Another little bit of vim configuration I wrote, this bit of code helps me to re-size a vim process running in a terminal.

As I mentioned before, I ended up running vim mostly in terminals, because next to editing code, I was doing a lot of other shell work. So, for a quick fix or small edit, the usual terminal size I use (classic 80 x 24), is more than enough, but for bigger jobs, I want more space.

Re-sizing the terminal window with the mouse and setting some vim settings (especially turning on line numbers) is too tedious, so instead, I set my heart on having a keyboard shortcut to automatically size vim up and down on demand.

Because vim and most modern terminal emulators can cooperate in this sense, it is sufficient to set the window size in vim, and the terminal emulator will resize accordingly. The following function does just that, and a tad more:

 1 " Function to size up.
 2 function SizeUpFunc()
 3     if exists("g:oldColumns")
 4         return
 5     endif
 6     " Save the current width.
 7     let g:oldColumns = &columns
 8     let g:oldLines = &lines
 9     " Reset column size when Vim quits.
10     au VimLeave * SizeDown
11     " Bigger width to make room for line numbers and the sign markers.
12     set columns=87 lines=999
13     " Turn on line numbers.
14     set number
15 endfunction
16 command SizeUp call SizeUpFunc()

The code is pretty simple. I use two global variables, oldColumns and oldLines, to store the original width and height of the terminal. If oldColumns already exists, I know that SizeUpFunc() has already been executed, and stop right there.

On line 10 I register the command SizeDown to the VimLeave event, i.e. when vim exits. This way, when I quit vim, the terminal will return to its original size.

The sizes on line 12 are simply my preference: I like the width to be wide enough to house a default line length (78 is my preference), plus enough space for the numbers on the left, and some space on the right to mark lines that are too long (using the colorcolumn feature in vim 7.3). As for the height, 999 is obviously way more than can fit on my screen, but this makes sure that vim will resize the terminal to the maximum possible height.

For convenience, I define a command called SizeUp on line 16.

Now, let’s move on the the counterpart to the above function, which sizes vim and the terminal down again.

 1 " Function to size down.
 2 function SizeDownFunc()
 3     if !exists("g:oldColumns")
 4         return
 5     endif
 6     " Restore the original size.
 7     let &columns = g:oldColumns
 8     let &lines = g:oldLines
 9     " Remove the variable.
10     unlet g:oldColumns
11     unlet g:oldLines
12 endfunction
13 command SizeDown call SizeDownFunc()

Again, I use oldColumns to see, if the terminal was resized or not, although this time, it’s the absence of that variable, that will cause the function to terminate early.

For the rest, I simply restore the old values and finally remove the global variables, to signify that, indeed, the terminal is back to what it used to be. And for good measure, I defined a command to go with this function as well.

To make my life easier, I mapped the commands to keyboard shortcuts:

1 " Mappings for SizeUp and SizeDown.
2 map <C-Up> :SizeUp<CR>
3 map <1b>Oa :SizeUp<CR>
4 map <C-Down> :SizeDown<CR>
5 map <1b>Ob :SizeDown<CR>

I had to use both symbolic names and byte-codes to get it to work, so if you’re trying to do something similar, your milage may vary with the above codes.

Lastly, because I am inherently lazy, I’ve added a little feature to start up vim in “expanded” mode. Using an environment variable, I tell vim to size up on startup:

1 " Resizing.
2 if $_VIMEXPAND == 1
3     SizeUp
4 endif

I use this together with an alias, which sets the environment variable before calling vim.

And that’s it for this little vim trick.

in Vim