3态“展开”、“折叠”和“半扩张”。树控制
我想做的是进行 3 状态树扩展。
我有三个不同的图标“展开”“折叠”“半展开”，我想用它们来显示部分填充的树控件，所有节点都初始化为半展开状态，然后单击“半展开”图标从服务器获取数据并填充树并使用“展开”图标打开该分支。
我尝试寻找它，但除了三态复选框之外找不到任何接近它的东西，但不知道当树只维护两种状态时如何在三态图标上使用它。
提前致谢。
What I'm trying to do is have a 3 state tree expansion.
I have three different icons for "expand" "collapse" "semi-expanded" which I want to use to show a partially populated tree control with all nodes initialized to semi-expanded state and then on clicking the "semi-expanded" icon it gets data from server and populates the tree and open that branch with "expanded" icon.
I tried looking for it but couldn't find anything close to it except the 3-state checkbox but don't know how to use it on 3 state icon when tree would only maintain 2 states.
Thanks in advance.
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我认为您正在寻找的称为延迟加载树。您可以在 Google 上搜索很多示例，但这里是一个很好的例子。
就请求的视觉部分而言（3 个不同的图标来显示分支或节点的状态） - 您可以使用自定义渲染器轻松处理该问题，方法是查看节点上的标志以了解其加载状态。
这有帮助吗？
I think what you are looking for is called a lazy-loading tree. There are lots of examples your can google for, but here is a great example.
As far as the visual part of your request goes (3 different icons to show that state of the branch or node) - you could easily handle that with a custom renderer, by looking at a flag on the node for it's load status.
Does that help?
三态树控件有点不常见，因此可能有点令人困惑；考虑到即使是简单的三态复选框也相对较少，用户可能不习惯它们。也许这就是为什么你没有找到这样的树控件。
因此，也许您应该考虑使用不需要三态控制的替代设计。
例如，节点可以从折叠节点开始。如果用户展开它，并且还没有数据，则显示带有文本“检索数据...”的单个子节点（以及进度轮或其他进度指示器，如果可以的话）并开始数据检索。当数据到达时，用实际数据替换该子节点。
A 3-State tree control is a bit uncommon and might therefore be a bit confusing; consider that even simple 3-state checkboxes are relatively rare and users may not be accustomed to them. Maybe that's why you didn't find such a tree control.
Thus, maybe you should consider using an alternate design that doesn't require 3-state controls.
For example, the node could start in collapsed node. If the user expands it, and there is no data yet, show a single sub node with the text "retrieving data..." (and a progress wheel or other progress indicator, if you can) and start data retrieval. When the data arrives, replace this sub node with the actual data.