[tabs] autogrow to the right to next tabstop #1233

src/lib/notcurses.c

@@ -1889,15 +1889,17 @@ ncplane_put(ncplane* n, int y, int x, const char* egc, int cols,
   // move to the next line. otherwise, simply fill any spaces we can. this has
   // already taken place by the time we get here, if it ought have happened.
   if(*egc == '\t'){
-    if(n->x >= n->lenx){
+    cols = TABSTOP - (n->x % TABSTOP);
+    if(n->x + 1 >= n->lenx){
       if(!n->scrolling && n->autogrow){
-        // FIXME might need autogrow to the next tab stop out
+        ncplane_resize_simple(n, n->leny, n->lenx + (cols ? cols - 1 : TABSTOP - 1));
+        // must refresh targ; resize invalidated it
+        targ = ncplane_cell_ref_yx(n, n->y, n->x);
       }
     }
     if(cell_load_direct(n, targ, " ", bytes, 1) < 0){
       return -1;
     }
-    cols = TABSTOP - (n->x % TABSTOP);
   }else{
     if(cell_load_direct(n, targ, egc, bytes, cols) < 0){
       return -1;

src/tests/tabs.cpp

@@ -124,6 +124,30 @@ TEST_CASE("TaBs") { // refreshing and delicious
     }
   }
 
+  SUBCASE("GrowWithTaBs") {
+    struct ncplane_options nopts{};
+    nopts.rows = 2;
+    nopts.cols = TABWIDTH;
+    nopts.flags = NCPLANE_OPTION_AUTOGROW;
+    auto n = ncplane_create(n_, &nopts);
+    unsigned y, x;
+    CHECK(16 == ncplane_putstr(n, "\t\t"));
+    ncplane_cursor_yx(n, &y, &x);
+    CHECK(y == 0);
+    CHECK(x == 16);
+    CHECK(16 == ncplane_dim_x(n));
+    CHECK(8 == ncplane_putstr(n, "\t"));
+    ncplane_cursor_yx(n, &y, &x);
+    CHECK(x == 24);
+    CHECK(24 == ncplane_dim_x(n));
+    for(unsigned i = 0 ; i < ncplane_dim_x(n) ; ++i){
+      char* c = ncplane_at_yx(n, 0, i, nullptr, nullptr);
+      REQUIRE(c);
+      CHECK(0 == strcmp(c, " "));
+      free(c);
+    }
+  }
+
   CHECK(0 == notcurses_stop(nc_));
 
 }