Re: Transparency issues

[Marko Mikulicic]

Pierre-Yves Rivaille wrote:
> On Mon, 20 Aug 2001, Marko Mikulicic wrote:
>
>
> >  Since NSTableView uses the same NSCell for all cells, that would
> > mean that the image is correctly displayed when at least two istances
> > of the same image are showed on screen.
>
> That is not true. There is a cell for each column.

ah, yes. I forgotten. I had images in one column only
so I didn't notice my mistake.

>  By default it is a
> NSTextFieldCell, but if you only need to display an image, you can do the
> following
>   [myTableColumn setDataCell: [NSImageCell new]];
> before inserting the column inside the tableView.
>
> Using an NSImageCell might solve some of the issue you had with an
> NSTextFieldCell, it is also more appropriate to use it when you only want
> to display images and no text.

I tried NSImageCell as well, but it puts a margin around the image I 
can't disable. Also it leaves the white background.

I solved the problem with using setBackgroundColor: [NSColor 
controlBackgroun] on the image.

> It is even possible to use specific cells for specific rows inside a
> tableColumn.
> To do this you should subclass NSTableColumn, and redefine
>   [NSTableColumn dataCellForRow:]
> so that it returns a specific cell for each row of the column.


I currently use the
- (void)tableView:(NSTableView *)aTableView
  willDisplayCell:(id)aCell
   forTableColumn:(NSTableColumn *)aTableColumn
          row:(int)rowIndex

interface because I can have up 10000 to rows, so I thought
it will change the image only for those items that are really shown.
If I set it using dataCellFor: i think I would waste space, no ?


> (This can be useful to avoid useless redrawing, as whenever you change a
> Cell in tableView:willDisplayCell:..., all part of the tableView that
> shares this cell are marked as needing display. If that do not seem clear,
> you can look at [NSTableView updateCell])
>
> (for further information on [NSTableColumn dataCellForRow:] you can look
> at
> developer.apple.com/techpubs/macosx/Cocoa/Reference/ApplicationKit/ObjC_classic/Classes/NSTableColumn.html#//apple_ref/occ/instm/NSTableColumn/dataCellForRow

I readed that.