find the biggest canvas on the page

1 files changed, 6 insertions, 2 deletions

diff --git a/js/record.concat.js b/js/record.concat.js
index e54b223..f4d06f4 100644
--- a/js/record.concat.js
+++ b/js/record.concat.js
@@ -911,8 +911,12 @@ function GifEncoder(){
 
   var canvases = document.getElementsByTagName("canvas")
   if (canvases.length == 0) { alert("no canvas found"); return; }
-
-  var source = canvases[0]
+  var biggest = 0, biggest_area = 0;
+  for (var i in canvases) {
+    var area = canvases[i].width*canvases[i].height
+    if (area > biggest_area) biggest = i;
+  }
+  var source = canvases[biggest]
 
   var encoder = new GifEncoder()
   encoder.on("encoded-frame", encoded_frame)