#4965: Implement intelligent scrolling of the sidebar in the docs.

Doc/tools/sphinxext/static/basic.css

@@ -38,6 +38,8 @@ div.related li.right {
 /* -- sidebar --------------------------------------------------------------- */
 
 div.sphinxsidebarwrapper {
+    position: relative;
+    top: 0;
     padding: 10px 5px 0 10px;
     word-wrap: break-word;
 }

Doc/tools/sphinxext/static/sidebar.js

+/*
+ * sidebar.js
+ * ~~~~~~~~~~
+ *
+ * This script makes the Sphinx sidebar collapsible and implements
+ * intelligent scrolling.
+ *
+ * .sphinxsidebar contains .sphinxsidebarwrapper.  This script adds
+ * in .sphixsidebar, after .sphinxsidebarwrapper, the #sidebarbutton
+ * used to collapse and expand the sidebar.
+ *
+ * When the sidebar is collapsed the .sphinxsidebarwrapper is hidden
+ * and the width of the sidebar and the margin-left of the document
+ * are decreased. When the sidebar is expanded the opposite happens.
+ * This script saves a per-browser/per-session cookie used to
+ * remember the position of the sidebar among the pages.
+ * Once the browser is closed the cookie is deleted and the position
+ * reset to the default (expanded).
+ *
+ * :copyright: Copyright 2007-2011 by the Sphinx team, see AUTHORS.
+ * :license: BSD, see LICENSE for details.
+ *
+ */
+
+$(function() {
+  // global elements used by the functions.
+  // the 'sidebarbutton' element is defined as global after its
+  // creation, in the add_sidebar_button function
+  var jwindow = $(window);
+  var jdocument = $(document);
+  var bodywrapper = $('.bodywrapper');
+  var sidebar = $('.sphinxsidebar');
+  var sidebarwrapper = $('.sphinxsidebarwrapper');
+
+  // original margin-left of the bodywrapper and width of the sidebar
+  // with the sidebar expanded
+  var bw_margin_expanded = bodywrapper.css('margin-left');
+  var ssb_width_expanded = sidebar.width();
+
+  // margin-left of the bodywrapper and width of the sidebar
+  // with the sidebar collapsed
+  var bw_margin_collapsed = '.8em';
+  var ssb_width_collapsed = '.8em';
+
+  // colors used by the current theme
+  var dark_color = $('.related').css('background-color');
+  var light_color = $('.document').css('background-color');
+
+  function get_viewport_height() {
+    if (window.innerHeight)
+      return window.innerHeight;
+    else
+      return jwindow.height();
+  }
+
+  function sidebar_is_collapsed() {
+    return sidebarwrapper.is(':not(:visible)');
+  }
+
+  function toggle_sidebar() {
+    if (sidebar_is_collapsed())
+      expand_sidebar();
+    else
+      collapse_sidebar();
+    // adjust the scrolling of the sidebar
+    scroll_sidebar();
+  }
+
+  function collapse_sidebar() {
+    sidebarwrapper.hide();
+    sidebar.css('width', ssb_width_collapsed);
+    bodywrapper.css('margin-left', bw_margin_collapsed);
+    sidebarbutton.css({
+        'margin-left': '0',
+        'height': bodywrapper.height()
+    });
+    sidebarbutton.find('span').text('»');
+    sidebarbutton.attr('title', _('Expand sidebar'));
+    document.cookie = 'sidebar=collapsed';
+  }
+
+  function expand_sidebar() {
+    bodywrapper.css('margin-left', bw_margin_expanded);
+    sidebar.css('width', ssb_width_expanded);
+    sidebarwrapper.show();
+    sidebarbutton.css({
+        'margin-left': ssb_width_expanded-12,
+        'height': bodywrapper.height()
+    });
+    sidebarbutton.find('span').text('«');
+    sidebarbutton.attr('title', _('Collapse sidebar'));
+    document.cookie = 'sidebar=expanded';
+  }
+
+  function add_sidebar_button() {
+    sidebarwrapper.css({
+        'float': 'left',
+        'margin-right': '0',
+        'width': ssb_width_expanded - 28
+    });
+    // create the button
+    sidebar.append(
+        '<div id="sidebarbutton"><span>&laquo;</span></div>'
+    );
+    var sidebarbutton = $('#sidebarbutton');
+    light_color = sidebarbutton.css('background-color');
+    // find the height of the viewport to center the '<<' in the page
+    var viewport_height = get_viewport_height();
+    sidebarbutton.find('span').css({
+        'display': 'block',
+        'margin-top': (viewport_height - sidebar.position().top - 20) / 2
+    });
+
+    sidebarbutton.click(toggle_sidebar);
+    sidebarbutton.attr('title', _('Collapse sidebar'));
+    sidebarbutton.css({
+        'color': '#FFFFFF',
+        'border-left': '1px solid ' + dark_color,
+        'font-size': '1.2em',
+        'cursor': 'pointer',
+        'height': bodywrapper.height(),
+        'padding-top': '1px',
+        'margin-left': ssb_width_expanded - 12
+    });
+
+    sidebarbutton.hover(
+      function () {
+          $(this).css('background-color', dark_color);
+      },
+      function () {
+          $(this).css('background-color', light_color);
+      }
+    );
+  }
+
+  function set_position_from_cookie() {
+    if (!document.cookie)
+      return;
+    var items = document.cookie.split(';');
+    for(var k=0; k<items.length; k++) {
+      var key_val = items[k].split('=');
+      var key = key_val[0];
+      if (key == 'sidebar') {
+        var value = key_val[1];
+        if ((value == 'collapsed') && (!sidebar_is_collapsed()))
+          collapse_sidebar();
+        else if ((value == 'expanded') && (sidebar_is_collapsed()))
+          expand_sidebar();
+      }
+    }
+  }
+
+  add_sidebar_button();
+  var sidebarbutton = $('#sidebarbutton');
+  set_position_from_cookie();
+
+
+  /* intelligent scrolling */
+  function scroll_sidebar() {
+    var sidebar_height = sidebarwrapper.height();
+    var viewport_height = get_viewport_height();
+    var offset = sidebar.position()['top'];
+    var wintop = jwindow.scrollTop();
+    var winbot = wintop + viewport_height;
+    var curtop = sidebarwrapper.position()['top'];
+    var curbot = curtop + sidebar_height;
+    // does sidebar fit in window?
+    if (sidebar_height < viewport_height) {
+      // yes: easy case -- always keep at the top
+      sidebarwrapper.css('top', $u.min([$u.max([0, wintop - offset - 10]),
+                            jdocument.height() - sidebar_height - 200]));
+    }
+    else {
+      // no: only scroll if top/bottom edge of sidebar is at
+      // top/bottom edge of window
+      if (curtop > wintop && curbot > winbot) {
+        sidebarwrapper.css('top', $u.max([wintop - offset - 10, 0]));
+      }
+      else if (curtop < wintop && curbot < winbot) {
+        sidebarwrapper.css('top', $u.min([winbot - sidebar_height - offset - 20,
+                              jdocument.height() - sidebar_height - 200]));
+      }
+    }
+  }
+  jwindow.scroll(scroll_sidebar);
+});