I have a WPF application that takes a snapshot image from a video file. The user can define the timestamp from which to take the image. The image is then saved to a temporary location on disk, and is then rendered into an <image> element.
The user should then be able to select a different timestamp, which then overwrites the temporary file on disk - this should then be displayed within the <image> element.
Using Image.Source = null;, I can clear the image file from the <image> element, so it displays a blank space instead. However, if the source image file is then overwritten with a new image (with the same name) and loaded into the <image> element, it still shows the old image.
I am using the following logic:
// Overwrite temporary file file here
// Clear out the reference to the temporary image
Image_Preview.Source = null;
// Load in new image (same source file name)
Image = new BitmapImage();
Image.BeginInit();
Image.CacheOption = BitmapCacheOption.OnLoad;
Image.UriSource = new Uri(file);
Image.EndInit();
Image_Preview.Source = Image;
The image displayed in the <image> element does not change, even though the original file has been completely replaced. Is there an image caching issue here that I am not aware of?
By default, WPF caches BitmapImages that are loaded from URIs.
You can avoid that by setting the BitmapCreateOptions.IgnoreImageCache flag:
var image = new BitmapImage();
image.BeginInit();
image.CreateOptions = BitmapCreateOptions.IgnoreImageCache;
image.CacheOption = BitmapCacheOption.OnLoad;
image.UriSource = new Uri(file);
image.EndInit();
Image_Preview.Source = image;
Or you load the BitmapImage directly from a Stream:
var image = new BitmapImage();
using (var stream = new FileStream(file, FileMode.Open, FileAccess.Read))
{
image.BeginInit();
image.CacheOption = BitmapCacheOption.OnLoad;
image.StreamSource = stream;
image.EndInit();
}
Image_Preview.Source = image;
Related
I have two assemblies, say assembly1 and assembly2.
In assembly2 there is a XAML file. In this XAML file I want to create an image.
What I want to do is setting the source of this image to a bitmap that is in a resx file from assembly1.
<Image Name="image1" Stretch="Fill" Source="???" />
How do I correctly reference to that bitmap file in XAML? Is there an easy "XAML-only" solution?
Okay, so I assume there is no thing such as an "XAML-only" solution.
Instead, I do it like this after the WPF control's Loaded event is called:
Assembly coreAssembly = Assembly.GetAssembly(typeof (otherAssembly.Resources));
var resourceManager = new ResourceManager("otherAssembly.Resources", coreAssembly);
// get image from core resources
Bitmap completeImage = (Bitmap) resourceManager.GetObject("Complete");
// apply image to WPF image
var memoryStream = new MemoryStream();
completeImage.Save(memoryStream, System.Drawing.Imaging.ImageFormat.Png);
BitmapImage bitmapImage = new BitmapImage();
bitmapImage.BeginInit();
bitmapImage.StreamSource = new MemoryStream(memoryStream.ToArray());
bitmapImage.EndInit();
this.myWpfImage.Source = bitmapImage;
i dont have a problem with binding a bitmapimage to image tag in codebehind for eg.
BitmapImage image = new BitmapImage();
imagetaginxaml.Source = image; // this will remove whatever image is currently on the image tag in xaml and attach the empty bitmapimage above
but i'm not able to get the image by doing the reverse, for example, i want to process the image that is currently on the image tag. i am not able to do this
BitmapImage image = imagetaginxaml.Source;
what should i do
Well, Image.Source is of type ImageSource, there is no quarantee that it will be a BitmapImage, it may be though. If the source is created by the XAML parser it will be a BitmapFrameDecode (which is an internal class). Anyway, the only save assignment is:
ImageSource source = img.Source;
otherwise you need to cast:
BitmapImage source = (BitmapImage)img.Source;
which will throw an exception if the Source is not of this type. So you can either save-cast or try-catch:
//(Possibly check for img.Source != null first)
BitmapImage source = img.Source as BitmapImage;
if (source != null)
{
//If img.Source is not null the cast worked.
}
try
{
BitmapImage source = (BitmapImage)img.Source;
//If this line is reached it worked.
}
catch (Exception)
{
//Cast failed
}
You could also check the type beforehand using img.SourceisBitmapImage.
How about using WriteableBitmap to make a copy of the image, and then using a MemoryStream to copy the original image into a copy?
// Create a WriteableBitmap from the Image control
WriteableBitmap bmp = new WriteableBitmap(imagetaginxaml, null);
// Load the contents of a MemoryStream from the WritableBitmap
MemoryStream m = new MemoryStream();
bmp.SaveJpeg(m, bmp.PixelWidth, bmp.PixelHeight, 0, 100);
// Read from the stream into a new BitmapImage object
m.Position = 0;
BitmapImage image = new BitmapImage();
image.SetSource(m);
// do something with the new BitmapImage object
// (for example, load another image control)
anotherimagetaginxaml.Source = image;
My app includes a Image control which has binding to a disk image file. I some condition, the image file need be updated. But the updating can't be done because the image file is open and can not be overwritten. What should I do?
You can try to remove the binding, so the image will not be used by your program
than overwrite the image file
and than re-add the binding
i'm not sure about this, but it's worth a try
Now my solution is:
To use a converter to convert the image path into BitmapImage.
in the converter, load the image using a FileStream and copy the data into a MemoryStream and finally close the FileStream.
BitmapImage bmp = new BitmapImage();
bmp.CacheOption = BitmapCacheOption.OnLoad;
bmp.BeginInit();
var fileStream = new FileStream(path, FileMode.Open, FileAccess.Read);
var memStream = new MemoryStream();
memStream.SetLength(fileStream.Length);
fileStream.Read(memStream.GetBuffer(), 0, (int)fileStream.Length);
memStream.Flush();
fileStream.Close();
bmp.StreamSource = memStream;
bmp.EndInit();
return bmp;
This is a simple Question (lets see)
I want to bind bitmap image to Image. For doing this in cs code u must write this line.
this.leftImage.Source = new BitmapImage(new Uri(#"C:\a.bmp"));
But I want make Binding from resources. Because In release time resources became part of project.exe file and if you make binding from file(Mean set Image.source with Image file address), you must always put image file in the same address(disaster programing) :)
One option is to get it from a resx file. You can do something similar to this. Assuming Images.resx contains a Left image bitmap.
leftImage.Source = ConvertBitmapToBitmapImage(Images.Left);
...
private BitmapImage ConvertBitmapToBitmapImage(Bitmap bitmap)
{
MemoryStream memoryStream = new MemoryStream();
bitmap.Save(memoryStream, ImageFormat.Png);
BitmapImage bitmapImage = new BitmapImage();
bitmapImage.BeginInit();
bitmapImage.StreamSource = new MemoryStream(memoryStream.ToArray());
bitmapImage.EndInit();
return bitmapImage;
}
With some more work, you can do this from XAML too.
In my Silverlight control, I am loading my background image from a stream:
BitmapImage img = new BitmapImage();
img.SetSource(stream);
Image background = new Image();
background.Source = img;
How can I find out the height of the bitmap image that was loaded from stream? None of the usual suspects (e.g., Property, DependencyProperty) seem to be available, neither on img, nor on background.
I would try:
img.Measure();
img.DesiredSize.Height;