From efdf435ba3b9334c15466a765257443b554aebfc Mon Sep 17 00:00:00 2001
From: Patrick Walton <pcwalton@mimiga.net>
Date: Tue, 15 Sep 2015 16:32:39 -0700
Subject: [PATCH] gfx: Paint the insertion point as a one-pixel wide line.

---
 components/layout/display_list_builder.rs | 65 ++++++++++++++++++++++-
 1 file changed, 64 insertions(+), 1 deletion(-)

diff --git a/components/layout/display_list_builder.rs b/components/layout/display_list_builder.rs
index 9a78c0d8909..bafe3d2be10 100644
--- a/components/layout/display_list_builder.rs
+++ b/components/layout/display_list_builder.rs
@@ -34,6 +34,7 @@ use gfx::display_list::{GradientStop, ImageDisplayItem, LineDisplayItem};
 use gfx::display_list::{OpaqueNode, SolidColorDisplayItem};
 use gfx::display_list::{StackingContext, TextDisplayItem, TextOrientation};
 use gfx::paint_task::THREAD_TINT_COLORS;
+use gfx::text::glyph::CharIndex;
 use gfx_traits::color;
 use ipc_channel::ipc::{self, IpcSharedMemory};
 use msg::compositor_msg::{ScrollPolicy, LayerId};
@@ -60,15 +61,19 @@ use style::values::computed::{LengthOrNone, LengthOrPercentage, LengthOrPercenta
 use style::values::specified::{AngleOrCorner, HorizontalDirection, VerticalDirection};
 use url::Url;
 use util::cursor::Cursor;
-use util::geometry::{Au, ZERO_POINT};
+use util::geometry::{AU_PER_PX, Au, ZERO_POINT};
 use util::logical_geometry::{LogicalPoint, LogicalRect, LogicalSize, WritingMode};
 use util::opts;
+use util::range::Range;
 
 /// The fake fragment ID we use to indicate the inner display list for `overflow: scroll`.
 ///
 /// FIXME(pcwalton): This is pretty ugly. Consider modifying `LayerId` somehow.
 const FAKE_FRAGMENT_ID_FOR_OVERFLOW_SCROLL: u32 = 1000000;
 
+/// The logical width of an insertion point: at the moment, a one-pixel-wide line.
+const INSERTION_POINT_LOGICAL_WIDTH: Au = Au(1 * AU_PER_PX);
+
 /// Whether a stacking context needs a layer or not.
 pub enum StackingContextLayerNecessity {
     Always(LayerId, ScrollPolicy),
@@ -229,6 +234,14 @@ pub trait FragmentDisplayListBuilding {
                                       stacking_relative_border_box: &Rect<Au>)
                                       -> ClippingRegion;
 
+    /// Builds the display items necessary to paint the selection and/or caret for this fragment,
+    /// if any.
+    fn build_display_items_for_selection_if_necessary(&self,
+                                                      display_list: &mut DisplayList,
+                                                      stacking_relative_border_box: &Rect<Au>,
+                                                      level: StackingLevel,
+                                                      clip: &ClippingRegion);
+
     /// Creates the text display item for one text fragment. This can be called multiple times for
     /// one fragment if there are text shadows.
     ///
@@ -882,6 +895,50 @@ impl FragmentDisplayListBuilding for Fragment {
         (*parent_clip).clone().intersect_rect(&Rect::new(clip_origin, clip_size))
     }
 
+    fn build_display_items_for_selection_if_necessary(&self,
+                                                      display_list: &mut DisplayList,
+                                                      stacking_relative_border_box: &Rect<Au>,
+                                                      level: StackingLevel,
+                                                      clip: &ClippingRegion) {
+        let scanned_text_fragment_info = match self.specific {
+            SpecificFragmentInfo::ScannedText(ref scanned_text_fragment_info) => {
+                scanned_text_fragment_info
+            }
+            _ => return,
+        };
+        let insertion_point_index = match scanned_text_fragment_info.insertion_point {
+            Some(insertion_point_index) => insertion_point_index,
+            None => return,
+        };
+        let range = Range::new(CharIndex(0), insertion_point_index);
+        let advance = scanned_text_fragment_info.run.advance_for_range(&range);
+
+        let insertion_point_bounds;
+        let cursor;
+        if !self.style.writing_mode.is_vertical() {
+            insertion_point_bounds =
+                Rect::new(Point2D::new(stacking_relative_border_box.origin.x + advance,
+                                       stacking_relative_border_box.origin.y),
+                          Size2D::new(INSERTION_POINT_LOGICAL_WIDTH,
+                                      stacking_relative_border_box.size.height));
+            cursor = Cursor::TextCursor;
+        } else {
+            insertion_point_bounds =
+                Rect::new(Point2D::new(stacking_relative_border_box.origin.x,
+                                       stacking_relative_border_box.origin.y + advance),
+                          Size2D::new(stacking_relative_border_box.size.width,
+                                      INSERTION_POINT_LOGICAL_WIDTH));
+            cursor = Cursor::VerticalTextCursor;
+        };
+
+        display_list.push(DisplayItem::SolidColorClass(box SolidColorDisplayItem {
+            base: BaseDisplayItem::new(insertion_point_bounds,
+                                       DisplayItemMetadata::new(self.node, &*self.style, cursor),
+                                       clip.clone()),
+            color: self.style().get_color().color.to_gfx_color(),
+        }), level);
+    }
+
     fn build_display_list(&mut self,
                           display_list: &mut DisplayList,
                           layout_context: &LayoutContext,
@@ -991,6 +1048,12 @@ impl FragmentDisplayListBuilding for Fragment {
                                                                   &stacking_relative_border_box,
                                                                   &clip);
             }
+
+            // Paint the selection point if necessary.
+            self.build_display_items_for_selection_if_necessary(display_list,
+                                                                &stacking_relative_border_box,
+                                                                level,
+                                                                &clip);
         }
 
         // Create special per-fragment-type display items.