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67 lines
2.7 KiB
Markdown
67 lines
2.7 KiB
Markdown
% notcurses_refresh(3)
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% nick black <nickblack@linux.com>
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% v1.4.2.3
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# NAME
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notcurses_refresh - redraw an externally-damaged display
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# SYNOPSIS
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**#include <notcurses/notcurses.h>**
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**int notcurses_refresh(const struct notcurses* nc, int* restrict rows, int* restrict cols);**
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# DESCRIPTION
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**notcurses_refresh** clears the screen, homes the cursor, checks the current
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terminal geometry, and repaints the most recently rendered frame. It can be
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called concurrently with all other Notcurses functions save
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**notcurses_render**. **notcurses_refresh** ought be called when the screen is
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externally damaged (as occurs when another program writes to the terminal, or
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if your program writes to the terminal using standard I/O). It is necessary to
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use **notcurses_refresh** in such a case (as opposed to simply calling
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**notcurses_render**), since **notcurses_render** optimizes its output by only
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writing internally-damaged cells. Notcurses has no way of knowing about
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external corruption; by tradition, Ctrl+L is bound to **notcurses_refresh**,
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and the user is responsible for requesting a hard redraw.
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A secondary use of this function is when the program is blocking on input (and
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perhaps not ready to render), and receives an **NCKEY_RESIZE** event (see
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**notcurses_input**). In this case, **notcurses_refresh** will acquire the new
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screen parameters, and repaint what it can. If you're prepared to call
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**notcurses_render**, it's better to do that in this case, and thus avoid
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unnecessary screen redrawing.
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If **rows** and/or **cols** is not NULL, they receive the new geometry.
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# NOTES
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If your program **is** in a render loop (i.e. rendering as quickly as
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possible, or at least at the refresh rate), there's not much point in
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erecting the machinery to trigger **notcurses_refresh** based off
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**NCKEY_RESIZE**. The latter is generated based upon receipt of the **SIGWINCH**
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signal, which is fundamentally racy with regards to the rest of the program.
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If your program truly relies on timely invocation of **notcurses_refresh**,
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it's a broken program. If you don't rely on it in a causal fashion, then just
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wait for the upcoming render.
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Highest performance in a rendering loop would actually call for disabling
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Notcurses's **SIGWINCH** handling in the call to **notcurses_init**, so that no
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time is spent handling a signal you're not going to use.
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# RETURN VALUES
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Returns 0 on success, and -1 on failure. The causes for failure include system
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error, programming error, closing of output, or allocation failure. None
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of these are particularly good things, and the most reasonable response to a
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**notcurses_refresh** failure is either to ignore it, or to weep and exit.
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# SEE ALSO
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**notcurses_init(3)**,
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**notcurses_input(3)**,
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**notcurses_render(3)**,
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**termios(3)**,
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**signal(7)**
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