如何使用 Canvas 作为 ItemsPaneltemplate 在项目面板中显示滚动条 [英] How to Visible ScrollBar In Items Panel With Canvas as ItemsPaneltemplate

问题描述

在我的应用程序中，我将 ItemsControl 与 Canvas 作为 ItemsPanelTemplate.itempanel source的items是thumb对象，可以拖拽.如果项目退出屏幕视图，我无法滚动查看它们.我想怎么做?我的代码如下:

In My Application I Have ItemsControl with Canvas as ItemsPanelTemplate. Items of itemspanel source is thumb object and can drag and drage. if items drop out of screen view , I dont can scroll to view them. How I Want To Do? My Code Is Below :

            <ItemsControl ScrollViewer.HorizontalScrollBarVisibility="Visible" ScrollViewer.VerticalScrollBarVisibility="Visible">
                <ItemsControl.ItemContainerStyle>
                    <Style>
                        <Setter Property="Canvas.Left" Value="{Binding XPosition}"/>
                        <Setter Property="Canvas.Top" Value="{Binding YPosition}"/>
                    </Style>
                </ItemsControl.ItemContainerStyle>
                <ItemsControl.ItemsPanel>
                    <ItemsPanelTemplate>
                        <Canvas/>
                    </ItemsPanelTemplate>
                </ItemsControl.ItemsPanel>
            </ItemsControl>

推荐答案

首先，你需要用一个 ScrollViewer 包围 ItemsControl(不像 ListBox，它有它在其控制模板中):

First of all, you need to surround the ItemsControl with a ScrollViewer (unlike ListBox, which has it in its control template):

<ScrollViewer>
    <ItemsControl> ... </ItemsControl>
<ScrollViewer>

其次，Canvas 不会在其子项之后调整自身大小.所以你有几个选择:

Secondly, a Canvas does not resize itself after its children. So you have a few options:

• 使用带有单个单元格的网格并使用 Margin 属性设置位置.
• 计算最大尺寸并设置 Canvas 的 Width 和 Height 属性.
• 从 Canvas 继承并覆盖 MeasureOverride 方法，以便它们反映子项的大小.(请参阅此答案.)

• Use a Grid with a single cell and set the positions using the Margin property.
• Calculate the maximum size and set the Canvas' Width and Height properties.
• Inherit from Canvas and override the MeasureOverride method so they reflect the children's sizes. (See this answer.)

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