[Rust - libgui] Allow calculating text layout size on a TextView

rust_programs/libgui/src/text_view.rs

@@ -19,6 +19,7 @@ use alloc::{
 };
 use axle_rt::AmcMessage;
 use core::fmt::Formatter;
+use core::ops::Add;
 use core::ptr;
 use file_manager_messages::{ReadFile, ReadFileResponse, FILE_SERVER_SERVICE_NAME};
 use libgui_derive::{Drawable, NestedLayerSlice, UIElement};
@@ -180,6 +181,34 @@ impl TextView {
         cursor_pos
     }
 
+    /// Note that this will respect the need to split onto newlines due to the size of the parent slice.
+    pub fn rendered_string_size(
+        s: &str,
+        font: &Font,
+        font_size: Size,
+        container_size: Size,
+        text_origin: Point,
+    ) -> Size {
+        // Pretend we're doing layout and keep track of the area we cross
+        let mut layout_size = Size::new(0, font.scaled_line_height(font_size));
+        let mut cursor_pos = text_origin;
+        for ch in s.chars() {
+            let next_cursor_pos = Self::next_cursor_pos_for_char(
+                cursor_pos,
+                ch,
+                font,
+                font_size,
+                container_size,
+            );
+            layout_size = layout_size + Size::new(
+                next_cursor_pos.x - cursor_pos.x,
+                next_cursor_pos.y - cursor_pos.y,
+            );
+            cursor_pos = next_cursor_pos;
+        }
+        layout_size
+    }
+
     pub fn cursor_pos(&self) -> CursorPos {
         *self.cursor_pos.borrow()
     }

rust_programs/ttf_renderer/src/render.rs

@@ -30,6 +30,8 @@ pub fn render_char_onto(
     render_glyph_onto(glyph, font, onto, draw_loc, draw_color, font_size)
 }
 
+/// Note that this implementation does not respect the need to split onto newlines due to the size
+/// of the parent container.
 pub fn rendered_string_size(s: &str, font: &Font, font_size: Size) -> Size {
     let scale_factor = font_size.height as f64 / font.units_per_em as f64;
     let mut bounding_box = Size::new(
@@ -68,9 +70,9 @@ pub fn render_antialiased_glyph_onto(
     let scaled_glyph_metrics = glyph.metrics().scale(scale_x, scale_y);
     let draw_loc = draw_loc
         + Point::new(
-            scaled_glyph_metrics.left_side_bearing,
-            scaled_glyph_metrics.top_side_bearing,
-        );
+        scaled_glyph_metrics.left_side_bearing,
+        scaled_glyph_metrics.top_side_bearing,
+    );
     let draw_box = Rect::from_parts(draw_loc, font_size);
     let mut dest_slice = onto.get_slice(draw_box);