option: Add center_row_if_space_available

README.md

@@ -630,6 +630,12 @@ Determines whether focus will *wrap* when at the first or
 last window of a row/column. Possible arguments are: `true`|`1` (default), or
 `false`|`0`.
 
+### `center_row_if_space_available`
+
+If there is empty space in the viewport, the row will be centered, leaving the
+same amount of empty space on each side (respecting `gaps_out`). Possible
+arguments are: `false`|`0` (default), or `true`|`1`.
+
 ### `overview_scale_content`
 
 Scales the content of the windows in overview mode, like GNOME/MacOS/Windows

src/main.cpp

@@ -35,6 +35,8 @@ APICALL EXPORT PLUGIN_DESCRIPTION_INFO PLUGIN_INIT(HANDLE handle) {
     // 0, 1
     HyprlandAPI::addConfigValue(PHANDLE, "plugin:scroller:focus_wrap", Hyprlang::INT{1});
     // 0, 1
+    HyprlandAPI::addConfigValue(PHANDLE, "plugin:scroller:center_row_if_space_available", Hyprlang::INT{0});
+    // 0, 1
     HyprlandAPI::addConfigValue(PHANDLE, "plugin:scroller:overview_scale_content", Hyprlang::INT{1});
     // a list of values used as standard widths for cyclesize in row mode, and in the cycling order
     // available options: onesixth, onefourth, onethird, onehalf, twothirds, one

src/row.cpp

@@ -942,6 +942,22 @@ void Row::recalculate_row_geometry()
         adjust_overview_columns();
         return;
     }
+    static auto* const *center_row = (Hyprlang::INT* const *)HyprlandAPI::getConfigValue(PHANDLE, "plugin:scroller:center_row_if_space_available")->getDataStaticPtr();
+    if (**center_row && pinned == nullptr) {
+        double lwidth = 0.0, rwidth = 0.0;
+        for (auto col = columns.first(); col != active; col = col->next()) {
+            lwidth += col->data()->get_geom_w();
+        }
+        for (auto col = active; col != nullptr; col = col->next()) {
+            rwidth += col->data()->get_geom_w();
+        }
+        double width = lwidth + rwidth;
+        if (width < max.w) {
+            double start = max.x + 0.5 * (max.w - width);
+            active->data()->set_geom_pos(start + lwidth, max.y);
+        }
+    }
+
     auto a_w = active->data()->get_geom_w();
     auto a_x = active->data()->get_geom_x();
     // Pinned will stay in place, with active having second priority to fit in