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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.
//
// Description: Provides a view port for a page of content for a DocumentPage.
//
using System.Windows; // UIElement
using System.Windows.Media; // Visual
namespace MS.Internal.Documents
{
/// <summary>
/// Provides a view port for a page of content for a DocumentPage.
/// </summary>
internal class DocumentPageHost : FrameworkElement
{
//-------------------------------------------------------------------
//
// Constructors
//
//-------------------------------------------------------------------
#region Constructors
/// <summary>
/// Create an instance of a DocumentPageHost.
/// </summary>
internal DocumentPageHost()
: base()
{
}
#endregion Constructors
//-------------------------------------------------------------------
//
// Internal Methods
//
//-------------------------------------------------------------------
#region Internal Methods
internal static void DisconnectPageVisual(Visual pageVisual)
{
// There might be a case where a visual associated with a page was
// inserted to a visual tree before. It got removed later, but GC did not
// destroy its parent yet. To workaround this case always check for the parent
// of page visual and disconnect it, when necessary.
Visual currentParent = VisualTreeHelper.GetParent(pageVisual) as Visual;
if (currentParent != null)
{
ContainerVisual pageVisualHost = currentParent as ContainerVisual;
if (pageVisualHost == null)
throw new ArgumentException(SR.DocumentPageView_ParentNotDocumentPageHost, "pageVisual");
DocumentPageHost docPageHost = VisualTreeHelper.GetParent(pageVisualHost) as DocumentPageHost;
if (docPageHost == null)
throw new ArgumentException(SR.DocumentPageView_ParentNotDocumentPageHost, "pageVisual");
docPageHost.PageVisual = null;
}
}
#endregion Internal Methods
//-------------------------------------------------------------------
//
// Internal Properties
//
//-------------------------------------------------------------------
#region Internal Properties
/// <summary>
/// Root of visual subtree hosted by this DocumentPageHost.
/// </summary>
internal Visual PageVisual
{
get
{
return _pageVisual;
}
set
{
ContainerVisual pageVisualHost;
if (_pageVisual != null)
{
pageVisualHost = VisualTreeHelper.GetParent(_pageVisual) as ContainerVisual;
Invariant.Assert(pageVisualHost != null);
pageVisualHost.Children.Clear();
this.RemoveVisualChild(pageVisualHost);
}
_pageVisual = value;
if (_pageVisual != null)
{
pageVisualHost = new ContainerVisual();
this.AddVisualChild(pageVisualHost);
pageVisualHost.Children.Add(_pageVisual);
pageVisualHost.SetValue(FlowDirectionProperty, FlowDirection.LeftToRight);
}
}
}
/// <summary>
/// Internal cached offset.
/// </summary>
internal Point CachedOffset;
#endregion Internal Properties
#region VisualChildren
/// <summary>
/// Derived class must implement to support Visual children. The method must return
/// the child at the specified index. Index must be between 0 and GetVisualChildrenCount-1.
///
/// By default a Visual does not have any children.
///
/// Remark:
/// During this virtual call it is not valid to modify the Visual tree.
/// </summary>
protected override Visual GetVisualChild(int index)
{
if (index != 0 || _pageVisual == null)
{
throw new ArgumentOutOfRangeException("index", index, SR.Visual_ArgumentOutOfRange);
}
return VisualTreeHelper.GetParent(_pageVisual) as Visual;
}
/// <summary>
/// Derived classes override this property to enable the Visual code to enumerate
/// the Visual children. Derived classes need to return the number of children
/// from this method.
///
/// By default a Visual does not have any children.
///
/// Remark: During this virtual method the Visual tree must not be modified.
/// </summary>
protected override int VisualChildrenCount
{
get { return _pageVisual != null ? 1 : 0; }
}
#endregion VisualChildren
private Visual _pageVisual;
}
}
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