From 95ba340fba0f2f2e21878c0d70a42d0f9a8b7c87 Mon Sep 17 00:00:00 2001
From: nick black <dankamongmen@gmail.com>
Date: Sat, 9 May 2020 01:25:00 -0400
Subject: [PATCH] ncplane_erase: fix bug in basecell preservation

---
 USAGE.md                          | 2 +-
 doc/man/man3/notcurses_plane.3.md | 3 +++
 include/notcurses/notcurses.h     | 2 +-
 src/lib/notcurses.c               | 2 ++
 4 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/USAGE.md b/USAGE.md
index 355d45ea2..5326d4aa6 100644
--- a/USAGE.md
+++ b/USAGE.md
@@ -544,7 +544,7 @@ int ncplane_mergedown(struct ncplane* restrict src, struct ncplane* restrict dst
 // Erase every cell in the ncplane, resetting all attributes to normal, all
 // colors to the default color, and all cells to undrawn. All cells associated
 // with this ncplane are invalidated, and must not be used after the call,
-// excluding the base cell.
+// excluding the base cell. The cursor is homed.
 void ncplane_erase(struct ncplane* n);
 ```
 
diff --git a/doc/man/man3/notcurses_plane.3.md b/doc/man/man3/notcurses_plane.3.md
index 7b0227356..85b97c4b8 100644
--- a/doc/man/man3/notcurses_plane.3.md
+++ b/doc/man/man3/notcurses_plane.3.md
@@ -196,6 +196,9 @@ expressed relative to the standard plane, and returns coordinates relative to
 of the rendering region. Only those cells where **src** intersects with **dst**
 might see changes. It is an error to merge a plane onto itself.
 
+**ncplane_erase** zeroes out every cell of the plane, dumps the egcpool, and
+homes the cursor. The base cell is preserved.
+
 ## Scrolling
 
 All planes, including the standard plane, are created with scrolling disabled.
diff --git a/include/notcurses/notcurses.h b/include/notcurses/notcurses.h
index f57e32609..9af09a3db 100644
--- a/include/notcurses/notcurses.h
+++ b/include/notcurses/notcurses.h
@@ -1629,7 +1629,7 @@ API int ncplane_mergedown(struct ncplane* RESTRICT src, struct ncplane* RESTRICT
 // Erase every cell in the ncplane, resetting all attributes to normal, all
 // colors to the default color, and all cells to undrawn. All cells associated
 // with this ncplane is invalidated, and must not be used after the call,
-// excluding the base cell.
+// *excluding* the base cell. The cursor is homed.
 API void ncplane_erase(struct ncplane* n);
 
 #define NCPALETTESIZE 256
diff --git a/src/lib/notcurses.c b/src/lib/notcurses.c
index dbb97fea1..30e11bf14 100644
--- a/src/lib/notcurses.c
+++ b/src/lib/notcurses.c
@@ -1773,8 +1773,10 @@ void ncplane_erase(ncplane* n){
   memset(n->fb, 0, sizeof(*n->fb) * n->lenx * n->leny);
   egcpool_dump(&n->pool);
   egcpool_init(&n->pool);
+  cell_init(&n->basecell);
   cell_load(n, &n->basecell, egc);
   free(egc);
+  n->y = n->x = 0;
 }
 
 void notcurses_cursor_enable(notcurses* nc){