From 5e0795ae1424b278d8590d31ea22237ab8e69716 Mon Sep 17 00:00:00 2001
From: Corwin <corwin@kuiper.dev>
Date: Sun, 2 Oct 2022 20:05:13 +0100
Subject: [PATCH] add garbage collection using hashmap retain

---
 agb/examples/sprites.rs   | 3 +--
 agb/src/display/object.rs | 8 ++++++++
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/agb/examples/sprites.rs b/agb/examples/sprites.rs
index 0ae5ffb5..c5ea5ba8 100644
--- a/agb/examples/sprites.rs
+++ b/agb/examples/sprites.rs
@@ -46,9 +46,8 @@ fn all_sprites(gfx: &ObjectController) {
         if count % 5 == 0 {
             image += 1;
             image %= SPRITES.len();
-            let objs_len = objs.len();
             for (i, obj) in objs.iter_mut().enumerate() {
-                let this_image = (image + i * SPRITES.len() / objs_len) % SPRITES.len();
+                let this_image = (image + i) % SPRITES.len();
                 obj.set_sprite(gfx.sprite(&SPRITES[this_image]));
             }
             gfx.commit();
diff --git a/agb/src/display/object.rs b/agb/src/display/object.rs
index 49006c55..2b6eaf23 100644
--- a/agb/src/display/object.rs
+++ b/agb/src/display/object.rs
@@ -741,6 +741,8 @@ impl ObjectController {
                 }
             }
         }
+
+        s.sprite_controller.gc();
     }
 
     pub(crate) fn new() -> Self {
@@ -1186,6 +1188,12 @@ impl SpriteControllerInner {
         Some(SpriteBorrow { sprite })
     }
 
+    /// Cleans up weak references to sprites and palettes no longer in vram
+    fn gc(&mut self) {
+        self.static_palette_map.retain(|_, v| v.strong_count() != 0);
+        self.static_sprite_map.retain(|_, v| v.strong_count() != 0);
+    }
+
     fn new() -> Self {
         Default::default()
     }