Language: HTML | XAML

How to decode an image (XAML)

Applies to Windows and Windows Phone

We show you how to load an image from a file, display it using the Image control, and create a BitmapDecoder object from it. A BitmapDecoder lets you access metadata and get pixel data from images.

For another example of decoding an image, see the Simple Imaging sample.

What you need to know




Step 1: Add a placeholder image

Add an Image element to your XAML file.

<Image x:Name="myImage" Source=""/>

You will later set the image file as the source of the myImage object.

Step 2: Use the file picker to pick an image file

Create a new FileOpenPicker object to let the user select a file to be opened. Set the file extension to filter for JPEG images. Then, display the picker.

async void DecodeImage()
    var picker = new Windows.Storage.Pickers.FileOpenPicker();
    var file = await picker.PickSingleFileAsync();

    if (file == null)
        // The user pressed Cancel.

Note  You can get a list of all the file extensions supported by the codecs installed on the system by using Windows.Graphics.Imaging.BitmapDecoder.GetDecoderInformationEnumerator.

Note  If the user cancels, the PickSingleFileAsync method returns a null object.

Step 3: Display the image in the Image control

Open the file using the Read access mode to get an IRandomAccessStream. Initialize a BitmapImage on this stream and then set it as the source of the Image control.

    var stream = await file.OpenAsync(Windows.Storage.FileAccessMode.Read);
    var bitmapImage = new Windows.UI.Xaml.Media.Imaging.BitmapImage();
    await bitmapImage.SetSourceAsync(stream);
    myImage.Source = bitmapImage;

Step 4: Create the decoder object

Create a BitmapDecoder object from the stream.

    var decoder = await Windows.Graphics.Imaging.BitmapDecoder.CreateAsync(stream);


Now that you have a decoder object you can use it to:

Related topics

Simple Imaging sample
How to read image metadata
How to get pixel data in the default format
How to get pixel data in a particular format
How to encode an image



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