Fix cursor dimensions with font offset

Previously cursor dimensions were not calculated correctly when a font
offset was specified, since the font offset was completely ignored.

This has been fixed by moving all the cursor logic from the font into
the Alacritty crate, applying the config's offsets before rasterizing
the cursors.

This has also fixed an issue with some cursors not being rendered as
double-width correctly when over double-width glyphs.

This fixes #2209.

10 files changed, 251 insertions, 224 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9dd71e5a..97f46d2e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -23,6 +23,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Resize events are not send to the shell anymore if dimensions haven't changed
 - Minor performance issues with underline and strikeout checks
 - Rare bug which would extend underline and strikeout beyond the end of line
+- Cursors not spanning two lines when over double-width characters
+- Incorrect cursor dimensions if the font offset isn't `0`
 
 ## Version 0.3.0
 
diff --git a/Cargo.lock b/Cargo.lock
index 43cee938..77e6be5c 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -33,7 +33,6 @@ dependencies = [
 name = "alacritty"
 version = "0.3.0"
 dependencies = [
- "arraydeque 0.4.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "base64 0.10.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "clap 2.33.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -130,11 +129,6 @@ dependencies = [
 ]
 
 [[package]]
-name = "arraydeque"
-version = "0.4.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-
-[[package]]
 name = "arrayvec"
 version = "0.4.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -2863,7 +2857,6 @@ dependencies = [
 "checksum approx 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)" = "f0e60b75072ecd4168020818c0107f2857bb6c4e64252d8d3983f6263b40a5c3"
 "checksum arc-swap 0.3.11 (registry+https://github.com/rust-lang/crates.io-index)" = "bc4662175ead9cd84451d5c35070517777949a2ed84551764129cedb88384841"
 "checksum argon2rs 0.2.5 (registry+https://github.com/rust-lang/crates.io-index)" = "3f67b0b6a86dae6e67ff4ca2b6201396074996379fba2b92ff649126f37cb392"
-"checksum arraydeque 0.4.5 (registry+https://github.com/rust-lang/crates.io-index)" = "f0ffd3d69bd89910509a5d31d1f1353f38ccffdd116dd0099bbd6627f7bd8ad8"
 "checksum arrayvec 0.4.10 (registry+https://github.com/rust-lang/crates.io-index)" = "92c7fb76bc8826a8b33b4ee5bb07a247a81e76764ab4d55e8f73e3a4d8808c71"
 "checksum atty 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)" = "9a7d5b8723950951411ee34d271d99dddcc2035a16ab25310ea2c8cfd4369652"
 "checksum autocfg 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "a6d640bee2da49f60a4068a7fae53acde8982514ab7bae8b8cea9e88cbcfd799"
diff --git a/Cargo.toml b/Cargo.toml
index d1ad1bc6..f0206d19 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -41,7 +41,6 @@ log = "0.4"
 clap = "2"
 fnv = "1"
 unicode-width = "0.1"
-arraydeque = "0.4"
 glutin = { version = "0.21.0-rc2", features = ["icon_loading"] }
 env_logger = "0.6.0"
 base64 = "0.10.0"
diff --git a/font/src/lib.rs b/font/src/lib.rs
index f23d0a0f..38a6f82f 100644
--- a/font/src/lib.rs
+++ b/font/src/lib.rs
@@ -213,6 +213,7 @@ impl ::std::ops::Add for Size {
     }
 }
 
+#[derive(Clone)]
 pub struct RasterizedGlyph {
     pub c: char,
     pub width: i32,
@@ -314,6 +315,7 @@ impl fmt::Debug for RasterizedGlyph {
     }
 }
 
+#[derive(Copy, Clone)]
 pub struct Metrics {
     pub average_advance: f64,
     pub line_height: f64,
diff --git a/src/cursor.rs b/src/cursor.rs
new file mode 100644
index 00000000..268f35fa
--- /dev/null
+++ b/src/cursor.rs
@@ -0,0 +1,98 @@
+// Copyright 2016 Joe Wilm, The Alacritty Project Contributors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Helpers for creating different cursor glyphs from font metrics
+
+use std::cmp;
+
+use font::{Metrics, RasterizedGlyph};
+
+use crate::ansi::CursorStyle;
+
+/// Width/Height of the cursor relative to the font width
+pub const CURSOR_WIDTH_PERCENTAGE: i32 = 15;
+
+pub fn get_cursor_glyph(
+    cursor: CursorStyle,
+    metrics: Metrics,
+    offset_x: i8,
+    offset_y: i8,
+    is_wide: bool,
+) -> RasterizedGlyph {
+    // Calculate the cell metrics
+    let height = metrics.line_height as i32 + i32::from(offset_y);
+    let mut width = metrics.average_advance as i32 + i32::from(offset_x);
+    let line_width = cmp::max(width * CURSOR_WIDTH_PERCENTAGE / 100, 1);
+
+    // Double the cursor width if it's above a double-width glyph
+    if is_wide {
+        width *= 2;
+    }
+
+    match cursor {
+        CursorStyle::HollowBlock => get_box_cursor_glyph(height, width, line_width),
+        CursorStyle::Underline => get_underline_cursor_glyph(width, line_width),
+        CursorStyle::Beam => get_beam_cursor_glyph(height, line_width),
+        CursorStyle::Block => get_block_cursor_glyph(height, width),
+    }
+}
+
+// Returns a custom underline cursor character
+pub fn get_underline_cursor_glyph(width: i32, line_width: i32) -> RasterizedGlyph {
+    // Create a new rectangle, the height is relative to the font width
+    let buf = vec![255u8; (width * line_width * 3) as usize];
+
+    // Create a custom glyph with the rectangle data attached to it
+    RasterizedGlyph { c: ' ', top: line_width, left: 0, height: line_width, width, buf }
+}
+
+// Returns a custom beam cursor character
+pub fn get_beam_cursor_glyph(height: i32, line_width: i32) -> RasterizedGlyph {
+    // Create a new rectangle that is at least one pixel wide
+    let buf = vec![255u8; (line_width * height * 3) as usize];
+
+    // Create a custom glyph with the rectangle data attached to it
+    RasterizedGlyph { c: ' ', top: height, left: 0, height, width: line_width, buf }
+}
+
+// Returns a custom box cursor character
+pub fn get_box_cursor_glyph(height: i32, width: i32, line_width: i32) -> RasterizedGlyph {
+    // Create a new box outline rectangle
+    let mut buf = Vec::with_capacity((width * height * 3) as usize);
+    for y in 0..height {
+        for x in 0..width {
+            if y < line_width
+                || y >= height - line_width
+                || x < line_width
+                || x >= width - line_width
+            {
+                buf.append(&mut vec![255u8; 3]);
+            } else {
+                buf.append(&mut vec![0u8; 3]);
+            }
+        }
+    }
+
+    // Create a custom glyph with the rectangle data attached to it
+    RasterizedGlyph { c: ' ', top: height, left: 0, height, width, buf }
+}
+
+// Returns a custom block cursor character
+pub fn get_block_cursor_glyph(height: i32, width: i32) -> RasterizedGlyph {
+    // Create a completely filled glyph
+    let buf = vec![255u8; (width * height * 3) as usize];
+
+    // Create a custom glyph with the rectangle data attached to it
+    RasterizedGlyph { c: ' ', top: height, left: 0, height, width, buf }
+}
diff --git a/src/display.rs b/src/display.rs
index 9e902b94..07ffdd0f 100644
--- a/src/display.rs
+++ b/src/display.rs
@@ -435,10 +435,11 @@ impl Display {
         let size_info = *terminal.size_info();
         let visual_bell_intensity = terminal.visual_bell.intensity();
         let background_color = terminal.background_color();
+        let metrics = self.glyph_cache.font_metrics();
 
         let window_focused = self.window.is_focused;
         let grid_cells: Vec<RenderableCell> =
-            terminal.renderable_cells(config, window_focused).collect();
+            terminal.renderable_cells(config, window_focused, metrics).collect();
 
         // Get message from terminal to ignore modifications after lock is dropped
         let message_buffer = terminal.message_buffer_mut().message();
@@ -479,7 +480,6 @@ impl Display {
 
         {
             let glyph_cache = &mut self.glyph_cache;
-            let metrics = glyph_cache.font_metrics();
             let mut rects = Rects::new(&metrics, &size_info);
 
             // Draw grid
diff --git a/src/lib.rs b/src/lib.rs
index 92ccb5a7..10c1faa6 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -31,6 +31,7 @@ pub mod macros;
 pub mod ansi;
 pub mod cli;
 pub mod config;
+mod cursor;
 pub mod display;
 pub mod event;
 pub mod event_loop;
diff --git a/src/renderer/mod.rs b/src/renderer/mod.rs
index 47851224..5182a6f6 100644
--- a/src/renderer/mod.rs
+++ b/src/renderer/mod.rs
@@ -32,7 +32,7 @@ use crate::gl::types::*;
 use crate::index::{Column, Line};
 use crate::renderer::rects::{Rect, Rects};
 use crate::term::color::Rgb;
-use crate::term::{self, cell, RenderableCell};
+use crate::term::{self, cell, RenderableCell, RenderableCellContent};
 
 pub mod rects;
 
@@ -950,11 +950,11 @@ impl<'a> RenderApi<'a> {
             .map(|(i, c)| RenderableCell {
                 line,
                 column: col + i,
-                chars: {
+                inner: RenderableCellContent::Chars({
                     let mut chars = [' '; cell::MAX_ZEROWIDTH_CHARS + 1];
                     chars[0] = c;
                     chars
-                },
+                }),
                 bg: color.unwrap_or(Rgb { r: 0, g: 0, b: 0 }),
                 fg: Rgb { r: 0, g: 0, b: 0 },
                 flags: cell::Flags::empty(),
@@ -983,6 +983,13 @@ impl<'a> RenderApi<'a> {
     }
 
     pub fn render_cell(&mut self, cell: RenderableCell, glyph_cache: &mut GlyphCache) {
+        // loader.load_glyph(&rasterized)
+        if let RenderableCellContent::Raw(ref raw) = cell.inner {
+            let glyph = self.load_glyph(raw);
+            self.add_render_item(&cell, &glyph);
+            return;
+        }
+
         // Get font key for cell
         // FIXME this is super inefficient.
         let font_key = if cell.flags.contains(cell::Flags::BOLD) {
@@ -996,8 +1003,10 @@ impl<'a> RenderApi<'a> {
         // Don't render text of HIDDEN cells
         let mut chars = if cell.flags.contains(cell::Flags::HIDDEN) {
             [' '; cell::MAX_ZEROWIDTH_CHARS + 1]
+        } else if let RenderableCellContent::Chars(chars) = cell.inner {
+            chars
         } else {
-            cell.chars
+            unimplemented!();
         };
 
         // Render tabs as spaces in case the font doesn't support it
diff --git a/src/renderer/rects.rs b/src/renderer/rects.rs
index 2e5cd85b..b4f8a012 100644
--- a/src/renderer/rects.rs
+++ b/src/renderer/rects.rs
@@ -96,7 +96,7 @@ impl<'a> Rects<'a> {
 
                     // Start a new line if the flag is present
                     if cell.flags.contains(line.flag) {
-                        *start = *cell;
+                        *start = cell.clone();
                         *end = cell.into();
                     } else {
                         line.range = None;
@@ -105,7 +105,7 @@ impl<'a> Rects<'a> {
                 // Check for new start of line
                 None => {
                     if cell.flags.contains(line.flag) {
-                        line.range = Some((*cell, cell.into()));
+                        line.range = Some((cell.clone(), cell.into()));
                     }
                 },
             };
diff --git a/src/term/mod.rs b/src/term/mod.rs
index 48eedef1..9e879ada 100644
--- a/src/term/mod.rs
+++ b/src/term/mod.rs
@@ -18,7 +18,8 @@ use std::ops::{Index, IndexMut, Range, RangeInclusive};
 use std::time::{Duration, Instant};
 use std::{io, mem, ptr};
 
-use arraydeque::ArrayDeque;
+use copypasta::{Clipboard, Load, Store};
+use font::{self, RasterizedGlyph, Size};
 use glutin::MouseCursor;
 use unicode_width::UnicodeWidthChar;
 
@@ -26,6 +27,7 @@ use crate::ansi::{
     self, Attr, CharsetIndex, Color, CursorStyle, Handler, NamedColor, StandardCharset,
 };
 use crate::config::{Config, VisualBellAnimation};
+use crate::cursor;
 use crate::grid::{
     BidirectionalIterator, DisplayIter, Grid, GridCell, IndexRegion, Indexed, Scroll,
     ViewportPosition,
@@ -37,8 +39,6 @@ use crate::selection::{self, Locations, Selection};
 use crate::term::cell::{Cell, Flags, LineLength};
 use crate::term::color::Rgb;
 use crate::url::{Url, UrlParser};
-use copypasta::{Clipboard, Load, Store};
-use font::{self, Size};
 
 #[cfg(windows)]
 use crate::tty;
@@ -158,12 +158,12 @@ pub struct RenderableCellsIter<'a> {
     grid: &'a Grid<Cell>,
     cursor: &'a Point,
     cursor_offset: usize,
-    mode: TermMode,
+    cursor_cell: Option<RasterizedGlyph>,
+    cursor_style: CursorStyle,
     config: &'a Config,
     colors: &'a color::List,
     selection: Option<RangeInclusive<index::Linear>>,
     url_highlight: &'a Option<RangeInclusive<index::Linear>>,
-    cursor_cells: ArrayDeque<[Indexed<Cell>; 3]>,
 }
 
 impl<'a> RenderableCellsIter<'a> {
@@ -176,6 +176,7 @@ impl<'a> RenderableCellsIter<'a> {
         config: &'b Config,
         selection: Option<Locations>,
         cursor_style: CursorStyle,
+        metrics: font::Metrics,
     ) -> RenderableCellsIter<'b> {
         let grid = &term.grid;
 
@@ -224,203 +225,143 @@ impl<'a> RenderableCellsIter<'a> {
             }
         }
 
+        // Load cursor glyph
+        let cursor = &term.cursor.point;
+        let cursor_cell =
+            if term.mode.contains(mode::TermMode::SHOW_CURSOR) && grid.contains(cursor) {
+                let offset_x = config.font().offset().x;
+                let offset_y = config.font().offset().y;
+
+                let is_wide = grid[cursor].flags.contains(cell::Flags::WIDE_CHAR)
+                    && (cursor.col + 1) < grid.num_cols();
+                Some(cursor::get_cursor_glyph(cursor_style, metrics, offset_x, offset_y, is_wide))
+            } else {
+                None
+            };
+
         RenderableCellsIter {
-            cursor: &term.cursor.point,
+            cursor,
             cursor_offset,
             grid,
             inner,
-            mode: term.mode,
             selection: selection_range,
             url_highlight: &grid.url_highlight,
             config,
             colors: &term.colors,
-            cursor_cells: ArrayDeque::new(),
+            cursor_cell,
+            cursor_style,
         }
-        .initialize(cursor_style)
-    }
-
-    fn push_cursor_cells(&mut self, original: Cell, cursor: Cell, wide: Cell) {
-        // Prints the char under the cell if cursor is situated on a non-empty cell
-        self.cursor_cells
-            .push_back(Indexed { line: self.cursor.line, column: self.cursor.col, inner: original })
-            .expect("won't exceed capacity");
-
-        // Prints the cursor
-        self.cursor_cells
-            .push_back(Indexed { line: self.cursor.line, column: self.cursor.col, inner: cursor })
-            .expect("won't exceed capacity");
-
-        // If cursor is over a wide (2 cell size) character,
-        // print the second cursor cell
-        if self.is_wide_cursor(&cursor) {
-            self.cursor_cells
-                .push_back(Indexed {
-                    line: self.cursor.line,
-                    column: self.cursor.col + 1,
-                    inner: wide,
-                })
-                .expect("won't exceed capacity");
-        }
-    }
-
-    fn populate_block_cursor(&mut self) {
-        let cell = &self.grid[self.cursor];
-        let text_color = self.config.cursor_text_color().unwrap_or(cell.bg);
-        let cursor_color = self.config.cursor_cursor_color().unwrap_or(cell.fg);
-
-        let original_cell = self.grid[self.cursor];
-
-        let mut cursor_cell = self.grid[self.cursor];
-        cursor_cell.fg = text_color;
-        cursor_cell.bg = cursor_color;
-
-        let mut wide_cell = cursor_cell;
-        wide_cell.c = ' ';
-
-        self.push_cursor_cells(original_cell, cursor_cell, wide_cell);
-    }
-
-    fn populate_char_cursor(&mut self, cursor_cell_char: char, wide_cell_char: char) {
-        let original_cell = self.grid[self.cursor];
-
-        let mut cursor_cell = self.grid[self.cursor];
-        let cursor_color = self.config.cursor_cursor_color().unwrap_or(cursor_cell.fg);
-        cursor_cell.c = cursor_cell_char;
-        cursor_cell.fg = cursor_color;
-
-        let mut wide_cell = cursor_cell;
-        wide_cell.c = wide_cell_char;
-
-        self.push_cursor_cells(original_cell, cursor_cell, wide_cell);
-    }
-
-    fn populate_underline_cursor(&mut self) {
-        self.populate_char_cursor(font::UNDERLINE_CURSOR_CHAR, font::UNDERLINE_CURSOR_CHAR);
-    }
-
-    fn populate_beam_cursor(&mut self) {
-        self.populate_char_cursor(font::BEAM_CURSOR_CHAR, ' ');
-    }
-
-    fn populate_box_cursor(&mut self) {
-        self.populate_char_cursor(font::BOX_CURSOR_CHAR, ' ');
     }
+}
 
-    #[inline]
-    fn is_wide_cursor(&self, cell: &Cell) -> bool {
-        cell.flags.contains(cell::Flags::WIDE_CHAR) && (self.cursor.col + 1) < self.grid.num_cols()
-    }
+#[derive(Clone, Debug)]
+pub enum RenderableCellContent {
+    Chars([char; cell::MAX_ZEROWIDTH_CHARS + 1]),
+    Raw(RasterizedGlyph),
+}
 
-    /// Populates list of cursor cells with the original cell
-    fn populate_no_cursor(&mut self) {
-        self.cursor_cells
-            .push_back(Indexed {
-                line: self.cursor.line,
-                column: self.cursor.col,
-                inner: self.grid[self.cursor],
-            })
-            .expect("won't exceed capacity");
-    }
+#[derive(Clone, Debug)]
+pub struct RenderableCell {
+    /// A _Display_ line (not necessarily an _Active_ line)
+    pub line: Line,
+    pub column: Column,
+    pub inner: RenderableCellContent,
+    pub fg: Rgb,
+    pub bg: Rgb,
+    pub bg_alpha: f32,
+    pub flags: cell::Flags,
+}
 
-    fn initialize(mut self, cursor_style: CursorStyle) -> Self {
-        if self.cursor_is_visible() {
-            match cursor_style {
-                CursorStyle::HollowBlock => {
-                    self.populate_box_cursor();
-                },
-                CursorStyle::Block => {
-                    self.populate_block_cursor();
-                },
-                CursorStyle::Beam => {
-                    self.populate_beam_cursor();
-                },
-                CursorStyle::Underline => {
-                    self.populate_underline_cursor();
-                },
-            }
+impl RenderableCell {
+    fn new(config: &Config, colors: &color::List, cell: Indexed<Cell>, selected: bool) -> Self {
+        // Lookup RGB values
+        let mut fg_rgb = Self::compute_fg_rgb(config, colors, cell.fg, cell.flags);
+        let mut bg_rgb = Self::compute_bg_rgb(colors, cell.bg);
+
+        let selection_background = config.colors().selection.background;
+        let bg_alpha = if let (true, Some(col)) = (selected, selection_background) {
+            // Override selection background with config colors
+            bg_rgb = col;
+            1.0
+        } else if selected ^ cell.inverse() {
+            // Invert cell fg and bg colors
+            mem::swap(&mut fg_rgb, &mut bg_rgb);
+            Self::compute_bg_alpha(cell.fg)
         } else {
-            self.populate_no_cursor();
+            Self::compute_bg_alpha(cell.bg)
+        };
+
+        // Override selection text with config colors
+        if let (true, Some(col)) = (selected, config.colors().selection.text) {
+            fg_rgb = col;
         }
-        self
-    }
 
-    /// Check if the cursor should be rendered.
-    #[inline]
-    fn cursor_is_visible(&self) -> bool {
-        self.mode.contains(mode::TermMode::SHOW_CURSOR) && self.grid.contains(self.cursor)
+        RenderableCell {
+            line: cell.line,
+            column: cell.column,
+            inner: RenderableCellContent::Chars(cell.chars()),
+            fg: fg_rgb,
+            bg: bg_rgb,
+            bg_alpha,
+            flags: cell.flags,
+        }
     }
 
-    fn compute_fg_rgb(&self, fg: Color, cell: &Cell) -> Rgb {
+    fn compute_fg_rgb(config: &Config, colors: &color::List, fg: Color, flags: cell::Flags) -> Rgb {
         match fg {
             Color::Spec(rgb) => rgb,
             Color::Named(ansi) => {
-                match (
-                    self.config.draw_bold_text_with_bright_colors(),
-                    cell.flags & Flags::DIM_BOLD,
-                ) {
+                match (config.draw_bold_text_with_bright_colors(), flags & Flags::DIM_BOLD) {
                     // If no bright foreground is set, treat it like the BOLD flag doesn't exist
-                    (_, self::cell::Flags::DIM_BOLD)
+                    (_, cell::Flags::DIM_BOLD)
                         if ansi == NamedColor::Foreground
-                            && self.config.colors().primary.bright_foreground.is_none() =>
+                            && config.colors().primary.bright_foreground.is_none() =>
                     {
-                        self.colors[NamedColor::DimForeground]
+                        colors[NamedColor::DimForeground]
                     },
                     // Draw bold text in bright colors *and* contains bold flag.
-                    (true, self::cell::Flags::BOLD) => self.colors[ansi.to_bright()],
+                    (true, cell::Flags::BOLD) => colors[ansi.to_bright()],
                     // Cell is marked as dim and not bold
-                    (_, self::cell::Flags::DIM) | (false, self::cell::Flags::DIM_BOLD) => {
-                        self.colors[ansi.to_dim()]
-                    },
+                    (_, cell::Flags::DIM) | (false, cell::Flags::DIM_BOLD) => colors[ansi.to_dim()],
                     // None of the above, keep original color.
-                    _ => self.colors[ansi],
+                    _ => colors[ansi],
                 }
             },
             Color::Indexed(idx) => {
                 let idx = match (
-                    self.config.draw_bold_text_with_bright_colors(),
-                    cell.flags & Flags::DIM_BOLD,
+                    config.draw_bold_text_with_bright_colors(),
+                    flags & Flags::DIM_BOLD,
                     idx,
                 ) {
-                    (true, self::cell::Flags::BOLD, 0..=7) => idx as usize + 8,
-                    (false, self::cell::Flags::DIM, 8..=15) => idx as usize - 8,
-                    (false, self::cell::Flags::DIM, 0..=7) => idx as usize + 260,
+                    (true, cell::Flags::BOLD, 0..=7) => idx as usize + 8,
+                    (false, cell::Flags::DIM, 8..=15) => idx as usize - 8,
+                    (false, cell::Flags::DIM, 0..=7) => idx as usize + 260,
                     _ => idx as usize,
                 };
 
-                self.colors[idx]
+                colors[idx]
             },
         }
     }
 
     #[inline]
-    fn compute_bg_alpha(&self, bg: Color) -> f32 {
+    fn compute_bg_alpha(bg: Color) -> f32 {
         match bg {
             Color::Named(NamedColor::Background) => 0.0,
             _ => 1.0,
         }
     }
 
-    fn compute_bg_rgb(&self, bg: Color) -> Rgb {
+    #[inline]
+    fn compute_bg_rgb(colors: &color::List, bg: Color) -> Rgb {
         match bg {
             Color::Spec(rgb) => rgb,
-            Color::Named(ansi) => self.colors[ansi],
-            Color::Indexed(idx) => self.colors[idx],
+            Color::Named(ansi) => colors[ansi],
+            Color::Indexed(idx) => colors[idx],
         }
     }
 }
 
-#[derive(Copy, Clone, Debug)]
-pub struct RenderableCell {
-    /// A _Display_ line (not necessarily an _Active_ line)
-    pub line: Line,
-    pub column: Column,
-    pub chars: [char; cell::MAX_ZEROWIDTH_CHARS + 1],
-    pub fg: Rgb,
-    pub bg: Rgb,
-    pub bg_alpha: f32,
-    pub flags: cell::Flags,
-}
-
 impl<'a> Iterator for RenderableCellsIter<'a> {
     type Item = RenderableCell;
 
@@ -431,23 +372,32 @@ impl<'a> Iterator for RenderableCellsIter<'a> {
     #[inline]
     fn next(&mut self) -> Option<Self::Item> {
         loop {
-            // Handle cursor
-            let (cell, selected, highlighted) = if self.cursor_offset == self.inner.offset()
-                && self.inner.column() == self.cursor.col
-            {
-                // Cursor cell
-                let mut cell = self.cursor_cells.pop_front().unwrap();
-                cell.line = self.inner.line();
-
-                // Since there may be multiple cursor cells (for a wide
-                // char), only update iteration position after all cursor
-                // cells have been drawn.
-                if self.cursor_cells.is_empty() {
-                    self.inner.next();
+            if self.cursor_offset == self.inner.offset() && self.inner.column() == self.cursor.col {
+                // Handle cursor
+                if let Some(cursor_cell) = self.cursor_cell.take() {
+                    let cell = Indexed {
+                        inner: self.grid[self.cursor],
+                        column: self.cursor.col,
+                        line: self.cursor.line,
+                    };
+                    let mut renderable_cell =
+                        RenderableCell::new(self.config, self.colors, cell, false);
+
+                    renderable_cell.inner = RenderableCellContent::Raw(cursor_cell);
+
+                    return Some(renderable_cell);
+                } else {
+                    let mut cell =
+                        RenderableCell::new(self.config, self.colors, self.inner.next()?, false);
+
+                    if self.cursor_style == CursorStyle::Block {
+                        std::mem::swap(&mut cell.bg, &mut cell.fg);
+                    }
+
+                    return Some(cell);
                 }
-                (cell, false, false)
             } else {
-                let cell = self.inner.next()?;
+                let mut cell = self.inner.next()?;
 
                 let index = Linear::new(self.grid.num_cols(), cell.column, cell.line);
 
@@ -460,51 +410,13 @@ impl<'a> Iterator for RenderableCellsIter<'a> {
                 }
 
                 // Underline URL highlights
-                let highlighted = self
-                    .url_highlight
-                    .as_ref()
-                    .map(|range| range.contains_(index))
-                    .unwrap_or(false);
-
-                (cell, selected, highlighted)
-            };
-
-            // Lookup RGB values
-            let mut fg_rgb = self.compute_fg_rgb(cell.fg, &cell);
-            let mut bg_rgb = self.compute_bg_rgb(cell.bg);
-
-            let selection_background = self.config.colors().selection.background;
-            let bg_alpha = if let (true, Some(col)) = (selected, selection_background) {
-                // Override selection background with config colors
-                bg_rgb = col;
-                1.0
-            } else if selected ^ cell.inverse() {
-                // Invert cell fg and bg colors
-                mem::swap(&mut fg_rgb, &mut bg_rgb);
-                self.compute_bg_alpha(cell.fg)
-            } else {
-                self.compute_bg_alpha(cell.bg)
-            };
-
-            // Override selection text with config colors
-            if let (true, Some(col)) = (selected, self.config.colors().selection.text) {
-                fg_rgb = col;
-            }
+                if self.url_highlight.as_ref().map(|range| range.contains_(index)).unwrap_or(false)
+                {
+                    cell.inner.flags.insert(Flags::UNDERLINE);
+                }
 
-            let mut flags = cell.flags;
-            if highlighted {
-                flags.insert(Flags::UNDERLINE);
+                return Some(RenderableCell::new(self.config, self.colors, cell, selected));
             }
-
-            return Some(RenderableCell {
-                line: cell.line,
-                column: cell.column,
-                chars: cell.chars(),
-                fg: fg_rgb,
-                bg: bg_rgb,
-                bg_alpha,
-                flags,
-            });
         }
     }
 }
@@ -1174,6 +1086,7 @@ impl Term {
         &'b self,
         config: &'b Config,
         window_focused: bool,
+        metrics: font::Metrics,
     ) -> RenderableCellsIter<'_> {
         let alt_screen = self.mode.contains(TermMode::ALT_SCREEN);
         let selection = self
@@ -1189,7 +1102,7 @@ impl Term {
             CursorStyle::HollowBlock
         };
 
-        RenderableCellsIter::new(&self, config, selection, cursor)
+        RenderableCellsIter::new(&self, config, selection, cursor, metrics)
     }
 
     /// Resize terminal to new dimensions
@@ -2497,8 +2410,18 @@ mod benches {
         let mut terminal = Term::new(&config, size, MessageBuffer::new());
         mem::swap(&mut terminal.grid, &mut grid);
 
+        let metrics = font::Metrics {
+            descent: 0.,
+            line_height: 0.,
+            average_advance: 0.,
+            underline_position: 0.,
+            underline_thickness: 0.,
+            strikeout_position: 0.,
+            strikeout_thickness: 0.,
+        };
+
         b.iter(|| {
-            let iter = terminal.renderable_cells(&config, false);
+            let iter = terminal.renderable_cells(&config, false, metrics);
             for cell in iter {
                 test::black_box(cell);
             }