mention SIGCONT along with SIGWINCH

NEWS.md

@@ -4,18 +4,19 @@ rearrangements of Notcurses.
 * 2.2.3 (not yet released)
   * Add `SIGILL` to the set of fatal signals we handle.
   * Added `NCKEY_SIGNAL`. `NCKEY_RESIZE` is now an alias for `NCKEY_SIGNAL`.
-  * `SIGCONT` now synthesizes a `NCKEY_SIGNAL`.
+  * `SIGCONT` now synthesizes a `NCKEY_SIGNAL`, just like `SIGWINCH`.
   * Add the `nctree` widget for line-oriented hierarchical data. See
     the new `notcurses_tree(3)` man page for complete information.
-  * Implemented `NCBLIT_PIXEL` for terminals reporting Sixel support.
-    Added `notcurses_check_pixel_support()` and its companion
-    `ncdirect_check_pixel_support()`, which must be called (and must return
-    success) before `NCBLIT_PIXEL` will be available. `NCBLIT_PIXEL` degrades
-    to `NCBLIT_3x2` until support is verified.
   * Ceased exporting `cell_fchannel()`, `cell_bchannel()`,
     `cell_set_fchannel()`, and `cell_set_bchannel()`. These functions were
     never safe for users. Everything a user might want to manipulate can be
     manipulated with more granular functions.
+  * Implemented `NCBLIT_PIXEL` for terminals reporting Sixel support.
+    Added `notcurses_check_pixel_support()` and its companion
+    `ncdirect_check_pixel_support()`, which must be called (and must return
+    success) before `NCBLIT_PIXEL` will be available. `NCBLIT_PIXEL` degrades
+    to `NCBLIT_3x2` until support is verified. This functionality ought be
+    considered experimental.
 
 * 2.2.2 (2021-02-18):
   * `notcurses_stats()` no longer qualifies its `notcurses*` argument with

doc/man/man3/notcurses_init.3.md

@@ -111,8 +111,9 @@ zero. The following flags are defined:
     itself, usually as one of the first lines.
 
 * **NCOPTION_NO_WINCH_SIGHANDLER**: A signal handler will usually be installed
-    for **SIGWINCH**, resulting in **NCKEY_RESIZE** events being generated on
-    input. With this flag, the handler will not be installed.
+    for **SIGWINCH** and **SIGCONT**, resulting in **NCKEY_RESIZE** events
+    being generated on input. With this flag, the handler will not be
+    installed.
 
 * **NCOPTION_NO_QUIT_SIGHANDLERS**: A signal handler will usually be installed
     for **SIGINT**, **SIGILL**, **SIGQUIT**, **SIGSEGV**, **SIGTERM**, and

src/lib/blit.c

@@ -835,6 +835,45 @@ braille_blit(ncplane* nc, int placey, int placex, int linesize,
   return total;
 }
 
+// monochromatic blitter for testing
+static inline int
+sixel_blit(ncplane* nc, int placey, int placex, int linesize,
+           const void* data, int begy, int begx,
+           int leny, int lenx, bool blendcolors){
+  int dimy, dimx, x, y;
+  int total = 0; // number of cells written
+  ncplane_dim_yx(nc, &dimy, &dimx);
+  int visy = begy;
+  for(y = placey ; visy < (begy + leny) && y < dimy ; ++y, visy += 6){
+    if(ncplane_cursor_move_yx(nc, y, placex)){
+      return -1;
+    }
+    int visx = begx;
+    for(x = placex ; visx < (begx + lenx) && x < dimx ; ++x, visx += 1){
+      char sixel[128];
+      unsigned bitsused = 0; // once 63, we're done
+      for(int sy = visy ; sy < dimy && sy < visy + 6 ; ++sy){
+        const uint32_t* rgb = (const uint32_t*)(data + (linesize * sy) + (visx * 4));
+        if(ffmpeg_trans_p(ncpixel_a(*rgb))){
+          continue;
+        }
+        bitsused |= (1u << (sy - visy));
+      }
+      nccell* c = ncplane_cell_ref_yx(nc, y, x);
+      int n = snprintf(sixel, sizeof(sixel), "#1;2;100;100;100#1%c", bitsused + 63);
+      if(n){
+        if(pool_blit_direct(&nc->pool, c, sixel, n, 1) <= 0){
+          return -1;
+        }
+      } // FIXME otherwise, reset?
+      cell_set_pixels(c, 1);
+    }
+  }
+  (void)blendcolors; // FIXME
+  return total;
+}
+
+/*
 static inline void
 break_sixel_comps(unsigned char comps[static 3], uint32_t rgba){
   comps[0] = ncpixel_r(rgba) * 100 / 255;
@@ -844,9 +883,8 @@ break_sixel_comps(unsigned char comps[static 3], uint32_t rgba){
 
 // Sixel blitter. Sixels are stacks 6 pixels high, and 1 pixel wide. RGB colors
 // are programmed as a set of registers, which are then referenced by the
-// stacks. There is also a RLE component, handled in rasterization. These can't
-// be represented as EGCs in the traditional manner FIXME maybe write them to
-// EGCpool and use a special code (2, presumably) to indicate no coloring?
+// stacks. There is also a RLE component, handled in rasterization.
+// A pixel block is indicated by setting cell_pixels_p().
 static inline int
 sixel_blit(ncplane* nc, int placey, int placex, int linesize,
            const void* data, int begy, int begx,
@@ -925,6 +963,7 @@ sixel_blit(ncplane* nc, int placey, int placex, int linesize,
   return total;
 #undef GROWTHFACTOR
 }
+*/
 
 // NCBLIT_DEFAULT is not included, as it has no defined properties. It ought
 // be replaced with some real blitter implementation by the calling widget.