1use std::sync::Arc;
2use std::time::Duration;
3use std::{ops::Range, path::PathBuf};
4
5use anyhow::Result;
6use editor::scroll::Autoscroll;
7use editor::{Editor, EditorEvent, SelectionEffects};
8use gpui::{
9 App, ClickEvent, Context, Entity, EventEmitter, FocusHandle, Focusable, InteractiveElement,
10 IntoElement, IsZero, ListState, ParentElement, Render, RetainAllImageCache, Styled,
11 Subscription, Task, WeakEntity, Window, list,
12};
13use language::LanguageRegistry;
14use settings::Settings;
15use theme::ThemeSettings;
16use ui::prelude::*;
17use workspace::item::{Item, ItemHandle};
18use workspace::{Pane, Workspace};
19
20use crate::markdown_elements::ParsedMarkdownElement;
21use crate::markdown_renderer::CheckboxClickedEvent;
22use crate::{
23 MovePageDown, MovePageUp, OpenFollowingPreview, OpenPreview, OpenPreviewToTheSide,
24 markdown_elements::ParsedMarkdown,
25 markdown_parser::parse_markdown,
26 markdown_renderer::{RenderContext, render_markdown_block},
27};
28
29const REPARSE_DEBOUNCE: Duration = Duration::from_millis(200);
30
31pub struct MarkdownPreviewView {
32 workspace: WeakEntity<Workspace>,
33 image_cache: Entity<RetainAllImageCache>,
34 active_editor: Option<EditorState>,
35 focus_handle: FocusHandle,
36 contents: Option<ParsedMarkdown>,
37 selected_block: usize,
38 list_state: ListState,
39 language_registry: Arc<LanguageRegistry>,
40 parsing_markdown_task: Option<Task<Result<()>>>,
41 mode: MarkdownPreviewMode,
42}
43
44#[derive(Clone, Copy, Debug, PartialEq)]
45pub enum MarkdownPreviewMode {
46 /// The preview will always show the contents of the provided editor.
47 Default,
48 /// The preview will "follow" the currently active editor.
49 Follow,
50}
51
52struct EditorState {
53 editor: Entity<Editor>,
54 _subscription: Subscription,
55}
56
57impl MarkdownPreviewView {
58 pub fn register(workspace: &mut Workspace, _window: &mut Window, _cx: &mut Context<Workspace>) {
59 workspace.register_action(move |workspace, _: &OpenPreview, window, cx| {
60 if let Some(editor) = Self::resolve_active_item_as_markdown_editor(workspace, cx) {
61 let view = Self::create_markdown_view(workspace, editor.clone(), window, cx);
62 workspace.active_pane().update(cx, |pane, cx| {
63 if let Some(existing_view_idx) =
64 Self::find_existing_independent_preview_item_idx(pane, &editor, cx)
65 {
66 pane.activate_item(existing_view_idx, true, true, window, cx);
67 } else {
68 pane.add_item(Box::new(view.clone()), true, true, None, window, cx)
69 }
70 });
71 cx.notify();
72 }
73 });
74
75 workspace.register_action(move |workspace, _: &OpenPreviewToTheSide, window, cx| {
76 if let Some(editor) = Self::resolve_active_item_as_markdown_editor(workspace, cx) {
77 let view = Self::create_markdown_view(workspace, editor.clone(), window, cx);
78 let pane = workspace
79 .find_pane_in_direction(workspace::SplitDirection::Right, cx)
80 .unwrap_or_else(|| {
81 workspace.split_pane(
82 workspace.active_pane().clone(),
83 workspace::SplitDirection::Right,
84 window,
85 cx,
86 )
87 });
88 pane.update(cx, |pane, cx| {
89 if let Some(existing_view_idx) =
90 Self::find_existing_independent_preview_item_idx(pane, &editor, cx)
91 {
92 pane.activate_item(existing_view_idx, true, true, window, cx);
93 } else {
94 pane.add_item(Box::new(view.clone()), false, false, None, window, cx)
95 }
96 });
97 editor.focus_handle(cx).focus(window);
98 cx.notify();
99 }
100 });
101
102 workspace.register_action(move |workspace, _: &OpenFollowingPreview, window, cx| {
103 if let Some(editor) = Self::resolve_active_item_as_markdown_editor(workspace, cx) {
104 // Check if there's already a following preview
105 let existing_follow_view_idx = {
106 let active_pane = workspace.active_pane().read(cx);
107 active_pane
108 .items_of_type::<MarkdownPreviewView>()
109 .find(|view| view.read(cx).mode == MarkdownPreviewMode::Follow)
110 .and_then(|view| active_pane.index_for_item(&view))
111 };
112
113 if let Some(existing_follow_view_idx) = existing_follow_view_idx {
114 workspace.active_pane().update(cx, |pane, cx| {
115 pane.activate_item(existing_follow_view_idx, true, true, window, cx);
116 });
117 } else {
118 let view =
119 Self::create_following_markdown_view(workspace, editor.clone(), window, cx);
120 workspace.active_pane().update(cx, |pane, cx| {
121 pane.add_item(Box::new(view.clone()), true, true, None, window, cx)
122 });
123 }
124 cx.notify();
125 }
126 });
127 }
128
129 fn find_existing_independent_preview_item_idx(
130 pane: &Pane,
131 editor: &Entity<Editor>,
132 cx: &App,
133 ) -> Option<usize> {
134 pane.items_of_type::<MarkdownPreviewView>()
135 .find(|view| {
136 let view_read = view.read(cx);
137 // Only look for independent (Default mode) previews, not Follow previews
138 view_read.mode == MarkdownPreviewMode::Default
139 && view_read
140 .active_editor
141 .as_ref()
142 .is_some_and(|active_editor| active_editor.editor == *editor)
143 })
144 .and_then(|view| pane.index_for_item(&view))
145 }
146
147 pub fn resolve_active_item_as_markdown_editor(
148 workspace: &Workspace,
149 cx: &mut Context<Workspace>,
150 ) -> Option<Entity<Editor>> {
151 if let Some(editor) = workspace
152 .active_item(cx)
153 .and_then(|item| item.act_as::<Editor>(cx))
154 && Self::is_markdown_file(&editor, cx)
155 {
156 return Some(editor);
157 }
158 None
159 }
160
161 fn create_markdown_view(
162 workspace: &mut Workspace,
163 editor: Entity<Editor>,
164 window: &mut Window,
165 cx: &mut Context<Workspace>,
166 ) -> Entity<MarkdownPreviewView> {
167 let language_registry = workspace.project().read(cx).languages().clone();
168 let workspace_handle = workspace.weak_handle();
169 MarkdownPreviewView::new(
170 MarkdownPreviewMode::Default,
171 editor,
172 workspace_handle,
173 language_registry,
174 window,
175 cx,
176 )
177 }
178
179 fn create_following_markdown_view(
180 workspace: &mut Workspace,
181 editor: Entity<Editor>,
182 window: &mut Window,
183 cx: &mut Context<Workspace>,
184 ) -> Entity<MarkdownPreviewView> {
185 let language_registry = workspace.project().read(cx).languages().clone();
186 let workspace_handle = workspace.weak_handle();
187 MarkdownPreviewView::new(
188 MarkdownPreviewMode::Follow,
189 editor,
190 workspace_handle,
191 language_registry,
192 window,
193 cx,
194 )
195 }
196
197 pub fn new(
198 mode: MarkdownPreviewMode,
199 active_editor: Entity<Editor>,
200 workspace: WeakEntity<Workspace>,
201 language_registry: Arc<LanguageRegistry>,
202 window: &mut Window,
203 cx: &mut Context<Workspace>,
204 ) -> Entity<Self> {
205 cx.new(|cx| {
206 let list_state = ListState::new(0, gpui::ListAlignment::Top, px(1000.));
207
208 let mut this = Self {
209 selected_block: 0,
210 active_editor: None,
211 focus_handle: cx.focus_handle(),
212 workspace: workspace.clone(),
213 contents: None,
214 list_state,
215 language_registry,
216 parsing_markdown_task: None,
217 image_cache: RetainAllImageCache::new(cx),
218 mode,
219 };
220
221 this.set_editor(active_editor, window, cx);
222
223 if mode == MarkdownPreviewMode::Follow {
224 if let Some(workspace) = &workspace.upgrade() {
225 cx.observe_in(workspace, window, |this, workspace, window, cx| {
226 let item = workspace.read(cx).active_item(cx);
227 this.workspace_updated(item, window, cx);
228 })
229 .detach();
230 } else {
231 log::error!("Failed to listen to workspace updates");
232 }
233 }
234
235 this
236 })
237 }
238
239 fn workspace_updated(
240 &mut self,
241 active_item: Option<Box<dyn ItemHandle>>,
242 window: &mut Window,
243 cx: &mut Context<Self>,
244 ) {
245 if let Some(item) = active_item
246 && item.item_id() != cx.entity_id()
247 && let Some(editor) = item.act_as::<Editor>(cx)
248 && Self::is_markdown_file(&editor, cx)
249 {
250 self.set_editor(editor, window, cx);
251 }
252 }
253
254 pub fn is_markdown_file<V>(editor: &Entity<Editor>, cx: &mut Context<V>) -> bool {
255 let buffer = editor.read(cx).buffer().read(cx);
256 if let Some(buffer) = buffer.as_singleton()
257 && let Some(language) = buffer.read(cx).language()
258 {
259 return language.name() == "Markdown".into();
260 }
261 false
262 }
263
264 fn set_editor(&mut self, editor: Entity<Editor>, window: &mut Window, cx: &mut Context<Self>) {
265 if let Some(active) = &self.active_editor
266 && active.editor == editor
267 {
268 return;
269 }
270
271 let subscription = cx.subscribe_in(
272 &editor,
273 window,
274 |this, editor, event: &EditorEvent, window, cx| {
275 match event {
276 EditorEvent::Edited { .. }
277 | EditorEvent::DirtyChanged
278 | EditorEvent::ExcerptsEdited { .. } => {
279 this.parse_markdown_from_active_editor(true, window, cx);
280 }
281 EditorEvent::SelectionsChanged { .. } => {
282 let selection_range = editor
283 .update(cx, |editor, cx| editor.selections.last::<usize>(cx).range());
284 this.selected_block = this.get_block_index_under_cursor(selection_range);
285 this.list_state.scroll_to_reveal_item(this.selected_block);
286 cx.notify();
287 }
288 _ => {}
289 };
290 },
291 );
292
293 self.active_editor = Some(EditorState {
294 editor,
295 _subscription: subscription,
296 });
297
298 self.parse_markdown_from_active_editor(false, window, cx);
299 }
300
301 fn parse_markdown_from_active_editor(
302 &mut self,
303 wait_for_debounce: bool,
304 window: &mut Window,
305 cx: &mut Context<Self>,
306 ) {
307 if let Some(state) = &self.active_editor {
308 self.parsing_markdown_task = Some(self.parse_markdown_in_background(
309 wait_for_debounce,
310 state.editor.clone(),
311 window,
312 cx,
313 ));
314 }
315 }
316
317 fn parse_markdown_in_background(
318 &mut self,
319 wait_for_debounce: bool,
320 editor: Entity<Editor>,
321 window: &mut Window,
322 cx: &mut Context<Self>,
323 ) -> Task<Result<()>> {
324 let language_registry = self.language_registry.clone();
325
326 cx.spawn_in(window, async move |view, cx| {
327 if wait_for_debounce {
328 // Wait for the user to stop typing
329 cx.background_executor().timer(REPARSE_DEBOUNCE).await;
330 }
331
332 let (contents, file_location) = view.update(cx, |_, cx| {
333 let editor = editor.read(cx);
334 let contents = editor.buffer().read(cx).snapshot(cx).text();
335 let file_location = MarkdownPreviewView::get_folder_for_active_editor(editor, cx);
336 (contents, file_location)
337 })?;
338
339 let parsing_task = cx.background_spawn(async move {
340 parse_markdown(&contents, file_location, Some(language_registry)).await
341 });
342 let contents = parsing_task.await;
343 view.update(cx, move |view, cx| {
344 let markdown_blocks_count = contents.children.len();
345 view.contents = Some(contents);
346 let scroll_top = view.list_state.logical_scroll_top();
347 view.list_state.reset(markdown_blocks_count);
348 view.list_state.scroll_to(scroll_top);
349 cx.notify();
350 })
351 })
352 }
353
354 fn move_cursor_to_block(
355 &self,
356 window: &mut Window,
357 cx: &mut Context<Self>,
358 selection: Range<usize>,
359 ) {
360 if let Some(state) = &self.active_editor {
361 state.editor.update(cx, |editor, cx| {
362 editor.change_selections(
363 SelectionEffects::scroll(Autoscroll::center()),
364 window,
365 cx,
366 |selections| selections.select_ranges(vec![selection]),
367 );
368 window.focus(&editor.focus_handle(cx));
369 });
370 }
371 }
372
373 /// The absolute path of the file that is currently being previewed.
374 fn get_folder_for_active_editor(editor: &Editor, cx: &App) -> Option<PathBuf> {
375 if let Some(file) = editor.file_at(0, cx) {
376 if let Some(file) = file.as_local() {
377 file.abs_path(cx).parent().map(|p| p.to_path_buf())
378 } else {
379 None
380 }
381 } else {
382 None
383 }
384 }
385
386 fn get_block_index_under_cursor(&self, selection_range: Range<usize>) -> usize {
387 let mut block_index = None;
388 let cursor = selection_range.start;
389
390 let mut last_end = 0;
391 if let Some(content) = &self.contents {
392 for (i, block) in content.children.iter().enumerate() {
393 let Some(Range { start, end }) = block.source_range() else {
394 continue;
395 };
396
397 // Check if the cursor is between the last block and the current block
398 if last_end <= cursor && cursor < start {
399 block_index = Some(i.saturating_sub(1));
400 break;
401 }
402
403 if start <= cursor && end >= cursor {
404 block_index = Some(i);
405 break;
406 }
407 last_end = end;
408 }
409
410 if block_index.is_none() && last_end < cursor {
411 block_index = Some(content.children.len().saturating_sub(1));
412 }
413 }
414
415 block_index.unwrap_or_default()
416 }
417
418 fn should_apply_padding_between(
419 current_block: &ParsedMarkdownElement,
420 next_block: Option<&ParsedMarkdownElement>,
421 ) -> bool {
422 !(current_block.is_list_item() && next_block.map(|b| b.is_list_item()).unwrap_or(false))
423 }
424
425 fn scroll_page_up(&mut self, _: &MovePageUp, _window: &mut Window, cx: &mut Context<Self>) {
426 let viewport_height = self.list_state.viewport_bounds().size.height;
427 if viewport_height.is_zero() {
428 return;
429 }
430
431 self.list_state.scroll_by(-viewport_height);
432 cx.notify();
433 }
434
435 fn scroll_page_down(&mut self, _: &MovePageDown, _window: &mut Window, cx: &mut Context<Self>) {
436 let viewport_height = self.list_state.viewport_bounds().size.height;
437 if viewport_height.is_zero() {
438 return;
439 }
440
441 self.list_state.scroll_by(viewport_height);
442 cx.notify();
443 }
444}
445
446impl Focusable for MarkdownPreviewView {
447 fn focus_handle(&self, _: &App) -> gpui::FocusHandle {
448 self.focus_handle.clone()
449 }
450}
451
452impl EventEmitter<()> for MarkdownPreviewView {}
453
454impl Item for MarkdownPreviewView {
455 type Event = ();
456
457 fn tab_icon(&self, _window: &Window, _cx: &App) -> Option<Icon> {
458 Some(Icon::new(IconName::FileDoc))
459 }
460
461 fn tab_content_text(&self, _detail: usize, cx: &App) -> SharedString {
462 self.active_editor
463 .as_ref()
464 .and_then(|editor_state| {
465 let buffer = editor_state.editor.read(cx).buffer().read(cx);
466 let buffer = buffer.as_singleton()?;
467 let file = buffer.read(cx).file()?;
468 let local_file = file.as_local()?;
469 local_file
470 .abs_path(cx)
471 .file_name()
472 .map(|name| format!("Preview {}", name.to_string_lossy()).into())
473 })
474 .unwrap_or_else(|| SharedString::from("Markdown Preview"))
475 }
476
477 fn telemetry_event_text(&self) -> Option<&'static str> {
478 Some("Markdown Preview Opened")
479 }
480
481 fn to_item_events(_event: &Self::Event, _f: impl FnMut(workspace::item::ItemEvent)) {}
482}
483
484impl Render for MarkdownPreviewView {
485 fn render(&mut self, _window: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
486 let buffer_size = ThemeSettings::get_global(cx).buffer_font_size(cx);
487 let buffer_line_height = ThemeSettings::get_global(cx).buffer_line_height;
488
489 v_flex()
490 .image_cache(self.image_cache.clone())
491 .id("MarkdownPreview")
492 .key_context("MarkdownPreview")
493 .track_focus(&self.focus_handle(cx))
494 .on_action(cx.listener(MarkdownPreviewView::scroll_page_up))
495 .on_action(cx.listener(MarkdownPreviewView::scroll_page_down))
496 .size_full()
497 .bg(cx.theme().colors().editor_background)
498 .p_4()
499 .text_size(buffer_size)
500 .line_height(relative(buffer_line_height.value()))
501 .child(div().flex_grow().map(|this| {
502 this.child(
503 list(
504 self.list_state.clone(),
505 cx.processor(|this, ix, window, cx| {
506 let Some(contents) = &this.contents else {
507 return div().into_any();
508 };
509
510 let mut render_cx =
511 RenderContext::new(Some(this.workspace.clone()), window, cx)
512 .with_checkbox_clicked_callback(cx.listener(
513 move |this, e: &CheckboxClickedEvent, window, cx| {
514 if let Some(editor) = this
515 .active_editor
516 .as_ref()
517 .map(|s| s.editor.clone())
518 {
519 editor.update(cx, |editor, cx| {
520 let task_marker =
521 if e.checked() { "[x]" } else { "[ ]" };
522
523 editor.edit(
524 vec![(e.source_range(), task_marker)],
525 cx,
526 );
527 });
528 this.parse_markdown_from_active_editor(
529 false, window, cx,
530 );
531 cx.notify();
532 }
533 },
534 ));
535
536 let block = contents.children.get(ix).unwrap();
537 let rendered_block = render_markdown_block(block, &mut render_cx);
538
539 let should_apply_padding = Self::should_apply_padding_between(
540 block,
541 contents.children.get(ix + 1),
542 );
543
544 div()
545 .id(ix)
546 .when(should_apply_padding, |this| {
547 this.pb(render_cx.scaled_rems(0.75))
548 })
549 .group("markdown-block")
550 .on_click(cx.listener(
551 move |this, event: &ClickEvent, window, cx| {
552 if event.click_count() == 2
553 && let Some(source_range) = this
554 .contents
555 .as_ref()
556 .and_then(|c| c.children.get(ix))
557 .and_then(|block: &ParsedMarkdownElement| {
558 block.source_range()
559 })
560 {
561 this.move_cursor_to_block(
562 window,
563 cx,
564 source_range.start..source_range.start,
565 );
566 }
567 },
568 ))
569 .map(move |container| {
570 let indicator = div()
571 .h_full()
572 .w(px(4.0))
573 .when(ix == this.selected_block, |this| {
574 this.bg(cx.theme().colors().border)
575 })
576 .group_hover("markdown-block", |s| {
577 if ix == this.selected_block {
578 s
579 } else {
580 s.bg(cx.theme().colors().border_variant)
581 }
582 })
583 .rounded_xs();
584
585 container.child(
586 div()
587 .relative()
588 .child(
589 div()
590 .pl(render_cx.scaled_rems(1.0))
591 .child(rendered_block),
592 )
593 .child(indicator.absolute().left_0().top_0()),
594 )
595 })
596 .into_any()
597 }),
598 )
599 .size_full(),
600 )
601 }))
602 }
603}