From 646a859e58b54a10c8622d8c926172be10f46809 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Per=20Andr=C3=A9=20R=C3=B8nsen?= <perandre@gmail.com>
Date: Thu, 9 Apr 2026 05:16:41 +0200
Subject: [PATCH] perf(SnippetStore): cache loaded images to avoid repeated
 disk reads

loadImage(for:) called NSImage(contentsOf:) on every SwiftUI render
pass, doing synchronous disk I/O on the main thread for each visible
image snippet. Add a simple NSCache so the file is read at most once
per session; cache entries are evicted automatically on memory pressure.
Invalidate the relevant entry on delete and on addImage so callers
always see the current image.
---
 Sources/SnippetStore.swift | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/Sources/SnippetStore.swift b/Sources/SnippetStore.swift
index b2405f0..edd3a0e 100644
--- a/Sources/SnippetStore.swift
+++ b/Sources/SnippetStore.swift
@@ -8,6 +8,9 @@ class SnippetStore: ObservableObject {
 
     private let fileURL: URL
     private let imagesDir: URL
+    /// In-memory cache — keyed by imageFileName. NSCache evicts automatically
+    /// under memory pressure, so this never grows unboundedly.
+    private let imageCache = NSCache<NSString, NSImage>()
 
     init() {
         let appSupport = FileManager.default.urls(for: .applicationSupportDirectory, in: .userDomainMask).first!
@@ -70,6 +73,9 @@ class SnippetStore: ObservableObject {
 
         do {
             try pngData.write(to: fileURL)
+            // Prime the cache with the already-decoded image so the first
+            // render after adding doesn't hit disk.
+            imageCache.setObject(image, forKey: fileName as NSString)
             let snippet = Snippet(title: "", value: "[image]", imageFileName: fileName)
             snippets.insert(snippet, at: 0)
             save()
@@ -83,8 +89,17 @@ class SnippetStore: ObservableObject {
     }
 
     func loadImage(for snippet: Snippet) -> NSImage? {
-        guard let url = imageURL(for: snippet) else { return nil }
-        return NSImage(contentsOf: url)
+        guard let name = snippet.imageFileName else { return nil }
+        // Return cached copy if available.
+        if let cached = imageCache.object(forKey: name as NSString) {
+            return cached
+        }
+        // Fall back to disk and populate the cache.
+        let url = imagesDir.appendingPathComponent(name)
+        guard FileManager.default.fileExists(atPath: url.path),
+              let image = NSImage(contentsOf: url) else { return nil }
+        imageCache.setObject(image, forKey: name as NSString)
+        return image
     }
 
     func update(_ snippet: Snippet) {
@@ -95,10 +110,11 @@ class SnippetStore: ObservableObject {
     }
 
     func delete(_ snippet: Snippet) {
-        // Clean up image file
+        // Clean up image file and cache entry.
         if let name = snippet.imageFileName {
             let url = imagesDir.appendingPathComponent(name)
             try? FileManager.default.removeItem(at: url)
+            imageCache.removeObject(forKey: name as NSString)
         }
         snippets.removeAll { $0.id == snippet.id }
         save()