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6502bench/CommonWPF/WPFExtensions.cs
Andy McFadden 41b6a97408 Populate toolbar icons
Extract some XAML icons from the VS2017 Image Library.  There's no
particular reason to prefer XAML over PNG, but somehow it feels
more forward-compatible.  (OTOH, defining images as ControlTemplate
instances is just weird.  Yay WPF.)
2019-06-11 14:38:08 -07:00

98 lines
3.8 KiB
C#

/*
* Copyright 2019 faddenSoft
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
using System;
using System.Diagnostics;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
namespace CommonWPF {
/// <summary>
/// Generic Visual helper.
/// </summary>
public static class VisualHelper {
/// <summary>
/// Find a child object in a WPF visual tree.
/// </summary>
/// <remarks>
/// Sample usage:
/// GridViewHeaderRowPresenter headerRow = listView.GetVisualChild&lt;GridViewHeaderRowPresenter&gt;();
///
/// From https://social.msdn.microsoft.com/Forums/vstudio/en-US/7d0626cb-67e8-4a09-a01e-8e56ee7411b2/gridviewcolumheader-radiobuttons?forum=wpf
/// </remarks>
/// <typeparam name="T"></typeparam>
/// <param name="referenceVisual"></param>
/// <returns></returns>
public static T GetVisualChild<T>(this Visual referenceVisual) where T : Visual {
Visual child = null;
for (Int32 i = 0; i < VisualTreeHelper.GetChildrenCount(referenceVisual); i++) {
child = VisualTreeHelper.GetChild(referenceVisual, i) as Visual;
if (child != null && child is T) {
break;
} else if (child != null) {
child = GetVisualChild<T>(child);
if (child != null && child is T) {
break;
}
}
}
return child as T;
}
}
/// <summary>
/// Add functions to get the element that's currently shown at the top of the ListView
/// window, and to scroll the list so that a specific item is at the top.
/// </summary>
public static class ListViewExtensions {
/// <summary>
/// Figures out which item index is at the top of the window. This only works for a
/// ListView with a VirtualizingStackPanel.
/// </summary>
/// <remarks>
/// See https://stackoverflow.com/q/2926722/294248 for an alternative approach that
/// uses hit-testing, as well as a copy of this approach.
/// </remarks>
/// <returns>The item index, or -1 if the list is empty.</returns>
public static int GetTopItemIndex(this ListView lv) {
if (lv.Items.Count == 0) {
return -1;
}
VirtualizingStackPanel vsp = lv.GetVisualChild<VirtualizingStackPanel>();
if (vsp == null) {
Debug.Assert(false, "ListView does not have a VirtualizingStackPanel");
return -1;
}
return (int) vsp.VerticalOffset;
}
/// <summary>
/// Scrolls the ListView so that the specified item is at the top. The standard
/// ListView.ScrollIntoView() makes the item visible but doesn't ensure a
/// specific placement.
/// </summary>
/// <remarks>
/// Equivalent to setting myListView.TopItem in WinForms.
/// </remarks>
public static void ScrollToTopItem(this ListView lv, object item) {
ScrollViewer sv = lv.GetVisualChild<ScrollViewer>();
sv.ScrollToBottom();
lv.ScrollIntoView(item);
}
}
}