Fix memory leak from font resizing

The source of the leak was loading up multiple copies of the FT_face
even when not necessary. Fonts are now appropriately cached for
FreeType when going through the `Rasterize::load_font` API.

Additionally, textures in the glyph cache are now reused.

The result of this is that resizing to already loaded fonts is free
from a memory consumption perspective.

1 files changed, 9 insertions, 8 deletions

diff --git a/src/display.rs b/src/display.rs
index 25318f0e..eb562e8f 100644
--- a/src/display.rs
+++ b/src/display.rs
@@ -240,14 +240,15 @@ impl Display {
         return Ok((glyph_cache, cell_width as f32, cell_height as f32));
     }
 
-    pub fn update_glyph_cache(&mut self, config: &Config, font_size_delta: i8)
-    {
-        let (glyph_cache, cell_width, cell_height) =
-            Self::new_glyph_cache(&self.window,
-                        &mut self.renderer, config, font_size_delta).unwrap();
-        self.glyph_cache = glyph_cache;
-        self.size_info.cell_width = cell_width;
-        self.size_info.cell_height = cell_height;
+    pub fn update_glyph_cache(&mut self, config: &Config, font_size_delta: i8) {
+        let cache = &mut self.glyph_cache;
+        self.renderer.with_loader(|mut api| {
+            let _ = cache.update_font_size(config.font(), font_size_delta, &mut api);
+        });
+
+        let metrics = cache.font_metrics();
+        self.size_info.cell_width = (metrics.average_advance + config.font().offset().x as f64) as f32;
+        self.size_info.cell_height = (metrics.line_height + config.font().offset().y as f64) as f32;
     }
 
     #[inline]