I want to use a webcam in c# code with Aforge.NET, but It didin't work because I don't use forms.
See my code below :
public partial class CapturePage : Page
{
private bool DeviceExist = false;
private FilterInfoCollection videoDevices;
private VideoCaptureDevice videoSource = null;
public CapturePage()
{
InitializeComponent();
getCamList();
startVideo();
}
// get the devices name
private void getCamList()
{
try
{
videoDevices = new FilterInfoCollection(FilterCategory.VideoInputDevice);
if (videoDevices.Count == 0)
throw new ApplicationException();
DeviceExist = true;
}
catch (ApplicationException)
{
DeviceExist = false;
}
}
//toggle start and stop button
private void startVideo() // as it's say
{
if (DeviceExist)
{
videoSource = new VideoCaptureDevice(videoDevices[0].MonikerString); // the only one webcam
videoSource.NewFrame += new NewFrameEventHandler(video_NewFrame);
CloseVideoSource();
// videoSource.DesiredFrameSize = new Size(160, 120); // deprecated ?
//videoSource.DesiredFrameRate = 10;
videoSource.Start();
}
else
{
// error
}
}
else
{
if (videoSource.IsRunning)
{
timer1.Enabled = false;
CloseVideoSource();
}
}
}
//eventhandler if new frame is ready
private void video_NewFrame(object sender, NewFrameEventArgs eventArgs)
{
Bitmap img = (Bitmap)eventArgs.Frame.Clone();
//do processing here
pictureBox1.Image = img; // But I can't have pictureBox in xaml ??
}
//close the device safely
private void CloseVideoSource()
{
if (!(videoSource == null))
if (videoSource.IsRunning)
{
videoSource.SignalToStop();
videoSource = null;
}
}
}
}
I tried this code in a form application, and it's work, but with a page, PictureBox are not referenced. Even if I reference it and create one in the code, this didn't work.
Can I, and how, use a PictureBox in a XAML Page ? Or there is an other solution tu use Aforge.net Webcam in Xaml Page ?
I succeded with changing the NewFrame methode like this:
private void video_NewFrame(object sender, NewFrameEventArgs eventArgs)
{
System.Drawing.Image imgforms = (System.Drawing.Bitmap)eventArgs.Frame.Clone();
BitmapImage bi = new BitmapImage();
bi.BeginInit();
MemoryStream ms = new MemoryStream();
imgforms.Save(ms, ImageFormat.Bmp);
ms.Seek(0, SeekOrigin.Begin);
bi.StreamSource = ms;
bi.EndInit();
//Using the freeze function to avoid cross thread operations
bi.Freeze();
//Calling the UI thread using the Dispatcher to update the 'Image' WPF control
Dispatcher.BeginInvoke(new ThreadStart(delegate
{
ImageWebcam.Source = bi; /*frameholder is the name of the 'Image' WPF control*/
}));
}
cheers !
You could use WindowsFormsHost to integrate this Page in your WPF application.
If you need a WPF bitmap you may "convert" it like desribed here: Load a WPF BitmapImage from a System.Drawing.Bitmap
Related
i am working with UWP desktop window app and I am trying to implement the functionality of taking the screenshots with saving it to a local file, but i got the error message :
System.NullReferenceException: 'Object reference not set to an instance of an object.
on await frame.SaveAsync(fileStream, CanvasBitmapFileFormat.Png, 1f); in the method SaveImageAsync.
Could you tell me what is going wrong?
namespace App5
{
public sealed partial class MainPage : Page
{
private SizeInt32 _lastSize;
private GraphicsCaptureItem _item;
private Direct3D11CaptureFramePool _framePool;
private GraphicsCaptureSession _session;
private CanvasDevice _canvasDevice;
private CompositionGraphicsDevice _compositionGraphicsDevice;
private Compositor _compositor;
private CompositionDrawingSurface _surface;
private CanvasBitmap _currentFrame;
private string _screenshotFilename = "test.png";
public MainPage()
{
this.InitializeComponent();
Setup();
}
private void Setup()
{
_canvasDevice = new CanvasDevice();
_compositionGraphicsDevice = CanvasComposition.CreateCompositionGraphicsDevice(
Window.Current.Compositor,
_canvasDevice);
_compositor = Window.Current.Compositor;
_surface = _compositionGraphicsDevice.CreateDrawingSurface(
new Size(400, 400),
DirectXPixelFormat.B8G8R8A8UIntNormalized,
DirectXAlphaMode.Premultiplied);
var visual = _compositor.CreateSpriteVisual();
visual.RelativeSizeAdjustment = Vector2.One;
var brush = _compositor.CreateSurfaceBrush(_surface);
brush.HorizontalAlignmentRatio = 0.5f;
brush.VerticalAlignmentRatio = 0.5f;
brush.Stretch = CompositionStretch.Uniform;
visual.Brush = brush;
ElementCompositionPreview.SetElementChildVisual(this, visual);
}
public async Task StartCaptureAsync()
{
var picker = new GraphicsCapturePicker();
GraphicsCaptureItem item = await picker.PickSingleItemAsync();
if (item != null)
{
StartCaptureInternal(item);
}
}
private void StartCaptureInternal(GraphicsCaptureItem item)
{
// Stop the previous capture if we had one.
StopCapture();
_item = item;
_lastSize = _item.Size;
_framePool = Direct3D11CaptureFramePool.Create(
_canvasDevice, // D3D device
DirectXPixelFormat.B8G8R8A8UIntNormalized, // Pixel format
2, // Number of frames
_item.Size); // Size of the buffers
_framePool.FrameArrived += (s, a) =>
{
using (var frame = _framePool.TryGetNextFrame())
{
ProcessFrame(frame);
}
};
_item.Closed += (s, a) =>
{
StopCapture();
};
_session = _framePool.CreateCaptureSession(_item);
_session.StartCapture();
}
public void StopCapture()
{
_session?.Dispose();
_framePool?.Dispose();
_item = null;
_session = null;
_framePool = null;
}
private void ProcessFrame(Direct3D11CaptureFrame frame)
{
bool needsReset = false;
bool recreateDevice = false;
if ((frame.ContentSize.Width != _lastSize.Width) ||
(frame.ContentSize.Height != _lastSize.Height))
{
needsReset = true;
_lastSize = frame.ContentSize;
}
try
{
CanvasBitmap canvasBitmap = CanvasBitmap.CreateFromDirect3D11Surface(
_canvasDevice,
frame.Surface);
_currentFrame = canvasBitmap;
FillSurfaceWithBitmap(canvasBitmap);
}
catch (Exception e) when (_canvasDevice.IsDeviceLost(e.HResult))
{
needsReset = true;
recreateDevice = true;
}
if (needsReset)
{
ResetFramePool(frame.ContentSize, recreateDevice);
}
}
private void FillSurfaceWithBitmap(CanvasBitmap canvasBitmap)
{
CanvasComposition.Resize(_surface, canvasBitmap.Size);
using (var session = CanvasComposition.CreateDrawingSession(_surface))
{
session.Clear(Colors.Transparent);
session.DrawImage(canvasBitmap);
}
}
private void ResetFramePool(SizeInt32 size, bool recreateDevice)
{
do
{
try
{
if (recreateDevice)
{
_canvasDevice = new CanvasDevice();
}
_framePool.Recreate(
_canvasDevice,
DirectXPixelFormat.B8G8R8A8UIntNormalized,
2,
size);
}
catch (Exception e) when (_canvasDevice.IsDeviceLost(e.HResult))
{
_canvasDevice = null;
recreateDevice = true;
}
} while (_canvasDevice == null);
}
private async void Button_ClickAsync(object sender, RoutedEventArgs e)
{
await StartCaptureAsync();
await SaveImageAsync(_screenshotFilename, _currentFrame);
}
private async Task SaveImageAsync(string filename, CanvasBitmap frame)
{
StorageFolder pictureFolder = KnownFolders.SavedPictures;
StorageFile file = await pictureFolder.CreateFileAsync(filename, CreationCollisionOption.ReplaceExisting);
using (var fileStream = await file.OpenAsync(FileAccessMode.ReadWrite))
{
await frame.SaveAsync(fileStream, CanvasBitmapFileFormat.Png, 1f);
}
}
}
}
This code is from a Windows Forms .Net Core project, but I just pasted in a WPF project and it works.
In WPF you have to add Nuget package System.Drawing.Common:
You also have to add references to:
using System.Windows.Forms;
using WindowsFormsIntegration;
using System.Drawing;
// take a screenshot
Bitmap bitmap = new Bitmap(Screen.PrimaryScreen.Bounds.Width, Screen.PrimaryScreen.Bounds.Height);
Graphics graphics = Graphics.FromImage(bitmap);
graphics.CopyFromScreen(0, 0, 0, 0, bitmap.Size);
// to save:
bitmap.Save(fileName);
The above code came from this project. I helped someone create sub images and search for sub images in a larger image. They had the screenshot code.
https://github.com/DataJuggler/SubImageCreator
This project is used to create sub images from a larger image and search for sub images in a larger image.
My application needs to invoke (off screen) browser on request and cleanup once it is done.
So I created an offscreen browser
public class OffScreenBrowser
{
private static ChromiumWebBrowser _browser;
private static CefSettings _settings;
public void Load(string url,System.Drawing.Size size)
{
if (Cef.IsInitialized) return;
Init(new BrowserProcessHandler());
_browser = new ChromiumWebBrowser(url) {Size = size};
_browser.NewScreenshot += _browser_NewScreenshot;
}
public System.Windows.Controls.Image BrowserImage { get; set; }
public Action NewScreenShotAction { get; set; }
private void _browser_NewScreenshot(object sender, EventArgs e)
{
var bitmap = _browser.ScreenshotOrNull();
Application.Current.Dispatcher.Invoke(new Action(() =>
{
using (MemoryStream memory = new MemoryStream())
{
bitmap.Save(memory, ImageFormat.Png);
memory.Position = 0;
BitmapImage bitmapImage = new BitmapImage();
bitmapImage.BeginInit();
bitmapImage.StreamSource = memory;
bitmapImage.CacheOption = BitmapCacheOption.OnLoad;
bitmapImage.EndInit();
BrowserImage = new System.Windows.Controls.Image() {Source = bitmapImage};
NewScreenShotAction();
}
}));
}
public void Close()
{
_browser.NewScreenshot -= _browser_NewScreenshot;
_browser.Dispose();
_settings.Dispose();
Cef.Shutdown();
}
public static void Init(IBrowserProcessHandler browserProcessHandler)
{
_settings = new CefSettings();
if (!Cef.Initialize(_settings, true, browserProcessHandler))
throw new Exception("Unable to Initialize Cef");
}
}
The idea is-on clicking a button create browser and on clicking another button close the browser
private OffScreenBrowser offScreenBrowser;
private void OPen_OnClick(object sender, RoutedEventArgs e)
{
var address = #"https://www.google.co.uk";
var width = 200;
var height = 100;
var windowSize = new System.Drawing.Size(width, height);
offScreenBrowser = new OffScreenBrowser();
offScreenBrowser.Load(address, windowSize);
offScreenBrowser.NewScreenShotAction = () =>
{
Browser.Content = offScreenBrowser.BrowserImage;
};
}
private void Close_OnClick(object sender, RoutedEventArgs e)
{
offScreenBrowser.Close();
}
On the first click it all works fine. On clicking close it seems like the cleanup is fine.
But when I click the open button for the second time I am getting an exception as below
"An unhandled exception of type 'System.AccessViolationException' occurred in CefSharp.Core.dll
Additional information: Attempted to read or write protected memory. This is often an indication that other memory is corrupt."
What am I doing wrong?
This is a limitation in Chromium framework.
CEF can only be Initialized/Shutdown once per process,
See Need to Know/Limitations for more details, this is a limitation of the underlying Chromium framework.
to solve this you can call the Cef.Initialize in the start form and you need to call it only once in your application
the you can call ChromiumWebBrowser many times inside any for of your application forms
it worked for me
I'm trying to have a rotating ad display in my WPF application. When I load the application the GetNewAd() method properly displays the advertisement. When I try to update the ad by calling my GetNewAd() method again, the chatHost is returning the new ad, but the image does not update in the UI. I have tried updating the image without the animation, but I still have the same problem. What am I missing here?
public class ncWindow
{
public ncWindow(Grid grid)
{
imgAd = new Image();
imgAd.Margin = new Thickness(2,2,2,2);
imgAd.HorizontalAlignment = HorizontalAlignment.Left;
imgAd.MouseDown += imgAd_MouseDown;
adTimer.Interval = 60000;
adTimer.Elapsed += adTimer_Elapsed;
adTimer.AutoReset = true;
adTimer.Start();
grid.Children.Add(imgAd);
}
public void GetNewAd()
{
DisplayedAd = chatHost.GetNewAd();
debug.Print("GetNewAd: " + DisplayedAd.VendorName + ", ImageData.Length = " + DisplayedAd.ImageData.Length);
BitmapImage image = new BitmapImage();
if (DisplayedAd.ImageData!=null && DisplayedAd.ImageData.Length>0)
{
using (var mem = new MemoryStream(DisplayedAd.ImageData))
{
mem.Position = 0;
image.BeginInit();
image.CacheOption = BitmapCacheOption.OnLoad;
image.StreamSource = mem;
image.EndInit();
}
}
else
return;
image.Freeze();
imgAd.Source = image;
}
private void adTimer_Elapsed(object source, ElapsedEventArgs e)
{
GetNewAd();
}
}
If the timer that calls your GetNewAd() method is not a DispatcherTimer, you'll explicitly have to invoke the assignment of the Image control's Source property in the UI thread:
image.Freeze(); // necessary for cross-thread access
imgAd.Dispatcher.BeginInvoke(new Action(() => imgAd.Source = image));
i am trying to download an image from the web save it in the media library , below is my code, am i missing something here, Thanks in advance
public void storePicture()
{
try
{
using (IsolatedStorageFile myIsolatedStorage = IsolatedStorageFile.GetUserStoreForApplication())
{
string url = #"http://mynokiablog.com/wp-content/uploads/2012/11/wp8.jpeg";
BitmapImage storeimage = new BitmapImage(new Uri(url));
// height and width are 0
int testheight = storeimage.PixelHeight;
int testwidth = storeimage.PixelWidth;
IsolatedStorageFileStream fileStream = myIsolatedStorage.CreateFile("testname");
// NullRefrenceException
WriteableBitmap wb = new WriteableBitmap(storeimage);
wb.SaveJpeg(fileStream, wb.PixelWidth, wb.PixelHeight, 0, 85);
fileStream.Close();
}
}
catch (Exception ex)
{
System.Diagnostics.Debug.WriteLine(ex.Message);
}
}
add event handler as below
storeimage.ImageOpened += bitmapImage_ImageOpened;
storeimage.ImageFailed += bitmapImage_ImageFailed;
storeimage.DownloadProgress += bitmapImage_DownloadProgress;
then in bitmapImage_DownloadProgress, create WritableBitMap and save
private void LoadIMG()
{
var bitmapImage = new BitmapImage { CreateOptions = BitmapCreateOptions.None };
bitmapImage.ImageOpened += bitmapImage_ImageOpened;
bitmapImage.ImageFailed += bitmapImage_ImageFailed;
bitmapImage.DownloadProgress += bitmapImage_DownloadProgress;
bitmapImage.UriSource = new Uri("http://ds.serving-sys.com/BurstingRes///Site-16990/Type-0/7b912e70-352a-454f-8ea7-5d5ecd6ebfae.gif");
}
private void bitmapImage_DownloadProgress(object sender, DownloadProgressEventArgs e)
{
}
private void bitmapImage_ImageFailed(object sender, ExceptionRoutedEventArgs e)
{
}
private void bitmapImage_ImageOpened(object sender, RoutedEventArgs e)
{
var userStoreForApplication = IsolatedStorageFile.GetUserStoreForApplication();
var writeableBitmap = new WriteableBitmap(sender as BitmapImage);
var isolatedStorageFileStream = userStoreForApplication.CreateFile("Myfile.gif");
writeableBitmap.SaveJpeg(isolatedStorageFileStream, writeableBitmap.PixelWidth, writeableBitmap.PixelHeight, 0, 85);
}
You can try it: http://www.kunal-chowdhury.com/2012/02/how-to-download-and-save-images-in-wp7.html#.TzUtWBSaLkM.twitter
Hope this helps.
I need to download a webcam image thru http, and refresh it at 10fps and display it on a WPF window. Right now I'm using this code:
Window1 wndMain;
BitmapImage img;
DispatcherTimer tmrRefresh;
public WCam(Window1 wndMain, string imguri)
{
this.wndMain = wndMain;
this.MouseLeftButtonDown += delegate { DragMove(); };
url = imguri;
InitializeComponent();
tmrRefresh = new DispatcherTimer(TimeSpan.FromMilliseconds(100),
DispatcherPriority.Normal, Refresh, Dispatcher.CurrentDispatcher);
}
private void Window_Loaded(object sender, RoutedEventArgs e)
{
if (url != "")
{
try
{
img = new BitmapImage();
img.BeginInit();
img.CacheOption = BitmapCacheOption.OnLoad;
img.CreateOptions = BitmapCreateOptions.IgnoreImageCache;
img.UriSource=(new Uri(url));
img.EndInit();
}
catch (Exception ex)
{
new WPopup().Show(ex.Message);
}
ImgBox.Source = img;
tmrRefresh.Start();
}
}
public void Refresh(object sender, EventArgs e)
{
try
{
img = new BitmapImage();
img.BeginInit();
img.CacheOption = BitmapCacheOption.OnLoad;
img.CreateOptions = BitmapCreateOptions.IgnoreImageCache;
img.UriSource = (new Uri(url));
img.EndInit();
}
catch (Exception ex)
{
new WPopup().Show(ex.Message);
}
ImgBox.Source = null;
ImgBox.Source = img;
}
It displays nothing, if I increase the timer interval to 1000 it displays images but the image goes away while it loads the next one. Also the window loads in awfully slowly.
Seperate the loading logic from the image.
Keep the loaded code as is, the refresh should download the image with a simple async(to keep ui running) request and only when finished change the image source to the local memory.