C# FrameworkTemplate.BuildVisualTree方法代码示例

//.........这里部分代码省略.........
                    string label = feContainer.Name;
                    if (label == null || label.Length == 0)
                        label = container.GetHashCode().ToString(System.Globalization.CultureInfo.InvariantCulture);

                    EventTrace.EventProvider.TraceEvent(EventTrace.Event.WClientParseInstVisTreeEnd, EventTrace.Keyword.KeywordXamlBaml, EventTrace.Level.Verbose,
                                                         String.Format(System.Globalization.CultureInfo.InvariantCulture, "Style.InstantiateSubTree for {0} {1}", container.GetType().Name, label));
                }
            }

            // It's not a FEF-style template, is it a non-empty optimized one?

            else if (frameworkTemplate != null && frameworkTemplate.HasXamlNodeContent)
            {
                // Yes, create from the optimized template content.
                EventTrace.EasyTraceEvent(EventTrace.Keyword.KeywordXamlBaml, EventTrace.Level.Verbose, EventTrace.Event.WClientParseInstVisTreeBegin);

                CheckForCircularReferencesInTemplateTree(container, frameworkTemplate );

                // Container is considered ChildIndex '0' (Self), but,
                // Container.ChildIndex isn't set

                List<DependencyObject> affectedChildren = new List<DependencyObject>(lastChildIndex);

                // Assign affectedChildren to container

                TemplatedFeChildrenField.SetValue(container, affectedChildren);

                DependencyObject treeRoot;

                // Load the content

                treeRoot = frameworkTemplate.LoadContent( container, affectedChildren);

                Debug.Assert(treeRoot == null || treeRoot is FrameworkElement || treeRoot is FrameworkContentElement,
                    "Root node of tree must be a FrameworkElement or FrameworkContentElement.  This should have been caught by set_VisualTree" );

                visualsCreated = true;

                if (feContainer != null && EventTrace.IsEnabled(EventTrace.Keyword.KeywordXamlBaml, EventTrace.Level.Verbose))
                {
                    string label = feContainer.Name;
                    if (label == null || label.Length == 0)
                        label = container.GetHashCode().ToString(System.Globalization.CultureInfo.InvariantCulture);

                    EventTrace.EventProvider.TraceEvent(EventTrace.Event.WClientParseInstVisTreeEnd, EventTrace.Keyword.KeywordXamlBaml, EventTrace.Level.Verbose,
                                                         String.Format(System.Globalization.CultureInfo.InvariantCulture, "Style.InstantiateSubTree for {0} {1}", container.GetType().Name, label));
                }
            }

            // No template was supplied.  Allow subclasses to provide the template.
            // This is currently only implemented for FrameworkElement's.

            else
            {
                if (feContainer != null)
                {
                    // This template will not be driven by the Style in any way.
                    // Rather, it will be built and initialized by the callee

                    // CALLBACK
#if DEBUG
                    Debug.Assert( feContainer._buildVisualTreeVerification == VerificationState.WaitingForBuildVisualTree,
                        "The BuildVisualTree override has triggered another call to itself.  This is not good - something between the two Style.InstantiateSubTree calls on the stack is doing A Very Bad Thing.");
                    feContainer._buildVisualTreeVerification = VerificationState.WaitingForAddCustomTemplateRoot;
                    bool exceptionThrown = true;
                    try
                    {
#endif

                    Debug.Assert(frameworkTemplate != null, "Only FrameworkTemplate has the ability to build a VisualTree by this means");
                    visualsCreated = frameworkTemplate.BuildVisualTree(feContainer);

#if DEBUG
                    exceptionThrown = false;
                    }
                    finally
                    {
                        if (!exceptionThrown)   // results are unreliable if an exception was thrown
                        {
                            if( visualsCreated )
                            {
                                Debug.Assert( feContainer._buildVisualTreeVerification == VerificationState.WaitingForBuildVisualTreeCompletion,
                                    "A derived class overriding BuildVisualTree must call AddCustomTemplateRoot to attach its custom subtree before exiting.");
                            }
                            else
                            {
                                Debug.Assert( feContainer._buildVisualTreeVerification == VerificationState.WaitingForAddCustomTemplateRoot,
                                    "If a derived class overriding BuildVisualTree has called AddCustomTemplateRoot to attach its custom subtree, its BuildVisualTree must return true to indicate that it has done so.");
                            }
                        }

                        // All done building this visual tree, stand by for the next one.
                        feContainer._buildVisualTreeVerification = VerificationState.WaitingForBuildVisualTree;
                    }
#endif
                }
            }

            return visualsCreated;
        }