From a0ba8537188cd5c29593b1c53a3569ac7f1a0bd7 Mon Sep 17 00:00:00 2001
From: Hanaasagi <ambiguous404@gmail.com>
Date: Wed, 8 Nov 2023 20:44:31 +0800
Subject: [PATCH] fix: precache n-1 and n+1 pages (#349)

---
 yazi-core/src/tab/folder.rs | 32 ++++++++++++++++++++++++--------
 yazi-fm/src/app.rs          |  6 ++----
 2 files changed, 26 insertions(+), 12 deletions(-)

diff --git a/yazi-core/src/tab/folder.rs b/yazi-core/src/tab/folder.rs
index 44a356a6..923def05 100644
--- a/yazi-core/src/tab/folder.rs
+++ b/yazi-core/src/tab/folder.rs
@@ -43,22 +43,38 @@ impl Folder {
 		self.prev(Default::default());
 
 		if self.page == old {
-			emit!(Pages(self.page)); // Force update
+			self.set_page(true); // Force update
 		}
 
 		true
 	}
 
-	pub fn set_page(&mut self, force: bool) -> bool {
+	pub fn set_page(&mut self, force: bool) {
 		let limit = MANAGER.layout.folder_height();
-		let new = if limit == 0 { 0 } else { self.cursor / limit };
+		if limit == 0 {
+			return;
+		}
+
+		let new = self.cursor / limit;
 		if !force && self.page == new {
-			return false;
+			return;
+		}
+
+		// Current page
+		emit!(Pages(new));
+
+		// Next page
+		let max_page = (self.files.len() + limit - 1) / limit;
+		if new < max_page && new + 1 != self.page {
+			emit!(Pages(new + 1));
+		}
+
+		// Previous page
+		if new > 1 && new - 1 != self.page {
+			emit!(Pages(new - 1));
 		}
 
 		self.page = new;
-		emit!(Pages(new));
-		true
 	}
 
 	pub fn next(&mut self, step: Step) -> bool {
@@ -115,11 +131,11 @@ impl Folder {
 	#[inline]
 	pub fn hovered(&self) -> Option<&File> { self.files.get(self.cursor) }
 
-	pub fn paginate(&self) -> &[File] {
+	pub fn paginate(&self, page: usize) -> &[File] {
 		let len = self.files.len();
 		let limit = MANAGER.layout.folder_height();
 
-		let start = (self.page * limit).min(len.saturating_sub(1));
+		let start = (page * limit).min(len.saturating_sub(1));
 		let end = (start + limit).min(len);
 		&self.files[start..end]
 	}
diff --git a/yazi-fm/src/app.rs b/yazi-fm/src/app.rs
index 3a83a297..40f80ae6 100644
--- a/yazi-fm/src/app.rs
+++ b/yazi-fm/src/app.rs
@@ -143,10 +143,8 @@ impl App {
 				}
 			}
 			Event::Pages(page) => {
-				if manager.current().page == page {
-					let targets = self.cx.manager.current().paginate();
-					tasks.precache_mime(targets, &self.cx.manager.mimetype);
-				}
+				let targets = self.cx.manager.current().paginate(page);
+				tasks.precache_mime(targets, &self.cx.manager.mimetype);
 			}
 			Event::Mimetype(mimes) => {
 				if manager.update_mimetype(mimes, tasks) {