From d5a672fda2d961eac5919d87008e6a2a21b69000 Mon Sep 17 00:00:00 2001
From: midasmatterhorn <248507632+midasmatterhorn@users.noreply.github.com>
Date: Thu, 15 Oct 2026 00:00:40 +0300
Subject: [PATCH] eps: an opacity mask in the editing data is named, not drawn
 whole (#2004)

---
 crates/eps/src/import/ai/read.rs  | 11 ++++++++++-
 crates/eps/src/import/ai/tests.rs |  8 ++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/crates/eps/src/import/ai/read.rs b/crates/eps/src/import/ai/read.rs
index e892369f1..558200ff5 100644
--- a/crates/eps/src/import/ai/read.rs
+++ b/crates/eps/src/import/ai/read.rs
@@ -1356,8 +1356,17 @@ impl<'a> Reader<'a> {
         self.frames.iter().all(|f| !matches!(&f.kind, Kind::Layer(a) if !a.visible))
     }
 
-    /// An object's dictionary: its name (`AIArtName`, or the XML id `AI10_ArtUID`).
+    /// An object's dictionary: its name (`AIArtName`, or the XML id `AI10_ArtUID`), and the
+    /// opacity mask it may carry.
     fn art_dictionary(&mut self, o: &Obj) {
+        // A mask (`/Mask`, keyed `AI9_Mask`): its art is on `X=` … `X+` lines, and drawing the
+        // object without it shows what the mask hides, so it must be named (#2004). A mask that
+        // is disabled changes nothing.
+        if let Some(mask) = o.obj("AI9_Mask").or_else(|| o.obj("Mask"))
+            && mask.nums("Disabled").first().copied() != Some(1.0)
+        {
+            self.unreadable("opacity masks");
+        }
         let name = match o.text("AIArtName") {
             Some(name) => name,
             None => match o.obj("AI10_ArtUID").and_then(Obj::content_text) {
diff --git a/crates/eps/src/import/ai/tests.rs b/crates/eps/src/import/ai/tests.rs
index aa482aaa3..c9ed212ee 100644
--- a/crates/eps/src/import/ai/tests.rs
+++ b/crates/eps/src/import/ai/tests.rs
@@ -667,6 +667,14 @@ fn what_it_doesnt_read_is_an_error_where_it_shows() {
     assert!(e.contains("pattern fills"), "{e}");
     let e = read(stream(&layer("/SymbolInstance :\n(Dot) /SymbolRef ,\n;\n")).as_bytes()).unwrap_err();
     assert!(e.contains("symbols"), "{e}");
+    // An opacity mask (#2004): drawing the layer's art whole would show what the mask hides, so
+    // the mask is named and the file is read from its PDF part instead.
+    let mask = "%_/ArtDictionary :\n%_/XMLUID : (M) ; (AI10_ArtUID) ,\n%_/Mask :\n%_1 /Bool (Linked) ,\n%_0 /Bool (Disabled) ,\n%_X=\n\
+                %_0 0 0 1 k\n%_0 0 m\n%_5 0 L\n%_5 5 L\n%_0 5 L\n%_0 0 L\n%_f\n%_X+\n%_ (Art) ,\n%_1 /Bool (Clipping) ,\n%_0 /Bool (Inverted) ,\n%_; (AI9_Mask) ,\n%_;\n";
+    let e = read(stream(&layer(mask)).as_bytes()).unwrap_err();
+    assert!(e.contains("opacity masks"), "{e}");
+    // A mask that is disabled changes nothing: the art reads.
+    read_ok(&layer(&mask.replace("%_0 /Bool (Disabled)", "%_1 /Bool (Disabled)")));
     // On a layer that doesn't show, it is left out of it.
     let hidden = "%AI5_BeginLayer\n0 1 1 1 0 0 0 1 255 79 79 0 50 0 Lb\n(Off) Ln\n1 2 frobnicate\n(J) 0 0 1 1 0 0 0 0 0 [1 0 0 1 0 0] p\nLB\n%AI5_EndLayer--\n";
     let r = read_ok(hidden);