view: fix display when inserting text at start of file

Before cebb24b36ac45cc7c6912481cacd29ef9d5c68b9 a mark
at the start of the file was treated specially to always
return position zero.

Since this was no longer the case the following would
insert text before the visible area:

 <PageDown><PageUp><PageUp>ifoo

1 files changed, 9 insertions, 2 deletions

diff --git a/view.c b/view.c
index 7dcc806..d6a3f3f 100644
--- a/view.c
+++ b/view.c
@@ -131,9 +131,16 @@ void view_tabwidth_set(View *view, int tabwidth) {
 static void view_clear(View *view) {
 	memset(view->lines, 0, view->lines_size);
 	if (view->start != view->start_last) {
-		view->start_mark = text_mark_set(view->text, view->start);
+		if (view->start == 0)
+			view->start_mark = EMARK;
+		else
+			view->start_mark = text_mark_set(view->text, view->start);
 	} else {
-		size_t start = text_mark_get(view->text, view->start_mark);
+		size_t start;
+		if (view->start_mark == EMARK)
+			start = 0;
+		else
+			start = text_mark_get(view->text, view->start_mark);
 		if (start != EPOS)
 			view->start = start;
 	}