Merge PR #321 from xc4pr: Text: the caret shows on dark slides and in empty placeholders

# Conflicts:
#	crates/engine/src/cmd/text.rs
#	crates/engine/src/tests.rs
#	crates/ui-egui/src/canvas.rs
#	crates/ui-egui/src/textures.rs

crates/engine/src/cmd/text.rs

@@ -4,7 +4,7 @@ use std::sync::Arc;
 
 use deckcraft_model::edit::{self as ed, Pos};
 use deckcraft_model::resolve::{self, Ctx};
-use deckcraft_model::text::{Align, AutoFit, Hyperlink, Run, RunKind, RunProps, TextBody};
+use deckcraft_model::text::{Align, AutoFit, Hyperlink, Paragraph, Run, RunKind, RunProps, TextBody};
 use deckcraft_model::{Presentation, ShapeId, ShapeKind};
 use serde_json::{Value, json};
 
@@ -188,6 +188,15 @@ pub fn layout_for(st: &DocState, t: &TextSel) -> Option<deckcraft_text::TextLayo
     }
     let sh = st.shape(t.shape)?;
     let body = sh.text.as_ref()?;
+    // A body nobody has typed into holds no paragraph. Lay it out as one empty paragraph, so
+    // the caret has a line to stand on.
+    let blank;
+    let body = if body.paragraphs.is_empty() {
+        blank = TextBody { paragraphs: vec![Paragraph::default()], ..body.clone() };
+        &blank
+    } else {
+        body
+    };
     let ctx = ctx_for(&st.doc, &st.selection)?;
     let x = xfrm_of(&st.doc, &st.selection, sh);
     let geo = deckcraft_render::shape_geometry(sh, x.w, x.h);
@@ -234,6 +243,22 @@ pub fn caret_line(st: &DocState, t: &TextSel) -> Option<(deckcraft_geom::Point,
     Some((m * deckcraft_geom::Point::new(cx, top), m * deckcraft_geom::Point::new(cx, bot)))
 }
 
+/// The colour of text typed at the caret. The canvas draws the caret in it, so the caret shows
+/// wherever the text does: light on a dark slide, dark on a light one. `None` when that text
+/// has no fill to take a colour from.
+pub fn caret_color(st: &DocState, t: &TextSel) -> Option<deckcraft_color::Rgba> {
+    if t.notes || t.cell.is_some() {
+        return None;
+    }
+    let sh = st.shape(t.shape)?;
+    let body = sh.text.as_ref()?;
+    let ctx = ctx_for(&st.doc, &st.selection)?;
+    let blank = Paragraph::default();
+    let para = body.paragraphs.get(t.caret.0).unwrap_or(&blank);
+    let props = resolve::run(&ctx, sh, para, &ed::props_at(body, t.caret));
+    Some(resolve::text_color(&ctx, &props)).filter(|c| c.a > 0)
+}
+
 fn pos_param(p: &Value, key: &str) -> Option<Pos> {
     let a = p.get(key)?.as_array()?;
     Some((a.first()?.as_u64()? as usize, a.get(1)?.as_u64()? as usize))

crates/engine/src/tests.rs

@@ -2494,3 +2494,48 @@ fn language_marks_text_and_no_proof_and_repeats_are_reported() {
     assert!(s.execute("review.spelling", &json!({})).unwrap().as_array().unwrap().is_empty());
     assert!(s.execute("format.language", &json!({"lang": "en US!"})).is_err());
 }
+
+#[test]
+fn an_empty_placeholder_has_a_caret() {
+    let mut s = session();
+    let title = s.doc().unwrap().current_slide().unwrap().shapes[0].id.0;
+    s.execute("text.edit", &json!({"id": title})).unwrap();
+    let st = s.doc().unwrap();
+    let sel = st.selection.text.clone().unwrap();
+    let layout = cmd::text::layout_for(st, &sel).unwrap();
+    let (x, top, bottom) = layout.caret(deckcraft_text::Pos { para: 0, ch: 0 }).expect("a caret in the empty title");
+    // A centred title: the caret stands in the middle of the text box, one line tall.
+    assert!((x - layout.inner.center().x).abs() < 1.0, "{x} in {:?}", layout.inner);
+    assert!(bottom - top > 20.0, "{top}..{bottom}");
+}
+
+#[test]
+fn the_caret_takes_the_colour_of_the_text() {
+    let caret = |theme: &str| {
+        let mut s = session();
+        s.execute("design.theme", &json!({"name": theme})).unwrap();
+        let title = s.doc().unwrap().current_slide().unwrap().shapes[0].id.0;
+        s.execute("text.edit", &json!({"id": title})).unwrap();
+        let st = s.doc().unwrap();
+        let empty = cmd::text::caret_color(st, &st.selection.text.clone().unwrap()).unwrap();
+        s.execute("text.insert", &json!({"text": "Typed"})).unwrap();
+        let st = s.doc().unwrap();
+        assert_eq!(cmd::text::caret_color(st, &st.selection.text.clone().unwrap()), Some(empty));
+        empty
+    };
+    // Dark text on the light theme, light text on the dark one: never black on a dark slide.
+    let (light, dark) = (caret("DeckCraft"), caret("Nocturne"));
+    assert!(light.r < 0x60 && light.g < 0x60 && light.b < 0x60, "{light:?}");
+    assert!(dark.r > 0xC0 && dark.g > 0xC0 && dark.b > 0xC0, "{dark:?}");
+    // Text set to red gets a red caret.
+    let mut s = session();
+    let title = s.doc().unwrap().current_slide().unwrap().shapes[0].id.0;
+    s.execute("text.edit", &json!({"id": title})).unwrap();
+    s.execute("text.insert", &json!({"text": "Red"})).unwrap();
+    s.execute("text.selectAll", &json!({})).unwrap();
+    s.execute("format.color", &json!({"color": "#FF0000"})).unwrap();
+    s.execute("text.move", &json!({"to": "end"})).unwrap();
+    let st = s.doc().unwrap();
+    let red = cmd::text::caret_color(st, &st.selection.text.clone().unwrap()).unwrap();
+    assert_eq!((red.r, red.g, red.b), (0xFF, 0, 0));
+}

crates/ui-egui/src/canvas.rs

@@ -137,7 +137,10 @@ pub fn show(app: &mut SlideApp, ui: &mut Ui) {
         Some((Target::Slides, d)) => {
             let idx = d.selection.slide;
             let doc = d.doc.clone();
-            app.textures.slide(ui.ctx(), &doc, idx, px, visible, true, crate::media::gif_key(&gifs), app.ui.grayscale, &times)
+            // A placeholder's prompt makes way for the caret once it is being typed into.
+            let typing_into = d.selection.text.as_ref().filter(|t| !t.notes && t.cell.is_none()).map(|t| t.shape);
+            let no_prompt = typing_into.filter(|id| d.shape(*id).and_then(|sh| sh.text.as_ref()).is_none_or(|body| body.is_empty()));
+            app.textures.slide(ui.ctx(), &doc, idx, px, visible, true, crate::media::gif_key(&gifs), app.ui.grayscale, &times, no_prompt)
         }
         Some((Target::Master { master }, d)) => master_tex(ui.ctx(), &d.doc, master, None, px, visible),
         Some((Target::Layout { master, layout }, d)) => master_tex(ui.ctx(), &d.doc, master, Some(layout), px, visible),
@@ -622,7 +625,9 @@ fn overlays(app: &mut SlideApp, ui: &Ui, painter: &egui::Painter, xf: Xf, t: &To
             ui.ctx().request_repaint_after(std::time::Duration::from_millis(300));
             // An empty placeholder shows the caret where typing begins too.
             if blink && let Some((top, bot)) = deckcraft_engine::cmd::text::caret_line(st, ts) {
-                painter.line_segment([xf.to_screen(top), xf.to_screen(bot)], Stroke::new(1.5, t.caret));
+                // In the colour of the text being typed: a black caret is lost on a dark slide.
+                let color = deckcraft_engine::cmd::text::caret_color(st, ts).map_or(t.caret, theme::to_color32);
+                painter.line_segment([xf.to_screen(top), xf.to_screen(bot)], Stroke::new(1.5, color));
             }
         }
     }

crates/ui-egui/src/textures.rs

@@ -21,6 +21,7 @@ struct Key {
     extra: u64,
     /// The pasteboard region the slide's drawing calls for (canvas only).
     want: Region,
+    skip_text: Option<ShapeId>,
 }
 
 struct Entry {
@@ -135,7 +136,8 @@ impl Textures {
     /// The canvas texture for slide `index`, the slide being `size` pixels, and the region it
     /// covers: the slide, grown over the pasteboard to show what reaches off the slide within
     /// `visible` (the canvas, in pixels from the slide's top-left corner). `extra` changes with the
-    /// GIF frames.
+    /// GIF frames. `skip_text` leaves out one shape's text (the prompt of a placeholder being typed
+    /// into).
     #[allow(clippy::too_many_arguments)]
     pub fn slide(
         &mut self,
@@ -148,6 +150,7 @@ impl Textures {
         extra: u64,
         grayscale: bool,
         gif_times: &[(ShapeId, f64)],
+        skip_text: Option<ShapeId>,
     ) -> Option<(TextureHandle, Region)> {
         let slide = p.slides.get(index)?.clone();
         let master = master_of(p, &slide);
@@ -172,6 +175,7 @@ impl Textures {
             edit,
             extra: extra ^ grayscale as u64,
             want,
+            skip_text,
         };
         if let Some(e) = &self.canvas
             && e.key == key
@@ -181,7 +185,16 @@ impl Textures {
         let t0 = crate::now_ms();
         let render = |region: Region| {
             let opts =
-                RenderOpts { scale, edit, gif_times, threads: threads(), offset: region.offset(), size: Some(region.size()), ..Default::default() };
+                RenderOpts {
+                scale,
+                edit,
+                gif_times,
+                skip_text,
+                threads: threads(),
+                offset: region.offset(),
+                size: Some(region.size()),
+                ..Default::default()
+            };
             deckcraft_render::render_slide_drawn(p, index, &opts)
         };
         let (mut img, drawn) = render(want);
@@ -236,6 +249,7 @@ impl Textures {
             edit: false,
             extra: 0,
             want: Region::slide(width_px, h),
+            skip_text: None,
         };
         self.clock += 1;
         let clock = self.clock;