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 return Some(editor);
156 }
157 None
158 }
159
160 fn create_markdown_view(
161 workspace: &mut Workspace,
162 editor: Entity<Editor>,
163 window: &mut Window,
164 cx: &mut Context<Workspace>,
165 ) -> Entity<MarkdownPreviewView> {
166 let language_registry = workspace.project().read(cx).languages().clone();
167 let workspace_handle = workspace.weak_handle();
168 MarkdownPreviewView::new(
169 MarkdownPreviewMode::Default,
170 editor,
171 workspace_handle,
172 language_registry,
173 window,
174 cx,
175 )
176 }
177
178 fn create_following_markdown_view(
179 workspace: &mut Workspace,
180 editor: Entity<Editor>,
181 window: &mut Window,
182 cx: &mut Context<Workspace>,
183 ) -> Entity<MarkdownPreviewView> {
184 let language_registry = workspace.project().read(cx).languages().clone();
185 let workspace_handle = workspace.weak_handle();
186 MarkdownPreviewView::new(
187 MarkdownPreviewMode::Follow,
188 editor,
189 workspace_handle,
190 language_registry,
191 window,
192 cx,
193 )
194 }
195
196 pub fn new(
197 mode: MarkdownPreviewMode,
198 active_editor: Entity<Editor>,
199 workspace: WeakEntity<Workspace>,
200 language_registry: Arc<LanguageRegistry>,
201 window: &mut Window,
202 cx: &mut Context<Workspace>,
203 ) -> Entity<Self> {
204 cx.new(|cx| {
205 let list_state = ListState::new(0, gpui::ListAlignment::Top, px(1000.));
206
207 let mut this = Self {
208 selected_block: 0,
209 active_editor: None,
210 focus_handle: cx.focus_handle(),
211 workspace: workspace.clone(),
212 contents: None,
213 list_state,
214 language_registry,
215 parsing_markdown_task: None,
216 image_cache: RetainAllImageCache::new(cx),
217 mode,
218 };
219
220 this.set_editor(active_editor, window, cx);
221
222 if mode == MarkdownPreviewMode::Follow {
223 if let Some(workspace) = &workspace.upgrade() {
224 cx.observe_in(workspace, window, |this, workspace, window, cx| {
225 let item = workspace.read(cx).active_item(cx);
226 this.workspace_updated(item, window, cx);
227 })
228 .detach();
229 } else {
230 log::error!("Failed to listen to workspace updates");
231 }
232 }
233
234 this
235 })
236 }
237
238 fn workspace_updated(
239 &mut self,
240 active_item: Option<Box<dyn ItemHandle>>,
241 window: &mut Window,
242 cx: &mut Context<Self>,
243 ) {
244 if let Some(item) = active_item
245 && item.item_id() != cx.entity_id()
246 && let Some(editor) = item.act_as::<Editor>(cx)
247 && Self::is_markdown_file(&editor, cx) {
248 self.set_editor(editor, window, cx);
249 }
250 }
251
252 pub fn is_markdown_file<V>(editor: &Entity<Editor>, cx: &mut Context<V>) -> bool {
253 let buffer = editor.read(cx).buffer().read(cx);
254 if let Some(buffer) = buffer.as_singleton()
255 && let Some(language) = buffer.read(cx).language() {
256 return language.name() == "Markdown".into();
257 }
258 false
259 }
260
261 fn set_editor(&mut self, editor: Entity<Editor>, window: &mut Window, cx: &mut Context<Self>) {
262 if let Some(active) = &self.active_editor
263 && active.editor == editor {
264 return;
265 }
266
267 let subscription = cx.subscribe_in(
268 &editor,
269 window,
270 |this, editor, event: &EditorEvent, window, cx| {
271 match event {
272 EditorEvent::Edited { .. }
273 | EditorEvent::DirtyChanged
274 | EditorEvent::ExcerptsEdited { .. } => {
275 this.parse_markdown_from_active_editor(true, window, cx);
276 }
277 EditorEvent::SelectionsChanged { .. } => {
278 let selection_range = editor
279 .update(cx, |editor, cx| editor.selections.last::<usize>(cx).range());
280 this.selected_block = this.get_block_index_under_cursor(selection_range);
281 this.list_state.scroll_to_reveal_item(this.selected_block);
282 cx.notify();
283 }
284 _ => {}
285 };
286 },
287 );
288
289 self.active_editor = Some(EditorState {
290 editor,
291 _subscription: subscription,
292 });
293
294 self.parse_markdown_from_active_editor(false, window, cx);
295 }
296
297 fn parse_markdown_from_active_editor(
298 &mut self,
299 wait_for_debounce: bool,
300 window: &mut Window,
301 cx: &mut Context<Self>,
302 ) {
303 if let Some(state) = &self.active_editor {
304 self.parsing_markdown_task = Some(self.parse_markdown_in_background(
305 wait_for_debounce,
306 state.editor.clone(),
307 window,
308 cx,
309 ));
310 }
311 }
312
313 fn parse_markdown_in_background(
314 &mut self,
315 wait_for_debounce: bool,
316 editor: Entity<Editor>,
317 window: &mut Window,
318 cx: &mut Context<Self>,
319 ) -> Task<Result<()>> {
320 let language_registry = self.language_registry.clone();
321
322 cx.spawn_in(window, async move |view, cx| {
323 if wait_for_debounce {
324 // Wait for the user to stop typing
325 cx.background_executor().timer(REPARSE_DEBOUNCE).await;
326 }
327
328 let (contents, file_location) = view.update(cx, |_, cx| {
329 let editor = editor.read(cx);
330 let contents = editor.buffer().read(cx).snapshot(cx).text();
331 let file_location = MarkdownPreviewView::get_folder_for_active_editor(editor, cx);
332 (contents, file_location)
333 })?;
334
335 let parsing_task = cx.background_spawn(async move {
336 parse_markdown(&contents, file_location, Some(language_registry)).await
337 });
338 let contents = parsing_task.await;
339 view.update(cx, move |view, cx| {
340 let markdown_blocks_count = contents.children.len();
341 view.contents = Some(contents);
342 let scroll_top = view.list_state.logical_scroll_top();
343 view.list_state.reset(markdown_blocks_count);
344 view.list_state.scroll_to(scroll_top);
345 cx.notify();
346 })
347 })
348 }
349
350 fn move_cursor_to_block(
351 &self,
352 window: &mut Window,
353 cx: &mut Context<Self>,
354 selection: Range<usize>,
355 ) {
356 if let Some(state) = &self.active_editor {
357 state.editor.update(cx, |editor, cx| {
358 editor.change_selections(
359 SelectionEffects::scroll(Autoscroll::center()),
360 window,
361 cx,
362 |selections| selections.select_ranges(vec![selection]),
363 );
364 window.focus(&editor.focus_handle(cx));
365 });
366 }
367 }
368
369 /// The absolute path of the file that is currently being previewed.
370 fn get_folder_for_active_editor(editor: &Editor, cx: &App) -> Option<PathBuf> {
371 if let Some(file) = editor.file_at(0, cx) {
372 if let Some(file) = file.as_local() {
373 file.abs_path(cx).parent().map(|p| p.to_path_buf())
374 } else {
375 None
376 }
377 } else {
378 None
379 }
380 }
381
382 fn get_block_index_under_cursor(&self, selection_range: Range<usize>) -> usize {
383 let mut block_index = None;
384 let cursor = selection_range.start;
385
386 let mut last_end = 0;
387 if let Some(content) = &self.contents {
388 for (i, block) in content.children.iter().enumerate() {
389 let Some(Range { start, end }) = block.source_range() else {
390 continue;
391 };
392
393 // Check if the cursor is between the last block and the current block
394 if last_end <= cursor && cursor < start {
395 block_index = Some(i.saturating_sub(1));
396 break;
397 }
398
399 if start <= cursor && end >= cursor {
400 block_index = Some(i);
401 break;
402 }
403 last_end = end;
404 }
405
406 if block_index.is_none() && last_end < cursor {
407 block_index = Some(content.children.len().saturating_sub(1));
408 }
409 }
410
411 block_index.unwrap_or_default()
412 }
413
414 fn should_apply_padding_between(
415 current_block: &ParsedMarkdownElement,
416 next_block: Option<&ParsedMarkdownElement>,
417 ) -> bool {
418 !(current_block.is_list_item() && next_block.map(|b| b.is_list_item()).unwrap_or(false))
419 }
420
421 fn scroll_page_up(&mut self, _: &MovePageUp, _window: &mut Window, cx: &mut Context<Self>) {
422 let viewport_height = self.list_state.viewport_bounds().size.height;
423 if viewport_height.is_zero() {
424 return;
425 }
426
427 self.list_state.scroll_by(-viewport_height);
428 cx.notify();
429 }
430
431 fn scroll_page_down(&mut self, _: &MovePageDown, _window: &mut Window, cx: &mut Context<Self>) {
432 let viewport_height = self.list_state.viewport_bounds().size.height;
433 if viewport_height.is_zero() {
434 return;
435 }
436
437 self.list_state.scroll_by(viewport_height);
438 cx.notify();
439 }
440}
441
442impl Focusable for MarkdownPreviewView {
443 fn focus_handle(&self, _: &App) -> gpui::FocusHandle {
444 self.focus_handle.clone()
445 }
446}
447
448impl EventEmitter<()> for MarkdownPreviewView {}
449
450impl Item for MarkdownPreviewView {
451 type Event = ();
452
453 fn tab_icon(&self, _window: &Window, _cx: &App) -> Option<Icon> {
454 Some(Icon::new(IconName::FileDoc))
455 }
456
457 fn tab_content_text(&self, _detail: usize, cx: &App) -> SharedString {
458 self.active_editor
459 .as_ref()
460 .and_then(|editor_state| {
461 let buffer = editor_state.editor.read(cx).buffer().read(cx);
462 let buffer = buffer.as_singleton()?;
463 let file = buffer.read(cx).file()?;
464 let local_file = file.as_local()?;
465 local_file
466 .abs_path(cx)
467 .file_name()
468 .map(|name| format!("Preview {}", name.to_string_lossy()).into())
469 })
470 .unwrap_or_else(|| SharedString::from("Markdown Preview"))
471 }
472
473 fn telemetry_event_text(&self) -> Option<&'static str> {
474 Some("Markdown Preview Opened")
475 }
476
477 fn to_item_events(_event: &Self::Event, _f: impl FnMut(workspace::item::ItemEvent)) {}
478}
479
480impl Render for MarkdownPreviewView {
481 fn render(&mut self, _window: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
482 let buffer_size = ThemeSettings::get_global(cx).buffer_font_size(cx);
483 let buffer_line_height = ThemeSettings::get_global(cx).buffer_line_height;
484
485 v_flex()
486 .image_cache(self.image_cache.clone())
487 .id("MarkdownPreview")
488 .key_context("MarkdownPreview")
489 .track_focus(&self.focus_handle(cx))
490 .on_action(cx.listener(MarkdownPreviewView::scroll_page_up))
491 .on_action(cx.listener(MarkdownPreviewView::scroll_page_down))
492 .size_full()
493 .bg(cx.theme().colors().editor_background)
494 .p_4()
495 .text_size(buffer_size)
496 .line_height(relative(buffer_line_height.value()))
497 .child(div().flex_grow().map(|this| {
498 this.child(
499 list(
500 self.list_state.clone(),
501 cx.processor(|this, ix, window, cx| {
502 let Some(contents) = &this.contents else {
503 return div().into_any();
504 };
505
506 let mut render_cx =
507 RenderContext::new(Some(this.workspace.clone()), window, cx)
508 .with_checkbox_clicked_callback(cx.listener(
509 move |this, e: &CheckboxClickedEvent, window, cx| {
510 if let Some(editor) = this
511 .active_editor
512 .as_ref()
513 .map(|s| s.editor.clone())
514 {
515 editor.update(cx, |editor, cx| {
516 let task_marker =
517 if e.checked() { "[x]" } else { "[ ]" };
518
519 editor.edit(
520 vec![(e.source_range(), task_marker)],
521 cx,
522 );
523 });
524 this.parse_markdown_from_active_editor(
525 false, window, cx,
526 );
527 cx.notify();
528 }
529 },
530 ));
531
532 let block = contents.children.get(ix).unwrap();
533 let rendered_block = render_markdown_block(block, &mut render_cx);
534
535 let should_apply_padding = Self::should_apply_padding_between(
536 block,
537 contents.children.get(ix + 1),
538 );
539
540 div()
541 .id(ix)
542 .when(should_apply_padding, |this| {
543 this.pb(render_cx.scaled_rems(0.75))
544 })
545 .group("markdown-block")
546 .on_click(cx.listener(
547 move |this, event: &ClickEvent, window, cx| {
548 if event.click_count() == 2
549 && let Some(source_range) = this
550 .contents
551 .as_ref()
552 .and_then(|c| c.children.get(ix))
553 .and_then(|block: &ParsedMarkdownElement| {
554 block.source_range()
555 })
556 {
557 this.move_cursor_to_block(
558 window,
559 cx,
560 source_range.start..source_range.start,
561 );
562 }
563 },
564 ))
565 .map(move |container| {
566 let indicator = div()
567 .h_full()
568 .w(px(4.0))
569 .when(ix == this.selected_block, |this| {
570 this.bg(cx.theme().colors().border)
571 })
572 .group_hover("markdown-block", |s| {
573 if ix == this.selected_block {
574 s
575 } else {
576 s.bg(cx.theme().colors().border_variant)
577 }
578 })
579 .rounded_xs();
580
581 container.child(
582 div()
583 .relative()
584 .child(
585 div()
586 .pl(render_cx.scaled_rems(1.0))
587 .child(rendered_block),
588 )
589 .child(indicator.absolute().left_0().top_0()),
590 )
591 })
592 .into_any()
593 }),
594 )
595 .size_full(),
596 )
597 }))
598 }
599}