Move current line up/down but keep cursor position

Question

I'm using:

" move current line up
imap [u <esc>:m .-2<CR>i
" move current line down
imap [d <esc>:m+<CR>i

But I'd like to keep the current cursor position, and I would like to expand the question to move up/down a block of text.

EDIT 1: for example:
The current line ->| need to move up is here

->| is the cursor's position that we need to keep moving.

Answer 1

ddp and ddkP put the cursor at the begin of the line.

The solution was found on http://vim.wikia.com/wiki/Moving_lines_up_or_down

For insert mode:

inoremap <A-j> <Esc>:m .+1<CR>==gi
inoremap <A-k> <Esc>:m .-2<CR>==gi

For blocks of code:

vnoremap <A-j> :m '>+1<CR>gv=gv
vnoremap <A-k> :m '<-2<CR>gv=gv

After selection of a block, press <A-j> to move the whole block down, <A-k> to move it up.

For normal mode:

nnoremap <A-j> :m .+1<CR>==
nnoremap <A-k> :m .-2<CR>==

Answer 2

I interpreted "keep position" as the cursor does not move, at all, which may not be what the question intended. Note: this only works with set nostartofline.

Partial answer for the insert-mode case: There are two cases to consider. The trick is to remember :move puts the cursor at the new position.

Current line up: instead of moving the current line up, we move the previous line to just below the cursor line.

inoremap [u <c-o>:-1m.<cr>

Current line down: instead of moving the current line down, we move the next line to just before the cursor line.

inoremap [d <c-o>:+1m-1<cr>

Note: in either case, we use inoremap and <c-o>, which are preferable to imap and <esc>...i.