|
// 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: The ContentHostHelper class contains static methods that are
// useful for performing common tasks with IContentHost.
//
using System; // Object
using System.Collections.Generic; // List<T>
using System.Windows; // IContentHost
using System.Windows.Controls; // TextBlock
using System.Windows.Controls.Primitives; // DocumentPageView
using System.Windows.Documents; // FlowDocument
using System.Windows.Media; // Visual
using MS.Internal.PtsHost; // FlowDocumentPage
namespace MS.Internal.Documents
{
/// <summary>
/// Static helper functions for dealing with IContentHost.
/// </summary>
internal static class ContentHostHelper
{
//-------------------------------------------------------------------
//
// Internal Methods
//
//-------------------------------------------------------------------
#region Internal Methods
/// <summary>
/// Given a ContentElement searches for associated IContentHost, if one exists.
/// </summary>
/// <param name="contentElement">Content element</param>
/// <returns>Associated IContentHost with ContentElement.</returns>
internal static IContentHost FindContentHost(ContentElement contentElement)
{
IContentHost ich = null;
DependencyObject parent;
TextContainer textContainer;
if (contentElement == null) { return null; }
// If the ContentElement is a TextElement, retrieve IContentHost form the owner
// of TextContainer.
if (contentElement is TextElement)
{
textContainer = ((TextElement)contentElement).TextContainer;
parent = textContainer.Parent;
if (parent is IContentHost) // TextBlock
{
ich = (IContentHost)parent;
}
else if (parent is FlowDocument) // Viewers
{
ich = GetICHFromFlowDocument((TextElement)contentElement, (FlowDocument)parent);
}
else if (textContainer.TextView != null && textContainer.TextView.RenderScope is IContentHost)
{
// TextBlock hosted in ControlTemplate
ich = (IContentHost)textContainer.TextView.RenderScope;
}
}
// else; cannot retrive IContentHost
return ich;
}
#endregion Internal Methods
//-------------------------------------------------------------------
//
// Private Methods
//
//-------------------------------------------------------------------
#region Private Methods
/// <summary>
/// Given a ContentElement within FlowDocument searches for associated IContentHost.
/// </summary>
/// <param name="contentElement">Content element</param>
/// <param name="flowDocument">FlowDocument hosting ContentElement.</param>
/// <returns>Associated IContentHost with ContentElement.</returns>
private static IContentHost GetICHFromFlowDocument(TextElement contentElement, FlowDocument flowDocument)
{
IContentHost ich = null;
List<DocumentPageView> pageViews;
ITextView textView = flowDocument.StructuralCache.TextContainer.TextView;
if (textView != null)
{
// If FlowDocument is hosted by FlowDocumentScrollViewer, the RenderScope
// is FlowDocumentView object which hosts PageVisual representing the content.
// This PageVisual is also IContentHost for the entire content of DocumentPage.
if (textView.RenderScope is FlowDocumentView) // FlowDocumentScrollViewer
{
if (VisualTreeHelper.GetChildrenCount(textView.RenderScope) > 0)
{
ich = VisualTreeHelper.GetChild(textView.RenderScope, 0) as IContentHost;
}
}
// Our best guess is that FlowDocument is hosted by DocumentViewerBase.
// In this case search the style for all DocumentPageViews.
// Having collection of DocumentPageViews, find for the one which hosts TextElement.
else if (textView.RenderScope is FrameworkElement)
{
pageViews = new List<DocumentPageView>();
FindDocumentPageViews(textView.RenderScope, pageViews);
for (int i = 0; i < pageViews.Count; i++)
{
if (pageViews[i].DocumentPage is FlowDocumentPage)
{
textView = (ITextView)((IServiceProvider)pageViews[i].DocumentPage).GetService(typeof(ITextView));
if (textView != null && textView.IsValid)
{
// Check if the page contains ContentElement. Check Start and End
// position, which will give desired results in most of the cases.
// Having hyperlink spanning more than 2 pages is not very common,
// and this code will not work with it correctly.
if (textView.Contains(contentElement.ContentStart) ||
textView.Contains(contentElement.ContentEnd))
{
ich = pageViews[i].DocumentPage.Visual as IContentHost;
}
}
}
}
}
}
return ich;
}
/// <summary>
/// Does deep Visual tree walk to retrieve all DocumentPageViews.
/// It stops recursing down into visual tree in following situations:
/// a) Visual is UIElement and it is not part of Contol Template,
/// b) Visual is DocumentPageView.
/// </summary>
/// <param name="root">FrameworkElement that is part of Control Template.</param>
/// <param name="pageViews">Collection of DocumentPageViews; found elements are appended here.</param>
/// <returns>Whether collection of DocumentPageViews has been updated.</returns>
private static void FindDocumentPageViews(Visual root, List<DocumentPageView> pageViews)
{
Invariant.Assert(root != null);
Invariant.Assert(pageViews != null);
if (root is DocumentPageView)
{
pageViews.Add((DocumentPageView)root);
}
else
{
FrameworkElement fe;
// Do deep tree walk to retrieve all DocumentPageViews.
// It stops recursing down into visual tree in following situations:
// a) Visual is UIElement and it is not part of Contol Template,
// b) Visual is DocumentPageView.
// Add to collection any DocumentPageViews found in the Control Template.
int count = root.InternalVisualChildrenCount;
for (int i = 0; i < count; i++)
{
Visual child = root.InternalGetVisualChild(i);
fe = child as FrameworkElement;
if (fe != null)
{
if (fe.TemplatedParent != null)
{
if (fe is DocumentPageView)
{
pageViews.Add(fe as DocumentPageView);
}
else
{
FindDocumentPageViews(fe, pageViews);
}
}
}
else
{
FindDocumentPageViews(child, pageViews);
}
}
}
}
#endregion Private Methods
}
}
|