Warn when glyphs cannot fit the atlas

core/Cargo.toml

@@ -10,3 +10,4 @@ image = { workspace = true }
 parley = { workspace = true }
 swash = { workspace = true }
 fxhash = { workspace = true }
+log = { workspace = true }

core/src/render/atlas.rs

@@ -76,10 +76,20 @@ impl GlyphAtlas {
         let w = image.placement.width;
         let h = image.placement.height;
         if w == 0 || h == 0 {
+            log::warn!(
+                "glyph {} in font {} rasterized at {w}x{h}; skipping it",
+                key.glyph,
+                key.font,
+            );
             self.entries.insert(key, None);
             return None;
         }
-        if w + PAD * 2 > PAGE || h + PAD * 2 > PAGE {
+        if w > PAGE - PAD * 2 || h > PAGE - PAD * 2 {
+            log::warn!(
+                "glyph {} in font {} rasterized at {w}x{h}, too large for the {PAGE}x{PAGE} atlas; skipping it",
+                key.glyph,
+                key.font,
+            );
             self.entries.insert(key, None);
             return None;
         }