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Basically map H and L based on the cursor positon. If I press H the cursor should go to top of the screen and if I press H again I want to scroll up by one page.

2 Answers 2

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This is actually a fantastic idea! I might steal this for my own .vimrc... :P

Anyway, this can be done with <expr> mappings. I also found this stack overflow answer extremely helpful. Onto the solution...

nnoremap <expr> H getcurpos()[1] == line("w0") ? "\<PageUp>" : "H"
nnoremap <expr> L getcurpos()[1] == line("w$") ? "\<PageDown>" : "L"

xnoremap <expr> H getcurpos()[1] == line("w0") ? "\<PageUp>" : "H"
xnoremap <expr> L getcurpos()[1] == line("w$") ? "\<PageDown>" : "L"

Basically, the way this works is by first evaluating a vimscript expression, and running the resulting string as a sequence of normal mode keys. The expression is

getcurpos()[1] == line("w0")

Note that getcurpos seems to be a vim 8 feature. If you're on an older vim and you don't have this, you could do getpos('.') instead.

getcurpos()[1] will give you the current line number, and line("w0") will give you the first visible line and line("w$") will give you the last visible line.


Further reading...

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    Can also just use line(). e.g. nnoremap <expr> H line('.') == line("w0") ? "\<PageUp>" : "H" Nov 14, 2017 at 18:57
  • Thanks for the answer, it works in regular vim8. One other suggestion to your answer is to put the cursor on the top line after <PageUp> and on the bottom line after the <PageDown> so that its easier to scroll pages. But unfortunately, I just started using Spacevim as it comes with tons of plugins and somehow the H and L move the cursor to the fourth line from the top and fourth line from the bottom. I guess I have to figure out how to disable it. I would be greatful, If any one can help me.
    – raj
    Nov 14, 2017 at 19:09
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    You probably have scrolloff set. That is the vertical distance in lines to keep the cursor from top or bottom of the display.
    – Wolf
    Nov 14, 2017 at 19:43
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I use a non-zero value for 'scrolloff' so this one handles &scrolloff > 0 and has a few other small enhancements compared to DJMcMayhem's fine submission:

  • Incorporates a suggestion that I like from this comment to keep the cursor at the top/bottom of the screen after paging up/down.
  • Uses line() rather than getcurpos() for consistency and to avoid any potential compatibility issues with getcurpos() and earlier versions of Vim
  • Uses the more Vim-like (to me anyways) CtrlF and CtrlB

.

nnoremap <expr> H line(".") - &scrolloff == line("w0") ? "\<C-B>H" : "H"
nnoremap <expr> L line(".") + &scrolloff == line("w$") ? "\<C-F>L" : "L"

Similarly for xnoremap.

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