Keep primatives for at most 2 previous buffers

Author: ids1024

tiny_skia/src/window/compositor.rs

@@ -168,11 +168,14 @@ pub fn present<T: AsRef<str>>(
         .map_err(|_| compositor::SurfaceError::Lost)?;
 
     let age = buffer.age();
-    if age != 0 {
-        while surface.primitives.len() as u8 > age {
-            let _ = surface.primitives.pop_front();
-        }
+
+    // Forget primatives for back buffers older than `age`
+    // Or if this is a new buffer, keep at most two.
+    let max = if age == 0 { 2 } else { age };
+    while surface.primitives.len() as u8 > max {
+        let _ = surface.primitives.pop_front();
     }
+
     let last_primitives = if surface.primitives.len() as u8 == age {
         surface.primitives.pop_front()
     } else {