WriteableBitmap class

Provides a BitmapSource that can be written to and updated.

Inheritance

Object

  DependencyObject

    ImageSource

      BitmapSource

        WriteableBitmap

Syntax

public sealed class WriteableBitmap : BitmapSource

Attributes

ActivatableAttribute(Windows.UI.Xaml.Media.Imaging.IWriteableBitmapFactory, NTDDI_WIN8)

MarshalingBehaviorAttribute(Agile)

ThreadingAttribute(Both)

VersionAttribute(NTDDI_WIN8)

WebHostHiddenAttribute()

Members

The WriteableBitmap class has these types of members:

• Constructors
• Methods
• Properties

Constructors

The WriteableBitmap class has these constructors.

Methods

The WriteableBitmap class has these methods. It also inherits methods from the Object class.

Properties

The WriteableBitmap class has these properties.

Remarks

The image source data of a WriteableBitmap is an underlying pixel buffer. WriteableBitmap.PixelBuffer cannot be written to directly, however, you can use language-specific techniques to access the buffer and change its contents.

• To access the pixel content from C# or Microsoft Visual Basic, you can use the AsStream extension method to access the underlying buffer as a stream.
• To access the pixel content from C++, you can query for the IBufferByteAccess type (defined in Robuffer.h) and directly access its Buffer property.

Examples

This example writes to the PixelBuffer property of WriteableBitmap as part of a transcoding scenario that will eventually use the WriteableBitmap as an Image.Source value and display the image. The code shown here comes from a larger code sample, the SDK XAML images sample.

using (IRandomAccessStream fileStream = await file.OpenAsync(Windows.Storage.FileAccessMode.Read)) 
{
    BitmapDecoder decoder = await BitmapDecoder.CreateAsync(fileStream); 
    // Scale image to appropriate size 
    BitmapTransform transform = new BitmapTransform() {  
        ScaledWidth = Convert.ToUInt32(Scenario4WriteableBitmap.PixelWidth), 
        ScaledHeight = Convert.ToUInt32(Scenario4WriteableBitmap.PixelHeight)
    }; 
    PixelDataProvider pixelData = await decoder.GetPixelDataAsync( 
        BitmapPixelFormat.Bgra8, // WriteableBitmap uses BGRA format 
        BitmapAlphaMode.Straight, 
        transform, 
        ExifOrientationMode.IgnoreExifOrientation, // This sample ignores Exif orientation 
        ColorManagementMode.DoNotColorManage
    ); 
 
    // An array containing the decoded image data, which could be modified before being displayed 
    byte[] sourcePixels = pixelData.DetachPixelData(); 
 
    // Open a stream to copy the image contents to the WriteableBitmap's pixel buffer 
    using (Stream stream = Scenario4WriteableBitmap.PixelBuffer.AsStream()) 
    { 
        await stream.WriteAsync(sourcePixels, 0, sourcePixels.Length); 
    }                     
}

Requirements

See also

BitmapSource

Image

BitmapDecoder

Windows.Graphics.Imaging namespace

XAML images sample

Build date: 12/4/2012