From dbf800f59831852ace25f95d92875fe360735566 Mon Sep 17 00:00:00 2001
From: Julian Hurst <julian.hurst92@gmail.com>
Date: Mon, 16 May 2022 18:19:41 +0200
Subject: Add page up and page down

---
 libui/widget/list/list.ha | 52 +++++++++++++++++++++++++++++++++--------------
 main.ha                   |  4 ++++
 2 files changed, 41 insertions(+), 15 deletions(-)

diff --git a/libui/widget/list/list.ha b/libui/widget/list/list.ha
index 57239f3..8500482 100644
--- a/libui/widget/list/list.ha
+++ b/libui/widget/list/list.ha
@@ -137,12 +137,29 @@ export fn notify(l: *listwidget, r: rune) bool = {
 	return false;
 };
 
+// Reset the list's frame based on the cursor. Returns whether the frame was
+// updated.
+fn reframe(l: *listwidget) bool = {
+	let reframed: bool = false;
+	if (l.cursor < l.frame.start) {
+		l.frame.end -= l.frame.start - l.cursor: u16;
+		l.frame.start = l.cursor: u16;
+		reframed = true;
+	};
+	if (l.cursor >= l.frame.end) {
+		l.frame.start += l.cursor: u16 - l.frame.end + 1;
+		l.frame.end = l.cursor: u16;
+		reframed = true;
+	};
+	return reframed;
+};
+
 // Move the list's cursor down one item. Returns the new cursor.
 export fn down(l: *listwidget) size = {
 	if (l.cursor < len(l.items) - 1) {
 		l.cursor += 1;
+		reframe(l);
 	};
-	reframe(l);
 	return l.cursor;
 };
 
@@ -150,26 +167,31 @@ export fn down(l: *listwidget) size = {
 export fn up(l: *listwidget) size = {
 	if (l.cursor > 0) {
 		l.cursor -= 1;
+		reframe(l);
 	};
-	reframe(l);
 	return l.cursor;
 };
 
-// Reset the list's frame based on the cursor. Returns whether the frame was
-// updated.
-fn reframe(l: *listwidget) bool = {
-	let reframed: bool = false;
-	if (l.cursor < l.frame.start) {
-		l.frame.end -= l.frame.start - l.cursor: u16;
-		l.frame.start = l.cursor: u16;
-		reframed = true;
+// Move the list's cursor up one page. Returns the new cursor.
+export fn pageup(l: *listwidget) size = {
+	if (l.cursor: int - l.sz.rows: int >= 0) {
+		l.cursor -= l.sz.rows;
+	} else {
+		l.cursor = 0z;
 	};
-	if (l.cursor >= l.frame.end) {
-		l.frame.start += l.cursor: u16 - l.frame.end + 1;
-		l.frame.end = l.cursor: u16;
-		reframed = true;
+	reframe(l);
+	return l.cursor;
+};
+
+// Move the list's cursor down one page. Returns the new cursor.
+export fn pagedown(l: *listwidget) size = {
+	if (l.cursor + l.sz.rows < len(l.items)) {
+		l.cursor += l.sz.rows;
+	} else {
+		l.cursor = len(l.items) - 1;
 	};
-	return reframed;
+	reframe(l);
+	return l.cursor;
 };
 
 // Move the list's cursor to the top (first item). Returns the new cursor.
diff --git a/main.ha b/main.ha
index 0aeda39..1af7662 100644
--- a/main.ha
+++ b/main.ha
@@ -35,6 +35,10 @@ fn runehandler(l: *widget::widget, r: rune) bool = {
 		list::down(l);
 	case 'k' =>
 		list::up(l);
+	case 'd' =>
+		list::pagedown(l);
+	case 'u' =>
+		list::pageup(l);
 	case 'l' =>
 		// to print properly suspend the ui, print, then resume
 		libui::suspend(&l.ui);
-- 
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