Add support for stretching tab bar to fill width of tab bar

Resolves #1914

config/src/config.rs

@@ -468,6 +468,10 @@ pub struct Config {
     #[dynamic(default)]
     pub tab_and_split_indices_are_zero_based: bool,
 
+    /// Specifies to fill the width of the window with the tab bar
+    #[dynamic(default)]
+    pub tab_bar_fill: bool,
+
     /// Specifies the maximum width that a tab can have in the
     /// tab bar.  Defaults to 16 glyphs in width.
     #[dynamic(default = "default_tab_max_width")]

docs/config/appearance.md

@@ -277,6 +277,8 @@ details.
   bar at the bottom of the window instead of the top
 * [tab_max_width](lua/config/tab_max_width.md) sets the maximum width, measured in cells,
   of a given tab when using retro tab mode.
+* [tab_bar_fill](lua/config/tab_bar_fill.md) sets the fancy tab bar to fill
+  the width of the title bar.
 
 #### Native (Fancy) Tab Bar appearance
 

docs/config/lua/config/tab_bar_title_fill.md

@@ -0,0 +1,15 @@
+---
+tags:
+  - tab_bar
+---
+# `tab_bar_fill`
+
+Specifies that the fancy tab bar should allow tab titles
+to take up the entire width of the tab bar.
+In this mode, maximum tab width is ignored.
+
+Defaults to false.
+
+```lua
+config.tab_bar_fill = true
+```

wezterm-gui/src/tabbar.rs

@@ -324,6 +324,14 @@ impl TabBarState {
 
         let mut active_tab_no = 0;
 
+        let config_tab_max_width = if config.tab_bar_fill {
+            // We have no layout, so this is a rough estimate
+            // The tab bar consists of the tab titles, the new tab button, and some padding
+            title_width.saturating_sub(new_tab.len() + 2 + tab_info.len()) / (tab_info.len())
+        } else {
+            config.tab_max_width
+        };
+
         let tab_titles: Vec<TitleText> = if config.show_tabs_in_tab_bar {
             tab_info
                 .iter()
@@ -337,7 +345,7 @@ impl TabBarState {
                         pane_info,
                         config,
                         false,
-                        config.tab_max_width,
+                        config_tab_max_width,
                     )
                 })
                 .collect()
@@ -346,18 +354,16 @@ impl TabBarState {
         };
         let titles_len: usize = tab_titles.iter().map(|s| s.len).sum();
         let number_of_tabs = tab_titles.len();
-
         let available_cells =
             title_width.saturating_sub(number_of_tabs.saturating_sub(1) + new_tab.len());
         let tab_width_max = if config.use_fancy_tab_bar || available_cells >= titles_len {
             // We can render each title with its full width
-            usize::max_value()
+            usize::MAX
         } else {
             // We need to clamp the length to balance them out
             available_cells / number_of_tabs
         }
-        .min(config.tab_max_width);
-
+        .min(config_tab_max_width);
         let mut line = Line::with_width(0, SEQ_ZERO);
 
         let mut x = 0;
@@ -400,9 +406,10 @@ impl TabBarState {
         }
 
         for (tab_idx, tab_title) in tab_titles.iter().enumerate() {
-            let tab_title_len = tab_title.len.min(tab_width_max);
+            // The title is allowed to grow to the max size of the computed tab width
+            let tab_title_max_len = tab_title.len.max(tab_width_max).min(tab_width_max);
             let active = tab_idx == active_tab_no;
-            let hover = !active && is_tab_hover(mouse_x, x, tab_title_len);
+            let hover = !active && is_tab_hover(mouse_x, x, tab_title_max_len);
 
             // Recompute the title so that it factors in both the hover state
             // and the adjusted maximum tab width based on available space.
@@ -412,7 +419,7 @@ impl TabBarState {
                 pane_info,
                 config,
                 hover,
-                tab_title_len,
+                tab_title_max_len,
             );
 
             let cell_attrs = if active {

wezterm-gui/src/termwindow/box_model.rs

@@ -239,6 +239,7 @@ pub struct Element {
     pub max_width: Option<Dimension>,
     pub min_width: Option<Dimension>,
     pub min_height: Option<Dimension>,
+    pub fill_width: bool,
 }
 
 impl Element {
@@ -262,6 +263,7 @@ impl Element {
             max_width: None,
             min_width: None,
             min_height: None,
+            fill_width: false,
         }
     }
 
@@ -689,8 +691,8 @@ impl super::TermWindow {
                 let mut block_pixel_height: f32 = 0.;
                 let mut computed_kids = vec![];
                 let mut max_x: f32 = 0.;
-                let mut float_width: f32 = 0.;
                 let mut y_coord: f32 = 0.;
+                let mut filled_layout_contexts = Vec::new();
 
                 for child in kids {
                     if child.display == DisplayType::Block {
@@ -713,40 +715,39 @@ impl super::TermWindow {
                             context.bounds.max_y() - (context.bounds.min_y() + y_coord),
                         ),
                     };
-                    let kid = self.compute_element(
-                        &LayoutContext {
-                            bounds,
-                            gl_state: context.gl_state,
-                            height: context.height,
-                            metrics: context.metrics,
-                            width: DimensionContext {
-                                dpi: context.width.dpi,
-                                pixel_cell: context.width.pixel_cell,
-                                pixel_max: max_width,
-                            },
-                            zindex: context.zindex + element.zindex,
+                    let layout_context = LayoutContext {
+                        bounds,
+                        gl_state: context.gl_state,
+                        height: context.height,
+                        metrics: context.metrics,
+                        width: DimensionContext {
+                            dpi: context.width.dpi,
+                            pixel_cell: context.width.pixel_cell,
+                            pixel_max: max_width,
                         },
-                        child,
-                    )?;
+                        zindex: context.zindex + element.zindex,
+                    };
+                    let kid = self.compute_element(&layout_context, child)?;
                     match child.float {
-                        Float::Right => {
-                            float_width += float_width.max(kid.bounds.width());
-                        }
                         Float::None => {
                             block_pixel_width += kid.bounds.width();
                             max_x = max_x.max(block_pixel_width);
                         }
+                        // Float right is taken care of below
+                        _ => {}
+                    }
+                    if child.fill_width {
+                        filled_layout_contexts.push(layout_context);
                     }
                     block_pixel_height = block_pixel_height.max(kid.bounds.height());
-
                     computed_kids.push(kid);
                 }
 
                 // Respect min-width
                 max_x = max_x.max(min_width);
 
-                let mut float_max_x = (max_x + float_width).min(max_width);
-
+                // Right floated things start at the right edge, and move left as needed
+                let mut float_max_x = max_width;
                 let pixel_height = (y_coord + block_pixel_height).max(min_height);
 
                 for (kid, child) in computed_kids.iter_mut().zip(kids.iter()) {
@@ -773,6 +774,63 @@ impl super::TermWindow {
                     }
                 }
 
+                // We have to compute fill after all elements have been floated
+                if filled_layout_contexts.len() > 0 {
+                    // This mechanism assumes that we don't mix float right and
+                    // fill width elements and try to have it work That is, we
+                    // assume all float right elements are all the way to the
+                    // right, in a row, and are not marked to be filled
+                    let mut available_min_right_x = context.bounds.max_x();
+                    let mut static_element_size = 0.;
+                    for (kid, child) in computed_kids.iter_mut().zip(kids.iter()) {
+                        // Subtract out the space from non-filling, non right-floating elements
+                        if !child.fill_width {
+                            match child.float {
+                                Float::Right => {
+                                    available_min_right_x =
+                                        available_min_right_x.min(kid.bounds.min_x());
+                                }
+                                Float::None => {
+                                    static_element_size += kid.bounds.width();
+                                }
+                            }
+                        }
+                    }
+                    let mut current_kid = 0;
+
+                    // We only fill from the leftmost point to the leftmost point of the first float right element.
+                    // We assume we have all the space not taken up by non-filled elements.
+                    let available_space = available_min_right_x - static_element_size;
+                    // Evenly distribute remaining space
+                    let new_width = available_space / filled_layout_contexts.len() as f32;
+                    // We know there is at least one kid or we would not be in this loop
+                    let mut new_origin = computed_kids.first().unwrap().bounds.origin.x;
+                    for (kid, child) in computed_kids.iter_mut().zip(kids.iter()) {
+                        let old_bounds = kid.bounds;
+                        if child.fill_width {
+                            // Recompute
+                            let layout_context = &mut filled_layout_contexts[current_kid];
+                            current_kid = current_kid + 1;
+                            layout_context.width = DimensionContext {
+                                dpi: context.width.dpi,
+                                pixel_cell: context.width.pixel_cell,
+                                pixel_max: max_width,
+                            };
+                            layout_context.bounds = euclid::rect(
+                                new_origin,
+                                old_bounds.origin.y,
+                                new_width,
+                                old_bounds.height(),
+                            );
+                            let new_kid = self.compute_element(layout_context, child)?;
+                            *kid = new_kid;
+                        } else {
+                            kid.translate(euclid::vec2(new_origin - old_bounds.origin.x, 0.));
+                        }
+                        new_origin = kid.bounds.max_x();
+                    }
+                }
+
                 computed_kids.sort_by(|a, b| a.zindex.cmp(&b.zindex));
 
                 let content_rect = euclid::rect(0., 0., max_x.min(max_width), pixel_height);

wezterm-gui/src/termwindow/render/fancy_tab_bar.rs

@@ -126,7 +126,12 @@ impl crate::TermWindow {
                         bottom: Dimension::Cells(0.),
                     })
                     .border(BoxDimension::new(Dimension::Pixels(0.)))
-                    .colors(bar_colors.clone()),
+                    .colors(bar_colors.clone())
+                    .float(if item.item == TabBarItem::LeftStatus {
+                        Float::None
+                    } else {
+                        Float::Right
+                    }),
                 TabBarItem::NewTabButton => Element::new(
                     &font,
                     ElementContent::Poly {
@@ -301,9 +306,11 @@ impl crate::TermWindow {
                 _ => 0.,
             })
             .sum();
+
         let max_tab_width = ((self.dimensions.pixel_width as f32 / num_tabs)
             - (1.5 * metrics.cell_size.width as f32))
             .max(0.);
+        let min_tab_width = 0.;
 
         // Reserve space for the native titlebar buttons
         if self
@@ -338,7 +345,12 @@ impl crate::TermWindow {
                 }
                 TabBarItem::Tab { tab_idx, active } => {
                     let mut elem = item_to_elem(item);
-                    elem.max_width = Some(Dimension::Pixels(max_tab_width));
+                    elem.min_width = Some(Dimension::Pixels(min_tab_width));
+                    if self.config.tab_bar_fill {
+                        elem.fill_width = true;
+                    } else {
+                        elem.max_width = Some(Dimension::Pixels(max_tab_width));
+                    }
                     elem.content = match elem.content {
                         ElementContent::Text(_) => unreachable!(),
                         ElementContent::Poly { .. } => unreachable!(),
@@ -442,8 +454,10 @@ impl crate::TermWindow {
             Dimension::Cells(0.5)
         };
 
+        let mut new_children = left_eles;
+        new_children.append(&mut right_eles);
         children.push(
-            Element::new(&font, ElementContent::Children(left_eles))
+            Element::new(&font, ElementContent::Children(new_children))
                 .vertical_align(VerticalAlign::Bottom)
                 .colors(bar_colors.clone())
                 .padding(BoxDimension {
@@ -454,11 +468,6 @@ impl crate::TermWindow {
                 })
                 .zindex(1),
         );
-        children.push(
-            Element::new(&font, ElementContent::Children(right_eles))
-                .colors(bar_colors.clone())
-                .float(Float::Right),
-        );
 
         let content = ElementContent::Children(children);