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 = Self::create_following_markdown_view(workspace, editor, window, cx);
119 workspace.active_pane().update(cx, |pane, cx| {
120 pane.add_item(Box::new(view.clone()), true, true, None, window, cx)
121 });
122 }
123 cx.notify();
124 }
125 });
126 }
127
128 fn find_existing_independent_preview_item_idx(
129 pane: &Pane,
130 editor: &Entity<Editor>,
131 cx: &App,
132 ) -> Option<usize> {
133 pane.items_of_type::<MarkdownPreviewView>()
134 .find(|view| {
135 let view_read = view.read(cx);
136 // Only look for independent (Default mode) previews, not Follow previews
137 view_read.mode == MarkdownPreviewMode::Default
138 && view_read
139 .active_editor
140 .as_ref()
141 .is_some_and(|active_editor| active_editor.editor == *editor)
142 })
143 .and_then(|view| pane.index_for_item(&view))
144 }
145
146 pub fn resolve_active_item_as_markdown_editor(
147 workspace: &Workspace,
148 cx: &mut Context<Workspace>,
149 ) -> Option<Entity<Editor>> {
150 if let Some(editor) = workspace
151 .active_item(cx)
152 .and_then(|item| item.act_as::<Editor>(cx))
153 && Self::is_markdown_file(&editor, cx)
154 {
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 {
249 self.set_editor(editor, window, cx);
250 }
251 }
252
253 pub fn is_markdown_file<V>(editor: &Entity<Editor>, cx: &mut Context<V>) -> bool {
254 let buffer = editor.read(cx).buffer().read(cx);
255 if let Some(buffer) = buffer.as_singleton()
256 && let Some(language) = buffer.read(cx).language()
257 {
258 return language.name() == "Markdown".into();
259 }
260 false
261 }
262
263 fn set_editor(&mut self, editor: Entity<Editor>, window: &mut Window, cx: &mut Context<Self>) {
264 if let Some(active) = &self.active_editor
265 && active.editor == editor
266 {
267 return;
268 }
269
270 let subscription = cx.subscribe_in(
271 &editor,
272 window,
273 |this, editor, event: &EditorEvent, window, cx| {
274 match event {
275 EditorEvent::Edited { .. }
276 | EditorEvent::DirtyChanged
277 | EditorEvent::ExcerptsEdited { .. } => {
278 this.parse_markdown_from_active_editor(true, window, cx);
279 }
280 EditorEvent::SelectionsChanged { .. } => {
281 let selection_range = editor
282 .update(cx, |editor, cx| editor.selections.last::<usize>(cx).range());
283 this.selected_block = this.get_block_index_under_cursor(selection_range);
284 this.list_state.scroll_to_reveal_item(this.selected_block);
285 cx.notify();
286 }
287 _ => {}
288 };
289 },
290 );
291
292 self.active_editor = Some(EditorState {
293 editor,
294 _subscription: subscription,
295 });
296
297 self.parse_markdown_from_active_editor(false, window, cx);
298 }
299
300 fn parse_markdown_from_active_editor(
301 &mut self,
302 wait_for_debounce: bool,
303 window: &mut Window,
304 cx: &mut Context<Self>,
305 ) {
306 if let Some(state) = &self.active_editor {
307 self.parsing_markdown_task = Some(self.parse_markdown_in_background(
308 wait_for_debounce,
309 state.editor.clone(),
310 window,
311 cx,
312 ));
313 }
314 }
315
316 fn parse_markdown_in_background(
317 &mut self,
318 wait_for_debounce: bool,
319 editor: Entity<Editor>,
320 window: &mut Window,
321 cx: &mut Context<Self>,
322 ) -> Task<Result<()>> {
323 let language_registry = self.language_registry.clone();
324
325 cx.spawn_in(window, async move |view, cx| {
326 if wait_for_debounce {
327 // Wait for the user to stop typing
328 cx.background_executor().timer(REPARSE_DEBOUNCE).await;
329 }
330
331 let (contents, file_location) = view.update(cx, |_, cx| {
332 let editor = editor.read(cx);
333 let contents = editor.buffer().read(cx).snapshot(cx).text();
334 let file_location = MarkdownPreviewView::get_folder_for_active_editor(editor, cx);
335 (contents, file_location)
336 })?;
337
338 let parsing_task = cx.background_spawn(async move {
339 parse_markdown(&contents, file_location, Some(language_registry)).await
340 });
341 let contents = parsing_task.await;
342 view.update(cx, move |view, cx| {
343 let markdown_blocks_count = contents.children.len();
344 view.contents = Some(contents);
345 let scroll_top = view.list_state.logical_scroll_top();
346 view.list_state.reset(markdown_blocks_count);
347 view.list_state.scroll_to(scroll_top);
348 cx.notify();
349 })
350 })
351 }
352
353 fn move_cursor_to_block(
354 &self,
355 window: &mut Window,
356 cx: &mut Context<Self>,
357 selection: Range<usize>,
358 ) {
359 if let Some(state) = &self.active_editor {
360 state.editor.update(cx, |editor, cx| {
361 editor.change_selections(
362 SelectionEffects::scroll(Autoscroll::center()),
363 window,
364 cx,
365 |selections| selections.select_ranges(vec![selection]),
366 );
367 window.focus(&editor.focus_handle(cx));
368 });
369 }
370 }
371
372 /// The absolute path of the file that is currently being previewed.
373 fn get_folder_for_active_editor(editor: &Editor, cx: &App) -> Option<PathBuf> {
374 if let Some(file) = editor.file_at(0, cx) {
375 if let Some(file) = file.as_local() {
376 file.abs_path(cx).parent().map(|p| p.to_path_buf())
377 } else {
378 None
379 }
380 } else {
381 None
382 }
383 }
384
385 fn get_block_index_under_cursor(&self, selection_range: Range<usize>) -> usize {
386 let mut block_index = None;
387 let cursor = selection_range.start;
388
389 let mut last_end = 0;
390 if let Some(content) = &self.contents {
391 for (i, block) in content.children.iter().enumerate() {
392 let Some(Range { start, end }) = block.source_range() else {
393 continue;
394 };
395
396 // Check if the cursor is between the last block and the current block
397 if last_end <= cursor && cursor < start {
398 block_index = Some(i.saturating_sub(1));
399 break;
400 }
401
402 if start <= cursor && end >= cursor {
403 block_index = Some(i);
404 break;
405 }
406 last_end = end;
407 }
408
409 if block_index.is_none() && last_end < cursor {
410 block_index = Some(content.children.len().saturating_sub(1));
411 }
412 }
413
414 block_index.unwrap_or_default()
415 }
416
417 fn should_apply_padding_between(
418 current_block: &ParsedMarkdownElement,
419 next_block: Option<&ParsedMarkdownElement>,
420 ) -> bool {
421 !(current_block.is_list_item() && next_block.map(|b| b.is_list_item()).unwrap_or(false))
422 }
423
424 fn scroll_page_up(&mut self, _: &MovePageUp, _window: &mut Window, cx: &mut Context<Self>) {
425 let viewport_height = self.list_state.viewport_bounds().size.height;
426 if viewport_height.is_zero() {
427 return;
428 }
429
430 self.list_state.scroll_by(-viewport_height);
431 cx.notify();
432 }
433
434 fn scroll_page_down(&mut self, _: &MovePageDown, _window: &mut Window, cx: &mut Context<Self>) {
435 let viewport_height = self.list_state.viewport_bounds().size.height;
436 if viewport_height.is_zero() {
437 return;
438 }
439
440 self.list_state.scroll_by(viewport_height);
441 cx.notify();
442 }
443}
444
445impl Focusable for MarkdownPreviewView {
446 fn focus_handle(&self, _: &App) -> gpui::FocusHandle {
447 self.focus_handle.clone()
448 }
449}
450
451impl EventEmitter<()> for MarkdownPreviewView {}
452
453impl Item for MarkdownPreviewView {
454 type Event = ();
455
456 fn tab_icon(&self, _window: &Window, _cx: &App) -> Option<Icon> {
457 Some(Icon::new(IconName::FileDoc))
458 }
459
460 fn tab_content_text(&self, _detail: usize, cx: &App) -> SharedString {
461 self.active_editor
462 .as_ref()
463 .and_then(|editor_state| {
464 let buffer = editor_state.editor.read(cx).buffer().read(cx);
465 let buffer = buffer.as_singleton()?;
466 let file = buffer.read(cx).file()?;
467 let local_file = file.as_local()?;
468 local_file
469 .abs_path(cx)
470 .file_name()
471 .map(|name| format!("Preview {}", name.to_string_lossy()).into())
472 })
473 .unwrap_or_else(|| SharedString::from("Markdown Preview"))
474 }
475
476 fn telemetry_event_text(&self) -> Option<&'static str> {
477 Some("Markdown Preview Opened")
478 }
479
480 fn to_item_events(_event: &Self::Event, _f: impl FnMut(workspace::item::ItemEvent)) {}
481}
482
483impl Render for MarkdownPreviewView {
484 fn render(&mut self, _window: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
485 let buffer_size = ThemeSettings::get_global(cx).buffer_font_size(cx);
486 let buffer_line_height = ThemeSettings::get_global(cx).buffer_line_height;
487
488 v_flex()
489 .image_cache(self.image_cache.clone())
490 .id("MarkdownPreview")
491 .key_context("MarkdownPreview")
492 .track_focus(&self.focus_handle(cx))
493 .on_action(cx.listener(MarkdownPreviewView::scroll_page_up))
494 .on_action(cx.listener(MarkdownPreviewView::scroll_page_down))
495 .size_full()
496 .bg(cx.theme().colors().editor_background)
497 .p_4()
498 .text_size(buffer_size)
499 .line_height(relative(buffer_line_height.value()))
500 .child(div().flex_grow().map(|this| {
501 this.child(
502 list(
503 self.list_state.clone(),
504 cx.processor(|this, ix, window, cx| {
505 let Some(contents) = &this.contents else {
506 return div().into_any();
507 };
508
509 let mut render_cx =
510 RenderContext::new(Some(this.workspace.clone()), window, cx)
511 .with_checkbox_clicked_callback(cx.listener(
512 move |this, e: &CheckboxClickedEvent, window, cx| {
513 if let Some(editor) = this
514 .active_editor
515 .as_ref()
516 .map(|s| s.editor.clone())
517 {
518 editor.update(cx, |editor, cx| {
519 let task_marker =
520 if e.checked() { "[x]" } else { "[ ]" };
521
522 editor.edit(
523 vec![(e.source_range(), task_marker)],
524 cx,
525 );
526 });
527 this.parse_markdown_from_active_editor(
528 false, window, cx,
529 );
530 cx.notify();
531 }
532 },
533 ));
534
535 let block = contents.children.get(ix).unwrap();
536 let rendered_block = render_markdown_block(block, &mut render_cx);
537
538 let should_apply_padding = Self::should_apply_padding_between(
539 block,
540 contents.children.get(ix + 1),
541 );
542
543 div()
544 .id(ix)
545 .when(should_apply_padding, |this| {
546 this.pb(render_cx.scaled_rems(0.75))
547 })
548 .group("markdown-block")
549 .on_click(cx.listener(
550 move |this, event: &ClickEvent, window, cx| {
551 if event.click_count() == 2
552 && let Some(source_range) = this
553 .contents
554 .as_ref()
555 .and_then(|c| c.children.get(ix))
556 .and_then(|block: &ParsedMarkdownElement| {
557 block.source_range()
558 })
559 {
560 this.move_cursor_to_block(
561 window,
562 cx,
563 source_range.start..source_range.start,
564 );
565 }
566 },
567 ))
568 .map(move |container| {
569 let indicator = div()
570 .h_full()
571 .w(px(4.0))
572 .when(ix == this.selected_block, |this| {
573 this.bg(cx.theme().colors().border)
574 })
575 .group_hover("markdown-block", |s| {
576 if ix == this.selected_block {
577 s
578 } else {
579 s.bg(cx.theme().colors().border_variant)
580 }
581 })
582 .rounded_xs();
583
584 container.child(
585 div()
586 .relative()
587 .child(
588 div()
589 .pl(render_cx.scaled_rems(1.0))
590 .child(rendered_block),
591 )
592 .child(indicator.absolute().left_0().top_0()),
593 )
594 })
595 .into_any()
596 }),
597 )
598 .size_full(),
599 )
600 }))
601 }
602}