I am working on an application that plays videos through the silverlight MediaElement object.
I have a large method which is responsible for the following
Opens a FileInfo item on the local file path of the video and strips the file name to get the first portion of the filename which we use as part of the license acquisition process
Sets the LicenseAcquirer on the MediaElement
Sets the Source property of the MediaElement
When this method is called, it actually causes the application to go into a "Not reponding" state for a couple of seconds. How do I avoid this? I have tried putting this all into a background worker but I have to invoke the UI thread for almost all of the calls and this didnt help it seemed to actually make things slower.
I have a busy box that shows while this all happens but that actually stops reporting progress in those seconds where the application is not responding. I understand why this is happening - a lot of work happening on the main UI thread, but how do I avoid this?
This is the code that is causing the trouble:
private void SetupMediaElement(String mediaElementType)
{
Messenger.Default.Send("Loading video...", "SetNowWatchingVideoBusyBoxText");
Messenger.Default.Send(true, "SetNowWatchingVideoBusyBox");
try
{
if (_mainMediaElement != null)
{
VideoItem vi = CurrentSession.NowPlayingVideoItem;
if (vi != null)
{
CurrentVideoItem = vi;
MustShowImage = true;
if (vi.ID != string.Empty)
{
String mediaId = String.Empty;
if (vi.LocalFilePath != DEMOVIDEOPATH)
{
if (vi.LocalFilePath != String.Empty)
{
var fi =
new FileInfo(vi.LocalFilePath);
if (fi.Exists)
{
mediaId = fi.Name.Substring(fi.Name.LastIndexOf('-') + 1,
(fi.Name.LastIndexOf('.') -
(fi.Name.LastIndexOf('-') + 1)));
}
}
else
{
Debug.WriteLine("localFilePath is empty");
}
Debug.WriteLine("MediaId = " + mediaId +
", SessionId = " +
CurrentSession.LoggedOnUser.SessionId +
",Ticket = " +
CurrentSession.LoggedOnUser.Ticket);
string licenseURL = GetLicenseURL(mediaId, CurrentSession.LoggedOnUser.SessionId,
CurrentSession.LoggedOnUser.Ticket);
if (licenseURL != string.Empty)
{
var la = new LicenseAcquirer
{
LicenseServerUriOverride
=
new Uri(
licenseURL)
};
la.AcquireLicenseCompleted += la_AcquireLicenseCompleted;
_mainMediaElement.LicenseAcquirer = la;
}
var fileInfo = new FileInfo(vi.LocalFilePath);
string playURL = #"file://" +
Path.Combine(CoreConfig.HOME_FULL_PATH, fileInfo.Name);
playURL = playURL.Replace("\\", #"/");
VideoURL = playURL;
}
else
{
VideoURL = vi.LocalFilePath;
Messenger.Default.Send(false, "SetNowWatchingVideoBusyBox");
}
_totalDurationSet = false;
TotalTime = FormatTextHoursMinutesSecond(_mainMediaElement.NaturalDuration.TimeSpan);
SetSliderPosition();
}
}
else
{
Messenger.Default.Send(false, "SetNowWatchingVideoBusyBox");
}
}
else
{
Messenger.Default.Send(false, "SetNowWatchingVideoBusyBox");
}
}
catch (Exception ex)
{
Debug.WriteLine(ex);
VideoURL = DEMOVIDEOPATH;
Messenger.Default.Send(false, "SetNowWatchingVideoBusyBox");
}
}
Thanks
EDIT:
So it turns out that the method posted above is NOT the cause of the delay - that code executes in under a second. The problem comes in when the media element's source is set and it reads the file to the end - large files take time and this is the delay. Am opening a new question based on this.
You should do some diagnostics to determine which line(s) are truely costing all that time, its unlikely that amount of time is spread evenly across the whole function.
Place that line (or lines) in a background thread (hopefully that line doesn't need to be on the UI thread).
So it turns out that the method posted above is NOT the cause of the delay - that code executes in under a second. The problem comes in when the media element's source is set and it reads the file to the end - large files take time and this is the delay. Am opening a new question based on this.
Related
We are working on a windows application which caters to an engineering calculation which are essentially very long running. So we are basically trying to keep the calculation module separate and working in a separate worker thread and pass it an Action delegate in method signature which will be invoked to report the calculation progress in the UI. The delegate handler declared in the UI will be updating the UI. We found that while a huge loop is running in the calculation, the UI is not showing the periodic progress and only displaying the final result. If a Thread Sleep for 1 millisecond is introduced in the calculation loop, the UI is getting updated correctly. This is not expected behavior as we are executing the calculation using a separate Task and updating the UI using BeginInvoke calls.
I have created a simple application to demonstrate our approach and code so that it is easier to understand. It is obvious that we are missing something very simple but cannot quite pin it down. Will appreciate any insights.
Thanks for reading.
private void cmdStart_Click(object sender, EventArgs e)
{
txtResultDIsplay.Text = "";
var maxIterations = long.Parse(txtIterationNo.Text.Trim());
var ui = TaskScheduler.FromCurrentSynchronizationContext();
Task<double> calculationTask = Task.Factory.StartNew<double>(
() => SumRootN(maxIterations, UpdateProgress));
var handleResultTask = calculationTask.ContinueWith((t) => DisplayResult(t),
CancellationToken.None, TaskContinuationOptions.OnlyOnRanToCompletion, ui);
}
private void DisplayResult(Task<double> calculationTask)
{
txtResultDIsplay.Text = "Final Calculation Result : " + calculationTask.Result.ToString();
}
private void UpdateProgress(string msg)
{
this.BeginInvoke((MethodInvoker)delegate
{
txtResultDIsplay.Text = msg;
});
}
public double SumRootN(long maxIterations, Action<string> progressUpdateDelegate)
{
int root = 20;
double result = 0;
for (long i = 1; i < maxIterations; i++)
{
Thread.Sleep(1);
result += Math.Exp(Math.Log(i) / root);
progressUpdateDelegate(result.ToString("0.00000"));
}
return result;
}
It is possible you are flooding the UI thread with your progress updates. You need to find a way to prevent lots of updates occurring.
We can solve the problem using tasks!
Task progressTask = null;
private void UpdateProgress(string msg)
{
//only schedule work if the task if not running
if(progressTask == null || progressTask.IsCompleted) //updates will end if there is an exception!
{
//Create a task representing the update
progressTask = Task.Factory.FromAsync<object>(BeginInvoke(new Action(() => txtResultDIsplay.Text = msg)), this.EndInvoke)
.ContinueWith(() => System.Threading.Thread.Sleep(100)); //add a sleep on the end
}
}
Note that locking will not do here as you want to skip the update if there is already an update occurring.
hi im working on a project that uses invoke and threads.. it is a simple remote desktop program with chat.. i got a sample here on the internet in c# winform, but i would like to convert it to wpf.. i have no problem in sending message to another client using the wpf program but it cannot receive ( or cannot read) the sent messages from the others.. i think it has something to do with the thread and the invoke method, i read that wpf does invoke differently and i did try the dispatcher.invoke, but it still doesnt do the trick
pls hellp
here's the code
wait = new Thread(new ThreadStart(waitForData));
wait.Start();
that snippet above is executed when a successful connection is made in tcpclient
private void waitForData()
{
try
{
NetworkStream read = tcpclnt.GetStream();
while (read.CanRead)
{
byte[] buffer = new byte[64];
read.Read(buffer, 0, buffer.Length);
s = new ASCIIEncoding().GetString(buffer);
System.Console.WriteLine("Recieved data:" + new ASCIIEncoding().GetString(buffer));
rcvMsg = new ASCIIEncoding().GetString(buffer) + "\n";
hasNewData = true;
bool f = false;
f = rcvMsg.Contains("##");
bool comand = false;
comand = rcvMsg.Contains("*+*-");
/*File receive*/
if (f)
{
string d = "##";
rcvMsg = rcvMsg.TrimStart(d.ToCharArray());
int lastLt = rcvMsg.LastIndexOf("|");
rcvMsg = rcvMsg.Substring(0, lastLt);
NetworkStream ns = tcpclnt.GetStream();
if (ns.CanWrite)
{
string dataS = "^^Y";
byte[] bf = new ASCIIEncoding().GetBytes(dataS);
ns.Write(bf, 0, bf.Length);
ns.Flush();
}
try
{
new Recieve_File().recieve_file(rcvMsg);
}
catch (Exception ec)
{
System.Console.WriteLine(ec.Message);
}
}
/*Command-shutdown/restart/logoff*/
else if (comand)
{
string com = "*+*-";
rcvMsg = rcvMsg.TrimStart(com.ToCharArray());
execute_command(rcvMsg);
}
else
{
this.Invoke(new setOutput(setOut));
Thread.Sleep(1000);
}
}
}
catch (Exception ex)
{
wait.Abort();
output.Text += "Error..... " + ex.StackTrace;
}
}
the snippet above is a code that listens if there is a message or command.. the line
this.invoke(new setoutput(setout)) is a code for appending text in the rtb
hope someone could help me thanks
You've posted a lot of code, but I'm assuming it's only the call to Control.Invoke which is causing the problem. In WPF, use Dispatcher.Invoke (or Dispatcher.BeginInvoke) instead, via the Dispatcher property on the relevant UI element.
I'd also strongly encourage you to:
Refactor your code into smaller methods
Stop catching just Exception except at the top level of any large operation (it should just be a fall-back; usually you catch specific exceptions)
Start following .NET naming conventions
Add a using directive for System so you can just write Console.WriteLine instead of System.Console.WriteLine everywhere
Use Encoding.ASCII instead of creating a new ASCIIEncoding each time you need one
Use a StreamReader to read character data from a stream, instead of reading it as binary data first and then encoding it
For either Stream or TextReader, don't ignore the return value from Read - it tells you how many bytes or characters have been read
I am new to silverlight , and I am experimenting with wia scanner integration. I know usng WIA.CommonDialog , showacquireimage() I can retrieve an image from the scanner. I am trying to access the device directly and execute the scan command to avoid user interaction.
I am able to connect to the device. But the only command available from the scanner is synchronize. I am trying to use the ExecuteCommand on the device object, but I am not sure what command to use. Any direction will be appreciated.
using (dynamic DeviceManager1 = AutomationFactory.CreateObject("WIA.DeviceManager"))
{
var deviceInfos = DeviceManager1.DeviceInfos;
for(int i= 1;i<=deviceInfos.Count;i++)
{
//check if the device is a scanner
if (deviceInfos.Item(i).Type.ToString() == "1")
{
var IDevice = deviceInfos.Item(i).Connect();
deviceN.Text = IDevice.Properties("Name").Value.ToString();
var dv = IDevice.Commands;
for (int j = 0; j <= dv.Count; j++)
{
deviceN.Text += " " + dv.Item(i).CommandID.ToString() + " " + dv.Item(i).Description.ToString();
}
}
}
}
You don't really need to deal with the device commands to scan the document. Instead you need to use the first device item under the device object. Here is a little example which works in itself, without failure checks for easier readability.
//using WIA;
bool showProgressBar = false;
DeviceManager deviceManager = new DeviceManagerClass();
foreach(DeviceInfo info in deviceManager.DeviceInfos)
{
if(info.Type == WiaDeviceType.ScannerDeviceType)
{
Device device = info.Connect();
ImageFile imageFile = null;
Item deviceItem = null;
//Read through the list of items under the device...
foreach(Item item in device.Items)
{
//Pick the very first one!
deviceItem = item;
break;
}
if(showProgressBar == true)
{
//Scan without GUI, but display the progress bar dialog.
CommonDialogClass commonDialog = new CommonDialogClass();
imageFile = (ImageFile)commonDialog.ShowTransfer(deviceItem, FormatID.wiaFormatBMP, false);
}
else
{
//Scan without GUI, no progress bar displayed...
imageFile = (ImageFile)deviceItem.Transfer(FormatID.wiaFormatBMP);
}
imageFile.SaveFile("C:\\image.bmp");
}
}
Before scanning (but after you connected to the device item), you probably need to set various device properties to select the scanning resolution, color depth and other things if the defaults are not good enough for your needs.
Not long ago I made an easy to use class to operate WIA-compatible scanners, you can download it from this page... It's for .Net Framework 2.0, C#. Maybe it could come handy in your project, you would be done with a few lines of code including setting the basic properties. :)
Is there a way to update the print queue status information contained in the PrintQueue object?
I've tried calling Refresh on the PrintQueue object but that doesn't really do anything. For instance, I've turned off the printer and the Control Panel correctly shows the printer as "Offline", however the QueueStatus property, as well as the IsOffline property don't reflect that - no matter how many times I call Refresh on both the PrintServer and the PrintQueue in question.
I've seen examples of how to get status information using WMI queries but I wonder - since these properties are available on the PrintQueue object - whether there is any way to use those.
After try to print your PrintDocument (System.Drawing.Printing), try to check status of printjobs.
First step:
Initialize your printDocument.
Second step:
Get your printer Name From System.Drawing.Printing.PrinterSettings.InstalledPrinters.Cast<string>();
And copy it into your printerDocument.PrinterSettings.PrinterName
Third step:
Try to print and dispose.
printerDocument.Print();
printerDocument.Dispose();
Last step: Run the check in a Task (do NOT block UI thread).
Task.Run(()=>{
if (!IsPrinterOk(printerDocument.PrinterSettings.PrinterName,checkTimeInMillisec))
{
// failed printing, do something...
}
});
Here is the implementation:
private bool IsPrinterOk(string name,int checkTimeInMillisec)
{
System.Collections.IList value = null;
do
{
//checkTimeInMillisec should be between 2000 and 5000
System.Threading.Thread.Sleep(checkTimeInMillisec);
using (System.Management.ManagementObjectSearcher searcher = new System.Management.ManagementObjectSearcher("SELECT * FROM Win32_PrintJob WHERE Name like '%" + name + "%'"))
{
value = null;
if (searcher.Get().Count == 0) // Number of pending document.
return true; // return because we haven't got any pending document.
else
{
foreach (System.Management.ManagementObject printer in searcher.Get())
{
value = printer.Properties.Cast<System.Management.PropertyData>().Where(p => p.Name.Equals("Status")).Select(p => p.Value).ToList();
break;
}
}
}
}
while (value.Contains("Printing") || value.Contains("UNKNOWN") || value.Contains("OK"));
return value.Contains("Error") ? false : true;
}
Good luck.
This is a complex question, because there are a lot of moving parts. My apologies in advance.
I'm trying to write a Silverlight control that hosts a Flash camera and microphone (since Silverlight doesn't support these things natively, worse luck). I've written a short little Flex application ("WLocalWebCam.swf") which handles the camera, and exposes two external methods: connect(uri:String, streamName:String), and disconnect(). I can call these successfully through JavaScript as follows (simplified to remove error handling, etc.):
function connectWebCam(webCamID, rtmpUri, streamName) {
var flashCam = getWebCam(webCamID);
flashCam.Connect(rtmpUri, streamName);
}
function disconnectWebCam(webCamID) {
var flashCam = getWebCam(webCamID);
flashCam.Disconnect();
}
function getWebCam(id) {
return document.getElementById(id);
}
When I call these functions from another JavaScript source (e.g., a button click handler), the web cam connects correctly up to the RTMP server (I'm using Wowza). However, when I call exactly these same functions on the same page from Silverlight, the Flash camera fails to connect to the RTMP server.
/// <summary>
/// Connect() invokes the connectWebCam() JavaScript function contained in the WebCam.js file on the website.
/// The connectWebCam() method in turn calls the Connect() method on the contained Flash web cam object.
/// </summary>
public void Connect()
{
ScriptObject connectWebCam = (ScriptObject)HtmlPage.Window.GetProperty("connectWebCam");
connectWebCam.InvokeSelf(CameraID, RtmpUri.ToString(), CameraID);
}
However, it fails in an interesting fashion. The ActionScript connect() method gets called, it successfully calls getConnection(), but the handleNetStatus event handler method never gets called, and the Wowza server never sees an attempt to connect.
Here's the ActionScript code I'm using, this time with the debugging bits left in.
public function connect(uri:String, name:String):void
{
rtmpUri = uri;
streamName = name;
logMessage("Beginning attempt to open connection; rtmpUri=" + rtmpUri + "; streamName = " + streamName);
logMessage("Retrieving camera.");
cam = Camera.getCamera();
if( cam != null )
{
logMessage("Retrieved camera.");
cam.setMode( 320, 240, 20 );
cam.setQuality( 0,0 );
}
else
{
logMessage("Unable to retrieve camera instance.");
}
logMessage("Retrieving microphone.");
mic = new Microphone();
if (mic == null)
{
logMessage("Unable to retrieve microphone instance.");
}
logMessage("Retrieving NetConnection.");
chatNC = getConnection();
}
private function getConnection(): NetConnection
{
var nc: NetConnection = new NetConnection();
if (nc != null)
{
logMessage("Retrieved NetConnection().");
nc.client = this;
nc.objectEncoding = ObjectEncoding.AMF0;
nc.addEventListener( NetStatusEvent.NET_STATUS, this.handleNetStatus );
logMessage("Connecting to " + rtmpUri);
nc.connect(rtmpUri); // <-- We get successfully to this point.
}
else
{
logMessage("Unable to retrieve new NetConnection()");
}
return nc;
}
private function handleNetStatus( event:NetStatusEvent ):void
{
logMessage("[SYSTEM MESSAGE] net status " + event.info.code + " type " + event.type); // <-- We never get this far. This bit never gets called.
switch( event.info.code )
{
case "NetConnection.Connect.Success":
publishVideoStream();
break;
default:
Alert.show("Error connecting: " + event.info.code, "Error Connecting");
break;
}
}
This has got me seriously scratching my head.
Does anyone know why the exact same ActionScript would behave differently if called from Silverlight vs. being called from JavaScript? Any suggestions on troubleshooting it?
Sigh. Never mind. Turns out it makes a difference if you try to connect to http://localhost/videochat instead of rtmp://localhost/videochat. It all works as expected when you give it the right parameters. I must have looked at that code a hundred times before I spotted what I did wrong.