Track whether a float context contains any floats

Author: nicoburns

src/compute/block.rs

@@ -100,6 +100,16 @@ impl BlockContext<'_> {
         self.content_box_insets[1] = self.insets[1] + content_box_x_insets[1];
     }
 
+    /// Whether the float context contains any floats
+    pub fn has_floats(&self) -> bool {
+        self.bfc.float_context.has_floats()
+    }
+
+    /// Whether the float context contains any floats that extend to or below min_y
+    pub fn has_active_floats(&self, min_y: f32) -> bool {
+        self.bfc.float_context.has_active_floats(min_y + self.y_offset)
+    }
+
     /// Position a floated box with the context
     pub fn place_floated_box(
         &mut self,

src/compute/float.rs

@@ -41,6 +41,8 @@ pub struct FloatContext {
     /// A list of non-overlapping horizontal segments within the context.
     /// Each segment has the same available width for it's entire height.
     placer: FloatPlacer,
+    /// Whether the float context contains any floats
+    has_floats: bool,
 }
 
 /// An empty "slot" that avoids floats that is suitable for non-floated content
@@ -92,9 +94,20 @@ impl FloatContext {
             left_floats: Vec::new(),
             right_floats: Vec::new(),
             placer: FloatPlacer::new(available_space),
+            has_floats: false,
         }
     }
 
+    /// Whether the float context contains any floats
+    pub fn has_floats(&self) -> bool {
+        self.has_floats
+    }
+
+    /// Whether the float context contains any floats that extend to or below min_y
+    pub fn has_active_floats(&self, min_y: f32) -> bool {
+        self.has_floats && self.placer.segment_end() > min_y
+    }
+
     /// Create a new empty `FloatContext`
     pub fn set_width(&mut self, available_space: AvailableSpace) {
         self.available_space = available_space;
@@ -136,6 +149,8 @@ impl FloatContext {
         //     }
         // };
 
+        self.has_floats = true;
+
         // Return the (x, y) coordinates of the positioned box
         match self.available_space {
             // Position won't actually be used if we're layouting under a min-content
@@ -216,13 +231,13 @@ impl Segment {
 struct FloatPlacer {
     // Calling into this
     bfc_width: f32,
-
+    /// A list of the "segments" in the float context.
     segments: Vec<Segment>,
-    // Left hwm in slot 0. Right hwm in slot 1.
-    // high_water_marks: [usize; 2],
     /// A closed-open range indicating which segment the last placed float
     /// was placed(on each side).
     last_placed_floats: [Range<usize>; 2],
+    // Left hwm in slot 0. Right hwm in slot 1.
+    // high_water_marks: [usize; 2],
     // left_float_high_water_mark: usize,
     // right_float_high_water_mark: usize,
 }
@@ -293,6 +308,10 @@ impl FloatPlacer {
         self.last_placed_floats[slot].end = self.last_placed_floats[slot].end.max(placement.end);
     }
 
+    fn segment_end(&self) -> f32 {
+        self.segments.last().map(|seg| seg.y.end).unwrap_or(0.0)
+    }
+
     fn place_float(
         &mut self,
         min_y: f32,