editor: Add minimap (#26893)

## Overview

This PR adds the minimap feature to the Zed editor, closely following
the [design from Visual Studio
Code](https://code.visualstudio.com/docs/getstarted/userinterface#_minimap).
When configured, a second instance of the editor will appear to the left
of the scrollbar. This instance is not interactive and it has a slimmed
down set of annotations, but it is otherwise just a zoomed-out version
of the main editor instance. A thumb shows the line boundaries of the
main viewport, as well as the progress through the document. Clicking on
a section of code in the minimap will jump the editor to that code.
Dragging the thumb will act like the scrollbar, moving sequentially
through the document.

![screenshot of Zed with three editors open and the minimap enabled,
showing the
slider](https://github.com/user-attachments/assets/4178d23a-a5ea-4e38-b871-06dd2a8f9560)

## New settings

This adds a `minimap` section to the editor settings with the following
keys:

### `show`

When to show the minimap in the editor.
This setting can take three values:
1. Show the minimap if the editor's scrollbar is visible: `"auto"`
2. Always show the minimap: `"always"`
3. Never show the minimap: `"never"` (default)

### `thumb`

When to show the minimap thumb.
This setting can take two values:
1. Show the minimap thumb if the mouse is over the minimap: `"hover"`
2. Always show the minimap thumb: `"always"` (default)

### `width`

The width of the minimap in pixels.

Default: `100`

### `font_size`

The font size of the minimap in pixels.

Default: `2`

## Providing feedback

In order to keep the PR focused on development updates, please use the
discussion thread for feature suggestions and usability feedback: #26894


## Features left to add

- [x] fix scrolling performance
- [x] user settings for enable/disable, width, text size, etc.
- [x] show overview of visible lines in minimap
- [x] clicking on minimap should navigate to the corresponding section
of code
- ~[ ] more prominent highlighting in the minimap editor~
- ~[ ] override scrollbar auto setting to always when minimap is set to
always show~

Release Notes:

- Added minimap for high-level overview and quick navigation of editor
contents.

---------

Co-authored-by: MrSubidubi <dev@bahn.sh>
Co-authored-by: Kirill Bulatov <kirill@zed.dev>

crates/agent/src/inline_assistant.rs

@@ -8,9 +8,10 @@ use anyhow::{Context as _, Result};
 use assistant_settings::AssistantSettings;
 use client::telemetry::Telemetry;
 use collections::{HashMap, HashSet, VecDeque, hash_map};
+use editor::display_map::EditorMargins;
 use editor::{
     Anchor, AnchorRangeExt, CodeActionProvider, Editor, EditorEvent, ExcerptId, ExcerptRange,
-    GutterDimensions, MultiBuffer, MultiBufferSnapshot, ToOffset as _, ToPoint,
+    MultiBuffer, MultiBufferSnapshot, ToOffset as _, ToPoint,
     actions::SelectAll,
     display_map::{
         BlockContext, BlockPlacement, BlockProperties, BlockStyle, CustomBlockId, RenderBlock,
@@ -458,11 +459,11 @@ impl InlineAssistant {
                 )
             });
 
-            let gutter_dimensions = Arc::new(Mutex::new(GutterDimensions::default()));
+            let editor_margins = Arc::new(Mutex::new(EditorMargins::default()));
             let prompt_editor = cx.new(|cx| {
                 PromptEditor::new_buffer(
                     assist_id,
-                    gutter_dimensions.clone(),
+                    editor_margins,
                     self.prompt_history.clone(),
                     prompt_buffer.clone(),
                     codegen.clone(),
@@ -577,11 +578,11 @@ impl InlineAssistant {
             )
         });
 
-        let gutter_dimensions = Arc::new(Mutex::new(GutterDimensions::default()));
+        let editor_margins = Arc::new(Mutex::new(EditorMargins::default()));
         let prompt_editor = cx.new(|cx| {
             PromptEditor::new_buffer(
                 assist_id,
-                gutter_dimensions.clone(),
+                editor_margins,
                 self.prompt_history.clone(),
                 prompt_buffer.clone(),
                 codegen.clone(),
@@ -650,6 +651,7 @@ impl InlineAssistant {
                 height: Some(prompt_editor_height),
                 render: build_assist_editor_renderer(prompt_editor),
                 priority: 0,
+                render_in_minimap: false,
             },
             BlockProperties {
                 style: BlockStyle::Sticky,
@@ -664,6 +666,7 @@ impl InlineAssistant {
                         .into_any_element()
                 }),
                 priority: 0,
+                render_in_minimap: false,
             },
         ];
 
@@ -1405,11 +1408,11 @@ impl InlineAssistant {
 
                     enum DeletedLines {}
                     let mut editor = Editor::for_multibuffer(multi_buffer, None, window, cx);
+                    editor.disable_scrollbars_and_minimap(cx);
                     editor.set_soft_wrap_mode(language::language_settings::SoftWrap::None, cx);
                     editor.set_show_wrap_guides(false, cx);
                     editor.set_show_gutter(false, cx);
                     editor.scroll_manager.set_forbid_vertical_scroll(true);
-                    editor.set_show_scrollbars(false, cx);
                     editor.set_read_only(true);
                     editor.set_show_edit_predictions(Some(false), window, cx);
                     editor.highlight_rows::<DeletedLines>(
@@ -1433,11 +1436,12 @@ impl InlineAssistant {
                             .bg(cx.theme().status().deleted_background)
                             .size_full()
                             .h(height as f32 * cx.window.line_height())
-                            .pl(cx.gutter_dimensions.full_width())
+                            .pl(cx.margins.gutter.full_width())
                             .child(deleted_lines_editor.clone())
                             .into_any_element()
                     }),
                     priority: 0,
+                    render_in_minimap: false,
                 });
             }
 
@@ -1595,9 +1599,9 @@ fn build_assist_editor_renderer(editor: &Entity<PromptEditor<BufferCodegen>>) ->
     let editor = editor.clone();
 
     Arc::new(move |cx: &mut BlockContext| {
-        let gutter_dimensions = editor.read(cx).gutter_dimensions();
+        let editor_margins = editor.read(cx).editor_margins();
 
-        *gutter_dimensions.lock() = *cx.gutter_dimensions;
+        *editor_margins.lock() = *cx.margins;
         editor.clone().into_any_element()
     })
 }