Added task queue

index.js

@@ -28,14 +28,172 @@ var barcodeTypes = formats.OneD | formats.PDF417 | formats.QRCode | formats.Data
 // Please visit https://www.dynamsoft.com/CustomerPortal/Portal/Triallicense.aspx or contact [email protected] to get a valid trial or full license.
 dbr.initLicense(license);
 
+/*
+ * https://github.com/Keillion/www.keillion.site/blob/v0/js/task-queue.js
+ */
+var TaskQueue = function(){
+    /// <summary>
+    /// @class TaskQueue
+    /// </summary>
+
+    this._queue = [];
+    this.isWorking = false;
+
+    /// <param name="timeout" type="int">
+    /// Timeout between task.
+    /// Between the interval, other work can be done, such as UI-response work.
+    /// </param>
+    this.timeout = 100;
+};
+
+TaskQueue.prototype.push = function(task, context, args, handleReturn){
+    /// <summary>
+    /// Push task. If <span>!isWorking</span>, start the task queue automatically.
+    /// </summary>
+
+    this._queue.push({
+        "task": task,
+        "context": context,
+        "args": args,
+        "handleReturn": handleReturn
+    });
+    if(!this.isWorking){
+        this.next();
+    }
+};
+
+TaskQueue.prototype.unshift = function(task, context, args, handleReturn){
+    /// <summary>
+    /// Push task. If <span>!isWorking</span>, start the task queue automatically.
+    /// </summary>
+
+    this._queue.unshift({
+        "task": task,
+        "context": context,
+        "args": args,
+        "handleReturn": handleReturn
+    });
+    if(!this.isWorking){
+        this.next();
+    }
+};
+
+TaskQueue.prototype.next = function(){
+    /// <summary>
+    /// Do the next task.
+    /// You need to call it manually in the end of your task.
+    /// To assure <function>next</function> will be called,
+    /// in some case you can put the function in <span>finally</span>,
+    /// in other case you should carefully handle <span>setTimeout</span>.
+    /// </summary>
+
+    if(this._queue.length == 0){
+        this.isWorking = false;
+        return;
+    }
+    this.isWorking = true;
+    var item = this._queue.shift();
+    var task = item.task;
+    var taskContext = item.context ? item.context : null;
+    var taskArguments = item.args ? item.args : [];
+    var handleReturn = item.handleReturn;
+    setTimeout(function(){
+        var ret = task.apply(taskContext, taskArguments);
+        if(typeof handleReturn == 'function'){
+            handleReturn(ret);
+        }
+    }, this.timeout);
+};
+
+/*
+TaskQueue.test = function(){
+    var taskQueue = new TaskQueue();
+    var task = function(mess){
+        console.log(mess);
+        taskQueue.next();
+    };
+    for(var i = 0; i < 100; ++i){
+        taskQueue.push(task, null, [i]);
+    }
+};*/
+
+
+
+
+
+
+var dbrTaskQueue = new TaskQueue();
+dbrTaskQueue.timeout = 0;
 module.exports = {
-    decodeFileAsync: dbr.decodeFileAsync,
-    decodeFileStreamAsync: dbr.decodeFileStreamAsync,
-    decodeBase64Async: dbr.decodeBase64Async,
-    decodeYUYVAsync: dbr.decodeYUYVAsync,
+    decodeFileAsync: function(){
+        var callback = arguments[2];
+        arguments[2] = function(){
+            try{
+                callback.apply(this, arguments);
+            }catch(ex){
+                setTimeout(function(){throw ex;},0); // when the user defined callback throw err, taskqueue can still work
+            }
+            dbrTaskQueue.next();
+        };
+        dbrTaskQueue.push(dbr.decodeFileAsync, null, Array.from(arguments));
+    },
+    decodeFileStreamAsync: function(){
+        var callback = arguments[3];
+        arguments[3] = function(){
+            try{
+                callback.apply(this, arguments);
+            }catch(ex){
+                setTimeout(function(){throw ex;},0); // when the user defined callback throw err, taskqueue can still work
+            }
+            dbrTaskQueue.next();
+        };
+        dbrTaskQueue.push(dbr.decodeFileStreamAsync, null, Array.from(arguments));
+    },
+    decodeBase64Async: function(){
+        var callback = arguments[2];
+        arguments[2] = function(){
+            try{
+                callback.apply(this, arguments);
+            }catch(ex){
+                setTimeout(function(){throw ex;},0); // when the user defined callback throw err, taskqueue can still work
+            }
+            dbrTaskQueue.next();
+        };
+        dbrTaskQueue.push(dbr.decodeBase64Async, null, Array.from(arguments));
+    },
+    decodeYUYVAsync: function(){
+        var callback = arguments[4];
+        arguments[4] = function(){
+            try{
+                callback.apply(this, arguments);
+            }catch(ex){
+                setTimeout(function(){throw ex;},0); // when the user defined callback throw err, taskqueue can still work
+            }
+            dbrTaskQueue.next();
+        };
+        dbrTaskQueue.push(dbr.decodeYUYVAsync, null, Array.from(arguments));
+    },
     formats: formats,
     initLicense: dbr.initLicense,
     barcodeTypes: barcodeTypes,
     setParameters: dbr.setParameters,
-    decodeBufferAsync: dbr.decodeBufferAsync
+    decodeBufferAsync: function(){
+        maxBufferLength = 1
+        if (arguments.length == 8) {
+            maxBufferLength = arguments[7]
+        }
+
+        if (dbrTaskQueue._queue.length > maxBufferLength) return; 
+
+        var callback = arguments[5];
+        arguments[5] = function(){
+            try{
+                callback.apply(this, arguments);
+            }catch(ex){
+                setTimeout(function(){throw ex;},0); // when the user defined callback throw err, taskqueue can still work
+            }
+            dbrTaskQueue.next();
+        };
+        dbrTaskQueue.push(dbr.decodeBufferAsync, null, Array.from(arguments));
+    },
 };