Preliminary SVG-edit Support

WYSIWYG SVG editing.

Still no support for mixed
SVG/MathML content, yet.

public/javascripts/page_helper.js

@@ -71,6 +71,69 @@ function addS5button(page_name) {
   }
 }
 
+function setupSVGedit(path){
+  var f = $('MarkupHelp');
+  var selected;
+  var before;
+  var after;
+// create a control button
+  if (f) {
+    var SVGeditButton = new Element('input', {id:'SVGeditButton', type:'button', value: 'Create an SVG graphic'});
+    f.insert({top: SVGeditButton});
+    SVGeditButton.disabled = true;
+    Event.observe(SVGeditButton, 'click', function(){
+      if (selected) {
+         var editor = window.open(path +'?source=data:image/svg+xml;base64,' + window.btoa(selected), 'Spoons!');
+      } else {
+         var editor = window.open(path, 'Spoons!');      
+      }
+    });
+  }   
+  var t = $('content');
+  
+  var callback = function(){
+// This is triggered by 'onmouseup' events
+    var sel = window.getSelection();
+    var a = sel.anchorOffset;
+    var f = sel.focusOffset;
+// A bit of ugliness, because Gecko-based browsers
+// don't support getSelection in textareas
+    if (t.selectionStart ) {
+      var begin = t.selectionStart;
+      var end = t.selectionEnd;
+    } else {
+      if( a < f) {
+        begin = a;
+        end = f;
+      } else {
+        begin = f;
+        end = a;
+      }
+    }
+// finally, slice up the textarea content into before, selected, & after pieces
+    before = t.value.slice(0, begin);
+    selected = t.value.slice(begin, end);
+    after = t.value.slice(end, t.value.length-1);
+    if (selected && selected != '') {
+      if ( selected.match(/^<svg(.|\n)*<\/svg>$/) ) {
+        SVGeditButton.disabled = false;
+        SVGeditButton.value = 'Edit existing SVG graphic';
+      } else {
+        SVGeditButton.disabled = true;
+      }
+    } else {
+      SVGeditButton.disabled = false;
+      SVGeditButton.value = 'Create SVG graphic';      
+    }
+  }
+  Event.observe(t, 'mouseup', callback );
+  var my_loc = window.location.protocol + '//' + window.location.host;
+  Event.observe(window, "message", function(event){
+    if(event.origin !== my_loc) { return;}
+    t.value = before + event.data + after;
+  });  
+}
+
 function updateSize(elt, w, h) {
    // adjust to the size of the user's browser area.
    // w and h are the original, unadjusted, width and height per row/column