Added default behaviors

src/behaviors.js

+export default {
+  "handlers": {
+    "ptr": function(proto) {
+      let self = this;
+      proto.createdCallback = function() {
+        let shadow = this.createShadowRoot();
+        let link = document.createElement("a");
+        link.innerHTML = this.getAttribute("target");
+        link.href = self.rewriteRelativeUrl(this.getAttribute("target"));
+        shadow.appendChild(link);
+      }
+    },
+    "ref": function(proto) {
+      let self = this;
+      proto.createdCallback = function() {
+        let shadow = this.createShadowRoot();
+        let link = document.createElement("a");
+        link.innerHTML = this.innerHTML;
+        link.href = self.rewriteRelativeUrl(this.getAttribute("target"));
+        shadow.appendChild(link);
+      }
+    },
+    "graphic": function(proto) {
+      let self = this;
+      proto.createdCallback = function() {
+        let shadow = this.createShadowRoot();
+        let img = new Image();
+        img.src = self.rewriteRelativeUrl(this.getAttribute("url"));
+        if (this.hasAttribute("width")) {
+          img.width = this.getAttribute("width").replace(/[^.0-9]/g, "");
+        }
+        if (this.hasAttribute("height")) {
+          img.height = this.getAttribute("height").replace(/[^.0-9]/g, "");
+        }
+        shadow.appendChild(img);
+      }
+    }
+  },
+  "fallbacks": {
+    "ptr": function() {
+      let self = this;
+      let elts = dom.getElementsByTagName("tei-ptr");
+      for (let i = 0; i < elts.length; i++) {
+        let content = document.createElement("a");
+        let elt = elts[i];
+        content.setAttribute("href", elt.getAttribute("target"));
+        content.innerHTML = elt.getAttribute("target");
+        elt.appendChild(content);
+        elt.addEventListener("click", function(event) {
+          window.location = self.rewriteRelativeUrl(this.getAttribute("target"));
+        });
+      }
+    }, 
+    "ref": function() {
+      let self = this;
+      let elts = dom.getElementsByTagName("tei-ref");
+      for (let i = 0; i < elts.length; i++) {
+        elts[i].addEventListener("click", function(event) {
+          window.location = self.rewriteRelativeUrl(this.getAttribute("target"));
+        });
+      }
+    },
+    "graphic": function() {
+      let self = this;
+      let elts = dom.getElementsByTagName("tei-graphic");
+      for (let i = 0; i < elts.length; i++) {
+        let content = new Image();
+        let elt = elts[i];
+        content.src = self.rewriteRelativeUrl(this.getAttribute("url"));
+        if (elt.hasAttribute("width")) {
+          content.width = elt.getAttribute("width").replace(/[^.0-9]/g, "");
+        }
+        if (elt.hasAttribute("height")) {
+          content.height = elt.getAttribute("height").replace(/[^.0-9]/g, "");
+        }
+        elt.appendChild(content);
+      }
+    }
+  }
+}
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