1

I am using AnyDac and TMS TAdvDbGrid (rather than plain TDbGrid), in case that makes any difference, but I suspect that there is a general solution.

I have a data aware grid, which should display a maximum of say 12 lines because of screen size. If the associated query returns less than 12 rows then I would like to change the DB Grid's height property accordingly (leaving some empty space below the newly poisiotned bottom og the grid, rather than within it).

I can post the code for that if requested, but my question is what event handler should I do it in?

I had thought to use the Query's AfterOpen() handler, but that is never trigeered.

What else is there? I could use the DB Grid's DrawCell() method, but that would be called frequently.

[Update] I added some tracing. I clciked on the master grid exactly once (its OnClick() gets called twice, but I tried this a few times and it is consistent).

Here's the trace:

2   00:00:25.225 [Detail grid scolled]  11:02:12 AM
2   00:00:25.228 [Detail grid scolled]  11:02:12 AM
2   00:00:25.229 [Detail grid scolled]  11:02:12 AM
2   00:00:25.231 [Detail grid scolled]  11:02:12 AM
2   00:00:25.233 [Detail grid scolled]  11:02:12 AM
2   00:00:25.234 [Clicked master grid]  11:02:12 AM
2   00:00:25.234 [Master grid scolled]  11:02:12 AM
2   00:00:25.325 [Clicked master grid]  11:02:12 AM

I notice a few things:

  • The detail grid is reported as being scrolled before the master grid is repoted as being clicked. I gues that's just the Windows message queue, but it does seem strange.

  • The master grid is reported as being clicked twice

  • Those 2 clicks seem to cause 2 sets of scrolling. The first reports scrolling 5 times; by coincidence (?) there are 5 columns on the detail grid. If there were more, or if processing on scroll was heavy, that ight be an overhead (and I can't understand enough to set & clear flags). Ideally I would like to hook that 2nd "group" which has only a single click, but I don't knwo how.

  • I can confirm AfterScoll as agood event to hook. It is only called when I clcik on a master grid row which is not the current row (i.s, when the content of the detail grid chages).

Any comments?

[Update++]

Since i am using an AnyDac TADQuery, I found that I can assign OrdersADQuery.Command.AfterOpen := OrdersADQueryAfterOpen; and that function will be called exactly once when I click a non-current row of the master grid.

That works for me, but fell free to comment on my previous upate if you think that it will help others

4

1 回答 1

3

尽管还有其他几种可能性，但根据我的经验，填充网格的数据集的 AfterScroll 事件是捕捉行数等变化以及数据集光标移动的最可靠的好地方。顺便说一句，您没有说是否要涵盖删除和插入。

于 2013-09-05T08:23:13.547 回答