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+// SPDX-License-Identifier: GPL-2.0-or-later
+/**
+ * @file
+ * Utility functions for previewing icon representation.
+ */
+/* Authors:
+ *   Jon A. Cruz
+ *   Bob Jamison
+ *   Other dudes from The Inkscape Organization
+ *   Abhishek Sharma
+ *   Anshudhar Kumar Singh <anshudhar2001@gmail.com>
+ *
+ * Copyright (C) 2004 Bob Jamison
+ * Copyright (C) 2005,2010 Jon A. Cruz
+ * Copyright (C) 2021 Anshudhar Kumar Singh
+ *
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
+
+#ifndef INKSCAPE_UTIL_PREVIEW_H
+#define INKSCAPE_UTIL_PREVIEW_H
+
+#include <cstdint>
+#include <cairomm/surface.h>
+
+#include "display/drawing.h"
+#include "async/channel.h"
+
+class SPDocument;
+class SPItem;
+
+namespace Inkscape {
+namespace UI {
+namespace Preview {
+
+/**
+ * Launch a background task to render a drawing to a surface.
+ *
+ * If the area to render is invalid, nothing is returned and no action is taken.
+ * Otherwise, first the drawing is snapshotted, then an async task is launched to render the drawing to a surface.
+ * Upon completion, the drawing is unsnapshotted on the calling thread and the result passed to onfinished().
+ * If the return object is destroyed before this happens, then the drawing will instead be destroyed on an unspecified
+ * thread while still in the snapshotted state.
+ *
+ * Contracts: (This isn't Rust, so we need a comment instead, and great trust in the caller.)
+ *
+ *    - The caller must ensure onfinished() remains valid to call during the lifetime of the return object.
+ *      (This is the same as for sigc::slots and connections.)
+ *
+ *    - The caller must not call drawing->unsnapshot(), or any other method that bypasses snapshotting.
+ *      However, it is ok to modify or destroy drawing in any other way, because the background task has shared
+ *      ownership of the drawing (=> Sync), and snapshotting prevents modification of the data being read by the
+ *      background task (=> Send/const).
+ */
+Cairo::RefPtr<Cairo::ImageSurface>
+render_preview(SPDocument *doc, std::shared_ptr<Inkscape::Drawing> drawing, uint32_t bg_color, Inkscape::DrawingItem *item,
+                                    unsigned width_in, unsigned height_in, Geom::Rect const &dboxIn);
+
+} // namespace Preview
+} // namespace UI
+} // namespace Inkscape
+
+#endif // INKSCAPE_UTIL_PREVIEW_H