feat: ask which lock screen to use on hyprland and niri

src/agent/lockpreview.h

@@ -0,0 +1,37 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+//
+// The user's own lock screen, rebuilt for its picture in the window that asks
+// which lock screen to use (LockChoice.qml): what hyprlock draws from its
+// config, with face-unlock's line at the top, or swaylock's background and
+// ring. A screenshot would take locking the screen. LockPreview.qml draws
+// what this returns.
+//
+// hyprlock places a widget from the corner or middle its halign and valign
+// name, with y upwards, and takes font sizes as points. Colours and sizes
+// here are hyprlang's: rgba(r, g, b, a), rgba(RRGGBBAA), 0xAARRGGBB, and
+// "x, y" in pixels or percent of the screen.
+
+#pragma once
+
+#include <QColor>
+#include <QSizeF>
+#include <QString>
+#include <QUrl>
+#include <QVariantList>
+
+namespace LockPreview
+{
+// The lock screen the user starts: the one their idle daemon or key runs,
+// else one that is installed. hyprlock, swaylock, another name, or empty.
+QString locker();
+
+// That lock screen's widgets, bottom first, as maps for LockPreview.qml.
+// output names the screen, for widgets meant for one monitor; wallpaper is
+// the desktop's picture, for a background that is a screenshot.
+QVariantList widgets(const QString &locker, const QSizeF &screen, const QString &output, const QUrl &wallpaper);
+
+// The pieces, apart for the tests.
+QVariantList hyprlock(const QString &configPath, const QSizeF &screen, const QString &output, const QUrl &wallpaper);
+QVariantList swaylock(const QString &configPath, const QUrl &wallpaper);
+QColor color(const QString &value);
+}