Use different kitty nonces for different runs

If we always start with kitty graphics id 1, successive
runs of ncplayer -bpixel -k will erase any previously-
printed graphics. Initialize it with random() in
sprite_init(). Break graphics erasure out from sprite_init()
into new interface sprite_clear_all(), defined only for kitty.
The latter is now guarded by NCOPTION_NO_CLEAR_BITMAPS.
Closes #1578.

src/lib/internal.h

@@ -457,7 +457,6 @@ typedef struct tinfo {
   pthread_mutex_t pixel_query; // only query for pixel support once
   int color_registers; // sixel color registers (post pixel_query_done)
   int sixel_maxx, sixel_maxy; // sixel size maxima (post pixel_query_done)
-  int sprixelnonce;      // next sprixel id
   int (*pixel_destroy)(const struct notcurses* nc, const struct ncpile* p, FILE* out, sprixel* s);
   // wipe out a cell's worth of pixels from within a sprixel. for sixel, this
   // means leaving out the pixels (and likely resizes the string). for kitty,
@@ -466,9 +465,10 @@ typedef struct tinfo {
   // perform the inverse of pixel_wipe, restoring an annihilated sprixcell.
   int (*pixel_rebuild)(sprixel* s, int y, int x, uint8_t* auxvec);
   int (*pixel_remove)(int id, FILE* out); // kitty only, issue actual delete command
-  int (*pixel_init)(int fd);     // called when support is detected
+  int (*pixel_init)(int fd);      // called when support is detected
   int (*pixel_draw)(const struct ncpile* p, sprixel* s, FILE* out);
-  int (*pixel_shutdown)(int fd); // called during context shutdown
+  int (*pixel_shutdown)(int fd);  // called during context shutdown
+  int (*pixel_clear_all)(int fd); // called during startup, kitty only
   int sprixel_scale_height; // sprixel must be a multiple of this many rows
   bool bitmap_supported;    // do we support bitmaps (post pixel_query_done)?
   bool sprixel_cursor_hack; // do sprixels reset the cursor? (mlterm)
@@ -963,9 +963,10 @@ int sprixel_load(sprixel* spx, char* s, int bytes, int pixy, int pixx, int parse
 int sixel_destroy(const notcurses* nc, const ncpile* p, FILE* out, sprixel* s);
 int kitty_destroy(const notcurses* nc, const ncpile* p, FILE* out, sprixel* s);
 int kitty_remove(int id, FILE* out);
-int kitty_init(int fd);
+int kitty_clear_all(int fd);
 int sixel_init(int fd);
-int sprite_init(const notcurses* nc);
+int sprite_init(const tinfo* t, int fd);
+int sprite_clear_all(const tinfo* t, int fd);
 int kitty_shutdown(int fd);
 int sixel_shutdown(int fd);
 sprixel* sprixel_by_id(const ncpile* n, uint32_t id);

src/lib/kitty.c

@@ -614,7 +614,8 @@ int kitty_draw(const ncpile* p, sprixel* s, FILE* out){
 }
 
 // clears all kitty bitmaps
-int kitty_init(int fd){
+int kitty_clear_all(int fd){
+//fprintf(stderr, "KITTY UNIVERSAL ERASE\n");
   return tty_emit("\e_Ga=d\e\\", fd);
 }
 

src/lib/notcurses.c

@@ -1081,7 +1081,7 @@ notcurses* notcurses_core_init(const notcurses_options* opts, FILE* outfp){
   if(ret->ttyfd >= 0){
     reset_term_attributes(ret);
     if(!(opts->flags & NCOPTION_NO_CLEAR_BITMAPS)){
-      if(sprite_init(ret)){
+      if(sprite_clear_all(&ret->tcache, ret->ttyfd)){
         free_plane(ret->stdplane);
         goto err;
       }

src/lib/sprite.c

@@ -194,11 +194,19 @@ int sprite_wipe(const notcurses* nc, sprixel* s, int ycell, int xcell){
   return r;
 }
 
-int sprite_init(const notcurses* nc){
-  if(!nc->tcache.pixel_init){
+int sprite_clear_all(const tinfo* t, int fd){
+  if(t->pixel_clear_all == NULL){
     return 0;
   }
-  return nc->tcache.pixel_init(nc->ttyfd);
+  return t->pixel_clear_all(fd);
+}
+
+int sprite_init(const tinfo* t, int fd){
+  sprixelid_nonce = random() % 0xffffffu;
+  if(t->pixel_init == NULL){
+    return 0;
+  }
+  return t->pixel_init(fd);
 }
 
 uint8_t* sprixel_auxiliary_vector(const sprixel* s){

src/lib/terminfo.c

@@ -20,16 +20,17 @@ setup_sixel_bitmaps(tinfo* ti){
 }
 
 static inline void
-setup_kitty_bitmaps(tinfo* ti){
+setup_kitty_bitmaps(tinfo* ti, int fd){
   ti->pixel_wipe = kitty_wipe;
   ti->pixel_destroy = kitty_destroy;
-  ti->pixel_init = kitty_init;
   ti->pixel_remove = kitty_remove;
   ti->pixel_draw = kitty_draw;
   ti->pixel_shutdown = kitty_shutdown;
   ti->sprixel_scale_height = 1;
   ti->pixel_rebuild = kitty_rebuild;
+  ti->pixel_clear_all = kitty_clear_all;
   set_pixel_blitter(kitty_blit);
+  sprite_init(ti, fd);
 }
 
 static bool
@@ -76,7 +77,7 @@ int terminfostr(char** gseq, const char* name){
 
 // Qui si convien lasciare ogne sospetto; ogne viltà convien che qui sia morta.
 static int
-apply_term_heuristics(tinfo* ti, const char* termname){
+apply_term_heuristics(tinfo* ti, const char* termname, int fd){
   if(!termname){
     // setupterm interprets a missing/empty TERM variable as the special value “unknown”.
     termname = "unknown";
@@ -91,7 +92,7 @@ apply_term_heuristics(tinfo* ti, const char* termname){
     ti->quadrants = true;
     ti->pixel_query_done = true;
     ti->bitmap_supported = true;
-    setup_kitty_bitmaps(ti);
+    setup_kitty_bitmaps(ti, fd);
   }else if(strstr(termname, "alacritty")){
     ti->alacritty_sixel_hack = true;
     ti->quadrants = true;
@@ -249,10 +250,9 @@ int interrogate_terminfo(tinfo* ti, int fd, const char* termname, unsigned utf8)
   }
   pthread_mutex_init(&ti->pixel_query, NULL);
   ti->pixel_query_done = false;
-  if(apply_term_heuristics(ti, termname)){
+  if(apply_term_heuristics(ti, termname, fd)){
     return -1;
   }
-  ti->sprixelnonce = 1;
   return 0;
 }