fix(wayland): skip fully off-surface blur regions

meson.build

@@ -1133,16 +1133,16 @@ if build_tests
     'battery_hook_state',
     'button_layout',
     'cairo_text_renderer',
-    'calendar_cache_permissions',
-    'cli_help',
-    'cli_parse',
-    'cli_schema',
     'caldav_client',
+    'calendar_cache_permissions',
     'calendar_credential_store',
     'calendar_discovery_state',
     'calendar_view_passed_event',
     'capsule_group_lane_override',
     'capsule_group_reconcile',
+    'cli_help',
+    'cli_parse',
+    'cli_schema',
     'clipboard_service',
     'clipboard_storage_permissions',
     'config_migration',
@@ -1172,34 +1172,34 @@ if build_tests
     'icon_resolver',
     'image_file_loader_data_uri',
     'image_source_log',
+    'inotify',
     'input_area',
     'input_dispatcher',
-    'input_readline_shortcuts',
     'input_password_mode',
-    'inotify',
+    'input_readline_shortcuts',
     'ipc_service',
     'jxl_decoder',
-    'keyboard_layout_label',
     'kde_color_scheme',
+    'keyboard_layout_label',
     'lane_selection_token',
-    'log',
     'location_service',
+    'log',
     'math_provider',
     'monitor_selector',
     'network_manager_security',
+    'niri_workspace_backend',
     'notification_dnd',
     'notification_filter',
     'notification_history_dismiss',
     'notification_history_utf8',
-    'niri_workspace_backend',
     'path_browse',
     'plugin_bindings',
     'plugin_catalog',
     'plugin_git_export',
     'plugin_i18n',
     'plugin_lifecycle',
-    'plugin_process',
     'plugin_manifest',
+    'plugin_process',
     'plugin_source_locks',
     'plugin_source_paths',
     'process',
@@ -1208,6 +1208,7 @@ if build_tests
     'security_primitives',
     'state_store',
     'string_utils',
+    'surface_blur_region',
     'system_monitor_service',
     'taskbar_widget',
     'template_apply_notify',
@@ -1220,12 +1221,12 @@ if build_tests
     'upower_charge_limit',
     'upower_device_catalog',
     'virtual_grid_view_gesture',
-    'webp_decoder',
+    'wallpaper_shuffle_state',
     'wayland_output_scale',
     'wayland_toplevels_identity',
+    'webp_decoder',
     'widget_action',
     'widget_definition',
-    'wallpaper_shuffle_state',
     'workspace_alert_service',
   ]
 

src/wayland/surface.cpp

@@ -676,13 +676,34 @@ bool Surface::prepareBlurEffect() {
   return true;
 }
 
+bool Surface::regionIntersectsBounds(const std::vector<InputRect>& rects, std::uint32_t width, std::uint32_t height) {
+  if (width == 0 || height == 0) {
+    return false;
+  }
+  for (const auto& r : rects) {
+    const std::int64_t right = static_cast<std::int64_t>(r.x) + r.width;
+    const std::int64_t bottom = static_cast<std::int64_t>(r.y) + r.height;
+    if (r.width > 0
+        && r.height > 0
+        && right > 0
+        && bottom > 0
+        && static_cast<std::int64_t>(r.x) < width
+        && static_cast<std::int64_t>(r.y) < height) {
+      return true;
+    }
+  }
+  return false;
+}
+
 void Surface::setBlurRegion(const std::vector<InputRect>& rects) {
   if (!prepareBlurEffect()) {
     return;
   }
 
+  // Hyprland renders a fully off-surface non-empty blur region as full-surface blur, so send null instead.
+  const bool hasVisibleRegion = regionIntersectsBounds(rects, m_width, m_height);
   wl_region* region = nullptr;
-  if (!rects.empty()) {
+  if (hasVisibleRegion) {
     region = wl_compositor_create_region(m_connection.compositor());
     if (region == nullptr) {
       traceSurfaceEvent(*this, "blur-set-skip-region-failed");
@@ -692,7 +713,11 @@ void Surface::setBlurRegion(const std::vector<InputRect>& rects) {
       wl_region_add(region, r.x, r.y, r.width, r.height);
     }
   }
-  traceBlurRegionEvent(*this, rects.empty() ? "blur-set-empty" : "blur-set", rects);
+  const char* traceLabel = "blur-set";
+  if (!hasVisibleRegion) {
+    traceLabel = rects.empty() ? "blur-set-empty" : "blur-set-offsurface";
+  }
+  traceBlurRegionEvent(*this, traceLabel, rects);
   ext_background_effect_surface_v1_set_blur_region(m_backgroundEffect, region);
   if (region != nullptr) {
     wl_region_destroy(region);

src/wayland/surface.h

@@ -113,6 +113,9 @@ class Surface {
   static std::vector<InputRect> tessellateRotatedRoundedRect(
       float centerX, float centerY, float width, float height, float radius, float rotationRad, int stripPx = 1
   );
+  // True when any rect covers at least one pixel of a `width` x `height` surface.
+  // Rects are surface-local, so they may legitimately sit partly or fully outside.
+  static bool regionIntersectsBounds(const std::vector<InputRect>& rects, std::uint32_t width, std::uint32_t height);
   void requestUpdate();
   void requestUpdateOnly();
   void requestLayout();

tests/surface_blur_region_test.cpp

@@ -0,0 +1,10 @@
+#include "test_check.h"
+#include "wayland/surface.h"
+
+int main() {
+  TEST_CHECK(!Surface::regionIntersectsBounds({InputRect{8, -39, 3056, 35}}, 3072, 49));
+
+  TEST_CHECK(Surface::regionIntersectsBounds({InputRect{8, -34, 3056, 35}}, 3072, 49));
+
+  return 0;
+}