detect browser zoom (chrome)

common/browser.js

@@ -116,18 +116,39 @@ AscBrowser.checkZoom = function()
     if (AscBrowser.isAndroid)
         return;
 
+	AscBrowser.zoom = 1.0;
+	AscBrowser.isRetina = false;
+
     if (AscBrowser.isChrome && !AscBrowser.isOpera && document && document.firstElementChild && document.body)
     {
-        document.firstElementChild.style.zoom = "reset";
-        AscBrowser.zoom = document.body.clientWidth / window.innerWidth;
-		
+        if (window.innerWidth > 300)
+			AscBrowser.zoom = window.outerWidth / window.innerWidth;
+
+        if (Math.abs(AscBrowser.zoom - 1) < 0.1)
+            AscBrowser.zoom = 1;
+
+        AscBrowser.zoom = window.outerWidth / window.innerWidth;
+
+        var _devicePixelRatio = window.devicePixelRatio / AscBrowser.zoom;
+
+        // device pixel ratio: кратно 0.5
+        _devicePixelRatio = (5 * (((2.5 + 10 * _devicePixelRatio) / 5) >> 0)) / 10;
+
+        AscBrowser.zoom = window.devicePixelRatio / _devicePixelRatio;
+        if (2 == _devicePixelRatio)
+            AscBrowser.isRetina = true;
+
+		// chrome 54.x: zoom = "reset" - clear retina zoom (windows)
+		//document.firstElementChild.style.zoom = "reset";
+		document.firstElementChild.style.zoom = 1.0 / AscBrowser.zoom;
+    }
+    else
+    {
 		AscBrowser.isRetina = (Math.abs(2 - (window.devicePixelRatio / AscBrowser.zoom)) < 0.01);
     }
 };
 
 AscBrowser.checkZoom();
-// detect retina (http://habrahabr.ru/post/159419/)
-AscBrowser.isRetina = (Math.abs(2 - (window.devicePixelRatio / AscBrowser.zoom)) < 0.01);
 
     //--------------------------------------------------------export----------------------------------------------------
     window['AscCommon'] = window['AscCommon'] || {};