Add custom cursors for macos

The macos target now also supports the custom beam and underline
cursors. The only thing left for this is now is testing and making sure
it works with tiny fonts.

font/src/darwin/mod.rs

@@ -461,6 +461,19 @@ impl Font {
     }
 
     pub fn get_glyph(&self, character: char, _size: f64, use_thin_strokes: bool) -> Result<RasterizedGlyph, Error> {
+        // Render custom symbols for underline and beam cursor
+        if character == super::UNDERLINE_CURSOR_CHAR {
+            let descent = -(self.ct_font.descent() as i32);
+            let width = self.glyph_advance('0') as i32;
+            return super::get_underline_cursor_glyph(descent, width);
+        } else if character == super::BEAM_CURSOR_CHAR {
+            let metrics = self.metrics();
+            let height = metrics.line_height;
+            let ascent = height - self.ct_font.descent() + 1.;
+            let width = self.glyph_advance('0') as i32;
+            return super::get_beam_cursor_glyph(ascent as i32, height as i32, width);
+        };
+
         let glyph_index = self.glyph_index(character)
             .ok_or(Error::MissingGlyph(character))?;
 

font/src/lib.rs

@@ -59,18 +59,12 @@ mod darwin;
 pub use darwin::*;
 
 /// Character used for the underline cursor
-#[cfg(not(target_os = "macos"))]
 // This is part of the private use area and should not conflict with any font
 pub const UNDERLINE_CURSOR_CHAR: char = '\u{10a3e2}';
-#[cfg(target_os = "macos")]
-pub const UNDERLINE_CURSOR_CHAR: char = '▁';
 
 /// Character used for the beam cursor
-#[cfg(not(target_os = "macos"))]
 // This is part of the private use area and should not conflict with any font
 pub const BEAM_CURSOR_CHAR: char = '\u{10a3e3}';
-#[cfg(target_os = "macos")]
-pub const BEAM_CURSOR_CHAR: char = '▎';
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct FontDesc {
@@ -217,6 +211,7 @@ impl Default for RasterizedGlyph {
 }
 
 // Returns a custom underline cursor character
+// TODO: Make sure this works with positive/0 descent -> small fonts
 pub fn get_underline_cursor_glyph(descent: i32, width: i32) -> Result<RasterizedGlyph, Error> {
     // Create a new rectangle, the height is half the distance between
     // bounding box bottom and the baseline
@@ -235,6 +230,7 @@ pub fn get_underline_cursor_glyph(descent: i32, width: i32) -> Result<Rasterized
 }
 
 // Returns a custom beam cursor character
+// TODO: Make sure this works with positive/0 descent -> small fonts
 pub fn get_beam_cursor_glyph(ascent: i32, height: i32, width: i32) -> Result<RasterizedGlyph, Error> {
     // Create a new rectangle
     let beam_width = (f64::from(width) / 5.) as i32;