feat: add an own lock screen with the bubble and your wallpaper

src/agent/wallpaper.h

@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+//
+// The picture behind face-unlock's own lock screen. By default the one on
+// the desktop. Hyprland, niri and the like leave the wallpaper to a program
+// of its own, so it comes from whichever of the common ones runs: swaybg,
+// awww (once swww), hyprpaper or wpaperd, each for every output.
+
+#pragma once
+
+#include <QHash>
+#include <QString>
+#include <QStringList>
+#include <QUrl>
+
+namespace Wallpaper
+{
+// The pictures for a lock by output name, "" for every other output.
+// setting is LockWallpaper: empty for the desktop's, "none", a picture, or a
+// folder to take one from at random.
+QHash<QString, QUrl> forLock(const QString &setting);
+// The one for this output.
+QUrl pick(const QHash<QString, QUrl> &pictures, const QString &output);
+
+// What the programs tell, by output name. Apart for the tests.
+QHash<QString, QString> fromSwaybg(const QStringList &args);
+// `awww query` and `swww query`.
+QHash<QString, QString> fromAwww(const QString &text);
+// `hyprctl hyprpaper listactive` and `wpaperctl all-wallpapers`.
+QHash<QString, QString> fromList(const QString &text);
+}