Editare

Partajați prin

BitmapDecoder Class

  • Reference

Definition

Namespace:
System.Windows.Media.Imaging
Assembly:
PresentationCore.dll

Represents a container for bitmap frames. Each bitmap frame is a BitmapSource. This abstract class provides a base set of functionality for all derived decoder objects.

public ref class BitmapDecoder abstract : System::Windows::Threading::DispatcherObject
public abstract class BitmapDecoder : System.Windows.Threading.DispatcherObject
type BitmapDecoder = class
    inherit DispatcherObject
Public MustInherit Class BitmapDecoder
Inherits DispatcherObject
Inheritance
Object
DispatcherObject
BitmapDecoder
Derived

Examples

The following example demonstrates how to use the Create(Uri, BitmapCreateOptions, BitmapCacheOption) method to create a decoder for a given image. The first BitmapFrame of the image is used as the source of an Image control.

BitmapDecoder uriBitmap = BitmapDecoder.Create(
   new Uri("sampleImages/waterlilies.jpg", UriKind.Relative),
   BitmapCreateOptions.None,
   BitmapCacheOption.Default);

// Create an image element;
Image uriImage = new Image();
uriImage.Width = 200;
// Set image source.
uriImage.Source = uriBitmap.Frames[0];

Dim uriBitmap As BitmapDecoder = BitmapDecoder.Create(New Uri("sampleImages/waterlilies.jpg", UriKind.Relative), BitmapCreateOptions.None, BitmapCacheOption.Default)

' Create an image element;
Dim uriImage As New Image()
uriImage.Width = 200
' Set image source.
uriImage.Source = uriBitmap.Frames(0)

The following code example demonstrates how to use the built in TiffBitmapDecoder to open and decode a Tagged Image File Format (TIFF) bitmap. The resulting BitmapSource is used as the Source of an Image element.


// Open a Stream and decode a TIFF image
Stream imageStreamSource = new FileStream("tulipfarm.tif", FileMode.Open, FileAccess.Read, FileShare.Read);
TiffBitmapDecoder decoder = new TiffBitmapDecoder(imageStreamSource, BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.Default);
BitmapSource bitmapSource = decoder.Frames[0];

// Draw the Image
Image myImage1 = new Image();
myImage1.Source = bitmapSource;
myImage1.Stretch = Stretch.None;
myImage1.Margin = new Thickness(20);

' Open a Stream and decode a TIFF image
Dim imageStreamSource As New FileStream("tulipfarm.tif", FileMode.Open, FileAccess.Read, FileShare.Read)
Dim decoder As New TiffBitmapDecoder(imageStreamSource, BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.Default)
Dim bitmapSource As BitmapSource = decoder.Frames(0)

' Draw the Image
Dim myImage1 As New Image()
myImage1.Source = bitmapSource
myImage1.Stretch = Stretch.None
myImage1.Margin = New Thickness(20)

Remarks

BitmapDecoder is not a BitmapFrame itself; rather, it is a container for BitmapFrame objects. Each BitmapFrame in the container can potentially have different attributes, including different sizes, resolutions, or palettes.

Unless a specific codec is selected, Windows Presentation Foundation (WPF) uses automatic run-time discovery to identify the format of an image and match it with the appropriate codec. This discovery process allows a codec developed by an independent software vendor (ISV) to be automatically discoverable by the system. To select a specific codec, the derived BitmapDecoder or BitmapEncoder, such as the TiffBitmapDecoder class, should be used.

Tagged Image File Format (TIFF) and Graphics Interchange Format (GIF) are the only implemented image formats that support multiple frames.

Constructors

BitmapDecoder()

Initializes a new instance of BitmapDecoder.

Properties

CodecInfo

Gets information that describes this codec.
ColorContexts

Gets a value that represents the color profile associated with a bitmap, if one is defined.
Dispatcher

Gets the Dispatcher this DispatcherObject is associated with.

(Inherited from DispatcherObject)
Frames

Gets the content of an individual frame within a bitmap.
IsDownloading

Gets a value that indicates if the decoder is currently downloading content.
Metadata

Gets an instance of BitmapMetadata that represents the global metadata associated with this bitmap, if metadata is defined.
Palette

Gets the BitmapPalette associated with this decoder.
Preview

Gets a BitmapSource that represents the global preview of this bitmap, if one is defined.
Thumbnail

Gets a BitmapSource that represents the thumbnail of the bitmap, if one is defined.

Methods

CheckAccess()

Determines whether the calling thread has access to this DispatcherObject.

(Inherited from DispatcherObject)
Create(Stream, BitmapCreateOptions, BitmapCacheOption)

Creates a BitmapDecoder from a Stream by using the specified BitmapCreateOptions and BitmapCacheOption.
Create(Uri, BitmapCreateOptions, BitmapCacheOption, RequestCachePolicy)

Creates a BitmapDecoder from a Uri by using the specified BitmapCreateOptions, BitmapCacheOption and RequestCachePolicy.
Create(Uri, BitmapCreateOptions, BitmapCacheOption)

Creates a BitmapDecoder from a Uri by using the specified BitmapCreateOptions and BitmapCacheOption.
CreateInPlaceBitmapMetadataWriter()

Creates an instance of InPlaceBitmapMetadataWriter, which can be used to update the metadata of a bitmap.
Equals(Object)

Determines whether the specified object is equal to the current object.

(Inherited from Object)
Finalize()

Frees resources and performs other cleanup operations before the BitmapDecoder is reclaimed by garbage collection.
GetHashCode()

Serves as the default hash function.

(Inherited from Object)
GetType()

Gets the Type of the current instance.

(Inherited from Object)
MemberwiseClone()

Creates a shallow copy of the current Object.

(Inherited from Object)
ToString()

Converts the current value of a BitmapDecoder to a String.
VerifyAccess()

Enforces that the calling thread has access to this DispatcherObject.

(Inherited from DispatcherObject)

Events

DownloadCompleted

Occurs when a BitmapDecoder has finished downloading bitmap content.
DownloadFailed

Occurs when bitmap content failed to download.
DownloadProgress

Occurs when a BitmapDecoder has made progress downloading bitmap content.

Applies to

See also