Here is my code -
public partial class MainWindow : Window
{
ConcurrentDictionary<int,BitmapSource> Cache = new ConcurrentDictionary<int,BitmapSource>(5, 199);
int width = 720;
int height = 480;
int stride = (width * 3 / 4 ) * 4 + 4;
int currentframe = 0;
public MainWindow()
{
InitializeComponent();
Thread t = new Thread(() =>
{
while (true)
{
for (int i = -9; i < 9; i++)
{
if (!Cache.ContainsKey(currentframe + i))
{
RenderFrameToCache(currentframe + i);
}
}
Thread.Sleep(500);
}
});
t.Start();
}
private object locker = new object();
private void RenderFrameToCache(int frame)
{
byte[] pixels;
//Create byte array
BitmapSource img = BitmapSource.Create(width, height, 96, 96, PixelFormats.Bgr24, null, pixels, stride);
Cache.AddOrUpdate(frame, img, (x,y) => img);
}
private BitmapSource GetBmpSource(int frame)
{
if (Cache.ContainsKey(frame))
{
return Cache[frame];
}
else
{
RenderFrameToCache(frame);
return Cache[frame];
}
}
private void TextBox_LostFocus(object sender, RoutedEventArgs e)
{
Cache.Clear();
image.Source = new BitmapImage();
}
private void Button_Click(object sender, RoutedEventArgs e)
{
currentframe++;
image.Source = GetBmpSource(currentframe);
}
private void Button_Click_1(object sender, RoutedEventArgs e)
{
currentframe--;
image.Source = GetBmpSource(currentframe);
}
}
The second thread is supposed to fill the dictionary with items so that they are on hand when the Window wants to display them.
Whenever a button is pressed, there is an InvalidOperationException. What is the problem?
Use thread safe ConcurrentDictionary.
From MSDN:
All these operations [TryAdd, TryUpdate, ...] are atomic and are thread-safe with regards to
all other operations on the ConcurrentDictionary class.
[...] For modifications and write operations to the dictionary,
ConcurrentDictionary uses fine-grained locking to ensure
thread safety. (Read operations on the dictionary are performed in a
lock-free manner.)
I solved the problem.
I had to use BitmapSource.Freeze each time I added a new BitmapSource.
This link is what explained it - Multi threading in WPF using C# (with background worker)
Related
this is just a simplified version of what I am trying to do
public partial class MainWindow : Window
{
private CancellationTokenSource tokenSource = new CancellationTokenSource();
public MainWindow()
{
InitializeComponent();
PrintButtonText("None");
}
private void PrintButtonText(string buttonText)
{
Console.WriteLine("Update!");
Task.Factory.StartNew(() =>
{
while (!tokenSource.Token.IsCancellationRequested)
{
Console.WriteLine("Button Pressed Text: " + buttonText);
}
}, tokenSource.Token);
}
private void Button1_Click(object sender, RoutedEventArgs e)
{
tokenSource.Cancel();
PrintButtonText("Button1");
}
private void Button2_Click(object sender, RoutedEventArgs e)
{
tokenSource.Cancel();
PrintButtonText("Button2");
}
}
After I do
tokenSource.Cancel();
PrintButtonText("Button1");
It's not able to start the task again and continue to print my line. I need it to work this way for my program.
I want to stop the thread and start it again with some different parameters. How can I achieve this? thanks
EDIT:
Since I didn't get a solution with my simplified version, here is full code and what I am trying to do. Basically, on wpf window camera rendering starts on start. There is a button to start saving to file, but in order to save I have to update the config and start "pipeline" again.
public partial class MainWindow : Window
{
private Pipeline pipeline = new Pipeline(); // Create and config the pipeline to sream color and depth frames.
private CancellationTokenSource tokenSource = new CancellationTokenSource();
private bool saveDataToFile = false;
public MainWindow()
{
InitializeComponent();
}
private void Window_Loaded(object sender, RoutedEventArgs e)
{
Config cfg = SetupConfig(false);
PipelineProfile pp = pipeline.Start(cfg);
StartRenderFrames(pp);
}
private void StartRenderFrames(PipelineProfile pp)
{
Colorizer colorizer = new Colorizer(); // The colorizer processing block used to visualize the depth frames.
// Allocate bitmaps for rendring. Since the sample aligns the depth frames to the color frames, both of the images will have the color resolution
using (var p = pp.GetStream(Stream.Color) as VideoStreamProfile)
{
imgColor.Source = new WriteableBitmap(p.Width, p.Height, 96d, 96d, PixelFormats.Rgb24, null);
imgDepth.Source = new WriteableBitmap(p.Width, p.Height, 96d, 96d, PixelFormats.Rgb24, null);
}
Action<VideoFrame> updateColor = UpdateImage(imgColor);
Action<VideoFrame> updateDepth = UpdateImage(imgDepth);
Task.Factory.StartNew(() =>
{
while (!tokenSource.Token.IsCancellationRequested)
{
// Wait for the next available FrameSet
using (var frames = pipeline.WaitForFrames())
{
var colorFrame = frames.ColorFrame.DisposeWith(frames);
var depthFrame = frames.DepthFrame.DisposeWith(frames);
// We colorize the depth frame for visualization purposes, .
var colorizedDepth = colorizer.Process(depthFrame).DisposeWith(frames);
// Render the frames.
Dispatcher.Invoke(DispatcherPriority.Render, updateDepth, colorizedDepth);
Dispatcher.Invoke(DispatcherPriority.Render, updateColor, colorFrame);
}
}
}, tokenSource.Token);
}
private Config SetupConfig(bool saveDepthFile)
{
Config cfg = new Config();
cfg.EnableStream(Stream.Depth, 640, 480, framerate: 15);
cfg.EnableStream(Stream.Color, 640, 480, format: Format.Rgb8, framerate: 15);
if (saveDepthFile)
{
cfg.EnableRecordToFile(#"C:\temp\My_test111.bag");
}
return cfg;
}
static Action<VideoFrame> UpdateImage(Image img)
{
var wbmp = img.Source as WriteableBitmap;
return new Action<VideoFrame>(frame =>
{
using (frame)
{
var rect = new Int32Rect(0, 0, frame.Width, frame.Height);
wbmp.WritePixels(rect, frame.Data, frame.Stride * frame.Height, frame.Stride);
}
});
}
private void StartSaving_Button_Click(object sender, RoutedEventArgs e)
{
tokenSource.Cancel();
pipeline.Stop();
// This is where I have a problem. Rendering thread does not stop before I want to start again.
Config cfg = SetupConfig(true);
PipelineProfile pp = pipeline.Start(cfg);
StartRenderFrames(pp);
}
}
You should use Microsoft's Reactive Framework (aka Rx) - NuGet System.Reactive.Windows.Forms and add using System.Reactive.Linq; - then you can do this:
private void Form1_Load(object sender, EventArgs e)
{
IObservable<string> button1Clicks =
Observable
.FromEventPattern<EventHandler, EventArgs>(h => button1.Click += h, h => button1.Click -= h)
.Select(ep => "Button1");
IObservable<string> button2Clicks =
Observable
.FromEventPattern<EventHandler, EventArgs>(h => button2.Click += h, h => button2.Click -= h)
.Select(ep => "Button2");
IDisposable subscription =
button1Clicks
.Merge(button2Clicks)
.StartWith("None")
.Select(x => Observable.Timer(TimeSpan.Zero, TimeSpan.FromMilliseconds(500.0)).Select(n => x))
.Switch()
.ObserveOn(this)
.Subscribe(x => Console.WriteLine(x));
}
That's the entire code needed to make what you want to work.
The only thing that you need to do is move subscription out into a private field and then simply call subscription.Dispose() to shut this all down.
This is much simpler than messing with cancellation tokens.
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
int currentProgress=-1;
while (currentProgress<length)
{
currentProgress=Worker.progress;
backgroundWorker1.ReportProgress(currentProgress);
Thread.Sleep(500);
length = Worker.UrlList.Count;
}
}
private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
int ix = e.ProgressPercentage;
progressBar1.Value = ix;
lblText.Text =ix+" %";
}
I wrote a program to download page sources by reading a file have about 1000 URLs. so I used Tasks to download pages async. here Worker.progress is the currently executed URL amount. though the debuger hits the backgroundWorker1.ReportProgress(currentProgress); it never enter to the backgroundWorker1_ProgressChanged.
private void StartButton_Click(object sender, EventArgs e)
{
t.makeUrlList(inputFile);
backgroundWorker1 = new BackgroundWorker();
backgroundWorker1.WorkerReportsProgress = true;
backgroundWorker1.DoWork += backgroundWorker1_DoWork;
backgroundWorker1.ProgressChanged += backgroundWorker1_ProgressChanged;
backgroundWorker1.RunWorkerAsync();
t.RunTasks();
Application.Exit();
}
background worker initializes when start button clicks...
here is where my tasks are created....
public void RunTasks()
{
if (numOfTasks > UrlList.Count)
numOfTasks=UrlList.Count-1;
Task[] t = new Task[numOfTasks];
int j = 0;
while ( j < UrlList.Count-1)
{
for (int i = 0; (i < t.Count())&&(j<UrlList.Count-1); i++)
{
try
{
if (t[i].IsCompleted || t[i].IsCanceled || t[i].IsFaulted)
{
t[i] = Task.Run(() => FindWIN(j));
j++;
progress = j;
}
}
catch (NullReferenceException ex)
{
t[i] = Task.Run(() => FindWIN(j));
j++;
progress = j;
}
}
}
}
If you want to BackgroundWorker supports updating progress information, the value of WorkerReportsProgress should be set to true . If this property is true , the user code can call ReportProgress for initiating event ProgressChanged .
Background worker initialization:-
backgroundWorker1 = new BackgroundWorker();
backgroundWorker1.WorkerReportsProgress = true;
backgroundWorker1.DoWork+=backgroundWorker1_DoWork;
backgroundWorker1.ProgressChanged+=backgroundWorker1_ProgressChanged;
backgroundWorker1.RunWorkerAsync();
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
int currentProgress = -1;
decimal length=1000;
while (currentProgress < length)
{
currentProgress = Worker.progress;
backgroundWorker1.ReportProgress(currentProgress);
Thread.Sleep(500);
length = Worker.UrlList.Count;
}
}
private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e) {
int ix = e.ProgressPercentage;
progressBar1.Value = ix;
lblText.Text = ix + " %";
}
See the demo code below. This is mostly untested, and certainly isn't 'production standard', but it should give you a good start!
It uses a ConcurrentQueue to hold the list of URLs to be processed. This is threadsafe, and makes life a lot easier.
It has a configurable number of urls and tasks. It's best not to make 1000 tasks, but instead have a queue of work items, and a smaller pool of Tasks which 'pull items' off the queue until it's empty. This means you can performance test different numbers of Tasks and find the best value for your problem.
It uses Invoke when updating the progress bar - this avoids the cross-thread exception.
No BackgroundWorker - just TaskFactory and Task
public partial class Form1 : Form
{
private const int UrlCount = 1000;
private const int taskCount = 10;
private ConcurrentQueue<string> urlList;
private List<Task> taskList;
public Form1()
{
InitializeComponent();
}
private void ResetQueue()
{
// fake up a number of strings to process
urlList = new ConcurrentQueue<string>(Enumerable.Range(0, UrlCount)
.Select(i => "http://www." + Guid.NewGuid().ToString() + ".com"));
}
private void button1_Click(object sender, EventArgs e)
{
ResetQueue();
var taskFactory = new TaskFactory();
// start a bunch of tasks
taskList = Enumerable.Range(0, taskCount).Select(i => taskFactory.StartNew(() => ProcessUrl()))
.ToList();
}
void ProcessUrl()
{
string current;
// keep grabbing items till the queue is empty
while (urlList.TryDequeue(out current))
{
// run your code
FindWIN(current);
// invoke here to avoid cross thread issues
Invoke((Action)(() => UpdateProgress()));
}
}
void FindWIN(string url)
{
// your code here
// as a demo, sleep a sort-of-random time between 0 and 100 ms
Thread.Sleep(Math.Abs(url.GetHashCode()) % 100);
}
void UpdateProgress()
{
// work out what percentage of the queue is processed
progressBar1.Value = (int)(100 - ((double)urlList.Count * 100.0 / UrlCount));
}
}
You should set WorkerReportsProgress property of your worker to true on initialization stage.
I have four PictureBoxes (each PictureBox represents one dice) and a Timer that changes every 100ms source pictures (loaded in memory as List<Bitmap> imagesLoadedFromIncludedResources).
Code:
private List<PictureBox> dices = new List<PictureBox>();
private void timer_diceImageChanger_Tick(object sender, EventArgs e)
{
foreach (PictureBox onePictureBox in dices)
{
oneDice.WaitOnLoad = false;
onePictureBox.Image = //... ;
oneDice.Refresh();
}
}
I need to change all the images at once - at this moment, you can see that the images are changing from left to right with a small delay.
I tried variant with one Thread for each PictureBox (using Control.Invoke method from this answer) - it is visually little better but not perfect.
You can try to suspend form's layout logic:
SuspendLayout();
// set images to pictureboxes
ResumeLayout(false);
Parallel.ForEach
(
dices,
new ParallelOptions { MaxDegreeOfParallelism = 4 },
(dice) =>
{
dice.Image = ...;
dice.WaitOnLoad = false;
dice.Refresh();
}
);
The problem is that UI controls can only be accessed from the UI thread. If you want to use this approach, you must create a copy of your PictureBoxes and then replace the UI ones once the operation is done.
Another approach would be creating two PictureBoxes, with the first one just on the top of the other one (hiding the latter)... you change all the images and then, once the processing is complete, you iterate all the ones in the back putting them on the top which would result in a lesser delay.
I'd approach this differently - it's been a while since I've played with WinForms stuff, but I'd probably take more control over the rendering of the images.
In this example I've got the images all in one source bitmap stacked vertically, stored as a resource in assembly:
namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
private Timer timer;
private Bitmap dice;
private int[] currentValues = new int[6];
private Random random = new Random();
public Form1()
{
InitializeComponent();
this.timer = new Timer();
this.timer.Interval = 500;
this.timer.Tick += TimerOnTick;
this.dice = Properties.Resources.Dice;
}
private void TimerOnTick(object sender, EventArgs eventArgs)
{
for (var i = 0; i < currentValues.Length; i++)
{
this.currentValues[i] = this.random.Next(1, 7);
}
this.panel1.Invalidate();
}
private void button1_Click(object sender, EventArgs e)
{
if (this.timer.Enabled)
{
this.timer.Stop();
}
else
{
this.timer.Start();
}
}
private void panel1_Paint(object sender, PaintEventArgs e)
{
e.Graphics.Clear(Color.White);
if (this.timer.Enabled)
{
for (var i = 0; i < currentValues.Length; i++)
{
e.Graphics.DrawImage(this.dice, new Rectangle(i * 70, 0, 60, 60), 0, (currentValues[i] - 1) * 60, 60, 60, GraphicsUnit.Pixel);
}
}
}
}
}
The source is here if it helps: http://sdrv.ms/Wx2Ets
I have a bit strange problem, which I find hard to debug
Sometimes I can't close my program and it freezes when I try to close it.
I made a large program for video image recognition.
I made a special button to close the camera. This button works with this by calling a function below, and it indeed, it does work.
private void exitcamera()
{
FinalVideo.SignalToStop();
FinalVideo.WaitForStop();
FinalVideo = null;
}
Notice that the original video was started like this
private void buttonStartCamera_Click(object sender, EventArgs e)
{
FinalVideo = new VideoCaptureDevice(VideoCaptureDevices[comboBox1.SelectedIndex].MonikerString);
FinalVideo.DesiredFrameSize = new System.Drawing.Size(640, 480);
FinalVideo.DesiredFrameRate = 90;
FinalVideo.NewFrame += new NewFrameEventHandler(FinalVideo_NewFrame);
FinalVideo.ProvideSnapshots = true; //snapshots
FinalVideo.Start();
}
Now my problem seems (and this is a guess because I can't debug this moment)
That some thread is still active wanting to update the main form with data.
However it might not be able to do so since that one is closing.
I think something like that is going on so I wrote on the main application form
private void MainForm_FormClosing(object sender, FormClosingEventArgs e)
{
// Thread.Sleep(1000); // not sure about these delays might help syncing threads
ExitCamera();
Thread.Sleep(1000);
}
However with that last code in place the program has even more trouble to exit.
I would like to send the subthreads an exit, but I dont know their names (if they have a name), I dont know how to list them or to instruct them to stop they are in another dll not my part of the code. From some dll's I dont have the code.
So are there ways of listing sub threads and then close them one by one, if one presses the uppercorner right cross to exit the application?
Well I managed to debug the program, and finally found what caused the problem.
It is a little bit strange since as a button I could stop the camera using the exitcamera function.
However, inside a _formclosing event the same routine didn't work although it worked after I had marked out the waitforstop function.
private void exitcamera()
{
FinalVideo.SignalToStop();
// FinalVideo.WaitForStop(); << marking out that one solved it
FinalVideo.NewFrame -= new NewFrameEventHandler(FinalVideo_NewFrame); // as sugested
FinalVideo = null;
}
I am still a bit confused about it, why this wont work in case a closing event. But it seems to be solved by this.
Maybe you have memory leaks problems caused by the event. You could try to unhook the event while exiting the programm :
FinalVideo.NewFrame -= new NewFrameEventHandler(FinalVideo_NewFrame);
Maybe this will help.
This helped with another problem when I wanted to show a preview, click a "grab" button, change the resolution of the camera from low res to high res, grab an image, and then change back to low res for the preview. Here is what worked, even though I had to abandon it because stopping and starting the camera reset the auto exposure so the picture was awful on the grabbed image:
using AForge.Video;
using AForge.Video.DirectShow;
public partial class Form1 : Form
{
private int PreviewRefreshDelayMS = 40;
private FilterInfoCollection VideoCaptureDevices;
private VideoCaptureDevice CustomerWebcam;
private int CustomerWebcam_CapabilitiesIndexMin;
private int CustomerWebcam_CapabilitiesIndexMax;
private bool bCustomerWebcam_capture;
private Bitmap CustomerWebcam_bitmap;
private System.DateTime CustomerWebcam_nextframetime = DateTime.Now;
public Form1()
{
InitializeComponent();
}
// Some good info to make this more robust
// http://haryoktav.wordpress.com/2009/03/21/webcam-in-c-aforgenet/
//
private void button1_Click(object sender, EventArgs e)
{
CustomerWebcam = new VideoCaptureDevice(VideoCaptureDevices[comboBox1.SelectedIndex].MonikerString);
CustomerWebcam.NewFrame += new NewFrameEventHandler(CustomerWebcam_NewFrame);
int indexMin = -1;
int MinPixels = 0;
int indexMax = -1;
int MaxPixels = 0;
for (int i = 0; i < CustomerWebcam.VideoCapabilities.Length; i++)
{
int pixels = CustomerWebcam.VideoCapabilities[i].FrameSize.Height * CustomerWebcam.VideoCapabilities[i].FrameSize.Width;
if (indexMin == -1) { indexMin = i; MinPixels = pixels; }
if (indexMax == -1) { indexMax = i; MaxPixels = pixels; }
if (pixels < MinPixels) { indexMin = i; MinPixels = pixels; }
if (pixels > MaxPixels) { indexMax = i; MaxPixels = pixels; }
}
CustomerWebcam_CapabilitiesIndexMin = indexMin;
CustomerWebcam_CapabilitiesIndexMax = indexMax;
CustomerWebcam.VideoResolution = CustomerWebcam.VideoCapabilities[indexMin];
CustomerWebcam.DisplayPropertyPage(IntPtr.Zero);
CustomerWebcam.Start();
}
void CustomerWebcam_NewFrame(object sender, NewFrameEventArgs eventArgs)
{
if (CustomerWebcam_bitmap != null)
{
CustomerWebcam_bitmap.Dispose();
CustomerWebcam_bitmap = null;
}
if (bCustomerWebcam_capture)
{
CustomerWebcam_bitmap = (Bitmap)eventArgs.Frame.Clone();
System.Random rnd = new Random();
CustomerWebcam_bitmap.Save("img" + Convert.ToString((int)(rnd.NextDouble() * 10000000)) + ".jpg", System.Drawing.Imaging.ImageFormat.Jpeg);
bCustomerWebcam_capture = false;
((Bitmap)eventArgs.Frame).Dispose();
}
else
if (DateTime.Now > CustomerWebcam_nextframetime)
{
CustomerWebcam_bitmap = (Bitmap)eventArgs.Frame.Clone();
pictureBox1.Image = CustomerWebcam_bitmap;
CustomerWebcam_nextframetime = DateTime.Now.AddMilliseconds(PreviewRefreshDelayMS);
((Bitmap)eventArgs.Frame).Dispose();
}
}
private void Form1_Load(object sender, EventArgs e)
{
VideoCaptureDevices = new FilterInfoCollection(FilterCategory.VideoInputDevice);
foreach (FilterInfo VideoCaptureDevice in VideoCaptureDevices)
{
comboBox1.Items.Add(VideoCaptureDevice.Name);
}
comboBox1.SelectedIndex = 0;
}
private void button2_Click(object sender, EventArgs e)
{
CustomerWebcam.SignalToStop();
CustomerWebcam = null;
}
private void Form1_FormClosing(object sender, FormClosingEventArgs e)
{
if (!(CustomerWebcam == null))
if (CustomerWebcam.IsRunning)
{
CustomerWebcam.SignalToStop();
CustomerWebcam = null;
}
}
private void button4_Click(object sender, EventArgs e)
{
bCustomerWebcam_capture = true;
}
}
One other thing to mention ... the AForge library was the most consistent way I was able to find for using a webcam to grab a still image and save as a JPEG without delving into the world of Windows 8 metro apps. I was hoping to use OpenCV.NET, or just the regular .NET API with DirectShow or WIA, but this was the most simple and it worked for me.
And here are some good samples that were hard to find but very useful: https://github.com/mdavid/aforge.net
I was dealing with this problem. Here is a simple way to stop the camera and close Win Form.
private void Form1_FormClosing(object sender, FormClosingEventArgs e)
{
if (FinalVideo != null)
{
if (FinalVideo.IsRunning)
{
FinalVideo.SignalToStop();
FinalVideo = null;
}
}
}
In my situation WaitForStop() was needed, but the code execution was deading inside the method.
I've replaced it right after the call to SignalToStop(), with:
while (m_Device.IsRunning) { }
This is the code involved on the AForge library:
public bool IsRunning
{
get
{
if (this.thread != null)
{
if (!this.thread.Join(0))
{
return true;
}
this.Free();
}
return false;
}
}
public void WaitForStop()
{
if (this.thread != null)
{
this.thread.Join();
this.Free();
}
}
Edit: this didn't fix the hang the 100% of times. Sometimes a call to a com object (mediaControl.Stop();) on the WorkerThread() method just took forever.
Avoid direct interaction with the form - hope to have a better solution than timer but solves problem. I
Static helper class
public static Bitmap StaticBitmap = new Bitmap(100,100);
Form
public void Cam_NewFrame(object sender, NewFrameEventArgs eventArgs)
{
lock (StaticHelper.StaticBitmap)
{
using (Bitmap b = (Bitmap)eventArgs.Frame)
{
StaticHelper.StaticBitmap = (Bitmap)b.Clone();
}
}
}
private void timer1_Tick(object sender, EventArgs e)
{
lock (StaticHelper.StaticBitmap)
{
pictureBox1.Image = (Bitmap)StaticHelper.StaticBitmap.Clone();
}
}
This will destroy your problem ( I have had this problem, i tried)
using System.Threading;
bool photo_was_taken = false;
private void buttonStartCamera_Click(object sender, EventArgs e)
{
Thread thread = new Thread(new ThreadStart(exitcamera));
thread.Start();
FinalVideo = new VideoCaptureDevice(VideoCaptureDevices[comboBox1.SelectedIndex].MonikerString);
FinalVideo.DesiredFrameSize = new System.Drawing.Size(640, 480);
FinalVideo.DesiredFrameRate = 90;
FinalVideo.NewFrame += new NewFrameEventHandler(FinalVideo_NewFrame);
FinalVideo.ProvideSnapshots = true; //snapshots
FinalVideo.Start();
}
private void FinalVideo_NewFrame(object sender, NewFrameEventArgs eventArgs)
{
// what you want to do ( your code is here )
photo_was_taken = true;
}
private void exitcamera()
{
while (!photo_was_taken)
{
Thread.Sleep(5); // you can change wait milliseconds
}
FinalVideo.SignalToStop();
FinalVideo.NewFrame -= new NewFrameEventHandler(FinalVideo_NewFrame);
//FinalVideo.WaitForStop();
while (FinalVideo.IsRunning)
{
FinalVideo.Stop();
// FinalVideo = null; >> // that is not condition
}
}
This is what you need, 100% working solutions:
private void FormMain_FormClosing(object sender, FormClosingEventArgs e)
{
Invoke((MethodInvoker) delegate
{
_videoSource.SignalToStop();
_videoSource.WaitForStop();
});
}
Please, let me add my working solution on closing a webcam with the wonderful library AForge.NET. It´s a pitty it development has been abandoned.
private void Form1_FormClosing(object sender, FormClosingEventArgs e)
{
if (videoCaptureSource != null)
{
while (videoCaptureSource.IsRunning) // Perhaps you need to limit the number of iterations
{
videoCaptureSource.SignalToStop();
videoCaptureSource.WaitForStop();
if (videoSourcePlayer != null)
{
videoSourcePlayer.SignalToStop();
videoSourcePlayer.WaitForStop();
//videoSourcePlayer.NewFrame -= new NewFrameEventHandler(videoSourcePlayer_NewFrame); // Uncomment this line if you have added an event handler
}
Thread.Sleep(3000);
}
videoCaptureSource = null;
videoDevices = null;
videoSourcePlayer = null;
}
}
When I only needed the frame attaching an event handler to the VideoCaptureDevice (not the VideoSourcePlayer) I couldn´t stop the video from the VideoCaptureDevice, instead I used an invisible VideoSourcePlayer and stopped it from there.
i tried some solution, but nothing work.
i partial solved adding a thread sleep after WaitForStop
if (FinalVideo != null)
{
if (FinalVideo.IsRunning)
{
FinalVideo.SignalToStop();
Thread.Sleep(1000);
}
}
if i try to call Stop application will be freeze
I am making an application using WPF and C#. What I'm trying to do is to print a lots of shapes on a canvas with some time in between when I push a button. At the moment when I push the button, everything just pops up at once. I have tried to sleep the thread for some time between every "print" but that doesn't help, it just take longer time before everything splash up at once. What I want to achive is that the shapes pop up one at a time with lets say 0.5 seconds in between. The code is the following:
private void Create_Click(object sender, RoutedEventArgs e)
{
Random random = new Random();
for (int i = 0; i < 50; i++)
{
Thread.Sleep(500);
Path f = FlowerFactory.createFlower(FlowerBP, true);
Canvas.SetLeft(f, random.Next(0, 1650));
Canvas.SetTop(f, random.Next(0,1000));
DrawBoard.Children.Add(f);
}}
You need to, first, run the loop in a background thread so that it doesn't block the UI from updating; and second, send the UI-rendering tasks back to the UI thread. For the first, you can use Task.Factory.StartNew, and for the second, use Dispatcher.Invoke:
Random random = new Random();
Task.Factory.StartNew(() =>
{
for (int i = 0; i < 50; i++)
{
Thread.Sleep(500);
Dispatcher.Invoke(DispatcherPriority.Render, new Action(() =>
{
Path f = FlowerFactory.createFlower(FlowerBP, true);
Canvas.SetLeft(f, random.Next(0, 1650));
Canvas.SetTop(f, random.Next(0,1000));
DrawBoard.Children.Add(f);
}));
}
});
It was bad decision to sleep your main thread that responsible for GUI.
Try to use DispatchTimer. For example:
DispatcherTimer m_dispatcherTimer = new DispatcherTimer();
int m_count = 50;
private void Init()
{
m_dispatcherTimer.Tick += new EventHandler(OnTick);
m_dispatcherTimer.Interval = new TimeSpan(0, 0, 1);
}
private void Create_Click(object sender, RoutedEventArgs e)
{
m_count = 50;
m_dispatcherTimer.Start();
}
private void OnTick(object sender, EventArgs e)
{
// Draw your shapes here
if(0>=--m_count)
{
m_dispatcherTimer.Stop();
}
}
using System.Reactive.Concurrency;
using System.Reactive.Linq;
...
var subscription = Observable.Interval(TimeSpan.FromSeconds(0.5)).Take(50).Subscribe(x=>CreateRandomFlower);