transition to alternate screen in interrogate_terminfo() #2131

src/lib/notcurses.c

@@ -1229,26 +1229,15 @@ notcurses* notcurses_core_init(const notcurses_options* opts, FILE* outfp){
   if(set_fd_nonblocking(ret->tcache.input.infd, 1, &ret->stdio_blocking_save)){
     goto err;
   }
-  // if not connected to an actual terminal, we're not going to try entering
-  // the alternate screen; we're not even going to bother clearing the screen.
-  if(ret->tcache.ttyfd >= 0){
-    if(!(opts->flags & NCOPTION_NO_ALTERNATE_SCREEN)){
-      const char* smcup = get_escape(&ret->tcache, ESCAPE_SMCUP);
-      if(smcup){
-        if(enter_alternate_screen(ret->ttyfp, &ret->tcache, false)){
-          free_plane(ret->stdplane);
-          goto err;
-        }
-      }
-      // perform an explicit clear since the alternate screen was requested
-      // (smcup *might* clear, but who knows? and it might not have been
-      // available in any case).
-      if(clear_and_home(ret, &ret->tcache, &ret->rstate.f)){
-        goto err;
-      }
-      // no need to reestablish a preserved cursor -- that only affects the
-      // standard plane, not the physical cursor that was just disrupted.
+  if(!(opts->flags & NCOPTION_NO_ALTERNATE_SCREEN)){
+    // perform an explicit clear since the alternate screen was requested
+    // (smcup *might* clear, but who knows? and it might not have been
+    // available in any case).
+    if(clear_and_home(ret, &ret->tcache, &ret->rstate.f)){
+      goto err;
     }
+    // no need to reestablish a preserved cursor -- that only affects the
+    // standard plane, not the physical cursor that was just disrupted.
   }
   // the sprite clear ought take place within the alternate screen, if it's
   // being used.

src/lib/termdesc.c

@@ -372,18 +372,31 @@ init_terminfo_esc(tinfo* ti, const char* name, escape_e idx,
                    GEOMCELL \
                    PRIDEVATTR
 
+// 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"
+
 // 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).
 // maybe that works, maybe it doesn't. then query both color registers
 // and geometry. send XTGETTCAP for terminal name. if 'minimal' is set, don't
 // send any identification queries (we've already identified the terminal).
 static int
-send_initial_queries(int fd, bool minimal){
+send_initial_queries(int fd, bool minimal, bool noaltscreen){
   const char *queries;
-  if(minimal){
-    queries = DSRCPR DIRECTIVES;
+  if(noaltscreen){
+    if(minimal){
+      queries = DSRCPR DIRECTIVES;
+    }else{
+      queries = DSRCPR IDQUERIES DIRECTIVES;
+    }
   }else{
-    queries = DSRCPR IDQUERIES DIRECTIVES;
+    if(minimal){
+      queries = SMCUP DSRCPR DIRECTIVES;
+    }else{
+      queries = SMCUP DSRCPR IDQUERIES DIRECTIVES;
+    }
   }
   size_t len = strlen(queries);
   loginfo("sending %lluB queries\n", (unsigned long long)len);
@@ -751,10 +764,11 @@ int interrogate_terminfo(tinfo* ti, const char* termtype, FILE* out, unsigned ut
       free(ti->tpreserved);
       return -1;
     }
+// FIXME need to enter alternate screen here
     // if we already know our terminal (e.g. on the linux console), there's no
     // need to send the identification queries. the controls are sufficient.
     bool minimal = (ti->qterm != TERMINAL_UNKNOWN);
-    if(send_initial_queries(ti->ttyfd, minimal)){
+    if(send_initial_queries(ti->ttyfd, minimal, noaltscreen)){
       free(ti->tpreserved);
       goto err;
     }
@@ -859,6 +873,15 @@ int interrogate_terminfo(tinfo* ti, const char* termtype, FILE* out, unsigned ut
        init_terminfo_esc(ti, "rmcup", ESCAPE_RMCUP, &tablelen, &tableused)){
       goto err;
     }
+    const char* smcup = get_escape(ti, ESCAPE_SMCUP);
+    if(smcup){
+      ti->in_alt_screen = 1;
+      // if we're not using the standard smcup, our initial hardcoded use of it
+      // presumably had no effect; warn the user.
+      if(strcmp(smcup, SMCUP)){
+        logwarn("warning: non-standard smcup!\n");
+      }
+    }
   }else{
     ti->escindices[ESCAPE_SMCUP] = 0;
     ti->escindices[ESCAPE_RMCUP] = 0;