[effects] Properly announce/remove support in blur/contrast if shader fails

Following the approach how it's done for X11: only create the interface
if the shader succeeded to compile and remove support again if it failed
to compile after a reconfigure.

REVIEW: 125444

effects/backgroundcontrast/contrast.cpp

@@ -37,11 +37,6 @@ static const QByteArray s_contrastAtomName = QByteArrayLiteral("_KDE_NET_WM_BACK
 
 ContrastEffect::ContrastEffect()
 {
-    KWayland::Server::Display *display = effects->waylandDisplay();
-    if (display) {
-        display->createContrastManager(this)->create();
-    }
-
     shader = ContrastShader::create();
 
     reconfigure(ReconfigureAll);
@@ -50,6 +45,11 @@ ContrastEffect::ContrastEffect()
     //     Should be included in _NET_SUPPORTED instead.
     if (shader && shader->isValid()) {
         net_wm_contrast_region = effects->announceSupportProperty(s_contrastAtomName, this);
+        KWayland::Server::Display *display = effects->waylandDisplay();
+        if (display) {
+            m_contrastManager = display->createContrastManager(this);
+            m_contrastManager->create();
+        }
     } else {
         net_wm_contrast_region = 0;
     }
@@ -81,8 +81,11 @@ void ContrastEffect::reconfigure(ReconfigureFlags flags)
     if (shader)
         shader->init();
 
-    if (!shader || !shader->isValid())
+    if (!shader || !shader->isValid()) {
         effects->removeSupportProperty(s_contrastAtomName, this);
+        delete m_contrastManager;
+        m_contrastManager = nullptr;
+    }
 }
 
 void ContrastEffect::updateContrastRegion(EffectWindow *w) const

effects/backgroundcontrast/contrast.h

@@ -28,6 +28,14 @@
 #include <QVector>
 #include <QVector2D>
 
+namespace KWayland
+{
+namespace Server
+{
+class ContrastManagerInterface;
+}
+}
+
 namespace KWin
 {
 
@@ -76,6 +84,7 @@ private:
     QRegion m_paintedArea; // actually painted area which is greater than m_damagedArea
     QRegion m_currentContrast; // keeps track of the currently contrasted area of non-caching windows(from bottom to top)
     QHash< const EffectWindow*, QMetaObject::Connection > m_contrastChangedConnections; // used only in Wayland to keep track of effect changed
+    KWayland::Server::ContrastManagerInterface *m_contrastManager = nullptr;
 };
 
 inline

effects/blur/blur.cpp

@@ -39,11 +39,6 @@ static const QByteArray s_blurAtomName = QByteArrayLiteral("_KDE_NET_WM_BLUR_BEH
 
 BlurEffect::BlurEffect()
 {
-    KWayland::Server::Display *display = effects->waylandDisplay();
-    if (display) {
-        display->createBlurManager(this)->create();
-    }
-
     shader = BlurShader::create();
 
     // Offscreen texture that's used as the target for the horizontal blur pass
@@ -60,6 +55,11 @@ BlurEffect::BlurEffect()
     //     Should be included in _NET_SUPPORTED instead.
     if (shader && shader->isValid() && target->valid()) {
         net_wm_blur_region = effects->announceSupportProperty(s_blurAtomName, this);
+        KWayland::Server::Display *display = effects->waylandDisplay();
+        if (display) {
+            m_blurManager = display->createBlurManager(this);
+            m_blurManager->create();
+        }
     } else {
         net_wm_blur_region = 0;
     }
@@ -100,8 +100,11 @@ void BlurEffect::reconfigure(ReconfigureFlags flags)
 
     windows.clear();
 
-    if (!shader || !shader->isValid())
+    if (!shader || !shader->isValid()) {
         effects->removeSupportProperty(s_blurAtomName, this);
+        delete m_blurManager;
+        m_blurManager = nullptr;
+    }
 }
 
 void BlurEffect::updateBlurRegion(EffectWindow *w) const

effects/blur/blur.h

@@ -27,6 +27,14 @@
 #include <QVector>
 #include <QVector2D>
 
+namespace KWayland
+{
+namespace Server
+{
+class BlurManagerInterface;
+}
+}
+
 namespace KWin
 {
 
@@ -98,6 +106,7 @@ private:
 
     QHash< const EffectWindow*, BlurWindowInfo > windows;
     typedef QHash<const EffectWindow*, BlurWindowInfo>::iterator CacheEntry;
+    KWayland::Server::BlurManagerInterface *m_blurManager = nullptr;
 };
 
 inline