1 files changed, 95 insertions, 0 deletions

diff --git a/js/preloader/PreloaderWorker.js b/js/preloader/PreloaderWorker.js
new file mode 100644
index 00000000..1b5b58ed
--- /dev/null
+++ b/js/preloader/PreloaderWorker.js
@@ -0,0 +1,95 @@
+/* <copyright>
+This file contains proprietary software owned by Motorola Mobility, Inc.<br/>
+No rights, expressed or implied, whatsoever to this software are provided by Motorola Mobility, Inc. hereunder.<br/>
+(c) Copyright 2011 Motorola Mobility, Inc.  All Rights Reserved.
+</copyright> */
+
+//PreloaderWorker makes the file downloading asynchronous. Preloader will continue to do script execution synchronously. PreloaderWorker allows script execution to start soon after the first download.
+//Note: File importing is probably not CPU intensive enough to run on a separate thread. But worth a test.
+//      Multi-threading will be more useful for math-intensive webGL or canvas calculations.
+
+self.onmessage = function(e){
+    var msgJson;
+    if(e && e.data){
+        msgJson = e.data;
+    }
+    //workerLog("worker received this: "+JSON.stringify(msgJson));
+    if(msgJson){
+        switch(msgJson.command){
+            case "start":
+                //workerLog('WORKER STARTED');
+                
+                downloadFiles(msgJson.jsFiles, msgJson.cssFiles, msgJson.baseUrl);
+                break;
+            case 'stop':
+              workerLog('WORKER STOPPED');
+              self.close(); // Terminates the worker.
+              break;
+            default:
+              workerLog('Unknown command');
+        }
+    }
+};
+
+ self.onerror = function(e){
+     workerLog("worker error: "+ e.message+" @file "+e.filename+" @line# "+e.lineno);
+     self.close(); // Terminates the worker.
+ }
+
+ var fileCounter  = 0;
+ var fileArrayLength = 0;
+
+ var xhrDownload = function(fileUrl, fileType, i){
+       var that = self,
+            req = new XMLHttpRequest();
+
+       if(fileType === "js"){
+            //workerLog("Worker will download: fileUrl="+fileUrl+" :: fileType="+fileType+" :: fileIndex="+i);
+            req.overrideMimeType && req.overrideMimeType("application/javascript");
+       }else if(fileType === "css"){
+            //workerLog("Worker will download: fileUrl="+fileUrl+" :: fileType="+fileType+" :: fileIndex="+i);
+            req.overrideMimeType && req.overrideMimeType("text/css");
+       }
+       req.onreadystatechange = function() {
+             if (req.readyState === 4) {
+                        if ((req.status === 200 || (req.status === 0 && req.responseText))) {
+                            fileCounter++;
+                            //workerLog("Status:"+req.status+" : fileUrl="+fileUrl+" :: fileIndex="+i);
+                            that.postMessage({command:"newFile", url:fileUrl, fileType:fileType, fileIndex:i, fileContent:req.responseText});
+
+                            //trying to clear some memory after last file is processed
+                            req.responseText = null;
+                            req = null;
+
+                            if(fileCounter === fileArrayLength){
+                                //workerLog("done downloading...shutting down this worker");
+                                that.close();
+                            }
+
+                        } else {
+                            workerLog("Status:"+req.status+" :: Unable to load "+fileUrl);
+                        }
+            }
+       }
+       req.open("GET", fileUrl, true);
+       req.send();
+}
+
+var downloadFiles = function(jsFiles, cssFiles, baseUrl){
+    var fileType, fileUrl;
+    fileArrayLength = jsFiles.concat(cssFiles).length;
+    for(var i=0;i<jsFiles.length;i++){
+        fileUrl = baseUrl + jsFiles[i].url;
+        fileType = jsFiles[i].type;
+        xhrDownload(fileUrl, fileType, i);
+    }
+    for(var j=0;j<cssFiles.length;j++){
+        fileUrl = baseUrl + cssFiles[j].url;
+        fileType = cssFiles[j].type;
+        xhrDownload(fileUrl, fileType, j);
+    }
+}
+
+ var workerLog = function(msg){
+     self.postMessage({command:"log", logMsg:msg});
+ }
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