WPF中TreeView.BringIntoView方法的替代方案
2021-06-07 02:05
标签：arch 没有 col null res contain data nbsp reac WPF中TreeView.BringIntoView方法的替代方案 周银辉 WPF中TreeView.BringIntoView（）方法并不是那么地好用，不少时候会没有效果，这里有一个替代方案，调用SelectItem（）方法可以展开并呈现TreeView上指定的Item： public static class TreeViewHelper { /// /// Expands all children of a TreeView /// /// The TreeView whose children will be expanded public static void ExpandAll(this TreeView treeView) { ExpandSubContainers(treeView); } /// /// Expands all children of a TreeView or TreeViewItem /// /// The TreeView or TreeViewItem containing the children to expand private static void ExpandSubContainers(ItemsControl parentContainer) { foreach (Object item in parentContainer.Items) { TreeViewItem currentContainer = parentContainer.ItemContainerGenerator.ContainerFromItem(item) as TreeViewItem; if (currentContainer != null && currentContainer.Items.Count > 0) { //expand the item currentContainer.IsExpanded = true; //if the item‘s children are not generated, they must be expanded if (currentContainer.ItemContainerGenerator.Status != GeneratorStatus.ContainersGenerated) { //store the event handler in a variable so we can remove it (in the handler itself) EventHandler eh = null; eh = new EventHandler(delegate { //once the children have been generated, expand those children‘s children then remove the event handler if (currentContainer.ItemContainerGenerator.Status == GeneratorStatus.ContainersGenerated) { ExpandSubContainers(currentContainer); currentContainer.ItemContainerGenerator.StatusChanged -= eh; } }); currentContainer.ItemContainerGenerator.StatusChanged += eh; } else //otherwise the children have already been generated, so we can now expand those children { ExpandSubContainers(currentContainer); } } } } /// /// Searches a TreeView for the provided object and selects it if found /// /// The TreeView containing the item /// The item to search and select public static void SelectItem(this TreeView treeView, object item) { ExpandAndSelectItem(treeView, item); } /// /// Finds the provided object in an ItemsControl‘s children and selects it /// /// The parent container whose children will be searched for the selected item /// The item to select /// private static bool ExpandAndSelectItem(ItemsControl parentContainer, object itemToSelect) { //check all items at the current level foreach (Object item in parentContainer.Items) { TreeViewItem currentContainer = parentContainer.ItemContainerGenerator.ContainerFromItem(item) as TreeViewItem; //if the data item matches the item we want to select, set the corresponding //TreeViewItem IsSelected to true if (item == itemToSelect && currentContainer != null) { currentContainer.IsSelected = true; currentContainer.BringIntoView(); currentContainer.Focus(); //the item was found return true; } } //if we get to this point, the selected item was not found at the current level, so we must check the children foreach (Object item in parentContainer.Items) { TreeViewItem currentContainer = parentContainer.ItemContainerGenerator.ContainerFromItem(item) as TreeViewItem; //if children exist if (currentContainer != null && currentContainer.Items.Count > 0) { //keep track of if the TreeViewItem was expanded or not bool wasExpanded = currentContainer.IsExpanded; //expand the current TreeViewItem so we can check its child TreeViewItems currentContainer.IsExpanded = true; //if the TreeViewItem child containers have not been generated, we must listen to //the StatusChanged event until they are if (currentContainer.ItemContainerGenerator.Status != GeneratorStatus.ContainersGenerated) { //store the event handler in a variable so we can remove it (in the handler itself) EventHandler eh = null; eh = new EventHandler(delegate { if (currentContainer.ItemContainerGenerator.Status == GeneratorStatus.ContainersGenerated) { if (ExpandAndSelectItem(currentContainer, itemToSelect) == false) { //The assumption is that code executing in this EventHandler is the result of the parent not //being expanded since the containers were not generated. //since the itemToSelect was not found in the children, collapse the parent since it was previously collapsed currentContainer.IsExpanded = false; } //remove the StatusChanged event handler since we just handled it (we only needed it once) currentContainer.ItemContainerGenerator.StatusChanged -= eh; } }); currentContainer.ItemContainerGenerator.StatusChanged += eh; } else //otherwise the containers have been generated, so look for item to select in the children { if (ExpandAndSelectItem(currentContainer, itemToSelect) == false) { //restore the current TreeViewItem‘s expanded state currentContainer.IsExpanded = wasExpanded; } else //otherwise the node was found and selected, so return true { return true; } } } } //no item was found return false; } } WPF中TreeView.BringIntoView方法的替代方案 标签：arch 没有 col null res contain data nbsp reac 原文地址：https://www.cnblogs.com/lonelyxmas/p/10761774.html
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