[sixel] use private scrolling #1433

src/lib/internal.h

@@ -321,7 +321,7 @@ typedef struct tinfo {
   // means leaving out the pixels (and likely resizes the string). for kitty,
   // this means dialing down their alpha to 0 (in equivalent space).
   int (*pixel_cell_wipe)(const struct notcurses* nc, sprixel* s, int y, int x);
-  int (*pixel_clear_all)(const struct notcurses* nc);
+  int (*pixel_init)(const struct notcurses* nc);
   bool pixel_query_done; // have we yet performed pixel query?
   bool sextants;  // do we have (good, vetted) Unicode 13 sextant support?
   bool braille;   // do we have Braille support? (linux console does not)
@@ -730,9 +730,10 @@ sprixel* sprixel_create(ncplane* n, const char* s, int bytes, int placey, int pl
                         int parse_start);
 API int sprite_wipe_cell(const notcurses* nc, sprixel* s, int y, int x);
 int sprite_kitty_annihilate(const notcurses* nc, const ncpile* p, FILE* out, sprixel* s);
-int sprite_kitty_clear_all(const notcurses* nc);
+int sprite_kitty_init(const notcurses* nc);
+int sprite_sixel_init(const notcurses* nc);
 int sprite_sixel_annihilate(const notcurses* nc, const ncpile* p, FILE* out, sprixel* s);
-int sprite_clear_all(const notcurses* nc);
+int sprite_init(const notcurses* nc);
 
 static inline void
 pool_release(egcpool* pool, nccell* c){

src/lib/kitty.c

@@ -287,6 +287,6 @@ int kitty_blit(ncplane* nc, int linesize, const void* data, int begy, int begx,
   return r;
 }
 
-int sprite_kitty_clear_all(const notcurses* nc){
+int sprite_kitty_init(const notcurses* nc){
   return tty_emit("\e_Ga=d\e\\", nc->ttyfd);
 }

src/lib/sixel.c

@@ -416,12 +416,7 @@ write_rle(int* printed, int color, FILE* fp, int seenrle, unsigned char crle){
 // Emit the sprixel in its entirety, plus enable and disable pixel mode.
 static int
 write_sixel_data(FILE* fp, int lenx, sixeltable* stab, int* parse_start){
-  // \e[?80: DECSDM "sixel scrolling" mode (put output at cursor location)
-  // \x90: 8-bit "device control sequence", lowercase q (start sixel)
-  // doesn't seem to work with at least xterm; we instead use '\ePq'
-  // FIXME i think we can print DESDM on the first one, and never again
-  *parse_start += fprintf(fp, "\e[?80h\ePq");
-
+  *parse_start = fprintf(fp, "\ePq");
   // Set Raster Attributes - pan/pad=1 (pixel aspect ratio), Ph=lenx, Pv=leny
   // using Ph/Pv causes a background to be drawn using color register 0 for all
   // unspecified pixels, which we do not want.
@@ -555,3 +550,10 @@ int sixel_blit(ncplane* nc, int linesize, const void* data, int begy, int begx,
   free(stable.table);
   return r;
 }
+
+int sprite_sixel_init(const notcurses* nc){
+  // \e[?8452: DECSDM private "sixel scrolling" mode keeps the sixel from
+  // scrolling, but puts it at the current cursor location (as opposed to
+  // the upper left corner of the screen).
+  return tty_emit("\e[?8452h", nc->ttyfd);
+}

src/lib/sprite.c

@@ -75,9 +75,9 @@ int sprite_wipe_cell(const notcurses* nc, sprixel* s, int ycell, int xcell){
   return r;
 }
 
-int sprite_clear_all(const notcurses* nc){
-  if(!nc->tcache.pixel_clear_all){
+int sprite_init(const notcurses* nc){
+  if(!nc->tcache.pixel_init){
     return 0;
   }
-  return nc->tcache.pixel_clear_all(nc);
+  return nc->tcache.pixel_init(nc);
 }