EPUB CFI: at_current() works

src/calibre/ebooks/oeb/display/cfi.coffee

@@ -579,11 +579,12 @@ class CanonicalFragmentIdentifier
 
         get_cfi = (ox, oy) ->
             try
-                cfi = this.at(ox, oy)
-                point = this.point(cfi)
+                cfi = window.cfi.at(ox, oy)
+                point = window.cfi.point(cfi)
             catch err
                 cfi = null
 
+            if cfi
                 if point.range != null
                     r = point.range
                     rect = r.getClientRects()[0]

src/calibre/ebooks/oeb/display/test-cfi/cfi-test.coffee

@@ -30,18 +30,23 @@ window_ypos = (pos=null) ->
     window.scrollTo(0, pos)
 
 mark_and_reload = (evt) ->
-    # Remove image in case the click was on the image itself, we want the cfi to
-    # be on the underlying element
     x = evt.clientX
     y = evt.clientY
     if evt.button == 2
         return # Right mouse click, generated only in firefox
-    reset = document.getElementById('reset')
-    if document.elementFromPoint(x, y) == reset
+
+    if document.elementFromPoint(x, y)?.getAttribute('id') in ['reset', 'viewport_mode']
         return
+
+    # Remove image in case the click was on the image itself, we want the cfi to
+    # be on the underlying element
     ms = document.getElementById("marker")
-    if ms
-        ms.parentNode?.removeChild(ms)
+    ms.style.display = 'none'
+
+    if document.getElementById('viewport_mode').checked
+        cfi = window.cfi.at_current()
+        window.cfi.scroll_to(cfi)
+        return
 
     fn = () ->
         try

src/calibre/ebooks/oeb/display/test-cfi/index.html

@@ -8,6 +8,7 @@
             body { 
                 font-family: sans-serif;
                 background-color: white;
+                padding-bottom: 500px;
             }
             
             h1, h2 { color: #005a9c }
@@ -48,7 +49,13 @@
         <div id="container">
             <h1 id="first-h1">Testing cfi.coffee</h1>
             <p>Click anywhere and the location will be marked with a marker, whose position is set via a CFI.</p>
-            <p><a id="reset" href="/">Reset CFI to None</a></p>
+            <p>
+                <a id="reset" href="/">Reset CFI to None</a>
+                &nbsp;
+                Test viewport location calculation:
+                <input type="checkbox" id="viewport_mode" title=
+                "Checking this will cause the window to scroll to a position based on a CFI calculated for the windows current position."/>
+            </p>
             <h2>A div with scrollbars</h2>
             <p>Scroll down and click on some elements. Make sure to hit both
             bold and not bold text as well as different points on the image</p>