Develop Reference

C# How to dispose of OpenFileDialog file

I use OpenFileDialog to get the path of an image and then set it to my image source property imgSelected.Source = new BitmapImage(new Uri(filenameSteg, UriKind.Absolute)); in a WPF application.
The thing is, I need to open that file again later but I can't open it since the file is being used by another process ( System.IO.IOException -> The process cannot access the file pathToFile because it is being used by another process.).
The code that needs to access it later it as follow :
bitmapSource = JpegBitmapDecoder.Create(File.Open(filenameSteg, FileMode.Open),
BitmapCreateOptions.None, BitmapCacheOption.OnLoad).Frames[0];
This bitmapSource is used to give that image to a WriteableBitmap and from there I go through the pixels.
Is there any way to dispose of a File opened with an OpenFileDialog ?
I tried to cast to to IDisposable, to use a using block and so on but this thing is persistent.
EDIT :
1 - I tried this (#ctacke answer) :
using (var stream = File.Open(filenameSteg, FileMode.Open)){
bitmapSource = JpegBitmapDecoder.Create(stream, BitmapCreateOptions.None,
BitmapCacheOption.OnLoad).Frames[0];}
But it still gives me the error about the process being already in used by another process because even though it will be disposed after, I still am trying to open the same file (filenameSteg) than I opened in the OpenFileDialog. (Or at least, that's how I see it.)
2 - I then tried this (based on #ctacke recommended link:
using (FileStream fileStream = new FileStream(filenameSteg+1, FileMode.Create)){
MemoryStream memoryStream = new MemoryStream();
BitmapImage bi = new BitmapImage();
byte[] fileBytes = File.ReadAllBytes(filenameSteg);
memoryStream.Write(fileBytes, 0, fileBytes.Length);
memoryStream.Position = 0;
bi.BeginInit();
bi.StreamSource = memoryStream;
bi.EndInit();
bitmapSource = bi;}
Note : Notice that I here ask for filenameSteg +1. That is because I wanted to test the rest of my method so I create a copy the file and simply added a 1 to its name. That being said, when using filenameSteg for real, it gave me the same error about being already in used which I again suspect is that I still am asking to open the same image that was previously opened in the OpenFileDialog.
3 - I thought of another approach which does not require me to dispose the opened image :
When I open the image for the first time in the OpenFileDialog, I store the byte array of the image in a variable so I could create the WriteableBitmap using the BitmapFactory and the byte array.
// This is in the OpenFileDialog. It is where I stock the image "pixels" in a byte array.
bytesArrayImage = File.ReadAllBytes(filenameSteg);
//And then later when I needed the WriteableBitmap, I used the byte array and the BitmapFactory
//imgSelected being the Image containing the image I opened in the OpenFileDialog, I used it's
//width and height
wb = BitmapFactory.New(Convert.ToInt32(imgSelected.Width),
Convert.ToInt32(imgSelected.Height)).FromByteArray(bytesArrayImage);
The problem with this approach is that, some pictures works fine and I can use the byte array to create the WriteableBitmap and go through it's pixels but in other cases it gives me an AccessViolationException stating : Attempted to read or write protected memory. This is often an indication that other memory is corrupt.. In other words, trying to bypass the dispose problem got me into another problem.

You should release the original image, something like this:
if(imgSelected.Source != null)
{
imgSelected.Source.Dispose;
}
imgSelected.Source = new BitmapImage(new Uri(filenameSteg, UriKind.Absolute));
Next, File.Open returns a stream, which you need to explicitly release.
using(var stream = File.Open(filenameSteg, FileMode.Open))
{
var bitmapSource = JpegBitmapDecoder.Create(stream,
BitmapCreateOptions.None, BitmapCacheOption.OnLoad).Frames[0];
}
See also: Load a BitmapSource and save using the same name in WPF -> IOException

C# / WinRT: How to save image to file

I'm an iOS developer learning Windows Store App development with no previous Microsoft technology experience.
I need to save an image to a file. I figured this would be easy, but I've been at it for a day and I've got nothing to show for it. Either this is extremely difficult in Windows, or I'm missing something due to ignorance of the platform / APIs.
The source of the image I need to save is Windows.UI.Xaml.Media.Imaging.RenderTargetBitmap. RenderTargetBitmap can return an image as either a source for Windows.UI.Xaml.Controls.Image or as a IBuffer.
I can verify that RenderTargetBitmap is rendering the image correctly. However, I have not been able to save the image to a file. I'd hoped that Image would have a Save() method, but it doesn't. So I figured I'd need to use the IBuffer somehow. I got close, I was able to save the buffer to disk, but it was unencoded, so I couldn't open it in anything.
So, next, I tried converting the buffer to a stream, encoding that into PNG with BitmapEncoder. That worked, but that left me with my PNG data in a IRandomAccessStream. I have no idea how to save a IRandomAccessStream to a file.
I tried 5-10 different convoluted approaches, such as going through type conversion hell to attempt to turn a IRandomAccessStream into an IBuffer so I could use .WriteAsync() on a file stream. I tried using a DataWriter on a file stream fed by a DataReader on my IRandomAccessStream but I ran into a type mismatch problem. Etc, etc.
So, how can I save my file? Here's what I got so far:
private async void saveButton_Click(object sender, RoutedEventArgs e)
{
//Create a new temporary image for saving
//Image tempImage = new Image();
//Create a render object
RenderTargetBitmap renderTargetBitmap = new RenderTargetBitmap();
//Render the app's display buffer
await renderTargetBitmap.RenderAsync(null);
//Set the temp image to the contents of the app's display buffer
//tempImage.Source = renderTargetBitmap;
//Create a new file picker, set the default name, and extenstion
FileSavePicker savePicker = new FileSavePicker();
savePicker.SuggestedFileName = "New LightTable.png";
savePicker.FileTypeChoices.Add("Image", new List<string>(){".png"});
//Get the file the user selected
StorageFile saveFile = await savePicker.PickSaveFileAsync();
//Only move on if the user actually selected a file
if (saveFile != null)
{
//Get a buffer of the pixels captured from the screen
Windows.Storage.Streams.IBuffer buffer = await renderTargetBitmap.GetPixelsAsync();
//Get a stream of the data in the buffer
System.IO.Stream stream = buffer.AsStream();
//Convert the stream into a IRandomAccessStream because I don't know what I'm doing.
Windows.Storage.Streams.IRandomAccessStream raStream = stream.AsRandomAccessStream();
//Attempt to encode the stream into a PNG
BitmapEncoder encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.PngEncoderId, raStream);
//Get a stream for the file the user selected
Windows.Storage.Streams.IRandomAccessStream fileStream = await saveFile.OpenAsync(Windows.Storage.FileAccessMode.ReadWrite);
//FIND SOME WAY TO SAVE raStream TO fileStream
//Something like:
// await fileStream.WriteAsync(raStream.AsStreamForRead());
}
}
Either I'm just missing the very end: how to write my raStream to a file, or my approach is totally off.
I appreciate the help. Keep in mind I've only been developing with Microsoft tech for a week now. I have no .NET, Silverlight, or other MS tech experience. Saving an encoded image from a UIImage control on iOS is a single method call, so the shear complexity of the solution I'm circling makes me think I'm missing something really easy that I just don't know about.

You need to set the pixel data into the StorageFile stream. See http://basquang.wordpress.com/2013/09/26/windows-store-8-1-save-visual-element-to-bitmap-image-file/ for an example.

Problems overwriting (re-saving) image when it was set as image source

Good day all,
I am having some trouble with image permissions.
I am loading an image from file, resizing it and then saving it out to another folder.
I am then displaying this like so:
uriSource = new Uri(Combine(imagesDirectoryTemp, generatedFileName), UriKind.Absolute);
imgAsset.Source = new BitmapImage(uriSource);
This is working fine, the trouble comes if the user then selects another image immediately after and tries to save it over the original file.
An exception is generated upon saving my image "ExternalException: A generic error occurred in GDI+."
After some playing around i have narrowed the error down to imgAsset.Source = new BitmapImage(uriSource); as removing this line and not setting the imagesource will allow me to overwrite this file many times.
I have also tried setting the source to something else, before re-saving in the hope that the old reference would be disposed, this was not the case.
How can i get past this error?
Thanks,
Kohan
Edit
Now using this code i am not getting the exception however the image source is not updating. Also since i am not using a SourceStream, im not sure what i need to dispose of to get this working.
uriSource = new Uri(Combine(imagesDirectoryTemp, generatedFileName), UriKind.Absolute);
imgTemp = new BitmapImage();
imgTemp.BeginInit();
imgTemp.CacheOption = BitmapCacheOption.OnLoad;
imgTemp.UriSource = uriSource;
imgTemp.EndInit();
imgAsset.Source = imgTemp;

You're almost there.
Using BitmapCacheOption.OnLoad was the best solution to keep your file from being locked.
To cause it to reread the file every time you also need to add BitmapCreateOptions.IgnoreImageCache.
Adding one line to your code should do it:
imgTemp.CreateOption = BitmapCreateOptions.IgnoreImageCache;
thus resulting in this code:
uriSource = new Uri(Combine(imagesDirectoryTemp, generatedFileName), UriKind.Absolute);
imgTemp = new BitmapImage();
imgTemp.BeginInit();
imgTemp.CacheOption = BitmapCacheOption.OnLoad;
imgTemp.CreateOptions = BitmapCreateOptions.IgnoreImageCache;
imgTemp.UriSource = uriSource;
imgTemp.EndInit();
imgAsset.Source = imgTemp;

When you load an Image in any WPF control it let's handle to your image and doesn't release it until you close your application. The reason for this... I dont know exactly, problably is relaying on some DirectX code behind the scene which never knows when the WPF application releases the image..
Use this code to load the image..
MemoryStream mstream = new MemoryStream();
System.Drawing.Bitmap bitmap = new Bitmap(imgName);
bitmap.Save(mstream, System.Drawing.Imaging.ImageFormat.Jpeg);
bitmap.Dispose(); // Releases the file.
mstream.Position = 0;
image.BeginInit();
image.StreamSource = mstream;
image.EndInit();
this.img.Source = image ;
it worked for me..

Sounds very much like the problem I had developing Intuipic, where WPF would not dispose of the image, thus locking the file. Check out this converter I wrote to deal with the problem.

.NET BitmapSource is locking file

I am using this C# code to access an image file in order to read metadata from it.
BitmapSource img = BitmapFrame.Create(uri);
Unfortunately the image file specified by uri becomes locked until the program ends. How do I prevent the image from being locked?

maybe this could help ?
edit
BitmapSource img = BitmapFrame.Create(uri,BitmapCreateOptions.None,BitmapCacheOption.OnLoad);
BitmapCreateOptions.None = default option
BitmapCacheOption.OnLoad = Caches the entire image into memory at load time. All requests for image data are filled from the memory store.
from here

If you want to be able to delete/change the file immediately afterwards, read the whole file into memory, and then give it the MemoryStream instead. For example:
MemoryStream data = new MemoryStream(File.ReadAllBytes(file));
BitmapSource bitmap = BitmapFrame.Create(data);

You can also use generic stream:
Stream stream = File.OpenRead(filename);
Bitmap template = new Bitmap(stream); // or (Bitmap) Bitmap.FromStream(stream)
stream.Close();

WPF BitmapSource ImageSource

I am binding an Image.Source property to the result of the property shown below.
public BitmapSource MyImageSource
{
get
{
BitmapSource source = null;
PngBitmapDecoder decoder;
using (var stream = new FileStream(#"C:\Temp\logo.png", FileMode.Open, FileAccess.Read, FileShare.Read))
{
decoder = new PngBitmapDecoder(stream, BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.None);
if (decoder.Frames != null && decoder.Frames.Count > 0)
source = decoder.Frames[0];
}
return source;
}
}
For some reason this is failing during the rendering of the image (Deep in the PresentationCore assembly). I am certain the image is not corrupt as I can successfully show the same image w/o the binding
<Image Name="FooImage" Source="/logo.png" />
I have to bind the image source in code because I will eventually be creating the image stream from a base64 string.
Anyone know if this is a bug w/ WPF? or am I doing something incorrectly?

The problem was the BitmapCacheOption option, changing to BitmapCacheOption.OnLoad works.
With BitmapCacheOption.None the BitmapSource isn’t decoded until the image is rendered, but the stream with the png in it is already disposed at that point. If you cache OnLoad, it’ll decode right away and cache the results, rather than trying to decode later when the stream no longer exists.

Also, have you tried just using a BitmapImage to load the image? It works fine with PNG, BMP, and JPEG.
It's also a specialized type of BitmapSource, so you could just replace your code in your property with this:
BitmapImage img = new BitmapImage(new Uri(#"C:\Temp\logo.png"));
return img;

Are you positive it's a PNG and not just a renamed Bitmap or Jpeg? If you create a new Bitmap image and then just rename it and change the file extension, this error is reproducible.
If I use a known PNG with your code, I don't get your issue, but a COM exception is thrown:
The handle is invalid. (Exception from HRESULT: 0x80070006 (E_HANDLE))
Can you try it out with a random PNG off the web and see if you get the same result?