kwineffects: Rename WindowPrePaintData::clip to opaque

"opaque" is more readable than "clip" and it precisely communicates
what that region actually is.

src/effects/blur/blur.cpp

@@ -542,22 +542,22 @@ void BlurEffect::prePaintWindow(EffectWindow* w, WindowPrePaintData& data, std::
         return;
     }
 
-    const QRegion oldClip = data.clip;
-    if (data.clip.intersects(m_currentBlur)) {
+    const QRegion oldOpaque = data.opaque;
+    if (data.opaque.intersects(m_currentBlur)) {
         // to blur an area partially we have to shrink the opaque area of a window
-        QRegion newClip;
-        for (const QRect &rect : data.clip) {
-            newClip |= rect.adjusted(m_expandSize, m_expandSize, -m_expandSize, -m_expandSize);
+        QRegion newOpaque;
+        for (const QRect &rect : data.opaque) {
+            newOpaque |= rect.adjusted(m_expandSize, m_expandSize, -m_expandSize, -m_expandSize);
         }
-        data.clip = newClip;
+        data.opaque = newOpaque;
 
         // we don't have to blur a region we don't see
-        m_currentBlur -= newClip;
+        m_currentBlur -= newOpaque;
     }
 
     // if we have to paint a non-opaque part of this window that intersects with the
     // currently blurred region we have to redraw the whole region
-    if ((data.paint - oldClip).intersects(m_currentBlur)) {
+    if ((data.paint - oldOpaque).intersects(m_currentBlur)) {
         data.paint |= m_currentBlur;
     }
 
@@ -579,7 +579,7 @@ void BlurEffect::prePaintWindow(EffectWindow* w, WindowPrePaintData& data, std::
 
     m_currentBlur |= expandedBlur;
 
-    m_paintedArea -= data.clip;
+    m_paintedArea -= data.opaque;
     m_paintedArea |= data.paint;
 }
 

src/effects/wobblywindows/wobblywindows.cpp

@@ -252,7 +252,7 @@ void WobblyWindowsEffect::prePaintWindow(EffectWindow* w, WindowPrePaintData& da
 
         // We have to reset the clip region in order to render clients below
         // opaque wobbly windows.
-        data.clip = QRegion();
+        data.opaque = QRegion();
 
         while ((presentTime - infoIt->clock).count() > 0) {
             const auto delta = std::min(presentTime - infoIt->clock, integrationStep);

src/libkwineffects/kwineffects.cpp

@@ -37,7 +37,7 @@ void WindowPrePaintData::setTranslucent()
 {
     mask |= Effect::PAINT_WINDOW_TRANSLUCENT;
     mask &= ~Effect::PAINT_WINDOW_OPAQUE;
-    clip = QRegion(); // cannot clip, will be transparent
+    opaque = QRegion(); // cannot clip, will be transparent
 }
 
 void WindowPrePaintData::setTransformed()

src/libkwineffects/kwineffects.h

@@ -2754,10 +2754,10 @@ public:
      */
     QRegion paint;
     /**
-     * The clip region will be subtracted from paint region of following windows.
-     * I.e. window will definitely cover it's clip region
+     * Region indicating the opaque content. It can be used to avoid painting
+     * windows occluded by the opaque region.
      */
-    QRegion clip;
+    QRegion opaque;
     /**
      * Simple helper that sets data to say the window will be painted as non-opaque.
      * Takes also care of changing the regions.

src/scene.cpp

@@ -346,7 +346,7 @@ void Scene::preparePaintGenericScreen()
             m_paintContext.phase2Data.append(Phase2Data{
                 .window = sceneWindow,
                 .region = infiniteRegion(),
-                .opaque = data.clip,
+                .opaque = data.opaque,
                 .mask = data.mask,
             });
         }
@@ -367,20 +367,20 @@ void Scene::preparePaintSimpleScreen()
         if (sceneWindow->isOpaque()) {
             const SurfaceItem *surfaceItem = sceneWindow->surfaceItem();
             if (surfaceItem) {
-                data.clip = surfaceItem->mapToGlobal(surfaceItem->shape());
+                data.opaque = surfaceItem->mapToGlobal(surfaceItem->shape());
             }
         } else if (toplevel->hasAlpha() && toplevel->opacity() == 1.0) {
             const SurfaceItem *surfaceItem = sceneWindow->surfaceItem();
             if (surfaceItem) {
                 const QRegion shape = surfaceItem->shape();
                 const QRegion opaque = surfaceItem->opaque();
-                data.clip = surfaceItem->mapToGlobal(shape & opaque);
+                data.opaque = surfaceItem->mapToGlobal(shape & opaque);
             }
         }
 
         const AbstractClient *client = dynamic_cast<const AbstractClient *>(toplevel);
         if (client && !client->decorationHasAlpha() && toplevel->opacity() == 1.0) {
-            data.clip |= sceneWindow->decorationShape().translated(sceneWindow->pos());
+            data.opaque |= sceneWindow->decorationShape().translated(sceneWindow->pos());
         }
 
         sceneWindow->resetPaintingEnabled();
@@ -389,7 +389,7 @@ void Scene::preparePaintSimpleScreen()
             m_paintContext.phase2Data.append(Phase2Data{
                 .window = sceneWindow,
                 .region = data.paint,
-                .opaque = data.clip,
+                .opaque = data.opaque,
                 .mask = data.mask,
             });
         }