From 8c53305a4c96f55e02c8a2aa15adc17d885a2bd9 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Fri, 27 Dec 2019 15:21:32 +0530
Subject: [PATCH] Server viewer: Make exit fullscreen action available in
 viewer controls. Fixes #1857677 [Add Exit full screen option in Content
 server controls](https://bugs.launchpad.net/calibre/+bug/1857677)

---
 src/pyj/read_book/overlay.pyj | 9 ++++++---
 src/pyj/utils.pyj             | 7 +++++++
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/src/pyj/read_book/overlay.pyj b/src/pyj/read_book/overlay.pyj
index 5957255f3f..30f05e6c56 100644
--- a/src/pyj/read_book/overlay.pyj
+++ b/src/pyj/read_book/overlay.pyj
@@ -19,7 +19,9 @@ from read_book.prefs.main import create_prefs_panel
 from read_book.toc import create_toc_panel
 from read_book.word_actions import create_word_actions_panel
 from session import get_device_uuid
-from utils import full_screen_element, is_ios, safe_set_inner_html
+from utils import (
+    full_screen_element, full_screen_supported, is_ios, safe_set_inner_html
+)
 from widgets import create_button, create_spinner
 
 
@@ -288,10 +290,11 @@ class MainOverlay:  # {{{
             full_screen_actions.push(
                 ac(_('Print'), _('Print book to PDF'), def(): self.overlay.hide(), ui_operations.print_book();, 'print'))
         else:
-            if not full_screen_element() and not is_ios:
+            if not is_ios and full_screen_supported():
+                text = _('Exit full screen') if full_screen_element() else _('Enter full screen')
                 # No fullscreen on iOS, see http://caniuse.com/#search=fullscreen
                 full_screen_actions.push(
-                    ac(_('Toggle full screen'), _('Toggle full screen mode'), def(): self.overlay.hide(), ui_operations.toggle_full_screen();, 'full-screen')
+                    ac(text, _('Toggle full screen mode'), def(): self.overlay.hide(), ui_operations.toggle_full_screen();, 'full-screen')
                 )
         if full_screen_actions.length:
             actions_div.appendChild(E.ul(*full_screen_actions))
diff --git a/src/pyj/utils.pyj b/src/pyj/utils.pyj
index e277b066e7..93e1747e10 100644
--- a/src/pyj/utils.pyj
+++ b/src/pyj/utils.pyj
@@ -75,6 +75,13 @@ def encode_query_with_path(query, path):
     return path + encode_query(query, '#')
 
 
+def full_screen_supported(elem):
+    elem = elem or document.documentElement
+    if elem.requestFullScreen or elem.webkitRequestFullScreen or elem.mozRequestFullScreen:
+        return True
+    return False
+
+
 def request_full_screen(elem):
     elem = elem or document.documentElement
     options = {'navigationUI': 'hide'}