而用户拖动列表视图项检测滚动时有必要 [英] Detect when scrolling is necessary while user drags listview items

问题描述

我采取的列表视图项目清理不使用OLE拖放。

I am implementing rearranging of listview items without using OLE drag and drop.

我已经成功地解决了大部分这个任务，除了滚动向上/向下，当用户想要在这个当前不可见的位置掉落物品。

I have successfully solved most of this task, except scrolling up/down when user wants to drop items at the position that is not currently visible.

我能够通过以下消息来向上/向下滚动列表视图：

I am able to scroll up/down listview by using following messages:

SendMessage(hwndListView, WM_VSCROLL, (WPARAM)SB_LINEUP, (LPARAM)0);
SendMessage(hwndListView, WM_VSCROLL, (WPARAM)SB_LINEDOWN, (LPARAM)0);

我需要搞清楚你的​​建议的何时何地的我需要发送这些邮件（我想这应该WM_MOUSEHOVER或类似的东西做什么？）。

I need your advice in figuring out when and where I need to send those messages ( I suppose it should be done on WM_MOUSEHOVER or something like that? ).

我只是不知道哪些信息，以及如何，如果需要滚动我应该检查。

的我感兴趣的实施默认滚动的拖放行为。的

我曾尝试使用列表视图命中测试，所以我可以检查的 LVHITTESTINFO为 LVHT_ABOVE >和 LVHT_BELOW ，但没有为我工作。

I have tried to use listview hit testing so I can examine LVHITTESTINFO for LVHT_ABOVE and LVHT_BELOW but that did not work for me.

的我从来没有能够在列表视图点击时要获取这些值... 的

我发现在使用定时器来实现这个其他编程语言的一些例子。我学习他们为我写这个帖子。

I have found some examples in other programming languages that use timers to implement this. I am studying them as I write this post.

列表视图是在报告模式，并支持多选。

Listview is in report mode and supports multiselection.

我处理下列消息：

LVN_BEGINDRAG  // I create drag image here
WM_MOUSEMOVE   // I update drag image here
WM_LBUTTONUP   // I rearrange items here and perform cleanup

我省略SSCCE保持这个职位短。如果需要，我可以将它张贴。如果需要进一步的信息，请发表评论。

I have omitted SSCCE to keep this post short. If needed I can post it. If further info is required please leave a comment.

推荐答案

presumably您拖放循环使用 SetCapture 来捕获鼠标输入。

Presumably your drag and drop loop uses SetCapture to capture mouse input.

所有你需要做的就是观看 WM_MOUSEMOVE 消息。当上面的顶部或下方的列表视图底部的鼠标移动，设置一个标志，表明你正在滚动，并使用启动一个定时器的SetTimer 。

All you have to do is watch for WM_MOUSEMOVE messages. When the mouse moves above the top or below the bottom of the listview, set a flag to indicate you are scrolling and start a timer using SetTimer.

每当定时器熄灭，滚动在适当的方向一条线，通过发送列表视图一个 WM_VSCROLL 消息。

Every time the timer goes off, scroll one line in the appropriate direction, by sending the listview a WM_VSCROLL message.

如果鼠标在列表视图内移回，或捕捉丢失（即你获得 WM_CAPTURECHANGED ），杀死你的计时器和停止滚动。

If the mouse moves back inside the listview, or the capture is lost (i.e. you get WM_CAPTURECHANGED), kill your timer and stop scrolling.

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