Many of the applications we write need to display things like option dialog boxes near a specific control. In most cases this is quite easy to handle as we can easily obtain the SIZE property of a control and work out our positioning from that. A slightly more difficult task is to position something relative to an EditTable cell because OpenInsight doesn't expose this information as a property or a method.

We've seen many attempts to calculate cell coordinates in Basic+ - we've even done it a few times ourselves and it's quite a pain, having to take into account all the different styles of the edit table, the width of columns, which columns are hidden and so forth.

Well, there's a really easy way to do this, and that's by asking the EditTable itself what the coordinates are via the standard Windows API SendMessage function. We just need to know what message to send to the EditTable.


DTM_READCELLRECT

The message we need is called DTM_READCELLRECT, and it returns the coordinates of the cell identified via the ACCESSPOS property. All we need to do is pass it the address of a RECT structure to fill in, which we then translate into a dynamic array which we can use further.

Here's a simple function to demonstrate this:



(The more pedantic amongst you may notice that we didn't reset ACCESSPOS after we updated it. The reason for this is simple - every low-level function in the EditTable updates ACCESSPOS to the required coordinates before executing, and you should never assume ACCESSPOS is at the correct coordinates - always set it yourself before use!)

You can download a text version of edt_GetCellRect here

Labels: EditTable, EditTable Cookbook, OpenInsight