加快列表框插入时间

发布于 2024-09-12 13:12:43 字数 278 浏览 5 评论 0原文

我需要将 950 个长度为 2500 个字符的字符串添加到列表框中。我下面使用的方法需要 2.5 秒，理想情况下需要在 500 毫秒以内完成。

Stopwatch sw = Stopwatch.StartNew();

listBox1.BeginUpdate();
listBox1.Items.AddRange(items.ToArray());
listBox1.EndUpdate();

sw.Stop();

优化插入时间的最佳方法是什么？

谢谢。

原文

I need to add 950 strings that are 2500 characters in length to a listbox. The method I am using below takes 2.5 seconds and ideally it needs to happen in less then 500ms.

Stopwatch sw = Stopwatch.StartNew();

listBox1.BeginUpdate();
listBox1.Items.AddRange(items.ToArray());
listBox1.EndUpdate();

sw.Stop();

What would be the best way to optimize the insertion time?

Thanks.

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甜扑 2024-09-19 13:12:43

您可以尝试的一件事是将这一行：更改

listBox1.Items.AddRange(items.ToArray());

为类似这样的内容：

foreach (var item in items)
{
    listBox1.Items.Add(item);
}

这样，在将项目放入您的项目之前，您就不需要创建一个全新的数组（ToArray() 调用）的开销。 列表框。

One thing you could try is changing this line:

listBox1.Items.AddRange(items.ToArray());

to something like this:

foreach (var item in items)
{
    listBox1.Items.Add(item);
}

That way, you do not have the overhead of creating a whole new array (the ToArray() call) before putting the items into your ListBox.

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空气里的味道 2024-09-19 13:12:43

列表框正在处理 2500 个字符。这就是缓慢的原因。所有这些数据，包括与数组的转换，在内存中都是微不足道的。因此，跳过 ToArray 步骤不会产生任何影响。如果您的用户必须水平滚动才能看到此信息，那么您很可能会陷入“慢”的境地。

如果没有，请考虑稍微重构一下。策略：仅输入在常规宽度列表框中可见的字符数（大约 100 个）。完整的字符串保留在幕后。

像这样创建一个帮助器类（如果您是那个肛门者，您可以将公共字符串转换为属性；-）：

    Class TruncatedListItem
        Public Content as string
        Overrides sub ToString() as string ' Pardon me if this is wrong I always use intellisense
            return Mid(Content,1,100)
        end sub
    end class

将这些项目添加到列表框中。当列表框中的项目不是字符串类型时，它会调用该项目的 ToString 方法（嘿，我们只是为了给列表框一个休息而定制的）并将其添加为字符串，然后项目集合显示为您的项目我补充道。（也保留开始/结束更新）
```
对于 Items 中的每个 itm 作为字符串
    暗淡 tli 作为新的 TruncatedListItem
    tli.内容 = itm
    列表框.add(tli)
next
```
当你想查看用户选择的内容时，不要像这样获取字符串：
```
MyString = Ctype(Listbox.SelectedItem,string) 
```
执行此操作
MyString = Ctype(ListBox.SelectedItem,TruncatedListItem).Content
现在我假设用户在某些时候仍然需要在选择之前查看所有 2500 个字符。除非他们是一个严重的困境，否则他们应该接受这种替代方案（事实上，滚动有优点）。
- 当他们双击某个项目时，在双击处理程序中，会在消息框中向他们显示完整文本。您可以在工具提示中告诉他们这样做。例如，在双击处理程序中： msgbox Ctype(ListBox.SelectedItem,TruncatedListItem).Content,,"Full Item Text"

祝你好运！

Listbox is dealing with 2500 characters. That is what is slow. All that data, including converting to/from arrays, is peanuts in memory. Hence skipping the ToArray step not making a difference. If your users have to scroll horizontally to see this info, chances are, you're stuck with 'slow.'

If not, consider refactoring a tiny bit. Strategy: only put as many characters - about 100 - as are viewable in a regular width listbox. Full strings are retained behind the scenes.

Make a helper class like so (you can convert the public string to a property if you're that anal;-):

    Class TruncatedListItem
        Public Content as string
        Overrides sub ToString() as string ' Pardon me if this is wrong I always use intellisense
            return Mid(Content,1,100)
        end sub
    end class

Add those items to the listbox. When an item in a listbox isn't of type string, it calls the item's ToString method (which hey, we just tailored to give the listbox a break) and adds that as a string, then the items collection appears as the items you've added. (keep the begin/end update too)
```
For each each itm as string in Items
    dim tli as new TruncatedListItem
    tli.Content = itm
    listbox.add(tli)
next
```
When you want to see what the user picked, instead of getting the string like this:
```
MyString = Ctype(Listbox.SelectedItem,string)  
```
do this
MyString = Ctype(ListBox.SelectedItem,TruncatedListItem).Content
Now I am assumming the user, at some point, still needs to see all 2500 chars before selecting. Unless they are a serious stick in the mud, they should settle for this alternative (In fact there are advantages to scrolling).
- When they double click an item, in the handler for double click, show them the full text in a messagebox. You could tell them to do that in a tooltip. For example, in the double-click handler: msgbox Ctype(ListBox.SelectedItem,TruncatedListItem).Content,,"Full Item Text"

Good luck!

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