Move the text_input_byte_offset_for_position from the FontMetrics to the Window

In preparation of having mutiple-lines TextInput, we will need to give more
data to this function so it no longer belong in FontMetrics

Also remove the unused FontMetric::line_height()

sixtyfps_runtime/corelib/graphics.rs

@@ -156,13 +156,6 @@ pub trait FontMetrics {
     /// Returns the size of the given string in logical pixels.
     /// When set, `max_width` means that one need to wrap the text so it does not go further than that
     fn text_size(&self, text: &str, max_width: Option<f32>) -> Size;
-    /// Returns the height of a line of text.
-    fn line_height(&self) -> f32;
-    /// Returns the (UTF-8) byte offset in the given text that refers to the character that contributed to
-    /// the glyph cluster that's visually nearest to the given x coordinate. This is used for hit-testing,
-    /// for example when receiving a mouse click into a text field. Then this function returns the "cursor"
-    /// position.
-    fn text_offset_for_x_position(&self, text: &str, x: f32) -> usize;
 }
 
 #[cfg(feature = "ffi")]

sixtyfps_runtime/corelib/items/text.rs

@@ -302,16 +302,9 @@ impl Item for TextInput {
         if !self.enabled() {
             return InputEventResult::EventIgnored;
         }
-
-        let text = self.text();
-        let font_metrics = window.font_metrics(
-            &self.cached_rendering_data,
-            &|| self.unresolved_font_request(),
-            Self::FIELD_OFFSETS.text.apply_pin(self),
-        );
         match event {
             MouseEvent::MousePressed { pos } => {
-                let clicked_offset = font_metrics.text_offset_for_x_position(&text, pos.x) as i32;
+                let clicked_offset = window.text_input_byte_offset_for_position(self, pos) as i32;
                 self.as_ref().pressed.set(true);
                 self.as_ref().anchor_position.set(clicked_offset);
                 self.as_ref().cursor_position.set(clicked_offset);
@@ -325,7 +318,7 @@ impl Item for TextInput {
             MouseEvent::MouseMoved { pos } => {
                 if self.as_ref().pressed.get() {
                     let clicked_offset =
-                        font_metrics.text_offset_for_x_position(&text, pos.x) as i32;
+                        window.text_input_byte_offset_for_position(self, pos) as i32;
                     self.as_ref().cursor_position.set(clicked_offset);
                 }
             }

sixtyfps_runtime/corelib/window.rs

@@ -66,6 +66,16 @@ pub trait PlatformWindow {
         reference_text: Pin<&crate::properties::Property<SharedString>>,
     ) -> Box<dyn crate::graphics::FontMetrics>;
 
+    /// Returns the (UTF-8) byte offset in the text property that refers to the character that contributed to
+    /// the glyph cluster that's visually nearest to the given coordinate. This is used for hit-testing,
+    /// for example when receiving a mouse click into a text field. Then this function returns the "cursor"
+    /// position.
+    fn text_input_byte_offset_for_position(
+        &self,
+        text_input: Pin<&crate::items::TextInput>,
+        pos: Point,
+    ) -> usize;
+
     /// Return self as any so the backend can upcast
     fn as_any(&self) -> &dyn core::any::Any;
 }

sixtyfps_runtime/rendering_backends/gl/fonts.rs

@@ -348,23 +348,6 @@ impl FontMetricsTrait for FontMetrics {
             max_width.map(|x| x * self.scale_factor),
         ) / self.scale_factor
     }
-
-    fn line_height(&self) -> f32 {
-        self.font.height()
-    }
-
-    fn text_offset_for_x_position(&self, text: &str, x: f32) -> usize {
-        let x = x * self.scale_factor;
-        let metrics = self.font.measure(self.letter_spacing.unwrap_or_default(), text);
-        let mut current_x = 0.;
-        for glyph in metrics.glyphs {
-            if current_x + glyph.advance_x / 2. >= x {
-                return glyph.byte_index;
-            }
-            current_x += glyph.advance_x;
-        }
-        text.len()
-    }
 }
 
 pub struct FontCache {

sixtyfps_runtime/rendering_backends/gl/graphics_window.rs

@@ -556,6 +556,40 @@ impl PlatformWindow for GraphicsWindow {
         ))
     }
 
+    fn text_input_byte_offset_for_position(
+        &self,
+        text_input: Pin<&sixtyfps_corelib::items::TextInput>,
+        pos: Point,
+    ) -> usize {
+        let scale_factor = self.scale_factor();
+        let cache_data = text_input
+            .cached_rendering_data
+            .get_or_update(&self.graphics_cache, || {
+                Some(crate::ItemGraphicsCacheEntry::Font(crate::fonts::FONT_CACHE.with(|cache| {
+                    cache.borrow_mut().font(
+                        text_input
+                            .unresolved_font_request()
+                            .merge(&self.default_font_properties.as_ref().get()),
+                        scale_factor,
+                        &text_input.text(),
+                    )
+                })))
+            })
+            .unwrap();
+        let font = cache_data.as_font();
+        let x = pos.x * scale_factor;
+        let text = text_input.text();
+        let metrics = font.measure(text_input.letter_spacing(), &text);
+        let mut current_x = 0.;
+        for glyph in metrics.glyphs {
+            if current_x + glyph.advance_x / 2. >= x {
+                return glyph.byte_index;
+            }
+            current_x += glyph.advance_x;
+        }
+        text.len()
+    }
+
     fn as_any(&self) -> &dyn std::any::Any {
         self
     }

sixtyfps_runtime/rendering_backends/qt/qt_window.rs

@@ -1316,6 +1316,28 @@ impl PlatformWindow for QtWindow {
         Box::new(get_font(unresolved_font_request_getter().merge(&self.default_font_properties())))
     }
 
+    fn text_input_byte_offset_for_position(
+        &self,
+        text_input: Pin<&sixtyfps_corelib::items::TextInput>,
+        pos: Point,
+    ) -> usize {
+        let font: QFont =
+            get_font(text_input.unresolved_font_request().merge(&self.default_font_properties()));
+        let string = qttypes::QString::from(text_input.text().as_str());
+        let x: f32 = pos.x;
+        cpp! { unsafe [font as "QFont", string as "QString", x as "float"] -> usize as "long long" {
+            QTextLayout layout(string, font);
+            layout.beginLayout();
+            layout.createLine();
+            layout.endLayout();
+            if (layout.lineCount() == 0)
+                return 0;
+            auto cur = layout.lineAt(0).xToCursor(x);
+            // convert to an utf8 pos;
+            return QStringView(string).left(cur).toUtf8().size();
+        }}
+    }
+
     fn as_any(&self) -> &dyn std::any::Any {
         self
     }
@@ -1369,28 +1391,6 @@ impl sixtyfps_corelib::graphics::FontMetrics for QFont {
         }};
         sixtyfps_corelib::graphics::Size::new(size.width as _, size.height as _)
     }
-
-    fn line_height(&self) -> f32 {
-        cpp! { unsafe [self as "const QFont*"]
-                -> f32 as "float"{
-            return QFontMetricsF(*self).height();
-        }}
-    }
-
-    fn text_offset_for_x_position(&self, text: &str, x: f32) -> usize {
-        let string = qttypes::QString::from(text);
-        cpp! { unsafe [self as "const QFont*", string as "QString", x as "float"] -> usize as "long long" {
-            QTextLayout layout(string, *self);
-            layout.beginLayout();
-            layout.createLine();
-            layout.endLayout();
-            if (layout.lineCount() == 0)
-                return 0;
-            auto cur = layout.lineAt(0).xToCursor(x);
-            // convert to an utf8 pos;
-            return QStringView(string).left(cur).toUtf8().size();
-        }}
-    }
 }
 
 thread_local! {

sixtyfps_runtime/rendering_backends/testing/lib.rs

@@ -18,7 +18,7 @@ You should use the `sixtyfps` crate instead.
 
 use image::GenericImageView;
 use sixtyfps_corelib::component::ComponentRc;
-use sixtyfps_corelib::graphics::{FontMetrics, Image, Size};
+use sixtyfps_corelib::graphics::{FontMetrics, Image, Point, Size};
 use sixtyfps_corelib::slice::Slice;
 use sixtyfps_corelib::window::{PlatformWindow, Window};
 use sixtyfps_corelib::{ImageInner, Property};
@@ -149,6 +149,14 @@ impl PlatformWindow for TestingWindow {
         Box::new(TestingFontMetrics::default())
     }
 
+    fn text_input_byte_offset_for_position(
+        &self,
+        _text_input: Pin<&sixtyfps_corelib::items::TextInput>,
+        _pos: Point,
+    ) -> usize {
+        0
+    }
+
     fn as_any(&self) -> &dyn std::any::Any {
         self
     }
@@ -161,14 +169,6 @@ impl FontMetrics for TestingFontMetrics {
     fn text_size(&self, text: &str, _max_width: Option<f32>) -> Size {
         Size::new(text.len() as f32 * 10., 10.)
     }
-
-    fn line_height(&self) -> f32 {
-        10.
-    }
-
-    fn text_offset_for_x_position(&self, _text: &str, _x: f32) -> usize {
-        0
-    }
 }
 
 /// Initialize the testing backend.