track wide char as reported by wcwidth(), add unit test #6

include/notcurses.h

@@ -45,7 +45,8 @@ typedef struct cell {
   uint32_t attrword;          // + 4b -> 8b
   // (channels & 0x8000000000000000ull): inherit styling from prior cell
   // (channels & 0x4000000000000000ull): foreground is *not* "default color"
-  // (channels & 0x3f00000000000000ull): reserved, must be 0
+  // (channels & 0x2000000000000000ull): wide character (left or right side)
+  // (channels & 0x1f00000000000000ull): reserved, must be 0
   // (channels & 0x00ffffff00000000ull): foreground in 3x8 RGB (rrggbb)
   // (channels & 0x0000000080000000ull): in the middle of a multicolumn glyph
   // (channels & 0x0000000040000000ull): background is *not* "default color"
@@ -295,6 +296,7 @@ cell_rgb_blue(uint32_t rgb){
 }
 
 #define CELL_FGDEFAULT_MASK 0x4000000000000000ull
+#define CELL_WIDEASIAN_MASK 0x2000000000000000ull
 #define CELL_BGDEFAULT_MASK 0x0000000040000000ull
 
 static inline void
@@ -349,6 +351,11 @@ cell_bg_default_p(const cell* c){
   return !(c->channels & CELL_BGDEFAULT_MASK);
 }
 
+static inline bool
+cell_wide_p(const cell* c){
+  return (c->channels & CELL_WIDEASIAN_MASK);
+}
+
 #ifdef __cplusplus
 } // extern "C"
 #endif

src/lib/notcurses.c

@@ -695,6 +695,11 @@ int cell_load(ncplane* n, cell* c, const char* gcluster){
     c->gcluster = *gcluster;
     return !!c->gcluster;
   }
+  if(cols > 1){
+    c->channels |= CELL_WIDEASIAN_MASK;
+  }else{
+    c->channels &= ~CELL_WIDEASIAN_MASK;
+  }
   size_t ulen;
   // FIXME feed in already-calculated lengths from prior utf8_egc_len()!
   int eoffset = egcpool_stash(&n->pool, gcluster, &ulen, &cols);

tests/ncplane.cpp

@@ -256,3 +256,18 @@ TEST_F(NcplaneTest, CellDuplicateCombining) {
   cell_release(n_, &cell5);
   cell_release(n_, &cell6);
 }
+
+TEST_F(NcplaneTest, CellMultiColumn) {
+  const char* w1 = "👨";
+  const char* w2 = "N";
+  cell c1 = CELL_TRIVIAL_INITIALIZER;
+  cell c2 = CELL_TRIVIAL_INITIALIZER;
+  auto u1 = cell_load(n_, &c1, w1);
+  auto u2 = cell_load(n_, &c2, w2);
+  ASSERT_EQ(strlen(w1), u1);
+  ASSERT_EQ(strlen(w2), u2);
+  EXPECT_TRUE(cell_wide_p(&c1));
+  EXPECT_FALSE(cell_wide_p(&c2));
+  cell_release(n_, &c1);
+  cell_release(n_, &c2);
+}