From 8f40b5b5541b2600af0f43a22753646f877cdddb Mon Sep 17 00:00:00 2001
From: Vlad Zahorodnii <vlad.zahorodnii@kde.org>
Date: Fri, 30 Aug 2024 00:16:37 +0300
Subject: [PATCH] plugins/blur: Fix a crash in BlurEffect::updateBlurRegion()

The updateBlurRegion() creates ItemEffect() objects to block direct
scanout. However, it doesn't take into account that the surface item
can be null when a window is added. It can happen with Xwayland
windows.

The blur effect creates ItemEffect objects for the SurfaceItem and the
DecorationItem, which is reasonable. But on the other hand, the blur
effect still operates per window. So this change simply makes the blur
effect register an ItemEffect with the WindowItem. When proper per
item effects are supported, this can be changed (the blur effect would
need to monitor the wl_surface getting added and removed).
---
 src/plugins/blur/blur.cpp | 7 +------
 src/plugins/blur/blur.h   | 4 ++--
 2 files changed, 3 insertions(+), 8 deletions(-)

diff --git a/src/plugins/blur/blur.cpp b/src/plugins/blur/blur.cpp
index 53b2b1fa7e..9cde73b9ba 100644
--- a/src/plugins/blur/blur.cpp
+++ b/src/plugins/blur/blur.cpp
@@ -266,12 +266,7 @@ void BlurEffect::updateBlurRegion(EffectWindow *w)
         BlurEffectData &data = m_windows[w];
         data.content = content;
         data.frame = frame;
-        if (content) {
-            data.surfaceEffect = ItemEffect(w->windowItem()->surfaceItem());
-        }
-        if (frame) {
-            data.surfaceEffect = ItemEffect(w->windowItem()->decorationItem());
-        }
+        data.windowEffect = ItemEffect(w->windowItem());
     } else {
         if (auto it = m_windows.find(w); it != m_windows.end()) {
             effects->makeOpenGLContextCurrent();
diff --git a/src/plugins/blur/blur.h b/src/plugins/blur/blur.h
index 94b6c50eef..091cb1c524 100644
--- a/src/plugins/blur/blur.h
+++ b/src/plugins/blur/blur.h
@@ -32,14 +32,14 @@ struct BlurEffectData
 {
     /// The region that should be blurred behind the window
     std::optional<QRegion> content;
-    ItemEffect surfaceEffect;
 
     /// The region that should be blurred behind the frame
     std::optional<QRegion> frame;
-    ItemEffect decorationEffect;
 
     /// The render data per screen. Screens can have different color spaces.
     std::unordered_map<Output *, BlurRenderData> render;
+
+    ItemEffect windowEffect;
 };
 
 class BlurEffect : public KWin::Effect