From c7afe4f3d74f0487c913ce49abc58fe59aaeac12 Mon Sep 17 00:00:00 2001
From: Tom Gundersen <teg@jklm.no>
Date: Sun, 5 Oct 2014 15:26:54 +0200
Subject: [PATCH] terminal/screen: add support for alternate screen buffers
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)
---
src/libsystemd-terminal/term-internal.h | 1 +
src/libsystemd-terminal/term-screen.c | 89 ++++++++++++++++++++++++++++++++-
2 files changed, 88 insertions(+), 2 deletions(-)
diff --git a/src/libsystemd-terminal/term-internal.h b/src/libsystemd-terminal/term-internal.h
index c78b9aa70a..53713dd64d 100644
--- a/src/libsystemd-terminal/term-internal.h
+++ b/src/libsystemd-terminal/term-internal.h
@@ -646,4 +646,5 @@ struct term_screen {
term_state state;
term_state saved;
+ term_state saved_alt;
};
diff --git a/src/libsystemd-terminal/term-screen.c b/src/libsystemd-terminal/term-screen.c
index c8a81658cb..54bb04752c 100644
--- a/src/libsystemd-terminal/term-screen.c
+++ b/src/libsystemd-terminal/term-screen.c
@@ -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;
@@ -427,6 +445,73 @@ static void screen_mode_change(term_screen *screen, unsigned int mode, bool dec,
}
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;