compositor: be more selective about how we expand the window box in getting coord (#13720)

* Be more selective about how we expand the window box here so that we're not overlapping with any neighbouring windows.

* Don't use getWindowInDirection to see if we're clear to expand the hit box. Instead, just see if our edge is close to the edge of the workspace.

* Clang-format changes

1 files changed, 49 insertions, 2 deletions

diff --git a/src/Compositor.cpp b/src/Compositor.cpp
index b6aaad00..844a19f9 100644
--- a/src/Compositor.cpp
+++ b/src/Compositor.cpp
@@ -1043,8 +1043,55 @@ PHLWINDOW CCompositor::vectorToWindowUnified(const Vector2D& pos, uint8_t proper
             if (!w->m_isFloating && w->m_isMapped && w->workspaceID() == WSPID && !w->isHidden() && !w->m_X11ShouldntFocus && !w->m_ruleApplicator->noFocus().valueOrDefault() &&
                 w != pIgnoreWindow && !isShadowedByModal(w)) {
                 CBox box = (properties & Desktop::View::USE_PROP_TILED) ? w->getWindowBoxUnified(properties) : CBox{w->m_position, w->m_size};
-                if ((properties & Desktop::View::INPUT_EXTENTS) && BORDER_GRAB_AREA > 0 && !w->isX11OverrideRedirect())
-                    box.expand(BORDER_GRAB_AREA);
+                if ((properties & Desktop::View::INPUT_EXTENTS) && BORDER_GRAB_AREA > 0 && !w->isX11OverrideRedirect()) {
+                    const auto  WORKAREA                    = PWORKSPACE->m_space->workArea();
+                    static auto isWindowCloseToWorkAreaEdge = [&](const Math::eDirection dir) -> bool {
+                        constexpr double STICK_THRESHOLD = 2.0; // This constant is taken from isAdjacent in CCompositor::getWindowInDirection
+                        double           aEdge           = -1;
+                        double           bEdge           = -1;
+
+                        switch (dir) {
+                            case Math::DIRECTION_LEFT:
+                                aEdge = WORKAREA.x;
+                                bEdge = box.x;
+                                break;
+                            case Math::DIRECTION_RIGHT:
+                                aEdge = WORKAREA.x + WORKAREA.width;
+                                bEdge = box.x + box.width;
+                                break;
+                            case Math::DIRECTION_UP:
+                                aEdge = WORKAREA.y;
+                                bEdge = box.y;
+                                break;
+                            case Math::DIRECTION_DOWN:
+                                aEdge = WORKAREA.y + WORKAREA.height;
+                                bEdge = box.y + box.height;
+                                break;
+                            default: break;
+                        }
+                        const double delta = aEdge - bEdge;
+                        if (std::abs(delta) < STICK_THRESHOLD)
+                            return true;
+                        else
+                            return false;
+                    };
+
+                    if (isWindowCloseToWorkAreaEdge(Math::eDirection::DIRECTION_LEFT)) {
+                        box.x -= BORDER_GRAB_AREA;
+                        box.width += BORDER_GRAB_AREA;
+                    }
+
+                    if (isWindowCloseToWorkAreaEdge(Math::eDirection::DIRECTION_RIGHT))
+                        box.width += BORDER_GRAB_AREA;
+
+                    if (isWindowCloseToWorkAreaEdge(Math::eDirection::DIRECTION_UP)) {
+                        box.y -= BORDER_GRAB_AREA;
+                        box.height += BORDER_GRAB_AREA;
+                    }
+
+                    if (isWindowCloseToWorkAreaEdge(Math::eDirection::DIRECTION_DOWN))
+                        box.height += BORDER_GRAB_AREA;
+                }
                 if (box.containsPoint(pos))
                     return w;
             }