[kitty] keyboard sanity across screens

A Notcurses program might shift between the regular and
alternate screen freely. At all times, we want the Kitty
keyboard protocol to be locked in. At the same time, we
always want a screen's keyboard state at the time we start
using it preserved, and restored when we're done. Thus:

start: optionally smcup, push the state, set the state, query
leave alternate: pop state, rmcup, push state, set state
enter alternate: pop state, smcup, push state, set state
done: pop state, optionally rmcup

"set state" means both XTMODKEYS and kitty set.

Closes #2249

src/lib/notcurses.c

@@ -71,12 +71,12 @@ int reset_term_attributes(const tinfo* ti, fbuf* f){
 static int
 notcurses_stop_minimal(void* vnc){
   notcurses* nc = vnc;
+  int ret = 0;
+  ret |= drop_signals(nc);
   // collect output into the memstream buffer, and then dump it directly using
   // blocking_write(), to avoid problems with unreliable fflush().
   fbuf* f = &nc->rstate.f;
   fbuf_reset(f);
-  int ret = 0;
-  ret |= drop_signals(nc);
   // be sure to write the restoration sequences *prior* to running rmcup, as
   // they apply to the screen (alternate or otherwise) we're actually using.
   const char* esc;
@@ -100,17 +100,20 @@ notcurses_stop_minimal(void* vnc){
     if(nc->tcache.tpreserved){
       ret |= tcsetattr(nc->tcache.ttyfd, TCSAFLUSH, nc->tcache.tpreserved);
     }
+    // don't use use leave_alternate_screen() here; we need pop the keyboard
+    // whether we're in regular or altnerate screen, and we need it done
+    // before returning to the regular screen if we're in the alternate.
     if(nc->tcache.kbdlevel){
       if(tty_emit(KKEYBOARD_POP, nc->tcache.ttyfd)){
         ret = -1;
       }
     }
-    if((esc = get_escape(&nc->tcache, ESCAPE_RMCUP))){
-      if(sprite_clear_all(&nc->tcache, f)){ // send this to f
-        ret = -1;
-      }
-      if(tty_emit(esc, nc->tcache.ttyfd)){ // but this goes to ttyfd
-        ret = -1;
+    if(nc->tcache.in_alt_screen){
+      if((esc = get_escape(&nc->tcache, ESCAPE_RMCUP))){
+        if(tty_emit(esc, nc->tcache.ttyfd)){
+          ret = -1;
+        }
+        nc->tcache.in_alt_screen = 0;
       }
     }
   }

src/lib/termdesc.c

@@ -367,13 +367,10 @@ init_terminfo_esc(tinfo* ti, const char* name, escape_e idx,
 // request the cell geometry of the textual area
 #define GEOMCELL "\x1b[18t"
 
-#define DIRECTIVES CSI_BGQ \
+#define DIRECTIVES KBDQUERY \
+                   CSI_BGQ \
                    SUMQUERY \
                    "\x1b[?1;3;256S" /* try to set 256 cregs */ \
-                   KKEYBOARD_PUSH \
-                   XTMODKEYS \
-                   KBDSUPPORT \
-                   KBDQUERY \
                    KITTYQUERY \
                    CREGSXTSM \
                    GEOMXTSM \
@@ -381,11 +378,16 @@ init_terminfo_esc(tinfo* ti, const char* name, escape_e idx,
                    GEOMCELL \
                    PRIDEVATTR
 
+// written whenever we switch between standard and alternate screen, or upon
+// startup (that's an entry into a screen! presumably the standard one).
+#define KBDENTER KKEYBOARD_PUSH XTMODKEYS KBDSUPPORT
+#define KBDLEAVE KKEYBOARD_POP // FIXME undo XTMODKEYS!
+
 // enter the alternate screen (smcup). we could technically get this from
 // terminfo, but everyone who supports it supports it the same way, and we
 // need to send it before our other directives if we're going to use it.
-#define SMCUP "\x1b[?1049h"
-#define RMCUP "\x1b[?1049l"
+#define SMCUP "\x1b[?1049h" KBDENTER
+#define RMCUP KBDLEAVE "\x1b[?1049l"
 
 // we send an XTSMGRAPHICS to set up 256 color registers (the most we can
 // currently take advantage of; we need at least 64 to use sixel at all).
@@ -397,9 +399,9 @@ send_initial_queries(int fd, bool minimal, bool noaltscreen){
   const char *queries;
   if(noaltscreen){
     if(minimal){
-      queries = DSRCPR DIRECTIVES;
+      queries = KBDENTER DSRCPR DIRECTIVES;
     }else{
-      queries = DSRCPR IDQUERIES DIRECTIVES;
+      queries = KBDENTER DSRCPR IDQUERIES DIRECTIVES;
     }
   }else{
     if(minimal){
@@ -416,6 +418,40 @@ send_initial_queries(int fd, bool minimal, bool noaltscreen){
   return 0;
 }
 
+int enter_alternate_screen(FILE* fp, tinfo* ti, bool flush){
+  if(ti->in_alt_screen){
+    return 0;
+  }
+  const char* smcup = get_escape(ti, ESCAPE_SMCUP);
+  if(smcup == NULL){
+    logerror("alternate screen is unavailable");
+    return -1;
+  }
+  if(term_emit(smcup, fp, false) || term_emit(KBDENTER, fp, flush)){
+    return -1;
+  }
+  ti->in_alt_screen = true;
+  return 0;
+}
+
+int leave_alternate_screen(FILE* fp, tinfo* ti){
+  if(!ti->in_alt_screen){
+    return 0;
+  }
+  const char* rmcup = get_escape(ti, ESCAPE_RMCUP);
+  if(rmcup == NULL){
+    logerror("can't leave alternate screen");
+    return -1;
+  }
+  if(term_emit(KBDLEAVE, fp, false) ||
+     term_emit(rmcup, fp, false) ||
+     term_emit(KBDENTER, fp, true)){
+    return -1;
+  }
+  ti->in_alt_screen = false;
+  return 0;
+}
+
 // if we get a response to the standard cursor locator escape, we know this
 // terminal supports it, hah.
 static int

src/lib/termdesc.h

@@ -321,39 +321,8 @@ term_emit(const char* seq, FILE* out, bool flush){
   return flush ? ncflush(out) : 0;
 }
 
-static inline int
-enter_alternate_screen(FILE* fp, tinfo* ti, bool flush){
-  if(ti->in_alt_screen){
-    return 0;
-  }
-  const char* smcup = get_escape(ti, ESCAPE_SMCUP);
-  if(smcup == NULL){
-    logerror("alternate screen is unavailable");
-    return -1;
-  }
-  if(term_emit(smcup, fp, flush)){
-    return -1;
-  }
-  ti->in_alt_screen = true;
-  return 0;
-}
-
-static inline int
-leave_alternate_screen(FILE* fp, tinfo* ti){
-  if(!ti->in_alt_screen){
-    return 0;
-  }
-  const char* rmcup = get_escape(ti, ESCAPE_RMCUP);
-  if(rmcup == NULL){
-    logerror("can't leave alternate screen");
-    return -1;
-  }
-  if(term_emit(rmcup, fp, true)){
-    return -1;
-  }
-  ti->in_alt_screen = false;
-  return 0;
-}
+int enter_alternate_screen(FILE* fp, tinfo* ti, bool flush);
+int leave_alternate_screen(FILE* fp, tinfo* ti);
 
 int cbreak_mode(tinfo* ti);