M3: in full screen a double-click selects a word, and full screen selects the Select tool (#1459)

Review on #2070 (CodeRabbit):
- A click turned the page on its release, so a double-click's second click,
  meant to select a word as the PR promises, landed on the next page. The
  turn now waits out egui's double-click time, and is dropped when a
  selection appears or full screen is left; a double-click on blank page
  area still turns once.
- Entering full screen from another tool left it on, and clicks only turn
  pages with Select while the quick tools are hidden. Full screen now selects
  Select and gives the earlier tool back on leaving, as Space's temporary
  Hand tool does.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Gv2WwdgjmBz33GWkwgNn3Q

crates/ui-egui/src/canvas.rs

@@ -470,6 +470,9 @@ pub struct DocView {
     clicks: u32,
     last_press_time: f64,
     last_press_pos: Option<Pos2>,
+    /// Full screen: a click's page turn, when it falls due (input time) and which way. It waits
+    /// out the double-click time, as the click may be the first of a double-click selecting a word.
+    present_turn: Option<(f64, bool)>,
     last_queue: Vec<RenderRequest>,
     /// Finished renders wait in the pool instead of reaching the view (tests): what the view
     /// shows before a raster arrives can be looked at however fast the renderer is.
@@ -761,6 +764,7 @@ impl DocView {
             clicks: 0,
             last_press_time: 0.0,
             last_press_pos: None,
+            present_turn: None,
             last_queue: Vec::new(),
             hold_rasters: false,
             viewport_w: 800.0,
@@ -4042,9 +4046,24 @@ pub fn document_area(app: &mut PdfCraftApp, index: usize, ui: &mut egui::Ui) {
         Some(comments::CanvasAction::CopyImageFile(p, i)) => image_action = Some(crate::edit_text_ui::ImageAction::CopyFile(p, i)),
         None => {}
     }
-    // Full screen: the click turned the page unless it did something else first.
+    // Full screen: the click turns the page unless it did something else first. It waits out the
+    // double-click time: turning on the first click's release sent a double-click's second click,
+    // meant to select a word, to the next page (review on #2070). A selection cancels it, and so
+    // does leaving full screen; a double-click elsewhere still turns once.
+    let now = ui.input(|i| i.time);
     if present_click && clicked_link.is_none() && view.selection.is_none() && view.clicks < 2 {
-        view.step_page(!present_back);
+        let delay = ui.ctx().options(|o| o.input_options.max_double_click_delay);
+        view.present_turn = Some((now + delay, !present_back));
+    }
+    if let Some((due, forward)) = view.present_turn {
+        if view.selection.is_some() || view.presentation.is_none() {
+            view.present_turn = None;
+        } else if now >= due {
+            view.present_turn = None;
+            view.step_page(forward);
+        } else {
+            ui.ctx().request_repaint_after(std::time::Duration::from_secs_f64((due - now).max(0.0)));
+        }
     }
     match clicked_link {
         Some(LinkTarget::Page(p, dest)) => view.go_to_dest(p, dest, info),

crates/ui-egui/src/lib.rs

@@ -521,6 +521,8 @@ pub struct PdfCraftApp {
     pub quick_tool: QuickTool,
     /// The tool to go back to when Space, held for a temporary Hand, is released.
     space_hand: Option<QuickTool>,
+    /// The tool before full screen, given back on leaving it (see [`Self::apply_full_screen`]).
+    full_screen_tool: Option<QuickTool>,
     /// Comment author, per-tool colours and widths, pin.
     pub comment_prefs: comments::CommentPrefs,
     /// Resolved colours, including the current OS theme when following the system.
@@ -910,6 +912,7 @@ impl PdfCraftApp {
             right_panel_closed: false,
             quick_tool: QuickTool::Select,
             space_hand: None,
+            full_screen_tool: None,
             comment_prefs: Default::default(),
             theme: ThemeKind::Light,
             theme_preference: ThemePreference::Light,
@@ -1597,6 +1600,14 @@ impl PdfCraftApp {
     /// time fitted to the screen while it is on (Acrobat's Full Screen Mode, #379, #1459), and
     /// gets its display back when it is off.
     pub fn apply_full_screen(&mut self, on: bool) {
+        // A click turns the page only with the Select tool, and full screen hides the tools:
+        // select it there, and give the tool back on leaving (review on #2070).
+        if on && !self.full_screen {
+            self.full_screen_tool = Some(self.quick_tool);
+            self.quick_tool = QuickTool::Select;
+        } else if !on && let Some(tool) = self.full_screen_tool.take() {
+            self.quick_tool = tool;
+        }
         self.full_screen = on;
         for view in &mut self.views {
             if on {

crates/ui-egui/tests/ui_group/text_select.rs

@@ -544,3 +544,50 @@ fn coalesced_primary_clicks_select_line_then_spaced_click_clears() {
         assert_eq!(doc.saved_bytes(), saved);
     }
 }
+
+/// Review on #2070: in full screen a click goes forward a page, but a double-click selects the
+/// word and stays: the click waits out the double-click time before turning. Turning on the first
+/// click's release had sent the second click to the next page. Leaving full screen meanwhile
+/// drops the pending turn.
+#[test]
+fn full_screen_double_click_selects_a_word_and_stays_on_the_page() {
+    // The same page twice.
+    let two_pages = String::from_utf8(two_lines())
+        .unwrap()
+        .replace("/Kids [3 0 R] /Count 1", "/Kids [3 0 R 6 0 R] /Count 2")
+        .replace(
+            "trailer",
+            "6 0 obj << /Type /Page /Parent 2 0 R /MediaBox [0 0 300 200] /Contents 4 0 R /Resources << /Font << /F1 5 0 R >> >> >> endobj\ntrailer",
+        )
+        .into_bytes();
+    let (mut h, _) = harness_with(two_pages, |_| {});
+    h.state_mut().apply_full_screen(true);
+    crate::support::wait_until(&mut h, "the page in full screen", |app| app.views[0].glyph_screen_pos(0, 5).is_some() && !app.render_pending());
+    let at = h.state().views[0].glyph_screen_pos(0, 5).expect("text layer");
+    h.hover_at(at);
+    h.run_steps(1);
+
+    // A double-click selects "quick" and stays on page 1, also once the double-click time is over.
+    click(&mut h, at);
+    click(&mut h, at);
+    assert_eq!(h.state().views[0].selected_text().as_deref(), Some("quick"));
+    h.run_steps(30);
+    assert_eq!(h.state().views[0].current, 0, "the double-click didn't turn the page");
+
+    // A single click turns it once the double-click time is over.
+    // Entering full screen again clears the selection.
+    h.state_mut().apply_full_screen(false);
+    h.state_mut().apply_full_screen(true);
+    h.run_steps(30);
+    click(&mut h, at);
+    h.run_steps(30);
+    assert_eq!(h.state().views[0].current, 1, "a click goes forward");
+
+    // A click right before leaving full screen doesn't turn the page after it.
+    h.state_mut().views[0].go_to_page(0);
+    h.run_steps(30);
+    click(&mut h, at);
+    h.state_mut().apply_full_screen(false);
+    h.run_steps(30);
+    assert_eq!(h.state().views[0].current, 0, "no page turn after leaving");
+}

crates/ui-egui/tests/view.rs

@@ -1759,3 +1759,26 @@ fn full_screen_keeps_two_page_view_as_spreads() {
     let v = &h.state().views[0];
     assert!(v.continuous() && v.layout == PageLayout::TwoUp, "two-page continuous view comes back");
 }
+
+/// Review on #2070: full screen hides the tools and a click turns the page only with Select, so
+/// entering it from another tool selects Select, and leaving gives the tool back.
+#[test]
+fn full_screen_clicks_turn_pages_whatever_tool_was_on() {
+    use pdfcraft_ui_egui::QuickTool;
+    let mut h = harness(&[]);
+    h.run_steps(4);
+    h.state_mut().quick_tool = QuickTool::Hand;
+    h.key_press_modifiers(Modifiers::COMMAND, Key::L);
+    h.run_steps(6);
+    assert!(h.state().full_screen);
+    assert_eq!(h.state().quick_tool, QuickTool::Select, "Select in full screen");
+    // Entering again (a second document asking for it) keeps the tool to give back.
+    h.state_mut().apply_full_screen(true);
+    let r = rect(&h, 0).expect("page 1 on screen");
+    click_with(&mut h, r.center(), Modifiers::NONE);
+    assert_eq!(h.state().views[0].current, 1, "a click goes forward");
+    h.key_press(Key::Escape);
+    h.run_steps(4);
+    assert!(!h.state().full_screen);
+    assert_eq!(h.state().quick_tool, QuickTool::Hand, "the tool from before is back");
+}