Prepare for improved font fallback handling in the GL backend

In order to determine the best list of fallback fonts for text
rendering, we need to know what text we're going to render. That's why
this patch passes the text through all the way.

sixtyfps_runtime/rendering_backends/gl/fonts.rs

@@ -125,7 +125,10 @@ pub(crate) fn load_system_font(canvas: &CanvasRc, request: &FontRequest) -> femt
 }
 
 #[cfg(target_os = "macos")]
-pub(crate) fn font_fallbacks_for_request(_request: &FontRequest) -> Vec<FontRequest> {
+pub(crate) fn font_fallbacks_for_request(
+    _request: &FontRequest,
+    _reference_text: &str,
+) -> Vec<FontRequest> {
     _request
         .family
         .as_ref()
@@ -153,7 +156,10 @@ pub(crate) fn font_fallbacks_for_request(_request: &FontRequest) -> Vec<FontRequ
 }
 
 #[cfg(not(target_os = "macos"))]
-pub(crate) fn font_fallbacks_for_request(_request: &FontRequest) -> Vec<FontRequest> {
+pub(crate) fn font_fallbacks_for_request(
+    _request: &FontRequest,
+    _reference_text: &str,
+) -> Vec<FontRequest> {
     vec![
         #[cfg(target_arch = "wasm32")]
         FontRequest {

sixtyfps_runtime/rendering_backends/gl/lib.rs

@@ -125,12 +125,18 @@ impl FontCache {
             .clone()
     }
 
-    fn font(&mut self, canvas: &CanvasRc, mut request: FontRequest, scale_factor: f32) -> GLFont {
+    fn font(
+        &mut self,
+        canvas: &CanvasRc,
+        mut request: FontRequest,
+        scale_factor: f32,
+        reference_text: &str,
+    ) -> GLFont {
         request.pixel_size = request.pixel_size.or(Some(DEFAULT_FONT_SIZE * scale_factor));
         request.weight = request.weight.or(Some(DEFAULT_FONT_WEIGHT));
 
         let primary_font = self.load_single_font(canvas, &request);
-        let fallbacks = font_fallbacks_for_request(&request);
+        let fallbacks = font_fallbacks_for_request(&request, reference_text);
 
         let fonts = core::iter::once(primary_font)
             .chain(
@@ -604,6 +610,7 @@ impl ItemRenderer for GLItemRenderer {
             &self.shared_data.canvas,
             text.unresolved_font_request().merge(&self.default_font_properties.as_ref().get()),
             self.scale_factor,
+            &text.text(),
         );
         let wrap = text.wrap() == TextWrap::word_wrap;
         let text_size = font.text_size(
@@ -695,6 +702,7 @@ impl ItemRenderer for GLItemRenderer {
                 .unresolved_font_request()
                 .merge(&self.default_font_properties.as_ref().get()),
             self.scale_factor,
+            &text_input.text(),
         );
 
         let paint = match self
@@ -707,7 +715,7 @@ impl ItemRenderer for GLItemRenderer {
         let metrics = self.draw_text_impl(
             width,
             height,
-            &text_input.text(),
+            sixtyfps_corelib::items::TextInput::FIELD_OFFSETS.text.apply_pin(text_input),
             text_input
                 .unresolved_font_request()
                 .merge(&self.default_font_properties.as_ref().get()),
@@ -759,7 +767,7 @@ impl ItemRenderer for GLItemRenderer {
             self.draw_text_impl(
                 text_input.width(),
                 text_input.height(),
-                &text_input.text(),
+                sixtyfps_corelib::items::TextInput::FIELD_OFFSETS.text.apply_pin(text_input),
                 text_input
                     .unresolved_font_request()
                     .merge(&self.default_font_properties.as_ref().get()),
@@ -1065,7 +1073,7 @@ impl GLItemRenderer {
         &mut self,
         max_width: f32,
         max_height: f32,
-        text: &str,
+        text: Pin<&Property<SharedString>>,
         font_request: FontRequest,
         paint: femtovg::Paint,
         horizontal_alignment: TextHorizontalAlignment,
@@ -1076,13 +1084,14 @@ impl GLItemRenderer {
             &self.shared_data.canvas,
             font_request,
             self.scale_factor,
+            &text.get(),
         );
 
         let paint = font.init_paint(letter_spacing, paint);
 
         let mut canvas = self.shared_data.canvas.borrow_mut();
         let (text_width, text_height) = {
-            let text_metrics = canvas.measure_text(0., 0., &text, paint).unwrap();
+            let text_metrics = canvas.measure_text(0., 0., &text.as_ref().get(), paint).unwrap();
             let font_metrics = canvas.measure_font(paint).unwrap();
             (text_metrics.width(), font_metrics.height())
         };
@@ -1099,7 +1108,7 @@ impl GLItemRenderer {
             TextVerticalAlignment::bottom => max_height - text_height,
         };
 
-        canvas.fill_text(translate_x, translate_y, text, paint).unwrap()
+        canvas.fill_text(translate_x, translate_y, text.get(), paint).unwrap()
     }
 
     fn colorize_image(
@@ -1412,11 +1421,12 @@ struct GLFontMetrics {
 
 impl FontMetrics for GLFontMetrics {
     fn text_size(&self, text: &str) -> Size {
-        self.font().text_size(self.request.letter_spacing.unwrap_or_default(), text, None)
+        self.font(text).text_size(self.request.letter_spacing.unwrap_or_default(), text, None)
     }
 
     fn text_offset_for_x_position<'a>(&self, text: &'a str, x: f32) -> usize {
-        let metrics = self.font().measure(self.request.letter_spacing.unwrap_or_default(), text);
+        let metrics =
+            self.font(text).measure(self.request.letter_spacing.unwrap_or_default(), text);
         let mut current_x = 0.;
         for glyph in metrics.glyphs {
             if current_x + glyph.advance_x / 2. >= x {
@@ -1429,11 +1439,12 @@ impl FontMetrics for GLFontMetrics {
 }
 
 impl GLFontMetrics {
-    fn font(&self) -> GLFont {
+    fn font(&self, reference_text: &str) -> GLFont {
         self.shared_data.loaded_fonts.borrow_mut().font(
             &self.shared_data.canvas,
             self.request.clone(),
             self.scale_factor,
+            reference_text,
         )
     }
 }