Add flows if requested to the display list info.

This will be used for hit testing.

src/components/gfx/display_list.rs

@@ -26,20 +26,20 @@ use std::arc::ARC;
 use std::arc;
 
 /// A list of rendering operations to be performed.
-pub struct DisplayList {
-    priv list: ~[DisplayItem]
+pub struct DisplayList<E> {
+    priv list: ~[DisplayItem<E>]
 }
 
-impl DisplayList {
+impl<E> DisplayList<E> {
     /// Creates a new display list.
-    pub fn new() -> DisplayList {
+    pub fn new() -> DisplayList<E> {
         DisplayList {
             list: ~[]
         }
     }
 
     /// Appends the given item to the display list.
-    pub fn append_item(&mut self, item: DisplayItem) {
+    pub fn append_item(&mut self, item: DisplayItem<E>) {
         // FIXME(Issue #150): crashes
         //debug!("Adding display item %u: %?", self.len(), item);
         self.list.push(item)
@@ -58,51 +58,54 @@ impl DisplayList {
 }
 
 /// One drawing command in the list.
-pub enum DisplayItem {
-    SolidColorDisplayItemClass(~SolidColorDisplayItem),
-    TextDisplayItemClass(~TextDisplayItem),
-    ImageDisplayItemClass(~ImageDisplayItem),
-    BorderDisplayItemClass(~BorderDisplayItem),
+pub enum DisplayItem<E> {
+    SolidColorDisplayItemClass(~SolidColorDisplayItem<E>),
+    TextDisplayItemClass(~TextDisplayItem<E>),
+    ImageDisplayItemClass(~ImageDisplayItem<E>),
+    BorderDisplayItemClass(~BorderDisplayItem<E>),
 }
 
 /// Information common to all display items.
-pub struct BaseDisplayItem {
+pub struct BaseDisplayItem<E> {
     /// The boundaries of the display item.
     ///
     /// TODO: Which coordinate system should this use?
     bounds: Rect<Au>,
+
+    /// Extra data: either the originating flow (for hit testing) or nothing (for rendering).
+    extra: E,
 }
 
 /// Renders a solid color.
-pub struct SolidColorDisplayItem {
-    base: BaseDisplayItem,
+pub struct SolidColorDisplayItem<E> {
+    base: BaseDisplayItem<E>,
     color: Color,
 }
 
 /// Renders text.
-pub struct TextDisplayItem {
-    base: BaseDisplayItem,
+pub struct TextDisplayItem<E> {
+    base: BaseDisplayItem<E>,
     text_run: ~SendableTextRun,
     range: Range,
     color: Color,
 }
 
 /// Renders an image.
-pub struct ImageDisplayItem {
-    base: BaseDisplayItem,
+pub struct ImageDisplayItem<E> {
+    base: BaseDisplayItem<E>,
     image: ARC<~Image>,
 }
 
 /// Renders a border.
-pub struct BorderDisplayItem {
-    base: BaseDisplayItem,
+pub struct BorderDisplayItem<E> {
+    base: BaseDisplayItem<E>,
     /// The width of the border.
     width: Au,
     /// The color of the border.
     color: Color,
 }
 
-impl DisplayItem {
+impl<E> DisplayItem<E> {
     /// Renders this display item into the given render context.
     fn draw_into_context(&self, render_context: &RenderContext) {
         match *self {

src/components/gfx/render_layers.rs

@@ -14,8 +14,12 @@ use geom::point::Point2D;
 use geom::rect::Rect;
 use geom::size::Size2D;
 
+/// The type representing the lack of extra display list data. This is used when sending display
+/// list data off to be rendered.
+pub type Nothing = ();
+
 pub struct RenderLayer {
-    display_list: DisplayList,
+    display_list: DisplayList<Nothing>,
     size: Size2D<uint>
 }
 

src/components/main/layout/block.rs

@@ -6,7 +6,8 @@
 
 use layout::box::{RenderBox};
 use layout::context::LayoutContext;
-use layout::display_list_builder::{DisplayListBuilder, FlowDisplayListBuilderMethods};
+use layout::display_list_builder::{DisplayListBuilder, ExtraDisplayListData};
+use layout::display_list_builder::{FlowDisplayListBuilderMethods};
 use layout::flow::{BlockFlow, FlowContext, FlowData, InlineBlockFlow};
 use layout::inline::InlineLayout;
 
@@ -175,11 +176,11 @@ impl BlockFlowData {
         });
     }
 
-    pub fn build_display_list_block(@mut self,
-                                builder: &DisplayListBuilder,
-                                dirty: &Rect<Au>, 
-                                offset: &Point2D<Au>,
-                                list: &Cell<DisplayList>) {
+    pub fn build_display_list_block<E:ExtraDisplayListData>(@mut self,
+                                                            builder: &DisplayListBuilder,
+                                                            dirty: &Rect<Au>, 
+                                                            offset: &Point2D<Au>,
+                                                            list: &Cell<DisplayList<E>>) {
         // add box that starts block context
         self.box.map(|&box| {
             box.build_display_list(builder, dirty, offset, list)
@@ -195,3 +196,4 @@ impl BlockFlowData {
         }
     }
 }
+

src/components/main/layout/box.rs

@@ -6,7 +6,7 @@
 
 use css::node_style::StyledNode;
 use layout::context::LayoutContext;
-use layout::display_list_builder::{DisplayListBuilder, ToGfxColor};
+use layout::display_list_builder::{DisplayListBuilder, ExtraDisplayListData, ToGfxColor};
 use layout::flow::FlowContext;
 use layout::model::BoxModel;
 use layout::text;
@@ -550,11 +550,11 @@ pub impl RenderBox {
     /// representing the box's stacking context. When asked to construct its constituent display
     /// items, each box puts its display items into the correct stack layer according to CSS 2.1
     /// Appendix E. Finally, the builder flattens the list.
-    fn build_display_list(&self,
-                          _: &DisplayListBuilder,
-                          dirty: &Rect<Au>,
-                          offset: &Point2D<Au>,
-                          list: &Cell<DisplayList>) {
+    fn build_display_list<E:ExtraDisplayListData>(&self,
+                                                  _: &DisplayListBuilder,
+                                                  dirty: &Rect<Au>,
+                                                  offset: &Point2D<Au>,
+                                                  list: &Cell<DisplayList<E>>) {
         let box_bounds = self.position();
         let absolute_box_bounds = box_bounds.translate(offset);
         debug!("RenderBox::build_display_list at rel=%?, abs=%?: %s",
@@ -582,6 +582,7 @@ pub impl RenderBox {
                     let text_display_item = ~TextDisplayItem {
                         base: BaseDisplayItem {
                             bounds: absolute_box_bounds,
+                            extra: ExtraDisplayListData::new(*self),
                         },
                         // FIXME(pcwalton): Allocation? Why?!
                         text_run: ~text_box.run.serialize(),
@@ -602,6 +603,7 @@ pub impl RenderBox {
                         let border_display_item = ~BorderDisplayItem {
                             base: BaseDisplayItem {
                                 bounds: absolute_box_bounds,
+                                extra: ExtraDisplayListData::new(*self),
                             },
                             width: Au::from_px(1),
                             color: rgb(0, 0, 200).to_gfx_color(),
@@ -621,6 +623,7 @@ pub impl RenderBox {
                         let border_display_item = ~BorderDisplayItem {
                             base: BaseDisplayItem {
                                 bounds: baseline,
+                                extra: ExtraDisplayListData::new(*self),
                             },
                             width: Au::from_px(1),
                             color: rgb(0, 200, 0).to_gfx_color(),
@@ -644,6 +647,7 @@ pub impl RenderBox {
                             let image_display_item = ~ImageDisplayItem {
                                 base: BaseDisplayItem {
                                     bounds: absolute_box_bounds,
+                                    extra: ExtraDisplayListData::new(*self),
                                 },
                                 image: image.clone(),
                             };
@@ -668,9 +672,9 @@ pub impl RenderBox {
 
     /// Adds the display items necessary to paint the background of this render box to the display
     /// list if necessary.
-    fn paint_background_if_applicable(&self,
-                                      list: &Cell<DisplayList>,
-                                      absolute_bounds: &Rect<Au>) {
+    fn paint_background_if_applicable<E:ExtraDisplayListData>(&self,
+                                                              list: &Cell<DisplayList<E>>,
+                                                              absolute_bounds: &Rect<Au>) {
         // FIXME: This causes a lot of background colors to be displayed when they are clearly not
         // needed. We could use display list optimization to clean this up, but it still seems
         // inefficient. What we really want is something like "nearest ancestor element that
@@ -683,6 +687,7 @@ pub impl RenderBox {
                 let solid_color_display_item = ~SolidColorDisplayItem {
                     base: BaseDisplayItem {
                         bounds: *absolute_bounds,
+                        extra: ExtraDisplayListData::new(*self),
                     },
                     color: background_color.to_gfx_color(),
                 };

src/components/main/layout/display_list_builder.rs

@@ -2,15 +2,13 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-///
-/// Constructs display lists from render boxes.
-///
-
-use core::cell::Cell;
+//! Constructs display lists from render boxes.
 
+use layout::box::RenderBox;
 use layout::context::LayoutContext;
 use layout::flow::FlowContext;
 
+use core::cell::Cell;
 use geom::point::Point2D;
 use geom::rect::Rect;
 use gfx::display_list::DisplayList;
@@ -19,6 +17,28 @@ use gfx;
 use newcss;
 use servo_util::tree::TreeNodeRef;
 
+/// Extra display list data is either nothing (if the display list is to be rendered) or the
+/// originating render box (if the display list is generated for hit testing).
+pub trait ExtraDisplayListData {
+    fn new(box: RenderBox) -> Self;
+}
+
+/// The type representing the lack of extra display list data. This is used when sending display
+/// list data off to be rendered.
+pub type Nothing = ();
+
+impl ExtraDisplayListData for Nothing {
+    fn new(_: RenderBox) -> Nothing {
+        ()
+    }
+}
+
+impl ExtraDisplayListData for RenderBox {
+    fn new(box: RenderBox) -> RenderBox {
+        box
+    }
+}
+
 /// A builder object that manages display list builder should mainly hold information about the
 /// initial request and desired result--for example, whether the `DisplayList` is to be used for
 /// painting or hit testing. This can affect which boxes are created.
@@ -30,30 +50,33 @@ pub struct DisplayListBuilder<'self> {
 }
 
 pub trait FlowDisplayListBuilderMethods {
-    fn build_display_list(&self, a: &DisplayListBuilder, b: &Rect<Au>, c: &Cell<DisplayList>);
-    fn build_display_list_for_child(&self,
-                                    a: &DisplayListBuilder,
-                                    b: FlowContext,
-                                    c: &Rect<Au>,
-                                    d: &Point2D<Au>,
-                                    e: &Cell<DisplayList>);
+    fn build_display_list<E:ExtraDisplayListData>(&self,
+                                                  a: &DisplayListBuilder,
+                                                  b: &Rect<Au>,
+                                                  c: &Cell<DisplayList<E>>);
+    fn build_display_list_for_child<E:ExtraDisplayListData>(&self,
+                                                            a: &DisplayListBuilder,
+                                                            b: FlowContext,
+                                                            c: &Rect<Au>,
+                                                            d: &Point2D<Au>,
+                                                            e: &Cell<DisplayList<E>>);
 }
 
 impl FlowDisplayListBuilderMethods for FlowContext {
-    fn build_display_list(&self,
-                          builder: &DisplayListBuilder,
-                          dirty: &Rect<Au>,
-                          list: &Cell<DisplayList>) {
+    fn build_display_list<E:ExtraDisplayListData>(&self,
+                                                  builder: &DisplayListBuilder,
+                                                  dirty: &Rect<Au>,
+                                                  list: &Cell<DisplayList<E>>) {
         let zero = gfx::geometry::zero_point();
         self.build_display_list_recurse(builder, dirty, &zero, list);
     }
 
-    fn build_display_list_for_child(&self,
-                                    builder: &DisplayListBuilder,
-                                    child_flow: FlowContext,
-                                    dirty: &Rect<Au>,
-                                    offset: &Point2D<Au>,
-                                    list: &Cell<DisplayList>) {
+    fn build_display_list_for_child<E:ExtraDisplayListData>(&self,
+                                                            builder: &DisplayListBuilder,
+                                                            child_flow: FlowContext,
+                                                            dirty: &Rect<Au>,
+                                                            offset: &Point2D<Au>,
+                                                            list: &Cell<DisplayList<E>>) {
         // Adjust the dirty rect to child flow context coordinates.
         do child_flow.with_base |child_node| {
             let abs_flow_bounds = child_node.position.translate(offset);

src/components/main/layout/flow.rs

@@ -28,7 +28,7 @@
 use layout::block::BlockFlowData;
 use layout::box::RenderBox;
 use layout::context::LayoutContext;
-use layout::display_list_builder::DisplayListBuilder;
+use layout::display_list_builder::{DisplayListBuilder, ExtraDisplayListData};
 use layout::inline::{InlineFlowData};
 
 use core::cell::Cell;
@@ -284,11 +284,11 @@ impl<'self> FlowContext {
         }
     }
 
-    pub fn build_display_list_recurse(&self,
-                                      builder: &DisplayListBuilder,
-                                      dirty: &Rect<Au>,
-                                      offset: &Point2D<Au>,
-                                      list: &Cell<DisplayList>) {
+    pub fn build_display_list_recurse<E:ExtraDisplayListData>(&self,
+                                                              builder: &DisplayListBuilder,
+                                                              dirty: &Rect<Au>,
+                                                              offset: &Point2D<Au>,
+                                                              list: &Cell<DisplayList<E>>) {
         do self.with_base |info| {
             debug!("FlowContext::build_display_list at %?: %s", info.position, self.debug_str());
         }

src/components/main/layout/inline.rs

@@ -7,7 +7,7 @@ use core;
 use layout::box::{CannotSplit, GenericRenderBoxClass, ImageRenderBoxClass, RenderBox};
 use layout::box::{SplitDidFit, SplitDidNotFit, TextRenderBoxClass, UnscannedTextRenderBoxClass};
 use layout::context::LayoutContext;
-use layout::display_list_builder::DisplayListBuilder;
+use layout::display_list_builder::{DisplayListBuilder, ExtraDisplayListData};
 use layout::flow::{FlowContext, FlowData, InlineFlow};
 use layout::text::{UnscannedMethods, adapt_textbox_with_range};
 
@@ -864,11 +864,11 @@ impl InlineFlowData {
         self.common.position.size.height = cur_y;
     }
 
-    pub fn build_display_list_inline(&self,
-                                     builder: &DisplayListBuilder,
-                                     dirty: &Rect<Au>,
-                                     offset: &Point2D<Au>,
-                                     list: &Cell<DisplayList>) {
+    pub fn build_display_list_inline<E:ExtraDisplayListData>(&self,
+                                                             builder: &DisplayListBuilder,
+                                                             dirty: &Rect<Au>,
+                                                             offset: &Point2D<Au>,
+                                                             list: &Cell<DisplayList<E>>) {
         // TODO(#228): Once we form line boxes and have their cached bounds, we can be smarter and
         // not recurse on a line if nothing in it can intersect the dirty region.
         debug!("FlowContext[%d]: building display list for %u inline boxes",

src/components/main/layout/model.rs

@@ -4,7 +4,7 @@
 
 //! Borders, padding, and margins.
 
-use layout::display_list_builder::ToGfxColor;
+use layout::display_list_builder::{ExtraDisplayListData, ToGfxColor};
 use layout::box::RenderBox;
 
 use core::cell::Cell;
@@ -76,7 +76,9 @@ impl BoxModel {
 impl RenderBox {
     /// Adds the display items necessary to paint the borders of this render box to a display list
     /// if necessary.
-    pub fn paint_borders_if_applicable(&self, list: &Cell<DisplayList>, abs_bounds: &Rect<Au>) {
+    pub fn paint_borders_if_applicable<E:ExtraDisplayListData>(&self,
+                                                               list: &Cell<DisplayList<E>>,
+                                                               abs_bounds: &Rect<Au>) {
         // Fast path.
         let border = do self.with_imm_base |base| {
             base.model.border
@@ -109,6 +111,7 @@ impl RenderBox {
                 let border_display_item = ~BorderDisplayItem {
                     base: BaseDisplayItem {
                         bounds: bounds,
+                        extra: ExtraDisplayListData::new(*self),
                     },
                     width: border_width,
                     color: color,