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terminal/screen: add support for alternate screen buffers

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Hook up SM/RM 47/1047-1049 and enable alternate screen buffers for term
applications.

(David: rebased on top of -git, renamed helpers and added docs)
This commit is contained in:
Tom Gundersen 2014-10-05 15:26:54 +02:00 committed by David Herrmann
parent 3ae49a8fdb
commit c7afe4f3d7
2 changed files with 88 additions and 2 deletions
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1
src/libsystemd-terminal/term-internal.h
View File

@ -646,4 +646,5 @@ struct term_screen {
term_state state;
term_state saved;
term_state saved_alt;
};

89
src/libsystemd-terminal/term-screen.c
View File

@ -77,6 +77,7 @@ int term_screen_new(term_screen **out, term_screen_write_fn write_fn, void *writ
screen->state.gl = &screen->g0;
screen->state.gr = &screen->g1;
screen->saved = screen->state;
screen->saved_alt = screen->saved;
r = term_page_new(&screen->page_main);
if (r < 0)
@ -367,6 +368,23 @@ static void screen_restore_state(term_screen *screen, term_state *from) {
screen->state = *from;
}
static void screen_reset_page(term_screen *screen, term_page *page) {
term_page_set_scroll_region(page, 0, page->height);
term_page_erase(page, 0, 0, page->width, page->height, &screen->state.attr, screen->age, false);
}
static void screen_change_alt(term_screen *screen, bool set) {
if (set) {
screen->page = screen->page_alt;
screen->history = NULL;
} else {
screen->page = screen->page_main;
screen->history = screen->history_main;
}
screen->page->age = screen->age;
}
static inline void set_reset(term_screen *screen, unsigned int flag, bool set) {
if (set)
screen->flags |= flag;
@ -426,6 +444,73 @@ static void screen_mode_change(term_screen *screen, unsigned int mode, bool dec,
screen_age_cursor(screen);
}
break;
case 47:
if (dec) {
/*
* XTERM-ASB: alternate-screen-buffer
* This enables/disables the alternate screen-buffer.
* It effectively saves the current page content and
* allows you to restore it when changing to the
* original screen-buffer again.
*/
screen_change_alt(screen, set);
}
break;
case 1047:
if (dec) {
/*
* XTERM-ASBPE: alternate-screen-buffer-post-erase
* This is the same as XTERM-ASB but erases the
* alternate screen-buffer before switching back to the
* original buffer. Use it to discard any data on the
* alternate screen buffer when done.
*/
if (!set)
screen_reset_page(screen, screen->page_alt);
screen_change_alt(screen, set);
}
break;
case 1048:
if (dec) {
/*
* XTERM-ASBCS: alternate-screen-buffer-cursor-state
* This has the same effect as DECSC/DECRC, but uses a
* separate state buffer. It is usually used in
* combination with alternate screen buffers to provide
* stacked state storage.
*/
if (set)
screen_save_state(screen, &screen->saved_alt);
else
screen_restore_state(screen, &screen->saved_alt);
}
break;
case 1049:
if (dec) {
/*
* XTERM-ASBX: alternate-screen-buffer-extended
* This combines XTERM-ASBPE and XTERM-ASBCS somewhat.
* When enabling, state is saved, alternate screen
* buffer is activated and cleared.
* When disabled, alternate screen buffer is cleared,
* then normal screen buffer is enabled and state is
* restored.
*/
if (set)
screen_save_state(screen, &screen->saved_alt);
screen_reset_page(screen, screen->page_alt);
screen_change_alt(screen, set);
if (!set)
screen_restore_state(screen, &screen->saved_alt);
}
break;
}
}
@ -1966,8 +2051,7 @@ static int screen_DECSTBM(term_screen *screen, const term_seq *seq) {
bottom = screen->page->height;
}
term_page_set_scroll_region(screen->page_main, top - 1, bottom - top + 1);
term_page_set_scroll_region(screen->page_alt, top - 1, bottom - top + 1);
term_page_set_scroll_region(screen->page, top - 1, bottom - top + 1);
screen_cursor_clear_wrap(screen);
screen_cursor_set(screen, 0, 0);
@ -4143,6 +4227,7 @@ void term_screen_soft_reset(term_screen *screen) {
screen->saved = screen->state;
screen->saved.cursor_x = 0;
screen->saved.cursor_y = 0;
screen->saved_alt = screen->saved;
screen->page = screen->page_main;
screen->history = screen->history_main;