Stub out more complicated RunMetrics.

src/servo/layout/inline.rs

@@ -351,7 +351,7 @@ impl FlowContext : InlineLayout {
                     // TODO: measure twice, cut once doesn't apply to text. Shouldn't need
                     // to measure text again here (should be inside TextBox.split)
                     let metrics = test_font.measure_text(d.run, d.offset, d.length);
-                    metrics.advance
+                    metrics.advance_width
                 },
                 // TODO: this should be set to the extents of its children
                 @GenericBox(*) => au(0),

src/servo/text/font.rs

@@ -2,6 +2,9 @@ pub use font_cache::FontCache;
 
 use au = gfx::geometry;
 use au::au;
+use geom::point::Point2D;
+use geom::rect::Rect;
+use geom::size::Size2D;
 use glyph::GlyphIndex;
 use libc::{ c_int, c_double, c_ulong };
 use native_font::NativeFont;
@@ -25,7 +28,15 @@ struct Font {
 }
 
 struct RunMetrics {
-    advance: au,
+    // may be negative due to negative width
+    advance_width: au,
+
+    ascent: au, // nonzero
+    descent: au, // nonzero
+
+    // this bounding box is relative to the left origin baseline.
+    // so, bounding_box.position.y = -ascent
+    bounding_box: Rect<au>
 }
 
 // Public API
@@ -42,14 +53,21 @@ pub trait FontMethods {
 pub impl Font : FontMethods {
     fn measure_text(run: &TextRun, offset: uint, length: uint) -> RunMetrics {
         // TODO: alter advance direction for RTL
-        // TODO: calculate actual bounding box as part of RunMetrics
         // TODO: using inter-char and inter-word spacing settings  when measuring text
         let mut advance = au(0);
+        let mut bounds = Rect(Point2D(au(0), self.metrics.em_size.scale_by(-self.metrics.em_ascent)),
+                          Size2D(au(0), self.metrics.em_size.scale_by(self.metrics.em_ascent + self.metrics.em_descent)));
         do run.glyphs.iter_glyphs_for_range(offset, length) |_i, glyph| {
             advance += glyph.advance()
         }
 
-        RunMetrics { advance: advance }
+        // TODO: support loose and tight bounding boxes
+
+        RunMetrics { advance_width: advance,
+                     bounding_box: bounds,
+                     ascent: self.metrics.em_size.scale_by(self.metrics.em_ascent),
+                     descent: self.metrics.em_size.scale_by(self.metrics.em_descent),
+                   }
     }
 
     fn buf(&self) -> @~[u8] {

src/servo/text/text_run.rs

@@ -31,8 +31,8 @@ impl TextRun {
         let font = ctx.font_cache.get_test_font();
         for self.iter_indivisible_pieces_for_range(offset, length) |piece_offset, piece_len| {
             let metrics = font.measure_text(&self, piece_offset, piece_len);
-            if metrics.advance > max_piece_width {
-                max_piece_width = metrics.advance;
+            if metrics.advance_width > max_piece_width {
+                max_piece_width = metrics.advance_width;
             }
         };