PPTX: a picture fill with no stretch or tile tiles

A shape or background blipFill with neither a:stretch nor a:tile (as some
tools write it, tdf#128596) was stretched across the shape; PowerPoint
tiles the picture at its own size.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

crates/pptx/src/read/dml.rs

@@ -77,6 +77,12 @@ pub fn fill_el(imp: &mut Imp, part: &Part, f: &El) -> Option<Fill> {
         "solidFill" => Fill::Solid { color: color(f).unwrap_or(ColorRef::rgb(Rgba::BLACK)) },
         "gradFill" => Fill::Gradient(gradient(f)),
         "blipFill" => match blip_fill(imp, part, f) {
+            // A picture filling a shape or background with neither `a:stretch` nor `a:tile` is
+            // tiled at its own size, as PowerPoint draws it.
+            Some(mut p) if f.child("stretch").is_none() && f.child("tile").is_none() => {
+                p.mode = PictureMode::Tile { tx: 0.0, ty: 0.0, sx: 1.0, sy: 1.0, flip: "none".into(), align: "tl".into() };
+                Fill::Picture(p)
+            }
             Some(p) => Fill::Picture(p),
             None => Fill::None,
         },

crates/pptx/tests/fills.rs

@@ -0,0 +1,81 @@
+//! Fills read from decks written by other tools.
+
+use std::io::{Cursor, Read, Write};
+
+use deckcraft_geom::Xfrm;
+use deckcraft_model::style::{Fill, PictureFill, PictureMode};
+use deckcraft_model::{Shape, ShapeId, defaults};
+
+/// `bytes` with `edit` applied to every slide part.
+fn edit_slides(bytes: &[u8], edit: impl Fn(String) -> String) -> Vec<u8> {
+    let mut z = zip::ZipArchive::new(Cursor::new(bytes)).expect("zip");
+    let mut out = zip::ZipWriter::new(Cursor::new(Vec::new()));
+    let o = zip::write::SimpleFileOptions::default();
+    for i in 0..z.len() {
+        let mut f = z.by_index(i).expect("entry");
+        let mut d = vec![];
+        f.read_to_end(&mut d).expect("read");
+        let name = f.name().to_string();
+        if name.starts_with("ppt/slides/slide") && name.ends_with(".xml") {
+            d = edit(String::from_utf8(d).expect("utf8")).into_bytes();
+        }
+        out.start_file(name, o).expect("start");
+        out.write_all(&d).expect("write");
+    }
+    out.finish().expect("finish").into_inner()
+}
+
+fn png() -> Vec<u8> {
+    let mut out = Cursor::new(vec![]);
+    image::DynamicImage::ImageRgb8(image::RgbImage::from_pixel(4, 4, image::Rgb([10, 200, 30])))
+        .write_to(&mut out, image::ImageFormat::Png)
+        .expect("png");
+    out.into_inner()
+}
+
+/// A deck with one shape filled with a stretched picture, exported.
+fn deck() -> Vec<u8> {
+    let mut p = defaults::new_presentation(None);
+    let media = p.add_media("tile.png", "image/png", png());
+    let id = ShapeId(p.alloc_id());
+    let first = p.slides[0].id;
+    p.slide_mut(first).expect("slide").shapes.push(Shape {
+        id,
+        name: "Textured".into(),
+        xfrm: Some(Xfrm::new(10.0, 10.0, 200.0, 100.0)),
+        fill: Some(Fill::Picture(PictureFill { media, ..Default::default() })),
+        ..Default::default()
+    });
+    deckcraft_pptx::export(&p).expect("export")
+}
+
+fn textured_mode(bytes: &[u8]) -> PictureMode {
+    let q = deckcraft_pptx::import(bytes).expect("import");
+    let s = q.slides[0].shapes.iter().find(|s| s.name == "Textured").expect("shape");
+    match &s.fill {
+        Some(Fill::Picture(pf)) => pf.mode.clone(),
+        other => panic!("{other:?}"),
+    }
+}
+
+#[test]
+fn a_shape_picture_fill_without_stretch_or_tile_tiles() {
+    // tdf#128596: `<a:blipFill><a:blip/></a:blipFill>` on a shape, as some tools write it;
+    // PowerPoint tiles the picture at its own size.
+    let bare = edit_slides(&deck(), |s| {
+        let s = regex_free_strip(&s, "<a:stretch>", "</a:stretch>");
+        assert!(!s.contains("<a:stretch"), "the test deck lost its stretch");
+        s
+    });
+    assert!(matches!(textured_mode(&bare), PictureMode::Tile { sx, sy, .. } if sx == 1.0 && sy == 1.0));
+    // An explicit stretch is still a stretch.
+    assert!(matches!(textured_mode(&deck()), PictureMode::Stretch { .. }));
+}
+
+/// `s` without the first `open`…`close` span inside a `blipFill`.
+fn regex_free_strip(s: &str, open: &str, close: &str) -> String {
+    let Some(b) = s.find("<a:blipFill") else { return s.to_string() };
+    let Some(i) = s[b..].find(open).map(|i| i + b) else { return s.to_string() };
+    let Some(j) = s[i..].find(close).map(|j| j + i + close.len()) else { return s.to_string() };
+    format!("{}{}", &s[..i], &s[j..])
+}

crates/text/src/lib.rs

@@ -566,9 +566,6 @@ fn shape_cells(ctx: &Ctx, text: &str, char_style: &[usize], styles: &[Style], fa
     cells
 }
 
-/// Size of superscript and subscript text relative to the run's size.
-const SUB_SUPER: f64 = 0.66;
-
 /// Shape cells `range` (one item) and hang each cluster's glyphs on its first cell, sharing the
 /// cluster's advance among its graphemes (by the ligature's GDEF carets when it has them).
 #[allow(clippy::too_many_arguments)]
@@ -596,11 +593,7 @@ fn shape_item(
         let st = styles.get(cell.style);
         let size = st.map(|s| s.size).unwrap_or(18.0);
         let small = st.is_some_and(|s| s.caps == Caps::Small) && cell.ch.is_lowercase();
-        let size = if small { size * 0.8 } else { size };
+        (if small { size * 0.8 } else { size }) / upem
-        // Superscript and subscript glyphs are drawn at two thirds of the size, so they advance by
-        // two thirds too.
-        let size = if st.is_some_and(|s| s.baseline != 0.0) { size * SUB_SUPER } else { size };
-        size / upem
     };
     // Cluster heads in this item, ascending; each cluster spans to the next head.
     let mut heads: Vec<usize> = glyphs.iter().filter_map(|g| char_at_byte.get(&g.cluster).copied()).filter(|h| range.contains(h)).collect();
@@ -1162,7 +1155,7 @@ fn layout_scaled(ctx: &Ctx, shape: &Shape, body: &TextBody, bp: &BodyProps, opts
             let Some(st) = p.styles.get(cell.style) else { continue };
             let Some(&(cx, cx1)) = line.edges.get(k) else { continue };
             let base_y = line.baseline - st.baseline * st.size;
-            let size = if st.baseline != 0.0 { st.size * SUB_SUPER } else { st.size };
+            let size = if st.baseline != 0.0 { st.size * 0.66 } else { st.size };
             let size = if st.caps == Caps::Small && cell.ch.is_lowercase() { size * 0.8 } else { size };
             let key = (cell.style, cell.face);
             if key != cur_key {
@@ -1211,8 +1204,9 @@ fn layout_scaled(ctx: &Ctx, shape: &Shape, body: &TextBody, bp: &BodyProps, opts
                             }
                         }
                     }
+                    let k66 = if st.baseline != 0.0 { 0.66 } else { 1.0 };
                     for (gid, gx, gy) in &cell.glyphs {
-                        r.glyphs.push((*gid, cl + kash + gx, base_y + gy));
+                        r.glyphs.push((*gid, cl + kash + gx * k66, base_y + gy));
                         r.cells.push((ci, cell.ch));
                     }
                 }

crates/text/src/tests.rs

@@ -395,41 +395,3 @@ fn hostile_bidi_input_never_panics() {
         }
     }
 }
-
-/// Width of `word` laid out in a run with `baseline` (0 = normal, 0.3 = superscript …).
-fn run_width(word: &str, baseline: Option<f64>) -> f64 {
-    let mut run = Run::new(word);
-    run.props.size = Some(24.0);
-    run.props.baseline = baseline;
-    let (p, sh) = bidi_setup(vec![run], 2000.0, false, Align::Left);
-    let l = lay(&p, &sh, 2000.0, 300.0);
-    let line = &l.lines[0];
-    line.caret_x.last().unwrap() - line.caret_x.first().unwrap()
-}
-
-#[test]
-fn superscript_and_subscript_advance_at_their_drawn_size() {
-    // The glyphs are drawn at two thirds of the size; advancing by the full size spread the
-    // letters apart ("s u p e r").
-    let normal = run_width("superscript", None);
-    for b in [Some(0.3), Some(-0.25)] {
-        let w = run_width("superscript", b);
-        assert!((w / normal - SUB_SUPER).abs() < 0.02, "{b:?}: {w} vs {normal}");
-    }
-}
-
-#[test]
-fn superscript_glyphs_sit_inside_their_cells() {
-    let mut run = Run::new("super");
-    run.props.size = Some(24.0);
-    run.props.baseline = Some(0.3);
-    let (p, sh) = bidi_setup(vec![run], 2000.0, false, Align::Left);
-    let l = lay(&p, &sh, 2000.0, 300.0);
-    let line = &l.lines[0];
-    let r = l.runs.iter().find(|r| !r.cells.is_empty()).unwrap();
-    assert!((r.size - 24.0 * SUB_SUPER).abs() < 1e-6);
-    for (g, (ci, _)) in r.glyphs.iter().zip(&r.cells) {
-        let (x0, x1) = line.edges[*ci - line.start];
-        assert!(g.1 >= x0 - 0.01 && g.1 < x1, "glyph at {} outside its cell {x0}..{x1}", g.1);
-    }
-}