Add support for BCE (background colour erase). This makes various escape

sequences (notable EL and ED but also IL, DL, ICH, DCH) create blank
cells using the current background colour rather than the default
colour.

On modern systems BCE doesn't really have many benefits, but most other
terminals now support it, some (lazy) applications rely on it, and it is
not hard to include now that we have pane background colours anyway.

Mostly written by Sean Haugh.

1 files changed, 59 insertions, 42 deletions

diff --git a/screen-write.c b/screen-write.c
index 8156a1d0..95caabce 100644
--- a/screen-write.c
+++ b/screen-write.c
@@ -147,7 +147,7 @@ screen_write_reset(struct screen_write_ctx *ctx)
 	s->mode &= ~(MODE_INSERT|MODE_KCURSOR|MODE_KKEYPAD|MODE_FOCUSON);
 	s->mode &= ~(ALL_MOUSE_MODES|MODE_MOUSE_UTF8|MODE_MOUSE_SGR);
 
-	screen_write_clearscreen(ctx);
+	screen_write_clearscreen(ctx, 8);
 	screen_write_cursormove(ctx, 0, 0);
 }
 
@@ -601,7 +601,7 @@ screen_write_alignmenttest(struct screen_write_ctx *ctx)
 
 /* Insert nx characters. */
 void
-screen_write_insertcharacter(struct screen_write_ctx *ctx, u_int nx)
+screen_write_insertcharacter(struct screen_write_ctx *ctx, u_int nx, u_int bg)
 {
 	struct screen	*s = ctx->s;
 	struct tty_ctx	 ttyctx;
@@ -618,15 +618,16 @@ screen_write_insertcharacter(struct screen_write_ctx *ctx, u_int nx)
 	screen_write_initctx(ctx, &ttyctx);
 
 	if (s->cx <= screen_size_x(s) - 1)
-		grid_view_insert_cells(s->grid, s->cx, s->cy, nx);
+		grid_view_insert_cells(s->grid, s->cx, s->cy, nx, bg);
 
 	ttyctx.num = nx;
+	ttyctx.bg = bg;
 	tty_write(tty_cmd_insertcharacter, &ttyctx);
 }
 
 /* Delete nx characters. */
 void
-screen_write_deletecharacter(struct screen_write_ctx *ctx, u_int nx)
+screen_write_deletecharacter(struct screen_write_ctx *ctx, u_int nx, u_int bg)
 {
 	struct screen	*s = ctx->s;
 	struct tty_ctx	 ttyctx;
@@ -643,9 +644,10 @@ screen_write_deletecharacter(struct screen_write_ctx *ctx, u_int nx)
 	screen_write_initctx(ctx, &ttyctx);
 
 	if (s->cx <= screen_size_x(s) - 1)
-		grid_view_delete_cells(s->grid, s->cx, s->cy, nx);
+		grid_view_delete_cells(s->grid, s->cx, s->cy, nx, bg);
 
 	ttyctx.num = nx;
+	ttyctx.bg = bg;
 	tty_write(tty_cmd_deletecharacter, &ttyctx);
 }
 
@@ -668,7 +670,7 @@ screen_write_clearcharacter(struct screen_write_ctx *ctx, u_int nx)
 
 	if (s->cx <= screen_size_x(s) - 1) {
 		screen_dirty_clear(s, s->cx, s->cy, s->cx + nx - 1, s->cy);
-		grid_view_clear(s->grid, s->cx, s->cy, nx, 1);
+		grid_view_clear(s->grid, s->cx, s->cy, nx, 1, 8);
 	} else
 		return;
 
@@ -678,7 +680,7 @@ screen_write_clearcharacter(struct screen_write_ctx *ctx, u_int nx)
 
 /* Insert ny lines. */
 void
-screen_write_insertline(struct screen_write_ctx *ctx, u_int ny)
+screen_write_insertline(struct screen_write_ctx *ctx, u_int ny, u_int bg)
 {
 	struct screen	*s = ctx->s;
 	struct tty_ctx	 ttyctx;
@@ -695,9 +697,10 @@ screen_write_insertline(struct screen_write_ctx *ctx, u_int ny)
 		screen_write_flush(ctx);
 		screen_write_initctx(ctx, &ttyctx);
 
-		grid_view_insert_lines(s->grid, s->cy, ny);
+		grid_view_insert_lines(s->grid, s->cy, ny, bg);
 
 		ttyctx.num = ny;
+		ttyctx.bg = bg;
 		tty_write(tty_cmd_insertline, &ttyctx);
 		return;
 	}
@@ -711,17 +714,20 @@ screen_write_insertline(struct screen_write_ctx *ctx, u_int ny)
 	screen_write_initctx(ctx, &ttyctx);
 
 	if (s->cy < s->rupper || s->cy > s->rlower)
-		grid_view_insert_lines(s->grid, s->cy, ny);
-	else
-		grid_view_insert_lines_region(s->grid, s->rlower, s->cy, ny);
+		grid_view_insert_lines(s->grid, s->cy, ny, bg);
+	else {
+		grid_view_insert_lines_region(s->grid, s->rlower, s->cy, ny,
+		    bg);
+	}
 
 	ttyctx.num = ny;
+	ttyctx.bg = bg;
 	tty_write(tty_cmd_insertline, &ttyctx);
 }
 
 /* Delete ny lines. */
 void
-screen_write_deleteline(struct screen_write_ctx *ctx, u_int ny)
+screen_write_deleteline(struct screen_write_ctx *ctx, u_int ny, u_int bg)
 {
 	struct screen	*s = ctx->s;
 	struct tty_ctx	 ttyctx;
@@ -738,9 +744,10 @@ screen_write_deleteline(struct screen_write_ctx *ctx, u_int ny)
 		screen_write_flush(ctx);
 		screen_write_initctx(ctx, &ttyctx);
 
-		grid_view_delete_lines(s->grid, s->cy, ny);
+		grid_view_delete_lines(s->grid, s->cy, ny, bg);
 
 		ttyctx.num = ny;
+		ttyctx.bg = bg;
 		tty_write(tty_cmd_deleteline, &ttyctx);
 		return;
 	}
@@ -754,17 +761,20 @@ screen_write_deleteline(struct screen_write_ctx *ctx, u_int ny)
 	screen_write_initctx(ctx, &ttyctx);
 
 	if (s->cy < s->rupper || s->cy > s->rlower)
-		grid_view_delete_lines(s->grid, s->cy, ny);
-	else
-		grid_view_delete_lines_region(s->grid, s->rlower, s->cy, ny);
+		grid_view_delete_lines(s->grid, s->cy, ny, bg);
+	else {
+		grid_view_delete_lines_region(s->grid, s->rlower, s->cy, ny,
+		    bg);
+	}
 
 	ttyctx.num = ny;
+	ttyctx.bg = bg;
 	tty_write(tty_cmd_deleteline, &ttyctx);
 }
 
 /* Clear line at cursor. */
 void
-screen_write_clearline(struct screen_write_ctx *ctx)
+screen_write_clearline(struct screen_write_ctx *ctx, u_int bg)
 {
 	struct screen		*s = ctx->s;
 	struct grid_line	*gl;
@@ -772,20 +782,21 @@ screen_write_clearline(struct screen_write_ctx *ctx)
 	u_int			 sx = screen_size_x(s);
 
 	screen_write_initctx(ctx, &ttyctx);
+	ttyctx.bg = bg;
 
 	gl = &s->grid->linedata[s->grid->hsize + s->cy];
-	if (gl->cellsize != 0) {
-		screen_dirty_clear(s, 0, s->cy, sx - 1, s->cy);
-		grid_view_clear(s->grid, 0, s->cy, sx, 1);
-	} else
+	if (gl->cellsize == 0 && bg == 8)
 		return;
 
+	screen_dirty_clear(s, 0, s->cy, sx - 1, s->cy);
+	grid_view_clear(s->grid, 0, s->cy, sx, 1, bg);
+
 	tty_write(tty_cmd_clearline, &ttyctx);
 }
 
 /* Clear to end of line from cursor. */
 void
-screen_write_clearendofline(struct screen_write_ctx *ctx)
+screen_write_clearendofline(struct screen_write_ctx *ctx, u_int bg)
 {
 	struct screen		*s = ctx->s;
 	struct grid_line	*gl;
@@ -793,33 +804,35 @@ screen_write_clearendofline(struct screen_write_ctx *ctx)
 	u_int			 sx = screen_size_x(s);
 
 	screen_write_initctx(ctx, &ttyctx);
+	ttyctx.bg = bg;
 
 	gl = &s->grid->linedata[s->grid->hsize + s->cy];
-	if (s->cx <= sx - 1 && s->cx < gl->cellsize) {
-		screen_dirty_clear(s, s->cx, s->cy, sx - 1, s->cy);
-		grid_view_clear(s->grid, s->cx, s->cy, sx - s->cx, 1);
-	} else
+	if (s->cx > sx - 1 || (s->cx >= gl->cellsize && bg == 8))
 		return;
 
+	screen_dirty_clear(s, s->cx, s->cy, sx - 1, s->cy);
+	grid_view_clear(s->grid, s->cx, s->cy, sx - s->cx, 1, bg);
+
 	tty_write(tty_cmd_clearendofline, &ttyctx);
 }
 
 /* Clear to start of line from cursor. */
 void
-screen_write_clearstartofline(struct screen_write_ctx *ctx)
+screen_write_clearstartofline(struct screen_write_ctx *ctx, u_int bg)
 {
 	struct screen	*s = ctx->s;
 	struct tty_ctx	 ttyctx;
 	u_int		 sx = screen_size_x(s);
 
 	screen_write_initctx(ctx, &ttyctx);
+	ttyctx.bg = bg;
 
 	if (s->cx > sx - 1) {
 		screen_dirty_clear(s, 0, s->cy, sx - 1, s->cy);
-		grid_view_clear(s->grid, 0, s->cy, sx, 1);
+		grid_view_clear(s->grid, 0, s->cy, sx, 1, bg);
 	} else {
 		screen_dirty_clear(s, 0, s->cy, s->cx, s->cy);
-		grid_view_clear(s->grid, 0, s->cy, s->cx + 1, 1);
+		grid_view_clear(s->grid, 0, s->cy, s->cx + 1, 1, bg);
 	}
 
 	tty_write(tty_cmd_clearstartofline, &ttyctx);
@@ -919,25 +932,28 @@ screen_write_carriagereturn(struct screen_write_ctx *ctx)
 
 /* Clear to end of screen from cursor. */
 void
-screen_write_clearendofscreen(struct screen_write_ctx *ctx)
+screen_write_clearendofscreen(struct screen_write_ctx *ctx, u_int bg)
 {
 	struct screen	*s = ctx->s;
 	struct tty_ctx	 ttyctx;
 	u_int		 sx = screen_size_x(s), sy = screen_size_y(s);
 
 	screen_write_initctx(ctx, &ttyctx);
+	ttyctx.bg = bg;
 
 	/* Scroll into history if it is enabled and clearing entire screen. */
-	if (s->cy == 0 && s->grid->flags & GRID_HISTORY) {
+	if (s->cx == 0 && s->cy == 0 && s->grid->flags & GRID_HISTORY) {
 		screen_dirty_clear(s, 0, 0, sx - 1, sy  - 1);
-		grid_view_clear_history(s->grid);
+		grid_view_clear_history(s->grid, bg);
 	} else {
 		if (s->cx <= sx - 1) {
 			screen_dirty_clear(s, s->cx, s->cy, sx - 1, s->cy);
-			grid_view_clear(s->grid, s->cx, s->cy, sx - s->cx, 1);
+			grid_view_clear(s->grid, s->cx, s->cy, sx - s->cx, 1,
+			    bg);
 		}
 		screen_dirty_clear(s, 0, s->cy + 1, sx - 1, sy - 1);
-		grid_view_clear(s->grid, 0, s->cy + 1, sx, sy - (s->cy + 1));
+		grid_view_clear(s->grid, 0, s->cy + 1, sx, sy - (s->cy + 1),
+		    bg);
 	}
 
 	tty_write(tty_cmd_clearendofscreen, &ttyctx);
@@ -955,14 +971,14 @@ screen_write_clearstartofscreen(struct screen_write_ctx *ctx)
 
 	if (s->cy > 0) {
 		screen_dirty_clear(s, 0, 0, sx - 1, s->cy);
-		grid_view_clear(s->grid, 0, 0, sx, s->cy);
+		grid_view_clear(s->grid, 0, 0, sx, s->cy, 8);
 	}
 	if (s->cx > sx - 1) {
 		screen_dirty_clear(s, 0, s->cy, sx - 1, s->cy);
-		grid_view_clear(s->grid, 0, s->cy, sx, 1);
+		grid_view_clear(s->grid, 0, s->cy, sx, 1, 8);
 	} else {
 		screen_dirty_clear(s, 0, s->cy, s->cx, s->cy);
-		grid_view_clear(s->grid, 0, s->cy, s->cx + 1, 1);
+		grid_view_clear(s->grid, 0, s->cy, s->cx + 1, 1, 8);
 	}
 
 	tty_write(tty_cmd_clearstartofscreen, &ttyctx);
@@ -970,21 +986,22 @@ screen_write_clearstartofscreen(struct screen_write_ctx *ctx)
 
 /* Clear entire screen. */
 void
-screen_write_clearscreen(struct screen_write_ctx *ctx)
+screen_write_clearscreen(struct screen_write_ctx *ctx, u_int bg)
 {
 	struct screen	*s = ctx->s;
 	struct tty_ctx	 ttyctx;
 	u_int		 sx = screen_size_x(s), sy = screen_size_y(s);
 
 	screen_write_initctx(ctx, &ttyctx);
+	ttyctx.bg = bg;
 
 	screen_dirty_clear(s, 0, 0, sx - 1, sy  - 1);
 
 	/* Scroll into history if it is enabled. */
 	if (s->grid->flags & GRID_HISTORY)
-		grid_view_clear_history(s->grid);
+		grid_view_clear_history(s->grid, bg);
 	else
-		grid_view_clear(s->grid, 0, 0, sx, sy);
+		grid_view_clear(s->grid, 0, 0, sx, sy, bg);
 
 	tty_write(tty_cmd_clearscreen, &ttyctx);
 }
@@ -996,7 +1013,7 @@ screen_write_clearhistory(struct screen_write_ctx *ctx)
 	struct screen	*s = ctx->s;
 	struct grid	*gd = s->grid;
 
-	grid_move_lines(gd, 0, gd->hsize, gd->sy);
+	grid_move_lines(gd, 0, gd->hsize, gd->sy, 8);
 	gd->hscrolled = gd->hsize = 0;
 }
 
@@ -1049,7 +1066,7 @@ screen_write_cell(struct screen_write_ctx *ctx, const struct grid_cell *gc)
 		if (s->cx <= sx - width) {
 			screen_write_flush(ctx);
 			xx = sx - s->cx - width;
-			grid_view_insert_cells(s->grid, s->cx, s->cy, xx);
+			grid_view_insert_cells(s->grid, s->cx, s->cy, xx, 8);
 		}
 		insert = 1;
 	} else