initial implementation of bufferline (#2759)

* initial implementation of bufferline

* fixed lint

* changed to 'bufferline', added enum for config modes, some cleanup

* fixed lint

* added file modification indicator

* removed redundant code, added proper themeing with fallback, changed 'file modified' indicator

* remove commented code

* Update helix-term/src/ui/editor.rs

simplify text and offset computation

Co-authored-by: Gokul Soumya <gokulps15@gmail.com>

* add ui.bufferline.background key for themes

Co-authored-by: lazytanuki <43273245+lazytanuki@users.noreply.github.com>

* address PR comments

* Update helix-term/src/ui/editor.rs

* simplify computation of editor area:

* change to set_stringn to avoid overflow

* Update configuration.md

Updates documentation to reflect decision re: defaulting to never showing bufferline.

* addressed pr comments

* fix build error

* address pr comments

* revert accidental change

Co-authored-by: Gokul Soumya <gokulps15@gmail.com>
Co-authored-by: lazytanuki <43273245+lazytanuki@users.noreply.github.com>
Co-authored-by: Seth Bromberger <sbromberger@users.noreply.github.com>

1 files changed, 75 insertions, 3 deletions

diff --git a/helix-term/src/ui/editor.rs b/helix-term/src/ui/editor.rs
index fa437a7e..d0def9ba 100644
--- a/helix-term/src/ui/editor.rs
+++ b/helix-term/src/ui/editor.rs
@@ -16,14 +16,14 @@ use helix_core::{
     LineEnding, Position, Range, Selection, Transaction,
 };
 use helix_view::{
-    document::Mode,
+    document::{Mode, SCRATCH_BUFFER_NAME},
     editor::{CompleteAction, CursorShapeConfig},
     graphics::{Color, CursorKind, Modifier, Rect, Style},
     input::{KeyEvent, MouseButton, MouseEvent, MouseEventKind},
     keyboard::{KeyCode, KeyModifiers},
     Document, Editor, Theme, View,
 };
-use std::borrow::Cow;
+use std::{borrow::Cow, path::PathBuf};
 
 use tui::buffer::Buffer as Surface;
 
@@ -619,6 +619,59 @@ impl EditorView {
         }
     }
 
+    /// Render bufferline at the top
+    pub fn render_bufferline(editor: &Editor, viewport: Rect, surface: &mut Surface) {
+        let scratch = PathBuf::from(SCRATCH_BUFFER_NAME); // default filename to use for scratch buffer
+        surface.clear_with(
+            viewport,
+            editor
+                .theme
+                .try_get("ui.bufferline.background")
+                .unwrap_or_else(|| editor.theme.get("ui.statusline")),
+        );
+
+        let bufferline_active = editor
+            .theme
+            .try_get("ui.bufferline.active")
+            .unwrap_or_else(|| editor.theme.get("ui.statusline.active"));
+
+        let bufferline_inactive = editor
+            .theme
+            .try_get("ui.bufferline")
+            .unwrap_or_else(|| editor.theme.get("ui.statusline.inactive"));
+
+        let mut x = viewport.x;
+        let current_doc = view!(editor).doc;
+
+        for doc in editor.documents() {
+            let fname = doc
+                .path()
+                .unwrap_or(&scratch)
+                .file_name()
+                .unwrap_or_default()
+                .to_str()
+                .unwrap_or_default();
+
+            let style = if current_doc == doc.id() {
+                bufferline_active
+            } else {
+                bufferline_inactive
+            };
+
+            let text = format!(" {}{} ", fname, if doc.is_modified() { "[+]" } else { "" });
+            let used_width = viewport.x.saturating_sub(x);
+            let rem_width = surface.area.width.saturating_sub(used_width);
+
+            x = surface
+                .set_stringn(x, viewport.y, text, rem_width as usize, style)
+                .0;
+
+            if x >= surface.area.right() {
+                break;
+            }
+        }
+    }
+
     pub fn render_gutter(
         editor: &Editor,
         doc: &Document,
@@ -1291,8 +1344,27 @@ impl Component for EditorView {
         // clear with background color
         surface.set_style(area, cx.editor.theme.get("ui.background"));
         let config = cx.editor.config();
+
+        // check if bufferline should be rendered
+        use helix_view::editor::BufferLine;
+        let use_bufferline = match config.bufferline {
+            BufferLine::Always => true,
+            BufferLine::Multiple if cx.editor.documents.len() > 1 => true,
+            _ => false,
+        };
+
+        // -1 for commandline and -1 for bufferline
+        let mut editor_area = area.clip_bottom(1);
+        if use_bufferline {
+            editor_area = editor_area.clip_top(1);
+        }
+
         // if the terminal size suddenly changed, we need to trigger a resize
-        cx.editor.resize(area.clip_bottom(1)); // -1 from bottom for commandline
+        cx.editor.resize(editor_area);
+
+        if use_bufferline {
+            Self::render_bufferline(cx.editor, area.with_height(1), surface);
+        }
 
         for (view, is_focused) in cx.editor.tree.views() {
             let doc = cx.editor.document(view.doc).unwrap();