allow enabling hypothesis by sending a message

felliott · felliott · commit 63ebf1a09221 · 2018-04-12T11:09:28.000-04:00
* The child frame now listens for `startHypothesis` events.  When
   received, it will inject the hypothesis client loader into the page
   and apply a class to the page body to move pdf.js action buttons to
   accomodate the H sidebar.  The start code will only be run once,
   subsequent attempts will do nothing.

   If the parent frame has loaded mfr.js, it can send the event by
   calling the `startHypothesis` method on the renderer class.  This
   will relay the event through pym.js.  If the parent frame has not
   loaded mfr.js, it may send the event via:

   `childIframe.contentWindow.postMessage('startHypothesis', parentDomain)`

   This feature must be enabled in MFR by setting the
   `PDF_EXTENSION_CONFIG_ENABLE_HYPOTHESIS` envvar to 1.
diff --git a/mfr/extensions/pdf/templates/viewer.mako b/mfr/extensions/pdf/templates/viewer.mako
@@ -37,15 +37,16 @@ http://sourceforge.net/adobe/cmap/wiki/License/
 
     <script src="debugger.js"></script>
     <script src="viewer.js"></script>
+
     % if enable_hypothesis:
-        <script src="https://hypothes.is/embed.js"></script>
-        <style>
-            #toolbarViewer {
-                position: relative;
-                margin-right: 36px;
-            }
-        </style>
+    <style>
+      body.show-hypothesis #toolbarViewer {
+        position: relative;
+        margin-right: 36px;
+      }
+    </style>
     % endif
+
   </head>
 
   <body tabindex="1" class="loadingInProgress">
diff --git a/mfr/server/static/js/mfr.child.js b/mfr/server/static/js/mfr.child.js
@@ -1,5 +1,6 @@
 ;(function() {
     'use strict';
+
     window.pymChild = new pym.Child();
 
     window.addEventListener('load', function () {
@@ -25,4 +26,27 @@
     window.pymChild.onMessage('resize', function () {
         window.pymChild.sendHeight();
     });
+
+    var hypothesisLoaded = false;
+
+    window.pymChild.onMessage('startHypothesis', startHypothesis);
+
+    window.addEventListener('message', function(event) {
+        if (event.data === 'startHypothesis') {
+            startHypothesis(event);
+        }
+    });
+
+    function startHypothesis(event) {
+        if (hypothesisLoaded) {
+            return;
+        }
+
+        var script = window.document.createElement('script');
+        script.type = 'text/javascript';
+        script.src = 'https://hypothes.is/embed.js';
+        window.document.head.appendChild(script);
+        window.document.body.classList.add('show-hypothesis');
+        hypothesisLoaded = true;
+    };
 })();
diff --git a/mfr/server/static/js/mfr.js b/mfr/server/static/js/mfr.js
@@ -111,6 +111,10 @@
             self.pymParent.sendMessage('resize', 'x');
         };
 
+        self.startHypothesis = function() {
+            self.pymParent.sendMessage('startHypothesis');
+        };
+
         return self;
     };
 
