From 88767e18612b35fa2a8dfe6e00b1e55d26e00829 Mon Sep 17 00:00:00 2001
From: Rob Wu <gwnRob@gmail.com>
Date: Sun, 24 Mar 2013 18:25:57 +0100
Subject: [PATCH] Improve download button and behaviour

Fix download button for top frames and sub frames

When PDF.js is the top frame, and the PDF URL is identical to
the top URL, download would fail. Fixed by adding a ? or & in these
cases.

When PDF.js is embedded in a frame from a different origin, download
would fail because window.open(url, '_parent') is ignored.
Fixed by using a.click() when available.
a.click() works in Chrome 25, Firefox 19, Opera 12.00 and IE 8.
Safari 5.1 does not support a.click()

Use a.download if available + documentation
---
 web/viewer.js | 37 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 36 insertions(+), 1 deletion(-)

diff --git a/web/viewer.js b/web/viewer.js
index 4fc521459..bd65b37b0 100644
--- a/web/viewer.js
+++ b/web/viewer.js
@@ -1063,8 +1063,43 @@ var PDFView = {
     }
     var url = this.url.split('#')[0];
 //#if !(FIREFOX || MOZCENTRAL)
+
+    var a = document.createElement('a');
+
+    // 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 ? '?' : '&';
+    }
+
     url += '#pdfjs.action=download';
-    window.open(url, '_parent');
+    if (a.click) {
+      // Use a.click() if available. Otherwise, Chrome might show
+      // "Unsafe JavaScript attempt to initiate a navigation change
+      //  for frame with URL" and not open the PDF at all.
+      // Supported by (not mentioned = untested):
+      // - Firefox 6 - 19 (4- does not support a.click, 5 ignores a.click)
+      // - Chrome 19 - 26 (18- does not support a.click)
+      // - Opera 9 - 12.15
+      // - Internet Explorer 6 - 10
+      // - Safari 6 (5.1- does not support a.click)
+      a.href = url;
+      a.target = '_parent';
+      // Use a.download if available. This increases the likelihood that
+      // the file is downloaded instead of opened by another PDF plugin.
+      if ('download' in a) {
+        var filename = url.match(/([^\/?#=]+\.pdf)/i);
+        a.download = filename ? filename[1] : 'file.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 {
+      window.open(url, '_parent');
+    }
 //#else
 //  // Document isn't ready just try to download with the url.
 //  if (!this.pdfDocument) {