Download PDF from cache for non-Firefox add-on

This feature relies on URL.createObjectURL, which is supported by
- Firefox 4
- Chrome 8
- Opera 15
- Internet Explorer 10

If the feature is missing, it falls back to downloading from the server.

The environment-specific code are put in ifdef's. Two methods are
defined:
- noData
  This function is used as a fallback in case of failure, it triggers
  a download directly from the server.
- triggerSaveAs(String url, optional String blob)
  This function attempts to show a Save As dialog for a given URL.
  It attempts to use the a.download attribute, if available, and
  falls back to window.open(<url>, '_parent') if unavailable.

See also http://caniuse.com/download

web/viewer.js

@@ -914,59 +914,55 @@ var PDFView = {
   },
 
   download: function pdfViewDownload() {
-    function noData() {
-      FirefoxCom.request('download', { originalUrl: url });
-    }
     var url = this.url.split('#')[0];
 //#if !(FIREFOX || MOZCENTRAL)
-
+    function noData() {
-    var a = document.createElement('a');
+      triggerSaveAs(url + '#pdfjs.action=download');
-
-    // If _parent == self, then opening an identical URL with different
-    // location hash will only cause a navigation, not a download.
-    if (window.top === window && !('download' in a) &&
-        url === window.location.href.split('#')[0]) {
-      url += url.indexOf('?') === -1 ? '?' : '&';
     }
+    function triggerSaveAs(url, blobUrl) {
+      // If blobUrl is not specified, fall back to non-blob url.
+      if (!blobUrl) blobUrl = url;
 
-    url += '#pdfjs.action=download';
+      var a = document.createElement('a');
-    if (a.click) {
+      if (a.click) {
-      // Use a.click() if available. Otherwise, Chrome might show
+        // Use a.click() if available. Otherwise, Chrome might show
-      // "Unsafe JavaScript attempt to initiate a navigation change
+        // "Unsafe JavaScript attempt to initiate a navigation change
-      //  for frame with URL" and not open the PDF at all.
+        //  for frame with URL" and not open the PDF at all.
-      // Supported by (not mentioned = untested):
+        // Supported by (not mentioned = untested):
-      // - Firefox 6 - 19 (4- does not support a.click, 5 ignores a.click)
+        // - Firefox 6 - 19 (4- does not support a.click, 5 ignores a.click)
-      // - Chrome 19 - 26 (18- does not support a.click)
+        // - Chrome 19 - 26 (18- does not support a.click)
-      // - Opera 9 - 12.15
+        // - Opera 9 - 12.15
-      // - Internet Explorer 6 - 10
+        // - Internet Explorer 6 - 10
-      // - Safari 6 (5.1- does not support a.click)
+        // - Safari 6 (5.1- does not support a.click)
-      a.href = url;
+        a.href = blobUrl;
-      a.target = '_parent';
+        a.target = '_parent';
-      // Use a.download if available. This increases the likelihood that
+        // Use a.download if available. This increases the likelihood that
-      // the file is downloaded instead of opened by another PDF plugin.
+        // the file is downloaded instead of opened by another PDF plugin.
-      if ('download' in a) {
+        if ('download' in a) {
-        var filename = url.match(/([^\/?#=]+\.pdf)/i);
+          var filename = url.match(/([^\/?#=]+\.pdf\b)(?!.*\.pdf\b)/i);
-        a.download = filename ? filename[1] : 'file.pdf';
+          a.download = filename ? filename[1] : 'document.pdf';
+        }
+        // <a> must be in the document for IE and recent Firefox versions.
+        // (otherwise .click() is ignored)
+        (document.body || document.documentElement).appendChild(a);
+        a.click();
+        a.parentNode.removeChild(a);
+      } else {
+        if (window.top === window &&
+            blobUrl.split('#')[0] === window.location.href.split('#')[0]) {
+          // If _parent == self, then opening an identical URL with different
+          // location hash will only cause a navigation, not a download.
+          var padCharacter = blobUrl.indexOf('?') === -1 ? '?' : '&';
+          blobUrl = blobUrl.replace(/#|$/, padCharacter + '$&');
+        }
+        window.open(blobUrl, '_parent');
       }
-      // <a> must be in the document for IE and recent Firefox versions.
-      // (otherwise .click() is ignored)
-      (document.body || document.documentElement).appendChild(a);
-      a.click();
-      a.parentNode.removeChild(a);
-    } else {
-      window.open(url, '_parent');
     }
 //#else
-//  // Document isn't ready just try to download with the url.
+//  function noData() {
-//  if (!this.pdfDocument) {
+//    FirefoxCom.request('download', { originalUrl: url });
-//    noData();
-//    return;
 //  }
-//  this.pdfDocument.getData().then(
+//  function triggerSaveAs(url, blobUrl) {
-//    function getDataSuccess(data) {
-//      var blob = PDFJS.createBlob(data.buffer, 'application/pdf');
-//      var blobUrl = window.URL.createObjectURL(blob);
-//
 //      FirefoxCom.request('download', { blobUrl: blobUrl, originalUrl: url },
 //        function response(err) {
 //          if (err) {
@@ -977,10 +973,23 @@ var PDFView = {
 //          window.URL.revokeObjectURL(blobUrl);
 //        }
 //      );
-//    },
+//  }
-//    noData // Error occurred try downloading with just the url.
-//  );
 //#endif
+    var URL = window.URL || window.webkitURL;
+    // If the PDF is not ready yet, or if createObjectURL is not supported,
+    // just try to download with the url.
+    if (!this.pdfDocument || !URL) {
+        noData();
+        return;
+    }
+    this.pdfDocument.getData().then(
+      function getDataSuccess(data) {
+        var blob = PDFJS.createBlob(data.buffer, 'application/pdf');
+        var blobUrl = URL.createObjectURL(blob);
+        triggerSaveAs(url, blobUrl);
+      },
+      noData // Error occurred try downloading with just the url.
+    );
   },
 
   fallback: function pdfViewFallback() {