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How to do a smart column resize in a WTableView?

Added by Vincenzo Romano 12 months ago

I need to display tabular data and am using the WTableView widget.
I'd like to adapt the column width to the actual content in either of the following "smart" ways:

  1. The maximum column content width including the header
  2. The maximum column content width NOT including the header
  3. The maximum column content width not exceeding a per-column-defined maximum
  4. Any other smart way I'm not thinking of :-)

Doing the first three would require me to know the actual size of the font to be used. Unless there's something else I'm missing I have no idea on how to get this done this way.

Of course, the first attempt has been to use WTableView::setColumnWidth( <col>,WLength::Auto ) on all the columns.
This produced a table with all columns squeezed to be a few pixel wide, defeating my personal concept of "'auto' length".

Any hint out there?


Replies (8)

RE: How to do a smart column resize in a WTableView? - Added by Koen Deforche 11 months ago

Hey,

This is not supported (partially for the reason you mention: we would need to know server-side how big text turns out client-side).
We could always guess this somewhat server-side, but then so could you buy simply looking at the text length of the model contents per column ?

And yes, 'auto' is not doing that.

Regards,
koen

RE: How to do a smart column resize in a WTableView? - Added by Vincenzo Romano 11 months ago

Just an OT question: what's 'auto' for?

RE: How to do a smart column resize in a WTableView? - Added by Koen Deforche 11 months ago

It's there because in some contexts, WLength::Auto does have a meaning, e.g. as a default width.

It is also explicilty supported in CSS and WLength is modeled after what is available in CSS.

Regards,
koen

RE: How to do a smart column resize in a WTableView? - Added by Vincenzo Romano 11 months ago

I've just tried a first easy approach: calculate the widths in percentage.
It doesn't work and I think it's because the WTableView is not a <TABLE>.
How can I guess the width of the font being used in a WTableView?

RE: How to do a smart column resize in a WTableView? - Added by Koen Deforche 11 months ago

Hey,

There is no accurate way of knowing the font size.

This width you can get in a layoutSizeChanged() call (after doing setLayoutSizeAware()), in a specialized WTableView class.

With Wt 3.2.1 this call will be invoked when your table is in a layout only, but in Wt 3.2.2 this event will be delivered even if the table is not in a layout (because it uses a layout itself).

Regards,
koen

RE: How to do a smart column resize in a WTableView? - Added by Vincenzo Romano 11 months ago

I'd like to go the percentage way, Koen, as it should be better when supporting different resolution screen.
Is there a way to express the column width in % of the container width?

RE: How to do a smart column resize in a WTableView? - Added by Koen Deforche 11 months ago

Hey Vincenzo,

Using setLayoutSizeAware() + layoutSizeChanged() you can react to the change of the table width.

Then you can work out an appropriate width for each column, taking into account 7 pixels that are used for padding and border (thus you need to substract (7 * model->columnCount()) from the total width and divide that width to the columns.

Regards,
koen

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