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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
//
//
#pragma warning disable 1634, 1691 // Allow suppression of certain presharp messages
using System.IO;
using System.Collections.ObjectModel;
using System.Net.Cache;
namespace System.Windows.Media.Imaging
{
#region LateBoundBitmapDecoder
/// <summary>
/// LateBoundBitmapDecoder is a container for bitmap frames. Each bitmap frame is an BitmapFrame.
/// Any BitmapFrame it returns are frozen
/// be immutable.
/// </summary>
public sealed class LateBoundBitmapDecoder : BitmapDecoder
{
#region Constructors
/// <summary>
/// Constructor
/// </summary>
internal LateBoundBitmapDecoder(
Uri baseUri,
Uri uri,
Stream stream,
BitmapCreateOptions createOptions,
BitmapCacheOption cacheOption,
RequestCachePolicy requestCachePolicy
)
: base(true)
{
_baseUri = baseUri;
_uri = uri;
_stream = stream;
_createOptions = createOptions;
_cacheOption = cacheOption;
_requestCachePolicy = requestCachePolicy;
// Check to see if we need to download content off thread
Uri uriToDecode = (_baseUri != null) ? new Uri(_baseUri, _uri) : _uri;
if (uriToDecode != null)
{
if (uriToDecode.Scheme == Uri.UriSchemeHttp ||
uriToDecode.Scheme == Uri.UriSchemeHttps)
{
// Begin the download
BitmapDownload.BeginDownload(this, uriToDecode, _requestCachePolicy, _stream);
_isDownloading = true;
}
}
if (_stream != null && !_stream.CanSeek)
{
// Begin the download
BitmapDownload.BeginDownload(this, uriToDecode, _requestCachePolicy, _stream);
_isDownloading = true;
}
}
#endregion
#region Properties
/// <summary>
/// If there is an palette, return it.
/// Otherwise, return null.
/// If the LateBoundDecoder is still downloading, the returned Palette is null.
/// </summary>
public override BitmapPalette Palette
{
get
{
VerifyAccess();
if (_isDownloading)
{
return null;
}
return Decoder.Palette;
}
}
/// <summary>
/// If there is an embedded color profile, return it.
/// Otherwise, return null.
/// If the LateBoundDecoder is still downloading, the returned ColorContext is null.
/// </summary>
public override ReadOnlyCollection<ColorContext> ColorContexts
{
get
{
VerifyAccess();
if (_isDownloading)
{
return null;
}
return Decoder.ColorContexts;
}
}
/// <summary>
/// If there is a global thumbnail, return it.
/// Otherwise, return null. The returned source is frozen.
/// If the LateBoundDecoder is still downloading, the returned Thumbnail is null.
/// </summary>
public override BitmapSource Thumbnail
{
get
{
VerifyAccess();
if (_isDownloading)
{
return null;
}
return Decoder.Thumbnail;
}
}
/// <summary>
/// The info that identifies this codec.
/// If the LateBoundDecoder is still downloading, the returned CodecInfo is null.
/// </summary>
public override BitmapCodecInfo CodecInfo
{
get
{
VerifyAccess();
if (_isDownloading)
{
return null;
}
return Decoder.CodecInfo;
}
}
/// <summary>
/// Access to the individual frames.
/// Since a LateBoundBitmapDecoder is downloaded asynchronously,
/// its possible the underlying frame collection may change once
/// content has been downloaded and decoded. When content is initially
/// downloading, the collection will always return at least one item
/// in the collection. When the download/decode is complete, the BitmapFrame
/// will automatically change its underlying content. i.e. Only the collection
/// object may change. The actual frame object will remain the same.
/// </summary>
public override ReadOnlyCollection<BitmapFrame> Frames
{
get
{
VerifyAccess();
// If the content is still being downloaded, create a collection
// with 1 item that will point to an empty bitmap
if (_isDownloading)
{
if (_readOnlyFrames == null)
{
_frames = new List<BitmapFrame>((int)1);
_frames.Add(
new BitmapFrameDecode(
0,
_createOptions,
_cacheOption,
this
)
);
_readOnlyFrames = new ReadOnlyCollection<BitmapFrame>(_frames);
}
return _readOnlyFrames;
}
else
{
return Decoder.Frames;
}
}
}
/// <summary>
/// If there is a global preview image, return it.
/// Otherwise, return null. The returned source is frozen.
/// If the LateBoundDecoder is still downloading, the returned Preview is null.
/// </summary>
public override BitmapSource Preview
{
get
{
VerifyAccess();
if (_isDownloading)
{
return null;
}
return Decoder.Preview;
}
}
/// <summary>
/// Returns the underlying decoder associated with this late bound decoder.
/// If the LateBoundDecoder is still downloading, the underlying decoder is null,
/// otherwise the underlying decoder is created on first access.
/// </summary>
public BitmapDecoder Decoder
{
get
{
VerifyAccess();
if (_isDownloading || _failed)
{
return null;
}
EnsureDecoder();
return _realDecoder;
}
}
/// <summary>
/// Returns if the decoder is downloading content
/// </summary>
public override bool IsDownloading
{
get
{
VerifyAccess();
return _isDownloading;
}
}
#endregion
#region Methods
///
/// Ensure that the underlying decoder is created
///
private void EnsureDecoder()
{
if (_realDecoder == null)
{
_realDecoder = BitmapDecoder.CreateFromUriOrStream(
_baseUri,
_uri,
_stream,
_createOptions & ~BitmapCreateOptions.DelayCreation,
_cacheOption,
_requestCachePolicy,
true
);
// Check to see if someone already got the frames
// If so, we need to ensure that the real decoder
// references the same frame as the one we already created
// Creating a new object would be bad.
if (_readOnlyFrames != null)
{
_realDecoder.SetupFrames(null, _readOnlyFrames);
//
// The frames have been transfered to the real decoder, so we no
// longer need them.
//
_readOnlyFrames = null;
_frames = null;
}
}
}
///
/// Called when download is complete
///
internal object DownloadCallback(object arg)
{
Stream newStream = (Stream)arg;
// Assert that we are able to seek the new stream
Debug.Assert(newStream.CanSeek == true);
_stream = newStream;
// If we are not supposed to delay create, then ensure the decoder
// otherwise it will be done on first access
if ((_createOptions & BitmapCreateOptions.DelayCreation) == 0)
{
try
{
EnsureDecoder();
}
catch(Exception e)
{
#pragma warning disable 6500
return ExceptionCallback(e);
#pragma warning restore 6500
}
}
_isDownloading = false;
_downloadEvent.InvokeEvents(this, null);
return null;
}
///
/// Called when download progresses
///
internal object ProgressCallback(object arg)
{
int percentComplete = (int)arg;
_progressEvent.InvokeEvents(this, new DownloadProgressEventArgs(percentComplete));
return null;
}
///
/// Called when an exception occurs
///
internal object ExceptionCallback(object arg)
{
_isDownloading = false;
_failed = true;
_failedEvent.InvokeEvents(this, new ExceptionEventArgs((Exception)arg));
return null;
}
#endregion
#region Internal Abstract
/// Need to implement this to derive from the "sealed" object
internal override void SealObject()
{
throw new NotImplementedException();
}
#endregion
#region Data Members
/// Is downloading data
private bool _isDownloading;
/// Is downloading data
private bool _failed;
/// Real decoder
private BitmapDecoder _realDecoder;
/// <summary>
/// the cache policy to use for web requests.
/// </summary>
private RequestCachePolicy _requestCachePolicy;
#endregion
}
#endregion
}
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