From 699698f5297ecc936d431e3d11a797afc87cee78 Mon Sep 17 00:00:00 2001
From: kkapsner <github@mail.kkapsner.de>
Date: Sat, 14 May 2016 19:12:45 +0200
Subject: [PATCH] Improved faking performance.

---
 lib/modifiedAPI.js | 31 ++++++++++++++++++++++---------
 1 file changed, 22 insertions(+), 9 deletions(-)

diff --git a/lib/modifiedAPI.js b/lib/modifiedAPI.js
index 944fad5..d130147 100644
--- a/lib/modifiedAPI.js
+++ b/lib/modifiedAPI.js
@@ -28,27 +28,40 @@
 			);
 		}
 		data = imageData.data;
+		var l = data.length;
+		var randomI = 65536;
+		var randomOffset = 0;
+		var randomNumbers = new Uint8Array(Math.min(65536, l));
 		
-		for (var i = 0, l = data.length; i < l; i += 1){
+		for (var i = 0; i < l; i += 1, randomI += 1){
+			if (randomI >= randomNumbers.length){
+				randomI = 0;
+				randomOffset += randomNumbers.length;
+				if (l - i < 65536){
+					randomNumbers = new Uint8Array(l - i);
+				}
+				window.crypto.getRandomValues(randomNumbers);
+			}
+			var rnd = randomNumbers[randomI];
 			var value = source[i];
 			if (value >= 0x80){
-				value = value ^ Math.floor(Math.random() * 0x20);
+				value = value ^ (rnd & 0x1F);
 			}
 			else if (value >= 0x40){
-				value = value ^ Math.floor(Math.random() * 0x10);
+				value = value ^ (rnd & 0x0F);
 			}
 			else if (value >= 0x20){
-				value = value ^ Math.floor(Math.random() * 0x08);
+				value = value ^ (rnd & 0x07);
 			}
 			else if (value >= 0x10){
-				value = value ^ Math.floor(Math.random() * 0x04);
+				value = value ^ (rnd & 0x03);
 			}
 			else if (value >= 0x08){
-				value = value ^ Math.floor(Math.random() * 0x02);
-			}
-			else if (value >= 0x04){
-				value = value ^ Math.floor(Math.random() * 0x01);
+				value = value ^ (rnd & 0x01);
 			}
+			// else if (value >= 0x04){
+				// value = value ^ (rnd * 0x00);
+			// }
 			data[i] = value;
 		}
 		var canvas = original.cloneNode(true);