[TStringGrid] RowHeights[aRow] set to 0: impossible to change back

[Fripsy]

Hi All,

I'm adding grouped lines in a stringgrid through the OnDrawCell event, I'm not creating a new component (yet).
I use the first column (0) as storage for the row's settings.

The grouped lines work fine (kinda like merge fields), so I decided to make those groups collapsable and expandable.
As there is no "RowHide" function, I do something like this in the OnDrawCell routine:

Code: [Select]


      if (Sender as TStringGrid).Cells[0, aRow] = 'Hidden' then
      begin
        (Sender as TStringGrid).RowHeights[aRow] := 0;
        (Sender as TStringGrid).Canvas.FillRect(aRect);
      end
      else
      begin
        (Sender as TStringGrid).RowHeights[aRow] := (Sender as TStringGrid).DefaultRowHeight;
        (Sender as TStringGrid).Canvas.FillRect(aRect);
      end;


The problem is, that once set RowHeights[aRow] to 0 (to hide the row), there is now way to set it back to normal: the row will not display.
If I set RowHeights[aRow] to 1, it works, but I get a 1px line for every row, which isn't "estétique"...

I already searched the grid.pas for a way to solve this, but I can't seem to find why this is happening.
I hope someone can shed a light on this.

Thanks,
Frank.

[Fripsy]

Just upgraded from Lazarus 1.2.6 to 1.4, same problem 

[zeljko]

Open an issue about it and attach example project.

[Fripsy]

Thanks zeljko, just added it to the bugtracker.

[rvk]

Thanks zeljko, just added it to the bugtracker.

May I ask why you consider this a bug?

You want to "reset" the height of a row in its own OnDrawCell.
But for rows with a height of 0 the OnDrawCell is never called.
(so you can't do it in that event)

Look in Grids.pas for TCustomGrid.DrawRow(aRow: Integer);
There you can see the procedure ends when R.Top>=R.Bottom (which is true for Rows of 0 height).

When you add a button for example with the code to reset the rowheight manually you see it works.

So this is not really a bug but a design-fault.

[Fripsy]

Hi rvk,

You're right, it is logical that the OnDrawCell is never called with a height of 0.
Sorry that I didn't think this through...

I wanted to delete the issue in the bugtracker but I can't seem to find it anymore...

Meanwhile, I created a workaround by commenting out the "exit" in the DrawRow procedure in grid.pas, and forcing a repaint of the grid.
This seems to work fine for the moment.

Thanks,
Frank.

[rvk]

I wanted to delete the issue in the bugtracker but I can't seem to find it anymore...

It's still on the first page in the bugtracker. (the bugtracker for Lazarus, that is, link in the bar at the left of the main forum-page)
http://bugs.freepascal.org/view.php?id=28005

Meanwhile, I created a workaround by commenting out the "exit" in the DrawRow procedure in grid.pas, and forcing a repaint of the grid.
This seems to work fine for the moment.

That is a workaround, yeah. But it seems kind of "hacky". I take it you will eventually change this and use some other way. I don't know what code changes the string in the stringgrid back from Hidden to something else but you could create a function (or class helper) changecell(X,Y: Integer; Value: String); and check in that function if the row should be visible or not. But it kind of all depends your design.