Change cursor shape on mode change

Fixes helix-editor#323. Due to terminal limitations we can only
change the shape of the primary cursor.

book/src/configuration.md

@@ -5,9 +5,26 @@ To override global configuration parameters, create a `config.toml` file located
 * Linux and Mac: `~/.config/helix/config.toml`
 * Windows: `%AppData%\helix\config.toml`
 
+Example config:
+
+```toml
+theme = "onedark"
+
+[editor]
+line-number = "relative"
+mouse = false
+
+[editor.cursor-shape]
+normal = "underline"
+insert = "block"
+
+[editor.file-picker]
+hidden = false
+```
+
 ## Editor
 
-`[editor]` section of the config.
+### `[editor]` Section
 
 | Key | Description | Default |
 |--|--|---------|
@@ -24,7 +41,28 @@ To override global configuration parameters, create a `config.toml` file located
 | `completion-trigger-len` | The min-length of word under cursor to trigger autocompletion | `2` |
 | `auto-info` | Whether to display infoboxes | `true` |
 
-`[editor.filepicker]` section of the config. Sets options for file picker and global search. All but the last key listed in the default file-picker configuration below are IgnoreOptions: whether hidden files and files listed within ignore files are ignored by (not visible in) the helix file picker and global search. There is also one other key, `max-depth` available, which is not defined by default.
+### `[editor.cursor-shape]` Section
+
+Defines the shape of cursor in each mode. Note that due to limitations
+of the terminal environment, only the primary cursor can change shape.
+
+| Key      | Description                                | Default     |
+| ---      | -----------                                | --------    |
+| `normal` | Cursor shape in [normal mode][normal mode] | `block`     |
+| `insert` | Cursor shape in [insert mode][insert mode] | `bar`       |
+| `select` | Cursor shape in [select mode][select mode] | `underline` |
+
+[normal mode]: ./keymap.md#normal-mode
+[insert mode]: ./keymap.md#insert-mode
+[select mode]: ./keymap.md#select--extend-mode
+
+### `[editor.filepicker]` Section
+
+Sets options for file picker and global search. All but the last key listed in
+the default file-picker configuration below are IgnoreOptions: whether hidden
+files and files listed within ignore files are ignored by (not visible in) the
+helix file picker and global search. There is also one other key, `max-depth`
+available, which is not defined by default.
 
 | Key | Description | Default |
 |--|--|---------|

helix-term/src/ui/editor.rs

@@ -250,7 +250,9 @@ impl EditorView {
 
             // Special-case: cursor at end of the rope.
             if range.head == range.anchor && range.head == text.len_chars() {
-                spans.push((cursor_scope, range.head..range.head + 1));
+                if i != primary_idx {
+                    spans.push((cursor_scope, range.head..range.head + 1));
+                }
                 continue;
             }
 
@@ -259,11 +261,15 @@ impl EditorView {
                 // Standard case.
                 let cursor_start = prev_grapheme_boundary(text, range.head);
                 spans.push((selection_scope, range.anchor..cursor_start));
-                spans.push((cursor_scope, cursor_start..range.head));
+                if i != primary_idx {
+                    spans.push((cursor_scope, cursor_start..range.head));
+                }
             } else {
                 // Reverse case.
                 let cursor_end = next_grapheme_boundary(text, range.head);
-                spans.push((cursor_scope, range.head..cursor_end));
+                if i != primary_idx {
+                    spans.push((cursor_scope, range.head..cursor_end));
+                }
                 spans.push((selection_scope, cursor_end..range.anchor));
             }
         }

helix-view/src/editor.rs

@@ -1,6 +1,6 @@
 use crate::{
     clipboard::{get_clipboard_provider, ClipboardProvider},
-    document::SCRATCH_BUFFER_NAME,
+    document::{Mode, SCRATCH_BUFFER_NAME},
     graphics::{CursorKind, Rect},
     theme::{self, Theme},
     tree::{self, Tree},
@@ -9,7 +9,7 @@ use crate::{
 
 use futures_util::future;
 use std::{
-    collections::BTreeMap,
+    collections::{BTreeMap, HashMap},
     io::stdin,
     path::{Path, PathBuf},
     pin::Pin,
@@ -22,7 +22,7 @@ use anyhow::Error;
 
 pub use helix_core::diagnostic::Severity;
 pub use helix_core::register::Registers;
-use helix_core::syntax;
+use helix_core::{hashmap, syntax};
 use helix_core::{Position, Selection};
 
 use serde::Deserialize;
@@ -103,14 +103,37 @@ pub struct Config {
     /// Whether to display infoboxes. Defaults to true.
     pub auto_info: bool,
     pub file_picker: FilePickerConfig,
+    /// Shape for cursor in each mode
+    pub cursor_shape: CursorShapeConfig,
+}
+
+#[derive(Debug, Clone, PartialEq, Deserialize)]
+#[serde(transparent)]
+pub struct CursorShapeConfig(HashMap<Mode, CursorKind>);
+
+impl std::ops::Deref for CursorShapeConfig {
+    type Target = HashMap<Mode, CursorKind>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl Default for CursorShapeConfig {
+    fn default() -> Self {
+        Self(hashmap!(
+            Mode::Insert => CursorKind::Bar,
+            Mode::Normal => CursorKind::Block,
+            Mode::Select => CursorKind::Underline,
+        ))
+    }
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Deserialize)]
 #[serde(rename_all = "kebab-case")]
 pub enum LineNumber {
     /// Show absolute line number
     Absolute,
-
     /// Show relative line number to the primary cursor
     Relative,
 }
@@ -135,6 +158,7 @@ impl Default for Config {
             completion_trigger_len: 2,
             auto_info: true,
             file_picker: FilePickerConfig::default(),
+            cursor_shape: CursorShapeConfig::default(),
         }
     }
 }
@@ -594,9 +618,15 @@ impl Editor {
             let inner = view.inner_area();
             pos.col += inner.x as usize;
             pos.row += inner.y as usize;
-            (Some(pos), CursorKind::Hidden)
+            let cursorkind = self
+                .config
+                .cursor_shape
+                .get(&doc.mode())
+                .copied()
+                .unwrap_or_default();
+            (Some(pos), cursorkind)
         } else {
-            (None, CursorKind::Hidden)
+            (None, CursorKind::default())
         }
     }