shadow: avoid fatal mutation of the windowBox for calcs

fixes #3865

3 files changed, 7 insertions, 1 deletions

diff --git a/src/helpers/Box.cpp b/src/helpers/Box.cpp
index 29aa81fa..3d57bc79 100644
--- a/src/helpers/Box.cpp
+++ b/src/helpers/Box.cpp
@@ -112,6 +112,10 @@ CBox CBox::roundInternal() {
     return CBox{std::floor(x), std::floor(y), std::floor(newW), std::floor(newH)};
 }
 
+CBox CBox::copy() const {
+    return CBox{*this};
+}
+
 Vector2D CBox::pos() const {
     return {x, y};
 }
diff --git a/src/helpers/Box.hpp b/src/helpers/Box.hpp
index cb07df06..5cb7f17f 100644
--- a/src/helpers/Box.hpp
+++ b/src/helpers/Box.hpp
@@ -52,6 +52,8 @@ class CBox {
     CBox&                    addExtents(const SWindowDecorationExtents& e);
     CBox&                    expand(const double& value);
 
+    CBox                     copy() const;
+
     SWindowDecorationExtents extentsFrom(const CBox&); // this is the big box
 
     Vector2D                 middle() const;
diff --git a/src/render/decorations/CHyprDropShadowDecoration.cpp b/src/render/decorations/CHyprDropShadowDecoration.cpp
index 7138dc20..d8972376 100644
--- a/src/render/decorations/CHyprDropShadowDecoration.cpp
+++ b/src/render/decorations/CHyprDropShadowDecoration.cpp
@@ -129,7 +129,7 @@ void CHyprDropShadowDecoration::draw(CMonitor* pMonitor, float a, const Vector2D
         CRegion saveDamage = g_pHyprOpenGL->m_RenderData.damage;
 
         g_pHyprOpenGL->m_RenderData.damage = fullBox;
-        g_pHyprOpenGL->m_RenderData.damage.subtract(windowBox.expand(-ROUNDING * pMonitor->scale)).intersect(saveDamage);
+        g_pHyprOpenGL->m_RenderData.damage.subtract(windowBox.copy().expand(-ROUNDING * pMonitor->scale)).intersect(saveDamage);
 
         alphaFB.bind();