Merge pull request #4962 from yurydelendik/issue-4943

Increases page cache size when needed

web/ui_utils.js

@@ -255,5 +255,11 @@ var Cache = function cacheCache(size) {
       data.shift().destroy();
     }
   };
+  this.resize = function (newSize) {
+    size = newSize;
+    while (data.length > size) {
+      data.shift().destroy();
+    }
+  };
 };
 

web/viewer.js

@@ -28,7 +28,7 @@ var DEFAULT_URL = 'compressed.tracemonkey-pldi-09.pdf';
 var DEFAULT_SCALE = 'auto';
 var DEFAULT_SCALE_DELTA = 1.1;
 var UNKNOWN_SCALE = 0;
-var CACHE_SIZE = 10;
+var DEFAULT_CACHE_SIZE = 10;
 var CSS_UNITS = 96.0 / 72.0;
 var SCROLLBAR_PADDING = 40;
 var VERTICAL_PADDING = 5;
@@ -91,7 +91,7 @@ var mozL10n = document.mozL10n || document.webL10n;
 //#include chromecom.js
 //#endif
 
-var cache = new Cache(CACHE_SIZE);
+var cache = new Cache(DEFAULT_CACHE_SIZE);
 var currentPageNumber = 1;
 
 //#include view_history.js
@@ -1964,6 +1964,10 @@ function updateViewarea() {
     return;
   }
 
+  var suggestedCacheSize = Math.max(DEFAULT_CACHE_SIZE,
+      2 * visiblePages.length + 1);
+  cache.resize(suggestedCacheSize);
+
   PDFView.renderHighestPriority(visible);
 
   var currentId = PDFView.page;