wayland/surface: add the output a surface is on the most

autotests/wayland/client/test_wayland_surface.cpp

@@ -865,7 +865,7 @@ void TestWaylandSurface::testOutput()
     m_display->dispatchEvents();
 
     // now enter it
-    serverSurface->setOutputs(QList<OutputInterface *>{serverOutput.get()});
+    serverSurface->setOutputs(QList<OutputInterface *>{serverOutput.get()}, serverOutput.get());
     QCOMPARE(serverSurface->outputs(), QList<OutputInterface *>{serverOutput.get()});
     QVERIFY(enteredSpy.wait());
     QCOMPARE(enteredSpy.count(), 1);
@@ -873,10 +873,10 @@ void TestWaylandSurface::testOutput()
     QCOMPARE(s->outputs(), QList<KWayland::Client::Output *>{clientOutput.get()});
 
     // adding to same should not trigger
-    serverSurface->setOutputs(QList<OutputInterface *>{serverOutput.get()});
+    serverSurface->setOutputs(QList<OutputInterface *>{serverOutput.get()}, serverOutput.get());
 
     // leave again
-    serverSurface->setOutputs(QList<OutputInterface *>());
+    serverSurface->setOutputs(QList<OutputInterface *>(), nullptr);
     QCOMPARE(serverSurface->outputs(), QList<OutputInterface *>());
     QVERIFY(leftSpy.wait());
     QCOMPARE(enteredSpy.count(), 1);
@@ -885,10 +885,10 @@ void TestWaylandSurface::testOutput()
     QCOMPARE(s->outputs(), QList<KWayland::Client::Output *>());
 
     // leave again should not trigger
-    serverSurface->setOutputs(QList<OutputInterface *>());
+    serverSurface->setOutputs(QList<OutputInterface *>(), nullptr);
 
     // and enter again, just to verify
-    serverSurface->setOutputs(QList<OutputInterface *>{serverOutput.get()});
+    serverSurface->setOutputs(QList<OutputInterface *>{serverOutput.get()}, serverOutput.get());
     QCOMPARE(serverSurface->outputs(), QList<OutputInterface *>{serverOutput.get()});
     QVERIFY(enteredSpy.wait());
     QCOMPARE(enteredSpy.count(), 2);

src/pointer_input.cpp

@@ -920,7 +920,8 @@ void CursorImage::updateCursorOutputs(const QPointF &pos)
         auto cursorSurface = m_serverCursor.surface->surface();
         if (cursorSurface) {
             const QRectF cursorGeometry(pos - m_currentSource->hotspot(), m_currentSource->size());
-            cursorSurface->setOutputs(waylandServer()->display()->outputsIntersecting(cursorGeometry.toAlignedRect()));
+            cursorSurface->setOutputs(waylandServer()->display()->outputsIntersecting(cursorGeometry.toAlignedRect()),
+                                      waylandServer()->display()->largestIntersectingOutput(cursorGeometry.toAlignedRect()));
         }
     }
 }

src/wayland/display.cpp

@@ -172,6 +172,21 @@ QList<OutputInterface *> Display::outputsIntersecting(const QRect &rect) const
     return outputs;
 }
 
+OutputInterface *Display::largestIntersectingOutput(const QRect &rect) const
+{
+    OutputInterface *returnOutput = nullptr;
+    uint64_t biggestArea = 0;
+    for (auto *output : std::as_const(d->outputs)) {
+        const QRect intersect = output->handle()->geometry().intersected(rect);
+        const uint64_t area = intersect.width() * intersect.height();
+        if (area > biggestArea) {
+            biggestArea = area;
+            returnOutput = output;
+        }
+    }
+    return returnOutput;
+}
+
 QList<SeatInterface *> Display::seats() const
 {
     return d->seats;

src/wayland/display.h

@@ -102,6 +102,7 @@ public:
     QList<OutputDeviceV2Interface *> outputDevices() const;
     QList<OutputInterface *> outputs() const;
     QList<OutputInterface *> outputsIntersecting(const QRect &rect) const;
+    OutputInterface *largestIntersectingOutput(const QRect &rect) const;
 
     /**
      * Gets the ClientConnection for the given @p client.

src/wayland/surface.cpp

@@ -75,7 +75,7 @@ void SurfaceInterfacePrivate::addChild(SubSurfaceInterface *child)
         });
     }
 
-    child->surface()->setOutputs(outputs);
+    child->surface()->setOutputs(outputs, primaryOutput);
     if (preferredBufferScale.has_value()) {
         child->surface()->setPreferredBufferScale(preferredBufferScale.value());
     }
@@ -947,7 +947,7 @@ QList<OutputInterface *> SurfaceInterface::outputs() const
     return d->outputs;
 }
 
-void SurfaceInterface::setOutputs(const QList<OutputInterface *> &outputs)
+void SurfaceInterface::setOutputs(const QList<OutputInterface *> &outputs, OutputInterface *primaryOutput)
 {
     QList<OutputInterface *> removedOutputs = d->outputs;
     for (auto it = outputs.constBegin(), end = outputs.constEnd(); it != end; ++it) {
@@ -976,7 +976,7 @@ void SurfaceInterface::setOutputs(const QList<OutputInterface *> &outputs)
         d->outputDestroyedConnections[o] = connect(o, &OutputInterface::removed, this, [this, o] {
             auto outputs = d->outputs;
             if (outputs.removeOne(o)) {
-                setOutputs(outputs);
+                setOutputs(outputs, d->primaryOutput);
             }
         });
 
@@ -990,11 +990,12 @@ void SurfaceInterface::setOutputs(const QList<OutputInterface *> &outputs)
     }
 
     d->outputs = outputs;
+    d->primaryOutput = primaryOutput;
     for (auto child : std::as_const(d->current->subsurface.below)) {
-        child->surface()->setOutputs(outputs);
+        child->surface()->setOutputs(outputs, primaryOutput);
     }
     for (auto child : std::as_const(d->current->subsurface.above)) {
-        child->surface()->setOutputs(outputs);
+        child->surface()->setOutputs(outputs, primaryOutput);
     }
 }
 

src/wayland/surface.h

@@ -281,7 +281,7 @@ public:
      *
      * @see outputs
      */
-    void setOutputs(const QList<OutputInterface *> &outputs);
+    void setOutputs(const QList<OutputInterface *> &outputs, OutputInterface *primaryOutput);
 
     /**
      * @returns All OutputInterfaces the SurfaceInterface is on.

src/wayland/surface_p.h

@@ -146,6 +146,7 @@ public:
     Transaction *lastTransaction = nullptr;
 
     QList<OutputInterface *> outputs;
+    OutputInterface *primaryOutput = nullptr;
     std::optional<qreal> preferredBufferScale;
     std::optional<OutputTransform> preferredBufferTransform;
 

src/waylandwindow.cpp

@@ -156,7 +156,8 @@ void WaylandWindow::updateClientOutputs()
     if (isDeleted()) {
         return;
     }
-    surface()->setOutputs(waylandServer()->display()->outputsIntersecting(frameGeometry().toAlignedRect()));
+    surface()->setOutputs(waylandServer()->display()->outputsIntersecting(frameGeometry().toAlignedRect()),
+                          waylandServer()->display()->largestIntersectingOutput(frameGeometry().toAlignedRect()));
     if (output()) {
         surface()->setPreferredBufferScale(output()->scale());
         surface()->setPreferredBufferTransform(output()->transform());