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//---------------------------------------------------------------------------
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
// Description: This file contains non-generated DrawingCollection
// methods.
//
// History:
//
// 2005/03/18 : timothyc - Created it.
//
//---------------------------------------------------------------------------
using System.Collections;
using System.Collections.Generic;
using System.Windows.Media.Animation;
using System.Windows.Markup;
namespace System.Windows.Media
{
/// <summary>
/// Collection of Drawing objects
/// </summary>
public sealed partial class DrawingCollection : Animatable, IList, IList<Drawing>
{
/// <summary>
/// Appends the entire input DrawingCollection, while only firing a single set of
/// public events. If an exception is thrown from the public events, the
/// Append operation is rolled back.
/// </summary>
internal void TransactionalAppend(DrawingCollection collectionToAppend)
{
// Use appendCount to avoid inconsistencies & runaway loops when
// this == collectionToAppend, and to ensure collectionToAppend.Count
// is only evaluated once.
int appendCount = collectionToAppend.Count;
// First, append the collection
for(int i = 0; i < appendCount; i++)
{
AddWithoutFiringPublicEvents(collectionToAppend.Internal_GetItem(i));
}
// Fire the public Changed event after all the elements have been added.
//
// If an exception is thrown, then the Append operation is rolled-back without
// firing additional events.
try
{
FireChanged();
}
catch (Exception)
{
// Compute the number of elements that existed before the append
int beforeAppendCount = Count - appendCount;
// Remove the appended elements in reverse order without firing Changed events.
for ( int i = Count - 1; // Start at the current last index
i >= beforeAppendCount; // Until the previous last index
i-- // Move to the preceding index
)
{
RemoveAtWithoutFiringPublicEvents(i);
}
// Avoid firing WritePostscript events (e.g., OnChanged) after rolling-back
// the current operation.
//
// This ensures that only a single set of events is fired for both exceptional &
// typical cases, and it's likely that firing events would cause another exception.
throw;
}
}
}
}
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