Prepare document snapshots before legacy saves

src/app_core/document_canvas.h

@@ -66,6 +66,17 @@ struct DocumentCanvasSnapshotResult {
     bool requires_renderer_payload_readback = false;
 };
 
+struct DocumentCanvasSaveSnapshotReport {
+    std::uint32_t width = 0;
+    std::uint32_t height = 0;
+    std::size_t layer_count = 0;
+    std::size_t frame_count = 0;
+    std::size_t captured_face_payloads = 0;
+    std::size_t pending_face_payloads = 0;
+    bool payload_complete = false;
+    bool can_export_ppi = false;
+};
+
 class DocumentCanvasClearServices {
 public:
     virtual ~DocumentCanvasClearServices() = default;
@@ -216,6 +227,21 @@ public:
     });
 }
 
+[[nodiscard]] inline DocumentCanvasSaveSnapshotReport make_document_canvas_save_snapshot_report(
+    const DocumentCanvasSnapshotResult& snapshot) noexcept
+{
+    return DocumentCanvasSaveSnapshotReport {
+        .width = snapshot.document.width(),
+        .height = snapshot.document.height(),
+        .layer_count = snapshot.layer_count,
+        .frame_count = snapshot.frame_count,
+        .captured_face_payloads = snapshot.captured_face_payloads,
+        .pending_face_payloads = snapshot.pending_face_payloads,
+        .payload_complete = !snapshot.requires_renderer_payload_readback,
+        .can_export_ppi = !snapshot.requires_renderer_payload_readback,
+    };
+}
+
 [[nodiscard]] inline pp::foundation::Result<DocumentCanvasClearPlan> plan_document_canvas_clear(
     bool has_canvas,
     float r = 0.0F,