Merge branch 'abstraction_for_detection' of https://github.com/samhed/noVNC

2 files changed, 38 insertions, 7 deletions

diff --git a/app/ui.js b/app/ui.js
index 347a2af..766736a 100644
--- a/app/ui.js
+++ b/app/ui.js
@@ -8,7 +8,7 @@
 
 import * as Log from '../core/util/logging.js';
 import _, { l10n } from './localization.js';
-import { isTouchDevice, isSafari, isIOS, isAndroid, dragThreshold }
+import { isTouchDevice, isSafari, hasScrollbarGutter, dragThreshold }
     from '../core/util/browser.js';
 import { setCapture, getPointerEvent } from '../core/util/events.js';
 import KeyTable from "../core/input/keysym.js";
@@ -1269,8 +1269,9 @@ const UI = {
             // Can't be clipping if viewport is scaled to fit
             UI.forceSetting('view_clip', false);
             UI.rfb.clipViewport  = false;
-        } else if (isIOS() || isAndroid()) {
-            // iOS and Android usually have shit scrollbars
+        } else if (!hasScrollbarGutter) {
+            // Some platforms have scrollbars that are difficult
+            // to use in our case, so we always use our own panning
             UI.forceSetting('view_clip', true);
             UI.rfb.clipViewport = true;
         } else {
diff --git a/core/util/browser.js b/core/util/browser.js
index 4b371e3..1554801 100644
--- a/core/util/browser.js
+++ b/core/util/browser.js
@@ -4,6 +4,8 @@
  * Licensed under MPL 2.0 (see LICENSE.txt)
  *
  * See README.md for usage and integration instructions.
+ *
+ * Browser feature support detection
  */
 
 import * as Log from './logging.js';
@@ -52,6 +54,38 @@ try {
 }
 export const supportsImageMetadata = _supportsImageMetadata;
 
+let _hasScrollbarGutter = true;
+try {
+    // Create invisible container
+    const container = document.createElement('div');
+    container.style.visibility = 'hidden';
+    container.style.overflow = 'scroll'; // forcing scrollbars
+    document.body.appendChild(container);
+
+    // Create a div and place it in the container
+    const child = document.createElement('div');
+    container.appendChild(child);
+
+    // Calculate the difference between the container's full width
+    // and the child's width - the difference is the scrollbars
+    const scrollbarWidth = (container.offsetWidth - child.offsetWidth);
+
+    // Clean up
+    container.parentNode.removeChild(container);
+
+    _hasScrollbarGutter = scrollbarWidth != 0;
+} catch (exc) {
+    Log.Error("Scrollbar test exception: " + exc);
+}
+export const hasScrollbarGutter = _hasScrollbarGutter;
+
+/*
+ * The functions for detection of platforms and browsers below are exported
+ * but the use of these should be minimized as much as possible.
+ *
+ * It's better to use feature detection than platform detection.
+ */
+
 export function isMac() {
     return navigator && !!(/mac/i).exec(navigator.platform);
 }
@@ -67,10 +101,6 @@ export function isIOS() {
             !!(/ipod/i).exec(navigator.platform));
 }
 
-export function isAndroid() {
-    return navigator && !!(/android/i).exec(navigator.userAgent);
-}
-
 export function isSafari() {
     return navigator && (navigator.userAgent.indexOf('Safari') !== -1 &&
                          navigator.userAgent.indexOf('Chrome') === -1);