templates: default: Add selection script

Shamelessly adapted from:

http://trilema.com/2015/that-spiffy-selection-thing

diff --git a/templates/default.lisp b/templates/default.lisp
index 1bb7435..16a9e01 100644 (file)
--- a/templates/default.lisp
+++ b/templates/default.lisp
@@ -1,6 +1,139 @@
 ;; Tarpit Lisp Blog Scaffolding -- default template
 ;;
 ;; TODO: Make a macro to obtain general forms such as the ones below
+
+(defconstant +js-selection+
+  "
+function findPos(obj) {
+  var curtop = 0;
+  while (obj && obj.offsetParent) {
+    curtop += obj.offsetTop; // todo: + webkit-transform
+    obj = obj.offsetParent;
+  }
+  return curtop;
+}
+var artificial = null;
+var prevhash = \"\";
+function scrollToHash() {
+  if (document.location.hash.replace(/^#/, \"\")==prevhash.replace(/^#/, \"\"))
+    return;
+  prevhash = document.location.hash;
+  if (document.location.hash.match(/#selection-[0-9.]+%/)) {
+    var p = parseFloat(document.location.hash.substring(1));
+    if (0 < p && p < 100 /*&& p%5 != 0*/) {
+      var content = document.getElementById(\"content\")
+      var y = findPos(content) + (content.offsetHeight)*p/100;
+      window.scrollTo(0, y-16);
+    }
+  }
+
+  var adr = document.location.hash.match(/#selection-(\\d+).(\\d+)-(\\d+).(\\d+)/);
+  if (adr) {
+    var pos=0,begin=null,end=null;
+    function recur(e) {
+      if (e.nodeType==1) pos = (pos&~1)+2;
+      if (e.nodeType==3) pos = pos|1;
+      if (pos==adr[1]) begin=[e, adr[2]];
+      if (pos==adr[3]) end  =[e, adr[4]];
+      for (var i=0; i<e.childNodes.length; i++)
+        recur(e.childNodes[i]);
+      if (e.childNodes.length>0 && e.lastChild.nodeType==3)
+        pos = (pos&~1)+2;
+    }
+    // remove old \"artificial\" span if any
+    if (artificial) {
+      artificial.previousSibling.data += artificial.childNodes[0].data;
+      artificial.parentNode.removeChild(artificial);
+    }
+    var content = document.getElementById(\"content\");
+    recur(content);
+    if (begin!=null && end!=null) {
+      // scroll to selection
+      if (begin[0].nodeType==3) {
+        var text = document.createTextNode(begin[0].data.substr(0, begin[1]));
+        artificial = document.createElement(\"SPAN\");
+        artificial.appendChild(document.createTextNode(begin[0].data.substr(begin[1])));
+
+        begin[0].parentNode.insertBefore(text, begin[0]);
+        begin[0].parentNode.replaceChild(artificial, begin[0]);
+
+        if (end[0]===begin[0])
+          end = [artificial.childNodes[0], end[1]-begin[1]];
+        begin = [artificial.childNodes[0], 0];
+        /* window.scrollTo(0, findPos(artificial)-8); */ artificial.scrollIntoView(true);
+      } else if (begin[0].nodeType==1) {
+        /* window.scrollTo(0, findPos(begin[0])-8);   */ begin[0].scrollIntoView(true);
+      }
+
+      if (window.getSelection) {
+        var sel = window.getSelection();
+        sel.removeAllRanges();
+        var range = document.createRange();
+        range.setStart(begin[0], begin[1]);
+        range.setEnd  (  end[0],   end[1]);
+        sel.addRange(range);
+      } else if (document.selection) { // IE
+      }
+    }
+  }
+}
+window.onhashchange = scrollToHash;
+var initScrollToHashDone = false;
+function initScrollToHash() {
+  if (!initScrollToHashDone) {
+    initScrollToHashDone = true;
+    scrollToHash();
+  }
+}
+window.onload = initScrollToHash;
+setTimeout(initScrollToHash, 500); /* onload can be delayed by counter code */
+
+//document.onselectionchange = /* only webkit has working document.onselectionchange */
+document.onmousedown = document.onmouseup = function(e) {
+  var newhash = \"\";
+  if (window.getSelection) {
+    var sel=window.getSelection();
+    if (!sel.isCollapsed) {
+      var pos=0,begin=[0,0],end=[0,0];
+      var range=sel.getRangeAt(0);
+      function recur(e) {
+        if (e===artificial) {
+          if (range.startContainer===e.childNodes[0]) begin=[pos, e.previousSibling.data.length+range.startOffset];
+          if (range.endContainer  ===e.childNodes[0]) end  =[pos, e.previousSibling.data.length+range.endOffset ];
+        } else {
+          if (e.nodeType==1) pos = (pos&~1)+2;
+          if (e.nodeType==3) pos = pos|1;
+          if (range.startContainer===e) begin=[pos, range.startOffset];
+          if (range.endContainer  ===e) end  =[pos, range.endOffset ];
+          for (var i=0; i<e.childNodes.length; i++)
+            recur(e.childNodes[i]);
+          if (e.childNodes.length>0 && e.lastChild.nodeType==3)
+            pos = (pos&~1)+2;
+        }
+      }
+
+      var content = document.getElementById(\"content\");
+      recur(content);
+      if (begin[0]>0 && end[0]>0) {
+        newhash = \"selection-\"+begin[0]+\".\"+begin[1]+\"-\"+end[0]+\".\"+end[1];
+      }
+    }
+  } else if (document.selection) { // IE
+  }
+
+  try {
+    var oldhash = location.hash.replace(/^#/, \"\");
+    if (oldhash != newhash) {
+      prevhash = newhash; /* avoid firing window.onhashchange and scrolling */
+      if (history.replaceState)
+        history.replaceState('', document.title, newhash==\"\" ? window.location.pathname : '#'+newhash);
+      else
+        location.hash = newhash;
+    }
+  } catch(e) {
+  }
+};")
+
 (defun tlbs-make-default (blist)
   (let* ((title (gethash "title" blist))
          (body (gethash "body" blist))
@@ -43,6 +176,8 @@
                  (:div :id "footer"
                   "Tarpit boringly generated by Common Lisp and tarpit-lbs; "
                    (:a :href "http://creativecommons.org/licenses/by-nc-sa/3.0/"
-                           "by-nc-sa")))))))))
+                           "by-nc-sa"))
+                 (:script :type "text/javascript"
+                          (cl-who:str +js-selection+)))))))))
     (setf (gethash "body" blist) new-body)
     blist))