Expand max font atlas size from 8k to 16k (emilk#5257)

When using fonts with an average of 50,000 characters,
'epaint texture atlas overflowed!' may be printed and cause problems.
It is necessary to expand the max value related to texture.

* Closes emilk#5256

---------

Co-authored-by: Emil Ernerfeldt <[email protected]>

crates/epaint/src/text/fonts.rs

@@ -633,7 +633,7 @@ impl FontsImpl {
             "pixels_per_point out of range: {pixels_per_point}"
         );
 
-        let texture_width = max_texture_side.at_most(8 * 1024);
+        let texture_width = max_texture_side.at_most(16 * 1024);
         let initial_height = 32; // Keep initial font atlas small, so it is fast to upload to GPU. This will expand as needed anyways.
         let atlas = TextureAtlas::new([texture_width, initial_height]);
 

crates/epaint/src/texture_atlas.rs

@@ -159,8 +159,8 @@ impl TextureAtlas {
     }
 
     fn max_height(&self) -> usize {
-        // the initial width is likely the max texture side size
-        self.image.width()
+        // the initial width is set to the max size
+        self.image.height().max(self.image.width())
     }
 
     /// When this get high, it might be time to clear and start over!