add grid PoC

src/poc/grid.c

@@ -0,0 +1,80 @@
+#include <notcurses/notcurses.h>
+
+struct ncvisual*
+draw_grid(struct ncplane* stdn){
+  int maxby, maxbx;
+  int cellpxy, cellpxx;
+  ncplane_pixelgeom(stdn, NULL, NULL, &cellpxy, &cellpxx, &maxby, &maxbx);
+  if(cellpxy <= 1 || cellpxx <= 1){
+    fprintf(stderr, "cell-pixel geometry: %d %d\n", cellpxy, cellpxx);
+    return NULL;
+  }
+  uint32_t* rgba = malloc(maxby * maxbx * sizeof(*rgba));
+  if(rgba == NULL){
+    return NULL;
+  }
+  // we want an inlay on each cell, so if they're 10 wide, we want pixels
+  // at 0, 9, 10, 19, 20, 29, etc.
+  for(int y = 0 ; y < maxby ; ++y){
+    uint32_t* row = rgba + y * maxbx;
+    memset(row, 0xff, maxbx * sizeof(*rgba));
+    for(int yi = 0 ; yi < cellpxy - 2 ; ++yi){
+      ++y;
+      if(y < maxby){
+        row = rgba + y * maxbx;
+        for(int x = 0 ; x < maxbx ; ++x){
+          uint32_t* px = row + x;
+          ncpixel_set_a(px, 255);
+          ncpixel_set_r(px, 255);
+          ncpixel_set_g(px, 255);
+          ncpixel_set_b(px, 255);
+          if((x += cellpxx - 1) < maxbx){
+            px = row + x;
+            ncpixel_set_a(px, 255);
+            ncpixel_set_r(px, 255);
+            ncpixel_set_g(px, 255);
+            ncpixel_set_b(px, 255);
+          }
+        }
+      }
+    }
+    ++y;
+    row = rgba + y * maxbx;
+    memset(row, 0xff, maxbx * sizeof(*rgba));
+  }
+  struct ncvisual* ncv = ncvisual_from_rgba(rgba, maxby, maxbx * sizeof(*rgba), maxbx);
+  return ncv;
+}
+
+int main(void){
+  struct notcurses_options opts = {
+    .flags = NCOPTION_NO_ALTERNATE_SCREEN |
+             NCOPTION_DRAIN_INPUT,
+  //  .loglevel = NCLOGLEVEL_TRACE,
+  };
+  struct notcurses* nc = notcurses_init(&opts, NULL);
+  if(nc == NULL){
+    return EXIT_FAILURE;
+  }
+  int dimy, dimx;
+  struct ncplane* stdn = notcurses_stddim_yx(nc, &dimy, &dimx);
+  struct ncvisual* ncv = draw_grid(stdn);
+  if(ncv == NULL){
+    notcurses_stop(nc);
+    return EXIT_FAILURE;
+  }
+  struct ncvisual_options vopts = {
+    .blitter = NCBLIT_PIXEL,
+    .flags = NCVISUAL_OPTION_NODEGRADE,
+  };
+  struct ncplane* bitn = ncvisual_render(nc, ncv, &vopts);
+  ncvisual_destroy(ncv);
+  if(bitn == NULL){
+    notcurses_stop(nc);
+    return EXIT_FAILURE;
+  }
+  // FIXME render it behind some text
+  notcurses_render(nc);
+  notcurses_stop(nc);
+  return EXIT_SUCCESS;
+}