feat(wallpaper): OCS browser for importing wallpaper packs

meson.build

@@ -22,7 +22,7 @@ if get_option('buildtype').startswith('release')
 endif
 
 core_deps = [
-  dependency('gtk4'),
+  dependency('gtk4', version: '>= 4.10'),
   dependency('gio-2.0'),
   dependency('gio-unix-2.0'),
   dependency('vte-2.91-gtk4'),
@@ -286,6 +286,12 @@ singularity_core_sources = files(
     'src/core/wallpaper_gallery.vala',
     'src/core/wallpaper_rotation_state.vala',
     'src/core/wallpaper_rotator.vala',
+    'src/core/wallpaper_sidecar.vala',
+    'src/core/wallpaper_ocs.vala',
+    'src/core/wallpaper_browse_cache.vala',
+    'src/core/wallpaper_thumbnail_cache.vala',
+    'src/core/wallpaper_provider.vala',
+    'src/core/settings_safety.vala',
     'src/core/wayland_gamma_backend.vala',
     'src/core/shortcut_manager.vala',
     'src/core/ush_portal.vala',
@@ -313,6 +319,8 @@ singularity_core_sources = files(
     'src/components/sidebar/views/settings_view.vala',
     'src/components/sidebar/pages/network_page.vala',
     'src/components/sidebar/pages/desktop_page.vala',
+    'src/components/sidebar/pages/wallpaper_ocs_browser.vala',
+    'src/components/sidebar/pages/provider_credential_group.vala',
     'src/components/sidebar/pages/sound_page.vala',
     'src/components/sidebar/pages/keyboard_page.vala',
     'src/components/sidebar/pages/accessibility_page.vala',
@@ -484,7 +492,7 @@ install_data('data/fan-control/dev.sinty.fan-control.policy',
 
 wallpaper_collections_test = executable('wallpaper-collections-test',
   sources: ['src/core/wallpaper_collections.vala', 'tests/wallpaper_collections_test.vala'],
-  dependencies: [dependency('gobject-2.0'), dependency('glib-2.0'), dependency('gio-2.0'), gee_dep],
+  dependencies: [dependency('gobject-2.0'), dependency('glib-2.0'), dependency('gio-2.0'), gee_dep, json_dep],
 )
 test('wallpaper-collections', wallpaper_collections_test)
 
@@ -499,11 +507,28 @@ wallpaper_gallery_test = executable('wallpaper-gallery-test',
   dependencies: [dependency('gobject-2.0'), dependency('gio-2.0'), gee_dep],
 )
 test('wallpaper-gallery', wallpaper_gallery_test)
-
 wallpaper_rotator_test = executable('wallpaper-rotator-test',
   sources: ['src/core/wallpaper_collections.vala', 'src/core/wallpaper_gallery.vala',
             'src/core/wallpaper_rotation_state.vala', 'src/core/wallpaper_rotator.vala',
             'tests/wallpaper_rotator_test.vala'],
-  dependencies: [dependency('gobject-2.0'), dependency('glib-2.0'), dependency('gio-2.0'), gee_dep],
+  dependencies: [dependency('gobject-2.0'), dependency('glib-2.0'), dependency('gio-2.0'), gee_dep, json_dep],
 )
 test('wallpaper-rotator', wallpaper_rotator_test)
+
+wallpaper_ocs_test = executable('wallpaper-ocs-test',
+  sources: ['src/core/wallpaper_ocs.vala', 'src/core/wallpaper_browse_cache.vala', 'src/core/wallpaper_thumbnail_cache.vala', 'src/core/wallpaper_provider.vala', 'src/core/wallpaper_collections.vala', 'tests/wallpaper_ocs_test.vala'],
+  dependencies: [dependency('gobject-2.0'), dependency('gio-2.0'), gee_dep, json_dep],
+)
+test('wallpaper-ocs', wallpaper_ocs_test)
+
+wallpaper_sidecar_test = executable('wallpaper-sidecar-test',
+  sources: ['src/core/wallpaper_sidecar.vala', 'tests/wallpaper_sidecar_test.vala'],
+  dependencies: [dependency('gobject-2.0'), dependency('gio-2.0'), gee_dep, json_dep],
+)
+test('wallpaper-sidecar', wallpaper_sidecar_test)
+
+settings_safety_test = executable('settings-safety-test',
+  sources: ['src/core/settings_safety.vala', 'tests/settings_safety_test.vala'],
+  dependencies: [dependency('gobject-2.0'), dependency('gio-2.0')],
+)
+test('settings-safety', settings_safety_test)

src/components/background/background.vala

@@ -1,5 +1,8 @@
 using Gtk;
 using GtkLayerShell;
+// GLib.Markup.escape_text -- used by the attribution overlay to safely
+// embed third-party OCS/Bing caption text in a Pango-markup Label.
+using GLib;
 
 namespace Singularity {
 
@@ -9,6 +12,54 @@ namespace Singularity {
         private Stack wp_stack;
         private bool _wp_showing_a = true;
         private uint _wp_clear_id = 0;
+        // Live-toggle for the attribution overlay. Background.vala reads
+        // show-wallpaper-attribution and routes through the existing
+        // empty-title-and-empty-author early-return path when false, so
+        // toggling it live (via the desktop settings page) hides or
+        // re-shows the overlay without waiting for the next wallpaper
+        // change. The schema id matches the rest of the shell
+        // (desktop_page.vala initialises the same way).
+        private GLib.Settings settings;
+
+        // Attribution overlay. wp_stack is the wallpaper cross-fade;
+        // the attribution Label sits on top of it in a Gtk.Overlay so
+        // the wallpaper texture is the lower layer and the text is
+        // painted over the corner of the screen. The label is hidden
+        // when both WallpaperManager.attribution_title and
+        // attribution_author are empty (the schema-default state and
+        // the explicit-clear state at every background-picture-uri
+        // write site).
+        private Gtk.Overlay? wp_overlay;
+        private Label attribution_label;
+        // Loads the attribution-label CSS once per process. Static +
+        // null-guarded the same way panel.vala's compact_rows_provider is,
+        // since Background windows are created per-monitor and the rules
+        // are process-global, not per-instance.
+        private static Gtk.CssProvider? attribution_css_provider = null;
+        // Corner-sample parameters. Sampled as a fractional rect inside
+        // the cached medium pixbuf so the sample tracks whatever size
+        // the manager uses for its display texture (currently 320x180,
+        // but the manager owns that decision). Bottom-left, 40% width x
+        // 30% height, with a small margin from the very edge so the
+        // sample doesn't include the empty space around the label.
+        private const double CORNER_SAMPLE_X_FRAC = 0.0;
+        private const double CORNER_SAMPLE_Y_FRAC = 0.65;
+        private const double CORNER_SAMPLE_W_FRAC = 0.40;
+        private const double CORNER_SAMPLE_H_FRAC = 0.30;
+        // Pixel margin from the screen edge to the attribution label.
+        // Bottom-left is clear of the dock (which is bottom-anchored
+        // and horizontally centered) at any reasonable screen width,
+        // but a 24px gutter keeps the scrim from clipping into the
+        // screen edge on rounded displays / ultrawide aspects.
+        private const int ATTRIBUTION_MARGIN = 24;
+        // topbar_lum_threshold -- copied from panel.vala (kept in sync
+        // with that constant by convention rather than a shared header,
+        // matching how the rest of the codebase pairs these CSS-class
+        // and contrast decisions). Above this luminance the wallpaper
+        // under the corner is "light", and the overlay switches to
+        // dark text; below it stays light text. 0.72 matches the
+        // value panel.vala uses for the top band.
+        private const double ATTRIBUTION_LUM_THRESHOLD = 0.72;
 
         public signal void first_painted();
         private bool _first_painted_done = false;
@@ -28,6 +79,7 @@ namespace Singularity {
             add_css_class("singularity");
             add_css_class("singularity-shell");
             add_css_class("background-window");
+            ensure_attribution_css();
 
             picture_a = new Picture();
             picture_a.content_fit = ContentFit.COVER;
@@ -39,9 +91,48 @@ namespace Singularity {
             wp_stack.transition_duration = 600;
             wp_stack.add_named(picture_a, "a");
             wp_stack.add_named(picture_b, "b");
-            set_child(wp_stack);
+
+            // Attribution overlay. The label is bottom-left-anchored
+            // (halign=START, valign=END, ATTRIBUTION_MARGIN gutter)
+            // and click-through so it never intercepts desktop mouse
+            // events. can_target=false is GTK4's correct way to make a
+            // widget hit-test-transparent; setting can_focus=false
+            // prevents the label from grabbing Tab focus out of the
+            // desktop. The scrim + padding + font live in the
+            // `attribution-label` CSS class, loaded by
+            // ensure_attribution_css() above (wallpaper-specific styling
+            // lives here, not in libsingularity, per review on
+            // libsingularity#13). The `light-bg` class on the Background
+            // window (toggled below) is the same one panel.vala uses, so
+            // the contrast rule is consistent across panel + overlay.
+            attribution_label = new Label("");
+            attribution_label.add_css_class("attribution-label");
+            attribution_label.halign = Align.START;
+            attribution_label.valign = Align.END;
+            attribution_label.xalign = 0.0f;
+            attribution_label.yalign = 1.0f;
+            attribution_label.margin_start = ATTRIBUTION_MARGIN;
+            attribution_label.margin_end = ATTRIBUTION_MARGIN;
+            attribution_label.margin_bottom = ATTRIBUTION_MARGIN;
+            attribution_label.margin_top = ATTRIBUTION_MARGIN;
+            attribution_label.visible = false;
+            attribution_label.can_focus = false;
+            attribution_label.can_target = false;
+            wp_overlay = new Gtk.Overlay();
+            wp_overlay.set_child(wp_stack);
+            wp_overlay.add_overlay(attribution_label);
+            set_child(wp_overlay);
 
             var manager = WallpaperManager.get_default();
+            // GSettings backing for the attribution toggle. Same schema id
+            // string as desktop_page.vala (dev.sinty.desktop). The
+            // changed[] handler re-runs update_attribution() so flipping
+            // the toggle in Settings immediately hides or re-shows the
+            // overlay for the wallpaper that's currently displayed.
+            settings = new GLib.Settings("dev.sinty.desktop");
+            settings.changed["show-wallpaper-attribution"].connect(() => {
+                update_attribution(WallpaperManager.get_default());
+            });
             // First load: set both pictures to avoid flash, no animation needed
             if (manager.display_texture != null) {
                 picture_a.set_paintable(manager.display_texture);
@@ -50,7 +141,13 @@ namespace Singularity {
             }
             manager.wallpaper_changed.connect(() => {
                 update_wallpaper(manager);
+                update_attribution(manager);
             });
+            // Initial bind for the case where WallpaperManager already
+            // has a display_texture and attribution on startup (warm
+            // restart): wallpaper_changed would not re-fire, so we
+            // call update_attribution() once explicitly.
+            update_attribution(manager);
             map.connect_after(() => {
                 if (_first_painted_done) return;
                 var clock = get_frame_clock();
@@ -97,6 +194,137 @@ namespace Singularity {
             });
         }
 
+        // Wallpaper attribution overlay (Background.vala).
+        //
+        // Sits in the bottom-left corner of the live desktop background
+        // as a single Gtk.Label over the wallpaper cross-fade. The scrim
+        // is a semi-transparent rounded rectangle so the text reads
+        // against both bright and dark wallpapers without an aggressive
+        // box, and the light-bg / non-light-bg pair matches the
+        // convention panel.vala already uses for the top band -- same
+        // colour tokens, same threshold (ATTRIBUTION_LUM_THRESHOLD = 0.72,
+        // defined above).
+        //
+        // The luminance class selects an opposing scrim/text pair
+        // independently of the active application theme, since wallpaper
+        // contrast cannot be inferred from the theme's text colour.
+        //
+        // Moved here from libsingularity's style.css (review on
+        // libsingularity#13: that stylesheet should stay limited to
+        // reusable widget styling, and this rule only exists for the
+        // wallpaper attribution overlay singularity-shell owns) -- rules
+        // and rationale unchanged, just relocated to the actual consumer.
+        private const string ATTRIBUTION_CSS = """
+.background-window .attribution-label {
+    border-radius: 8px;
+    padding: 6px 12px;
+    font-size: 13px;
+    font-weight: 400;
+}
+.background-window.light-bg .attribution-label {
+    /* Bright wallpaper: dark scrim with light foreground. */
+    background-color: alpha(black, 0.65);
+    color: white;
+    text-shadow: 0 1px 2px alpha(black, 0.45);
+}
+.background-window:not(.light-bg) .attribution-label {
+    /* Dark wallpaper: light scrim with dark foreground. */
+    background-color: alpha(white, 0.72);
+    color: black;
+    text-shadow: 0 1px 2px alpha(white, 0.35);
+}
+""";
+
+        // Registers ATTRIBUTION_CSS once per process, the same way
+        // panel.vala's compact_rows_provider is registered: a static
+        // nullable CssProvider, guarded by a null-check, loaded on first
+        // Background construction.
+        private static void ensure_attribution_css() {
+            if (attribution_css_provider != null) return;
+            var display = Gdk.Display.get_default();
+            if (display == null) return;
+            attribution_css_provider = new Gtk.CssProvider();
+            attribution_css_provider.load_from_string(ATTRIBUTION_CSS);
+            Gtk.StyleContext.add_provider_for_display(
+                display,
+                attribution_css_provider,
+                Gtk.STYLE_PROVIDER_PRIORITY_APPLICATION
+            );
+        }
+
+        // Bind the attribution overlay to the WallpaperManager. Called
+        // on every wallpaper_changed signal -- which now fires on URI
+        // changes AND on attribution-only changes (see WallpaperManager
+        // reload()), so a single signal covers both cases.
+        //
+        // Text format: title (bold) and author (dim-label) concatenated
+        // with a middle-dot separator. Markup-escape both because the
+        // data comes from third-party OCS / Bing caption strings that
+        // the parsers accept leniently -- an unescaped & < > in the
+        // text would otherwise be a Pango parse error and crash the
+        // label render.
+        //
+        // Contrast: sample the bottom-left corner rectangle from
+        // WallpaperManager.corner_luminance_frac() and compare against
+        // ATTRIBUTION_LUM_THRESHOLD. Above threshold = light
+        // background under the text = use dark text via .light-bg
+        // class on the Background window; below = dark background =
+        // use light text. Same `light-bg` CSS class the panel uses,
+        // extended in the stylesheet for .background-window.light-bg.
+        private void update_attribution(WallpaperManager manager) {
+            string title = manager.attribution_title ?? "";
+            string author = manager.attribution_author ?? "";
+            // The user-toggleable show-wallpaper-attribution gsettings key
+            // shares the same early-return path as the no-title-and-no-author
+            // case below: when the overlay is hidden for any reason we
+            // clear the contrast class too, so re-enabling the toggle (or
+            // loading a wallpaper that carries attribution) re-samples
+            // cleanly on the next wallpaper_changed.
+            if (!settings.get_boolean("show-wallpaper-attribution")) {
+                title = "";
+                author = "";
+            }
+            if (title == "" && author == "") {
+                attribution_label.visible = false;
+                attribution_label.label = "";
+                // Remove the contrast class too: a hidden overlay
+                // shouldn't keep the .light-bg class set on the
+                // window, because if a future wallpaper is loaded
+                // without attribution we still want the window to
+                // re-sample cleanly on the next wallpaper_changed.
+                remove_css_class("light-bg");
+                return;
+            }
+            string safe_title = Markup.escape_text(title, -1);
+            string safe_author = Markup.escape_text(author, -1);
+            string markup;
+            if (title != "" && author != "") {
+                markup = "<b>%s</b>  ·  %s".printf(safe_title, safe_author);
+            } else if (title != "") {
+                markup = "<b>%s</b>".printf(safe_title);
+            } else {
+                markup = safe_author;
+            }
+            // CSS class is not a supported Pango span attribute.
+            attribution_label.set_markup(markup);
+            attribution_label.visible = true;
+
+            // Sample the corner. The pixbuf aspect matches the screen
+            // aspect so a fractional bottom-left corner maps 1:1 to a
+            // fractional bottom-left corner of the screen at the same
+            // proportional position.
+            double lum = manager.corner_luminance_frac(
+                CORNER_SAMPLE_X_FRAC,
+                CORNER_SAMPLE_Y_FRAC,
+                CORNER_SAMPLE_W_FRAC,
+                CORNER_SAMPLE_H_FRAC);
+            if (lum >= 0.0) {
+                bool light_bg = lum > ATTRIBUTION_LUM_THRESHOLD;
+                if (light_bg) add_css_class("light-bg");
+                else remove_css_class("light-bg");
+            }
+        }
+
         private void update_wallpaper(WallpaperManager manager) {
             if (manager.display_texture == null) return;
             // Write to the off-screen picture, then crossfade to it

src/components/desktop/desktop_icons.vala

@@ -583,7 +583,16 @@ namespace Singularity {
             }
             if (content_type.has_prefix("image/")) {
                 menu.add_item("Set as Wallpaper", "preferences-desktop-wallpaper-symbolic", () => {
-                    settings.set_string("background-picture-uri", file.get_uri());
+                    // A drag-and-drop file from the file manager
+                    // has no OCS/Bing metadata, so the attribution
+                    // overlay has nothing to show for this URI.
+                    // Explicit clear (rather than rely on the
+                    // schema default) so a previous OCS-imported
+                    // wallpapers title/author cannot bleed through
+                    // and appear over this new image.
+                    SettingsSafety.set_string(settings, "background-picture-uri", file.get_uri());
+                    SettingsSafety.set_string(settings, "background-attribution-title", "");
+                    SettingsSafety.set_string(settings, "background-attribution-author", "");
                 });
             }
             menu.add_separator();