layout: Take min-height and max-height into account

src/components/main/layout/block.rs

@@ -12,24 +12,33 @@
 //!
 //! CB: Containing Block of the current flow.
 
-use layout::box_::{Box, ImageBox, ScannedTextBox};
+use layout::box_::{Box, ImageBox, MainBoxKind, ScannedTextBox};
 use layout::construct::FlowConstructor;
 use layout::context::LayoutContext;
-use layout::display_list_builder::{DisplayListBuilder, ExtraDisplayListData};
-use layout::floats::{FloatKind, Floats, PlacementInfo};
+use layout::display_list_builder::{DisplayListBuilder, DisplayListBuildingInfo};
+use layout::floats::{ClearBoth, ClearLeft, ClearRight, FloatKind, Floats, PlacementInfo};
 use layout::flow::{BaseFlow, BlockFlowClass, FlowClass, Flow, ImmutableFlowUtils};
-use layout::flow::{mut_base, PreorderFlowTraversal, PostorderFlowTraversal, MutableFlowUtils};
+use layout::flow::{MutableFlowUtils, PreorderFlowTraversal, PostorderFlowTraversal, mut_base};
 use layout::flow;
-use layout::model::{MaybeAuto, Specified, Auto, specified_or_none, specified};
+use layout::model::{Auto, IntrinsicWidths, MarginCollapseInfo, MarginsCollapse};
+use layout::model::{MarginsCollapseThrough, MaybeAuto, NoCollapsibleMargins, Specified, specified};
+use layout::model::{specified_or_none};
 use layout::wrapper::ThreadSafeLayoutNode;
-use style::computed_values::{position};
+use style::ComputedValues;
+use style::computed_values::{clear, position};
 
-use std::cell::RefCell;
 use geom::{Point2D, Rect, Size2D};
-use gfx::display_list::{DisplayListCollection, DisplayList};
+use gfx::color;
+use gfx::display_list::{BackgroundAndBorderLevel, BlockLevel, RootOfStackingContextLevel};
+use gfx::display_list::{StackingContext};
+use gfx::render_task::RenderLayer;
+use servo_msg::compositor_msg::{FixedPosition, LayerId, Scrollable};
 use servo_util::geometry::Au;
 use servo_util::geometry;
 use servo_util::smallvec::{SmallVec, SmallVec0};
+use style::computed_values::{LPA_Auto, LPA_Length, LPA_Percentage, LPN_Length, LPN_None};
+use style::computed_values::{LPN_Percentage, LP_Length, LP_Percentage};
+use sync::Arc;
 
 /// Information specific to floated blocks.
 pub struct FloatedBlockInfo {
@@ -98,7 +107,7 @@ impl HeightConstraintSolution {
                                                   content_height: Au,
                                                   available_height: Au,
                                                   static_y_offset: Au)
-                                               -> HeightConstraintSolution {
+                                                  -> HeightConstraintSolution {
         // Distance from the top edge of the Absolute Containing Block to the
         // top margin edge of a hypothetical box that would have been the
         // first box of the element.
@@ -265,6 +274,115 @@ impl HeightConstraintSolution {
     }
 }
 
+/// Performs height calculations potentially multiple times, taking `height`, `min-height`, and
+/// `max-height` into account. After each call to `next()`, the caller must call `.try()` with the
+/// current calculated value of `height`.
+///
+/// See CSS 2.1 § 10.7.
+struct CandidateHeightIterator {
+    height: MaybeAuto,
+    max_height: Option<Au>,
+    min_height: Au,
+    candidate_value: Au,
+    status: CandidateHeightIteratorStatus,
+}
+
+impl CandidateHeightIterator {
+    pub fn new(style: &ComputedValues, auto_value: Au, is_absolutely_positioned: bool)
+               -> CandidateHeightIterator {
+        // Per CSS 2.1 § 10.7, if the height is not *specified explicitly*, then we ignore
+        // `min-height` and `max-height`. Heights are considered to be specified explicitly if the
+        // element is absolutely positioned or the value of the containing block's height depends
+        // on the content.
+        //
+        // TODO(pcwalton): Consider heights specified explicitly if the containing block's height
+        // depends on the content.
+        let height_specified_explicitly = is_absolutely_positioned;
+
+        let height = match style.Box.get().height {
+            LPA_Percentage(percent) if height_specified_explicitly => {
+                Specified(auto_value.scale_by(percent))
+            }
+            LPA_Percentage(_) | LPA_Auto => Auto,
+            LPA_Length(length) => Specified(length),
+        };
+        let max_height = match style.Box.get().max_height {
+            LPN_Percentage(percent) if height_specified_explicitly => {
+                Some(auto_value.scale_by(percent))
+            }
+            LPN_Percentage(_) | LPN_None => None,
+            LPN_Length(length) => Some(length),
+        };
+        let min_height = match style.Box.get().min_height {
+            LP_Percentage(percent) if height_specified_explicitly => auto_value.scale_by(percent),
+            LP_Percentage(_) => Au(0),
+            LP_Length(length) => length,
+        };
+
+        CandidateHeightIterator {
+            height: height,
+            max_height: max_height,
+            min_height: min_height,
+            candidate_value: Au(0),
+            status: InitialCandidateHeightStatus,
+        }
+    }
+
+    pub fn next<'a>(&'a mut self) -> Option<(MaybeAuto, &'a mut Au)> {
+        self.status = match self.status {
+            InitialCandidateHeightStatus => TryingHeightCandidateHeightStatus,
+            TryingHeightCandidateHeightStatus => {
+                match self.max_height {
+                    Some(max_height) if self.candidate_value > max_height => {
+                        TryingMaxCandidateHeightStatus
+                    }
+                    _ if self.candidate_value < self.min_height => TryingMinCandidateHeightStatus,
+                    _ => FoundCandidateHeightStatus,
+                }
+            }
+            TryingMaxCandidateHeightStatus => {
+                if self.candidate_value < self.min_height {
+                    TryingMinCandidateHeightStatus
+                } else {
+                    FoundCandidateHeightStatus
+                }
+            }
+            TryingMinCandidateHeightStatus | FoundCandidateHeightStatus => {
+                FoundCandidateHeightStatus
+            }
+        };
+
+        match self.status {
+            TryingHeightCandidateHeightStatus => Some((self.height, &mut self.candidate_value)),
+            TryingMaxCandidateHeightStatus => {
+                Some((Specified(self.max_height.unwrap()), &mut self.candidate_value))
+            }
+            TryingMinCandidateHeightStatus => {
+                Some((Specified(self.min_height), &mut self.candidate_value))
+            }
+            FoundCandidateHeightStatus => None,
+            InitialCandidateHeightStatus => fail!(),
+        }
+    }
+}
+
+enum CandidateHeightIteratorStatus {
+    InitialCandidateHeightStatus,
+    TryingHeightCandidateHeightStatus,
+    TryingMaxCandidateHeightStatus,
+    TryingMinCandidateHeightStatus,
+    FoundCandidateHeightStatus,
+}
+
+// A helper function used in height calculation.
+fn translate_including_floats(cur_y: &mut Au, delta: Au, inorder: bool, floats: &mut Floats) {
+    *cur_y = *cur_y + delta;
+
+    if inorder {
+        floats.translate(Point2D(Au(0), -delta));
+    }
+}
+
 /// The real assign-heights traversal for flows with position 'absolute'.
 ///
 /// This is a traversal of an Absolute Flow tree.
@@ -1288,25 +1406,36 @@ impl BlockFlow {
                 // margin because of erroneous height calculation in Box_.
                 // Check this when that has been fixed.
                 let height_used_val = box_.border_box.get().size.height;
-                HeightConstraintSolution::solve_vertical_constraints_abs_replaced(height_used_val,
-                                                                                  margin_top,
-                                                                                  margin_bottom,
-                                                                                  top,
-                                                                                  bottom,
-                                                                                  content_height,
-                                                                                  available_height,
-                                                                                  static_y_offset)
+                solution = Some(HeightConstraintSolution::solve_vertical_constraints_abs_replaced(
+                        height_used_val,
+                        margin_top,
+                        margin_bottom,
+                        top,
+                        bottom,
+                        content_height,
+                        available_height,
+                        static_y_offset));
             } else {
-                HeightConstraintSolution::solve_vertical_constraints_abs_nonreplaced(
-                    height_used_val,
-                    margin_top,
-                    margin_bottom,
-                    top,
-                    bottom,
-                    content_height,
-                    available_height,
-                    static_y_offset)
-            };
+                let mut candidate_height_iterator =
+                    CandidateHeightIterator::new(style, containing_block_height, true);
+
+                for (height_used_val, new_candidate_height) in candidate_height_iterator {
+                    solution =
+                        Some(HeightConstraintSolution::solve_vertical_constraints_abs_nonreplaced(
+                            height_used_val,
+                            margin_top,
+                            margin_bottom,
+                            top,
+                            bottom,
+                            content_height,
+                            available_height,
+                            static_y_offset));
+
+                    *new_candidate_height = solution.unwrap().height
+                }
+            }
+
+            let solution = solution.unwrap();
 
             let mut margin = box_.margin.get();
             margin.top = solution.margin_top;