1 files changed, 41 insertions, 0 deletions
diff --git a/src/async/background-progress.h b/src/async/background-progress.h
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+++ b/src/async/background-progress.h
@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/** \file Background-progress
+ * A Progress object that reports progress thread-safely over a Channel.
+ */
+#ifndef INKSCAPE_ASYNC_BACKGROUND_PROGRESS_H
+#define INKSCAPE_ASYNC_BACKGROUND_PROGRESS_H
+
+#include <functional>
+#include "channel.h"
+#include "progress.h"
+
+namespace Inkscape {
+namespace Async {
+
+template <typename... T>
+class BackgroundProgress final
+    : public Progress<T...>
+{
+public:
+    /**
+     * Construct a Progress object which becomes cancelled as soon as \a channel is closed,
+     * and reports progress by calling \a onprogress over \a channel.
+     *
+     * The result can only be used within the lifetime of \a channel.
+     */
+    BackgroundProgress(Channel::Source &channel, std::function<void(T...)> &onprogress)
+        : channel(&channel)
+        , onprogress(std::move(onprogress)) {}
+
+private:
+    Channel::Source *channel;
+    std::function<void(T...)> onprogress;
+
+    bool _keepgoing() const override { return channel->operator bool(); }
+    bool _report(T const &... progress) override { return channel->run(std::bind(onprogress, progress...)); }
+};
+
+} // namespace Async
+} // namespace Inkscape
+
+#endif // INKSCAPE_ASYNC_BACKGROUND_PROGRESS_H