Simply and fix reframe and introduce bounds checks for setcursor

2 files changed, 28 insertions, 14 deletions

diff --git a/cmd/il.ha b/cmd/il.ha
index afc1ee5..b6d1efb 100644
--- a/cmd/il.ha
+++ b/cmd/il.ha
@@ -61,6 +61,22 @@ export fn main() void = {
 		if (r == 'K') {
 			list::frameup(&li);
 		};
+		if (r == 'd') {
+			const nextpage = li.cursor + li.frame.end - li.frame.start;
+			fmt::errorln(nextpage)!;
+			list::setcursor(&li, nextpage);
+			fmt::errorln(li.frame.start)!;
+			fmt::errorln(li.frame.end)!;
+			fmt::errorln()!;
+		};
+		if (r == 'u') {
+			const prevpage = li.cursor - (li.frame.end - li.frame.start);
+			fmt::errorln(prevpage)!;
+			list::setcursor(&li, prevpage);
+			fmt::errorln(li.frame.start)!;
+			fmt::errorln(li.frame.end)!;
+			fmt::errorln()!;
+		};
 		if (r == 'g') {
 			list::top(&li);
 		};
diff --git a/tui/widget/list/scrolllist.ha b/tui/widget/list/scrolllist.ha
index 2f18ef0..0079363 100644
--- a/tui/widget/list/scrolllist.ha
+++ b/tui/widget/list/scrolllist.ha
@@ -120,27 +120,25 @@ export fn bottom(li: *scrolllist) void = {
 };
 
 export fn setcursor(li: *scrolllist, newpos: int) void = {
-	li.cursor = newpos;
+	if (newpos < 0) {
+		li.cursor = 0;
+	} else if (newpos > len(li.items): int) {
+		li.cursor = len(li.items): int - 1;
+	} else {
+		li.cursor = newpos;
+	};
 	reframe(li);
 };
 
 fn reframe(li: *scrolllist) void = {
-	if (li.cursor > li.frame.end) {
+	if (li.cursor >= li.frame.end) {
 		const diff = li.frame.end - li.frame.start;
-		li.frame.start = if (li.cursor <= len(li.items): int - diff) li.cursor else len(li.items): int - diff;
-		li.frame.end = if (li.frame.start + diff > len(li.items): int) {
-			yield len(li.items): int;
-		} else {
-			yield li.frame.start + diff;
-		};
+		li.frame.end = li.cursor + 1;
+		li.frame.start = li.frame.end - diff;
 	} else if (li.cursor < li.frame.start) {
 		const diff = li.frame.end - li.frame.start;
-		li.frame.end = if (li.cursor > diff) li.cursor else diff;
-		li.frame.start = if (li.frame.end - diff < 0) {
-			yield 0;
-		} else {
-			yield li.frame.end - diff;
-		};
+		li.frame.start = li.cursor;
+		li.frame.end = li.frame.start + diff;
 	};
 	assert(li.frame.start >= 0);
 	assert(li.frame.end <= len(li.items): int);