Plan document export snapshot routing

src/app_core/document_export.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include "app_core/app_dialog.h"
+#include "app_core/document_canvas.h"
 #include "document/document.h"
 #include "foundation/result.h"
 
@@ -137,6 +138,11 @@ enum class DocumentExportExecutionKind {
     timelapse,
 };
 
+enum class DocumentExportSnapshotRouteAction {
+    use_document_snapshot_writer,
+    use_legacy_export,
+};
+
 struct DocumentExportMenuPlan {
     DocumentExportMenuKind kind = DocumentExportMenuKind::jpeg;
     DocumentExportMenuAction action = DocumentExportMenuAction::show_jpeg_dialog;
@@ -156,6 +162,16 @@ struct DocumentExportSuccessDialogPlan {
     bool show_dialog = false;
 };
 
+struct DocumentExportSnapshotRoutePlan {
+    DocumentExportExecutionKind kind = DocumentExportExecutionKind::equirectangular_file;
+    DocumentExportSnapshotRouteAction action = DocumentExportSnapshotRouteAction::use_legacy_export;
+    bool payload_complete = false;
+    bool target_supported = false;
+    bool platform_supported = false;
+    bool uses_document_snapshot_writer = false;
+    std::string_view fallback_reason;
+};
+
 class DocumentExportMenuServices {
 public:
     virtual ~DocumentExportMenuServices() = default;
@@ -408,6 +424,38 @@ public:
     return "Document export failed";
 }
 
+[[nodiscard]] constexpr DocumentExportSnapshotRoutePlan plan_document_export_snapshot_route(
+    DocumentExportExecutionKind kind,
+    DocumentCanvasSaveSnapshotReport report,
+    bool target_supported,
+    bool platform_supported) noexcept
+{
+    DocumentExportSnapshotRoutePlan plan;
+    plan.kind = kind;
+    plan.payload_complete = report.payload_complete;
+    plan.target_supported = target_supported;
+    plan.platform_supported = platform_supported;
+
+    if (!platform_supported) {
+        plan.fallback_reason = "document snapshot export is disabled on this platform";
+        return plan;
+    }
+
+    if (!target_supported) {
+        plan.fallback_reason = "document snapshot export does not support this target";
+        return plan;
+    }
+
+    if (!report.payload_complete) {
+        plan.fallback_reason = "document snapshot still requires renderer payload readback";
+        return plan;
+    }
+
+    plan.action = DocumentExportSnapshotRouteAction::use_document_snapshot_writer;
+    plan.uses_document_snapshot_writer = true;
+    return plan;
+}
+
 [[nodiscard]] constexpr DocumentExportCollectionTargetPlan plan_document_export_collection_target(
     DocumentExportCollectionKind kind,
     bool use_work_directory_collection) noexcept