Choose your own font and size (#1154)

* Refactor text layout: don't need &Fonts in all functions
* Replace indexing in Fonts with member function
* Wrap Fonts in a Mutex
* Remove mutex for Font::glyph_info_cache
* Remove RwLock around Font::characters
* Put FontsImpl and GalleyCache behind the same Mutex
* Round font sizes to whole pixels before deduplicating them
* Make TextStyle !Copy
* Implement user-named TextStyle:s
* round font size earlier
* Cache fonts based on family and size
* Move TextStyle into egui and Style
* Remove body_text_style
* Query graphics about max texture size and use that as font atlas size
* Recreate texture atlas when it is getting full

egui_glium/src/painter.rs

@@ -16,6 +16,7 @@ use {
 };
 
 pub struct Painter {
+    max_texture_side: usize,
     program: glium::Program,
 
     textures: AHashMap<egui::TextureId, Rc<SrgbTexture2d>>,
@@ -27,6 +28,9 @@ pub struct Painter {
 
 impl Painter {
     pub fn new(facade: &dyn glium::backend::Facade) -> Painter {
+        use glium::CapabilitiesSource as _;
+        let max_texture_side = facade.get_capabilities().max_texture_size as _;
+
         let program = program! {
             facade,
             120 => {
@@ -49,6 +53,7 @@ impl Painter {
         .expect("Failed to compile shader");
 
         Painter {
+            max_texture_side,
             program,
             textures: Default::default(),
             #[cfg(feature = "epi")]
@@ -56,6 +61,10 @@ impl Painter {
         }
     }
 
+    pub fn max_texture_side(&self) -> usize {
+        self.max_texture_side
+    }
+
     /// Main entry-point for painting a frame.
     /// You should call `target.clear_color(..)` before
     /// and `target.finish()` after this.