Fix span widths

[sigmike]

Following my comment on #407 (comment)

To make the spec pass I rewrote the way width is distributed on cells with colspan > 1.
Before that it allocated space evenly, which is a problem when other cells in a table already have allocated space.

For example this table:

| aaa | b |
| c       |

If "aaa" has a width of 150, "b" and "c" a width of 50, and the column widths are set to 150 and 50, then there's room for everything.
Without the patch it would allocate 150 to the first column, and 100 to the second one (total width 200 / colspan 2).

With the patch it allocates widths in 2 passes:

• first only allocate width for cells with colspan == 1
• then for cells with colspan > 1: distribute only the width that does not fit in the already allocate widths

I made the same change for height but it probably needs a spec.

I also had to change the way extra space in table is distributed.

[practicingruby]

Hi, can you add a comment here with a realistic use case for me to confirm the problem with? A table with all empty cells seems like a pathological case to me.

[sigmike]

Here's the code to illustrate the example given above:

table([
  ["a", "b"],
  [{:content => "c", :colspan => 2}],
], column_widths: [150, 50])

move_down 10

table([
  ["a", "b"],
  ["c", "d"],
], column_widths: [150, 50])

The 2 tables will have different widths without the patch.

[practicingruby]

@sigmike: that gives me what I need to review further, thanks. Right now there is a massive backlog of pull requests that need to be looked at, but since this addresses a defect hopefully it will be processed soon.

[sigmike]

Actually this loop will never exit if all columns have reached their max width.

[practicingruby]

Bummer. Please revise and then we'll re-open the pull request when you are ready.