupMoveUpEvents(
     target: object,
     e: React.PointerEvent,