yaft: remove support for double-width characters

for our usecase (output of system commands), this is not necessary

src/gui/widget/yaft/ctrlseq/csi.cpp

@@ -335,8 +335,6 @@ void YaFT_p::set_mode(struct parm_t *parm)
 			mode |= MODE_AMRIGHT;
 		} else if (pmode == 25) {
 			mode |= MODE_CURSOR;
-		} else if (pmode == 8901) {
-			mode |= MODE_VWBS;
 		}
 	}
 
@@ -359,8 +357,6 @@ void YaFT_p::reset_mode(struct parm_t *parm)
 			wrap_occured = false;
 		} else if (pmode == 25) {
 			mode &= ~MODE_CURSOR;
-		} else if (pmode == 8901) {
-			mode &= ~MODE_VWBS;
 		}
 	}
 

src/gui/widget/yaft/ctrlseq/esc.cpp

@@ -27,12 +27,7 @@
 /* function for control character */
 void YaFT_p::bs(void)
 {
-	if (mode & MODE_VWBS
-		&& cursor.x - 1 >= 0
-		&& cells[cursor.y][cursor.x - 1].width == NEXT_TO_WIDE)
-		move_cursor(0, -2);
-	else
-		move_cursor(0, -1);
+	move_cursor(0, -1);
 }
 
 void YaFT_p::tab(void)

src/gui/widget/yaft/yaft_priv.cpp

@@ -116,7 +116,6 @@ void YaFT_p::erase_cell(int y, int x)
 	cellp->glyphp     = glyph[DEFAULT_CHAR];
 	cellp->color_pair = color_pair; /* bce */
 	cellp->attribute  = ATTR_RESET;
-	cellp->width      = HALF;
 	line_dirty[y] = true;
 }
 
@@ -126,20 +125,8 @@ void YaFT_p::copy_cell(int dst_y, int dst_x, int src_y, int src_x)
 
 	dst = &cells[dst_y][dst_x];
 	src = &cells[src_y][src_x];
-
-	if (src->width == NEXT_TO_WIDE) {
-		return;
-	} else if (src->width == WIDE && dst_x == (cols - 1)) {
-		erase_cell(dst_y, dst_x);
-	} else {
-		*dst = *src;
-		if (src->width == WIDE) {
-			dst  = &cells[dst_y][dst_x + 1];
-			*dst = *src;
-			dst->width = NEXT_TO_WIDE;
-		}
-		line_dirty[dst_y] = true;
-	}
+	*dst = *src;
+	line_dirty[dst_y] = true;
 }
 
 int YaFT_p::set_cell(int y, int x, const struct glyph_t *glyphp)
@@ -161,23 +148,10 @@ int YaFT_p::set_cell(int y, int x, const struct glyph_t *glyphp)
 	}
 
 	cell.attribute  = attribute;
-	cell.width      = (glyph_width)glyphp->width;
 
 	cells[y][x] = cell;
 	line_dirty[y] = true;
-
-	if (cell.width == WIDE && x + 1 < cols) {
-		cell.width = NEXT_TO_WIDE;
-		cells[y][x + 1] = cell;
-		return WIDE;
-	}
-
-	if (cell.width == HALF /* isolated NEXT_TO_WIDE cell */
-		&& x + 1 < cols
-		&& cells[y][x + 1].width == NEXT_TO_WIDE) {
-		erase_cell(y, x + 1);
-	}
-	return HALF;
+	return 1;
 }
 
 void YaFT_p::swap_lines(int i, int j)
@@ -789,16 +763,12 @@ void YaFT_p::draw_line(int line)
 		col_pair = cellp->color_pair;
 
 		/* check wide character or not */
-		glyph_w = (cellp->width == HALF) ? CELL_WIDTH: CELL_WIDTH * 2;
+		glyph_w = CELL_WIDTH;
 		bdf_padding = my_ceil(glyph_w, BITS_PER_BYTE) * BITS_PER_BYTE - glyph_w;
-		if (cellp->width == WIDE)
-			bdf_padding += CELL_WIDTH;
 
 		/* check cursor positon */
 		if ((mode & MODE_CURSOR && line == cursor.y)
-			&& (col == cursor.x
-			|| (cellp->width == WIDE && (col + 1) == cursor.x)
-			|| (cellp->width == NEXT_TO_WIDE && (col - 1) == cursor.x))) {
+			&& col == cursor.x) {
 			col_pair.fg = DEFAULT_BG;
 			col_pair.bg = ACTIVE_CURSOR_COLOR;
 		}

src/gui/widget/yaft/yaft_priv.h

@@ -123,7 +123,6 @@ class YaFT_p
 		MODE_ORIGIN  = 0x01, /* origin mode: DECOM */
 		MODE_CURSOR  = 0x02, /* cursor visible: DECTCEM */
 		MODE_AMRIGHT = 0x04, /* auto wrap: DECAWM */
-		MODE_VWBS    = 0x08, /* variable-width backspace */
 	};
 
 	struct esc_t {
@@ -132,17 +131,10 @@ class YaFT_p
 		enum esc_state state;
 	};
 
-	enum glyph_width {
-		NEXT_TO_WIDE = 0,
-		HALF,
-		WIDE,
-	};
-
 	struct cell_t {
 		const struct glyph_t *glyphp;   /* pointer to glyph */
 		struct color_pair_t color_pair; /* color (fg, bg) */
 		int attribute;                  /* bold, underscore, etc... */
-		enum glyph_width width;         /* wide char flag: WIDE, NEXT_TO_WIDE, HALF */
 	};
 
 	struct framebuffer_t {