Wpf 当托管在ItemsControl中时,自定义IScrollInfo面板将失去滚动功能
我正在尝试使用该界面创建自定义面板,但收效甚微。如果我在XAML的自定义面板中手动声明项,我可以让它工作,但是当我将它放入Wpf 当托管在ItemsControl中时,自定义IScrollInfo面板将失去滚动功能,wpf,panel,scrollviewer,itemscontrol,Wpf,Panel,Scrollviewer,Itemscontrol,我正在尝试使用该界面创建自定义面板,但收效甚微。如果我在XAML的自定义面板中手动声明项,我可以让它工作,但是当我将它放入ItemsControl时,滚动功能停止。如果有人能告诉我哪里出了问题,我将不胜感激。下面是面板的代码(相当长,但很简单): using IScrollInfoExample.Extentions; using System; using System.Windows; using System.Windows.Controls; using System.Windows.C
ItemsControl
时,滚动功能停止。如果有人能告诉我哪里出了问题,我将不胜感激。下面是面板的代码(相当长,但很简单):
using IScrollInfoExample.Extentions;
using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Controls.Primitives;
using System.Windows.Media;
namespace IScrollInfoExample
{
public class ExampleScrollPanel : Panel, IScrollInfo
{
private TranslateTransform _trans = new TranslateTransform();
private Size _extent = new Size(0, 0);
private Size _viewport = new Size(0, 0);
private Point _offset;
private const double _scrollAmount = 3;
public ExampleScrollPanel()
{
Loaded += ExampleScrollPanel_Loaded;
RenderTransform = (_trans = new TranslateTransform());
}
public bool CanHorizontallyScroll { get; set; } = false;
public bool CanVerticallyScroll { get; set; } = true;
public double HorizontalOffset
{
get { return _offset.X; }
}
public double VerticalOffset
{
get { return _offset.Y; }
}
public double ExtentHeight
{
get { return _extent.Height; }
}
public double ExtentWidth
{
get { return _extent.Width; }
}
public double ViewportHeight
{
get { return _viewport.Height; }
}
public double ViewportWidth
{
get { return _viewport.Width; }
}
public ScrollViewer ScrollOwner { get; set; }
public void LineUp()
{
SetVerticalOffset(VerticalOffset - _scrollAmount);
}
public void PageUp()
{
SetVerticalOffset(VerticalOffset - _viewport.Height);
}
public void MouseWheelUp()
{
SetVerticalOffset(VerticalOffset - _scrollAmount);
}
public void LineDown()
{
SetVerticalOffset(VerticalOffset + _scrollAmount);
}
public void PageDown()
{
SetVerticalOffset(VerticalOffset + _viewport.Height);
}
public void MouseWheelDown()
{
SetVerticalOffset(VerticalOffset + _scrollAmount);
}
public void LineLeft()
{
SetHorizontalOffset(HorizontalOffset - _scrollAmount);
}
public void PageLeft()
{
SetHorizontalOffset(HorizontalOffset - _viewport.Width);
}
public void MouseWheelLeft()
{
LineLeft();
}
public void LineRight()
{
SetHorizontalOffset(HorizontalOffset + _scrollAmount);
}
public void PageRight()
{
SetHorizontalOffset(HorizontalOffset + _viewport.Width);
}
public void MouseWheelRight()
{
LineRight();
}
public Rect MakeVisible(Visual visual, Rect rectangle)
{
return new Rect();
}
public void SetHorizontalOffset(double offset)
{
if (offset < 0 || _viewport.Width >= _extent.Width)
{
offset = 0;
}
else if (offset + _viewport.Width >= _extent.Width)
{
offset = _extent.Width - _viewport.Width;
}
_offset.X = offset;
if (ScrollOwner != null) ScrollOwner.InvalidateScrollInfo();
_trans.X = -offset;
}
public void SetVerticalOffset(double offset)
{
offset = CoerceVerticalOffset(offset);
_offset.Y = offset;
_trans.Y = -offset;
if (ScrollOwner != null) ScrollOwner.InvalidateScrollInfo();
}
private double CoerceVerticalOffset(double offset)
{
if (offset < 0 || _viewport.Height >= _extent.Height)
{
offset = 0;
}
else if (offset + _viewport.Height >= _extent.Height)
{
offset = _extent.Height - _viewport.Height;
}
return offset;
}
private void ExampleScrollPanel_Loaded(object sender, RoutedEventArgs e)
{
ScrollViewer scrollOwner = this.GetParentOfType<ScrollViewer>();
if (scrollOwner != null) ScrollOwner = scrollOwner;
}
protected override Size MeasureOverride(Size availableSize)
{
UpdateScrollInfo(availableSize);
Size totalSize = new Size();
foreach (UIElement child in InternalChildren)
{
child.Measure(availableSize);
totalSize.Height += child.DesiredSize.Height;
totalSize.Width = Math.Max(totalSize.Width, child.DesiredSize.Width);
}
return base.MeasureOverride(totalSize);
}
protected override Size ArrangeOverride(Size finalSize)
{
UpdateScrollInfo(finalSize);
double verticalPosition = 0;
int childCount = InternalChildren.Count;
for (int i = 0; i < childCount; i++)
{
UIElement child = InternalChildren[i];
child.Arrange(new Rect(0, verticalPosition, finalSize.Width, finalSize.Height));
verticalPosition += child.DesiredSize.Height;
}
return base.ArrangeOverride(finalSize);
}
private void UpdateScrollInfo(Size availableSize)
{
bool viewportChanged = false, extentChanged = false;
Size extent = CalculateExtent(availableSize);
if (extent != _extent)
{
_extent = extent;
extentChanged = true;
}
if (availableSize != _viewport)
{
_viewport = availableSize;
viewportChanged = true;
}
if (extentChanged || viewportChanged) ScrollOwner?.InvalidateScrollInfo();
}
private Size CalculateExtent(Size availableSize)
{
Size totalExtentSize = new Size();
foreach (UIElement child in InternalChildren)
{
child.Measure(availableSize);
totalExtentSize.Height += child.DesiredSize.Height;
totalExtentSize.Width = Math.Max(totalExtentSize.Width, child.DesiredSize.Width);
}
return totalExtentSize;
}
}
}
以及背后的代码:
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Windows;
namespace IScrollInfoExample
{
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
Buttons = new ObservableCollection<string>();
IEnumerable<int> characterCodes = Enumerable.Range(65, 26);
foreach (int characterCode in characterCodes) Buttons.Add(((char)characterCode).ToString().ToUpper());
}
public static readonly DependencyProperty ButtonsProperty = DependencyProperty.Register(nameof(Buttons), typeof(ObservableCollection<string>), typeof(MainWindow), null);
public ObservableCollection<string> Buttons
{
get { return (ObservableCollection<string>)GetValue(ButtonsProperty); }
set { SetValue(ButtonsProperty, value); }
}
}
}
使用System.Collections.Generic;
使用System.Collections.ObjectModel;
使用System.Linq;
使用System.Windows;
名称空间IScrollInfoExample
{
公共部分类主窗口:窗口
{
公共主窗口()
{
初始化组件();
按钮=新的ObservableCollection();
IEnumerable characterCodes=可枚举范围(65,26);
foreach(字符代码中的int characterCode)按钮。添加(((char)characterCode.ToString().ToUpper());
}
public static readonly dependencProperty buttonproperty=dependencProperty.Register(按钮名称)、类型(ObservableCollection)、类型(主窗口)、空值);
公共可观察收集按钮
{
获取{return(observateCollection)GetValue(buttonProperty);}
set{SetValue(按钮属性,值);}
}
}
}
首先查看XAML,您可以看到手动添加的按钮
对象。运行应用程序,您应该会在面板中看到一些垂直滚动的按钮。。。到目前为止,一切顺利。如果在mouseweelUp
或mouseweelDown
方法中放置断点并滚动,您会注意到断点会立即被击中
现在,如果您用手动创建的按钮注释掉下方的示例ScrollPanel
,并取消注释上面的ItemsControl
,您将看到滚动项目的功能已经消失。我的问题是“当自定义面板位于ItemsControl
元素中时,如何使滚动工作?”
请注意,ScrollOwner
属性是使用自定义的GetParentOfType
方法填充的,该方法成功地找到了相应的ScrollViewer
,而不是此问题的原因。因此,我没有为此方法包含基于VisualTreeHelper
的代码
此外,我注意到,一旦面板位于
ItemsControl
内,滚动条就不再出现,但我进行了检查,并且面板的范围
和视口
值似乎仍在成功更新。任何帮助都将不胜感激。项目控件没有自己的ScrollViewer
,它无法访问您为此目的提供的外部控件。您需要使用ItemsControl.Template
属性在ItemsControl
可以访问的地方添加ScrollViewer
,如下所示:
<ItemsControl ItemsSource="{Binding Buttons, RelativeSource={RelativeSource
AncestorType={x:Type Local:MainWindow}}}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<Local:ExampleScrollPanel />
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.Template>
<ControlTemplate TargetType="{x:Type ItemsControl}">
<!--Add the ScrollViewer here, inside the ControlTemplate-->
<ScrollViewer CanContentScroll="True">
<!--Your items will be added here-->
<ItemsPresenter/>
</ScrollViewer>
</ControlTemplate>
</ItemsControl.Template>
<ItemsControl.ItemTemplate>
<DataTemplate>
<Button Height="100" Width="250" HorizontalAlignment="Center"
Content="{Binding}" />
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
请注意,您必须将ScrollViewer
的设置为True
,以通知它您已在面板中实现了IScrollInfo
界面,并希望接管滚动功能。现在工作正常。非常感谢,这个问题我已经困扰了很久了!
<ItemsControl ItemsSource="{Binding Buttons, RelativeSource={RelativeSource
AncestorType={x:Type Local:MainWindow}}}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<Local:ExampleScrollPanel />
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.Template>
<ControlTemplate TargetType="{x:Type ItemsControl}">
<!--Add the ScrollViewer here, inside the ControlTemplate-->
<ScrollViewer CanContentScroll="True">
<!--Your items will be added here-->
<ItemsPresenter/>
</ScrollViewer>
</ControlTemplate>
</ItemsControl.Template>
<ItemsControl.ItemTemplate>
<DataTemplate>
<Button Height="100" Width="250" HorizontalAlignment="Center"
Content="{Binding}" />
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>