Merge #819: Keep a missing graphic missing when it is pasted into another document (#720)

# Conflicts:
#	crates/engine/src/cmd/object.rs

crates/engine/src/cmd/links.rs

@@ -569,6 +569,52 @@ mod shared_asset_tests {
         assert_eq!((g.asset, g.crop), (same, [1.0; 4]));
         assert_eq!(dst.assets.len(), 2);
     }
+
+    #[test]
+    fn pasted_missing_graphic_does_not_show_an_unrelated_target_asset() {
+        use designcraft_doc::build::NewDocument;
+        use designcraft_doc::{Asset, Graphic, Item, ItemId, Shape, SpreadRef};
+        let mut src = Document::new(&NewDocument::default());
+        let mut dst = Document::new(&NewDocument::default());
+        // The source graphic points at an asset the source does not have; the target uses that id for another image.
+        let missing = AssetId(src.alloc());
+        dst.assets.insert(
+            missing,
+            Arc::new(Asset {
+                id: missing,
+                name: "p.png".into(),
+                mime: "image/png".into(),
+                link: None,
+                data: Arc::new(png(8, 4)),
+                pixels: None,
+                page: 0,
+                pdf_crop: Default::default(),
+                pdf_box: None,
+            }),
+        );
+        let iid = ItemId(src.alloc());
+        let mut it = Item::new(
+            iid,
+            src.default_layer(),
+            Shape::Rectangle,
+            designcraft_geom::shapes::rectangle(designcraft_geom::Rect::new(0.0, 0.0, 9.0, 9.0)),
+        );
+        it.content = Content::Graphic(Graphic {
+            asset: missing,
+            size: (4.0, 4.0),
+            xf: designcraft_geom::Affine::IDENTITY,
+            clip: None,
+            auto_fit: Default::default(),
+            fit_align: 4,
+            crop: [1.0; 4],
+            wrap: Default::default(),
+        });
+        src.insert_item(SpreadRef::Doc(0), it, None).unwrap();
+        let ids = super::super::object::duplicate_from(&mut dst, &src, &[iid], SpreadRef::Doc(0), designcraft_geom::Vec2::ZERO).unwrap();
+        let g = dst.item(ids[0]).and_then(|i| i.graphic()).unwrap();
+        assert_ne!(g.asset, missing);
+        assert!(!dst.assets.contains_key(&g.asset));
+    }
 }
 
 #[cfg(test)]

crates/engine/src/cmd/object.rs

@@ -6,8 +6,8 @@ use std::sync::Arc;
 
 use designcraft_color::BlendMode;
 use designcraft_doc::{
-    Content, Document, Effects, Fill, Item, ItemId, ItemLoc, ParaFormat, Selection, Shape, SpreadRef, Story, StoryId, Stroke, TextFrame,
-    TextFrameOptions, TextSel,
+    AssetId, Content, Document, Effects, Fill, Item, ItemId, ItemLoc, ParaFormat, Selection, Shape, SpreadRef, Story, StoryId, Stroke,
+    TextFrame, TextFrameOptions, TextSel,
 };
 use designcraft_geom::{Affine, Point, Rect, Vec2, shapes};
 use serde_json::{Value, json};
@@ -948,13 +948,24 @@ pub fn duplicate_from(dst: &mut Document, src: &Document, ids: &[ItemId], to: Sp
     Ok(out)
 }
 
+/// The id to reference in `dst` for asset `id` of `src`. When `src` lacks the asset (a missing graphic), an id that `dst`
+/// already uses for a different asset is swapped for a fresh unused one so the reference stays missing instead of showing
+/// an unrelated image.
+fn adopt_or_dangle(dst: &mut Document, src: &Document, id: AssetId) -> AssetId {
+    match dst.adopt_asset(src, id) {
+        Some(a) => a,
+        None if dst.assets.contains_key(&id) => AssetId(dst.alloc()),
+        None => id,
+    }
+}
+
 fn renumber(dst: &mut Document, src: &Document, it: &mut Item, stories: &mut HashMap<StoryId, StoryId>) {
     it.id = ItemId(dst.alloc());
     let my_id = it.id;
     if let Some(m) = it.media.as_mut()
         && let Some(p) = m.poster
     {
-        m.poster = dst.adopt_asset(src, p).or(Some(p));
+        m.poster = Some(adopt_or_dangle(dst, src, p));
     }
     match &mut it.content {
         Content::Text(tf) => {
@@ -966,9 +977,8 @@ fn renumber(dst: &mut Document, src: &Document, it: &mut Item, stories: &mut Has
                     st.id = n;
                     let mut assets = HashMap::new();
                     for a in designcraft_doc::story_asset_refs(&st) {
-                        if let Some(na) = dst.adopt_asset(src, a)
-                            && na != a
-                        {
+                        let na = adopt_or_dangle(dst, src, a);
+                        if na != a {
                             assets.insert(a, na);
                         }
                     }
@@ -985,9 +995,7 @@ fn renumber(dst: &mut Document, src: &Document, it: &mut Item, stories: &mut Has
             }
         }
         Content::Graphic(g) => {
-            if let Some(a) = dst.adopt_asset(src, g.asset) {
-                g.asset = a;
-            }
+            g.asset = adopt_or_dangle(dst, src, g.asset);
         }
         Content::Group { items } => {
             for c in items.iter_mut() {