Subsurface implementation, with C++ API

This adds support for subsurfaces to QWaylandCompositor and
QWaylandSurface.

Task-number: QTBUG-49809
Change-Id: I2fa9ee4dcd1f48a2a28dab536f9cd6edc716e42b
Reviewed-by: Giulio Camuffo <giuliocamuffo@gmail.com>

4 files changed, 90 insertions, 6 deletions

diff --git a/examples/wayland/qwindow-compositor/compositorwindow.cpp b/examples/wayland/qwindow-compositor/compositorwindow.cpp
index a902a7d0d..4b69022f2 100644
--- a/examples/wayland/qwindow-compositor/compositorwindow.cpp
+++ b/examples/wayland/qwindow-compositor/compositorwindow.cpp
@@ -107,7 +107,8 @@ void CompositorWindow::paintGL()
         if (surface && surface->isMapped()) {
             QSize s = surface->size();
             if (!s.isEmpty()) {
-                QRectF surfaceGeometry(view->position(), s);
+                QPointF pos = view->position() + view->parentPosition();
+                QRectF surfaceGeometry(pos, s);
                 QOpenGLTextureBlitter::Origin surfaceOrigin =
                     view->currentBuffer().origin() == QWaylandSurface::OriginTopLeft
                     ? QOpenGLTextureBlitter::OriginTopLeft
diff --git a/examples/wayland/qwindow-compositor/windowcompositor.cpp b/examples/wayland/qwindow-compositor/windowcompositor.cpp
index f271570de..57d6b382f 100644
--- a/examples/wayland/qwindow-compositor/windowcompositor.cpp
+++ b/examples/wayland/qwindow-compositor/windowcompositor.cpp
@@ -88,6 +88,8 @@ void WindowCompositor::create()
     connect(this, &QWaylandCompositor::surfaceCreated, this, &WindowCompositor::onSurfaceCreated);
     connect(defaultInputDevice(), &QWaylandInputDevice::cursorSurfaceRequest, this, &WindowCompositor::adjustCursorSurface);
     connect(defaultInputDevice()->drag(), &QWaylandDrag::dragStarted, this, &WindowCompositor::startDrag);
+
+    connect(this, &QWaylandCompositor::subsurfaceChanged, this, &WindowCompositor::onSubsurfaceChanged);
 }
 
 void WindowCompositor::onSurfaceCreated(QWaylandSurface *surface)
@@ -96,6 +98,9 @@ void WindowCompositor::onSurfaceCreated(QWaylandSurface *surface)
     connect(surface, &QWaylandSurface::mappedChanged, this, &WindowCompositor::surfaceMappedChanged);
     connect(surface, &QWaylandSurface::redraw, this, &WindowCompositor::triggerRender);
     connect(surface, &QWaylandSurface::offsetForNextFrame, this, &WindowCompositor::frameOffset);
+
+    connect(surface, &QWaylandSurface::subsurfacePositionChanged, this, &WindowCompositor::onSubsurfacePositionChanged);
+
     WindowCompositorView *view = new WindowCompositorView;
     view->setSurface(surface);
     view->setOutput(outputFor(m_window));
@@ -167,9 +172,17 @@ void WindowCompositor::onStartResize(QWaylandInputDevice *, QWaylandShellSurface
     emit startResize(int(edges));
 }
 
-void WindowCompositor::onSetTransient(QWaylandSurface *parentSurface, const QPoint &relativeToParent, QWaylandShellSurface::FocusPolicy focusPolicy)
+void WindowCompositor::onSetTransient(QWaylandSurface *parent, const QPoint &relativeToParent, QWaylandShellSurface::FocusPolicy focusPolicy)
 {
-    qDebug() << "Transient window support not implemented" << parentSurface << relativeToParent << focusPolicy;
+    QWaylandShellSurface *surface = qobject_cast<QWaylandShellSurface*>(sender());
+    WindowCompositorView *view = findView(surface->surface());
+
+    if (view) {
+        raise(view);
+        WindowCompositorView *parentView = findView(parent);
+        if (parentView)
+            view->setPosition(parentView->position() + relativeToParent);
+    }
 }
 
 void WindowCompositor::onSetPopup(QWaylandInputDevice *inputDevice, QWaylandSurface *parent, const QPoint &relativeToParent)
@@ -186,6 +199,23 @@ void WindowCompositor::onSetPopup(QWaylandInputDevice *inputDevice, QWaylandSurf
     }
 }
 
+void WindowCompositor::onSubsurfaceChanged(QWaylandSurface *child, QWaylandSurface *parent)
+{
+    WindowCompositorView *view = findView(child);
+    WindowCompositorView *parentView = findView(parent);
+    view->setParentView(parentView);
+}
+
+void WindowCompositor::onSubsurfacePositionChanged(const QPoint &position)
+{
+    QWaylandSurface *surface = qobject_cast<QWaylandSurface*>(sender());
+    if (!surface)
+        return;
+    WindowCompositorView *view = findView(surface);
+    view->setPosition(position);
+    triggerRender();
+}
+
 void WindowCompositor::triggerRender()
 {
     m_window->requestUpdate();
@@ -288,8 +318,35 @@ void WindowCompositor::handleDrag(WindowCompositorView *target, QMouseEvent *me)
         currentDrag->drop();
 }
 
+// We only have a flat list of views, plus pointers from child to parent,
+// so maintaining a stacking order gets a bit complex. A better data
+// structure is left as an exercise for the reader.
+
+static int findEndOfChildTree(const QList<WindowCompositorView*> &list, int index)
+{
+    int n = list.count();
+    WindowCompositorView *parent = list.at(index);
+    while (index + 1 < n) {
+        if (list.at(index+1)->parentView() != parent)
+            break;
+        index = findEndOfChildTree(list, index + 1);
+    }
+    return index;
+}
+
 void WindowCompositor::raise(WindowCompositorView *view)
 {
-    m_views.removeOne(view);
-    m_views.append(view);
+    int startPos = m_views.indexOf(view);
+    int endPos = findEndOfChildTree(m_views, startPos);
+
+    int n = m_views.count();
+    int tail =  n - endPos - 1;
+
+    //bubble sort: move the child tree to the end of the list
+    for (int i = 0; i < tail; i++) {
+        int source = endPos + 1 + i;
+        int dest = startPos + i;
+        for (int j = source; j > dest; j--)
+            m_views.swap(j, j-1);
+    }
 }
diff --git a/examples/wayland/qwindow-compositor/windowcompositor.h b/examples/wayland/qwindow-compositor/windowcompositor.h
index 98cc88f6a..7a4f90aad 100644
--- a/examples/wayland/qwindow-compositor/windowcompositor.h
+++ b/examples/wayland/qwindow-compositor/windowcompositor.h
@@ -56,17 +56,22 @@ class WindowCompositorView : public QWaylandView
 {
     Q_OBJECT
 public:
-    WindowCompositorView() : m_texture(0), m_shellSurface(0) {}
+    WindowCompositorView() : m_texture(0), m_shellSurface(0), m_parentView(0) {}
     GLuint getTexture();
     QPointF position() const { return m_position; }
     void setPosition(const QPointF &pos) { m_position = pos; }
     bool isCursor() const;
     bool hasShell() const { return m_shellSurface; }
+    void setParentView(WindowCompositorView *parent) { m_parentView = parent; }
+    WindowCompositorView *parentView() const { return m_parentView; }
+    QPointF parentPosition() const { return m_parentView ? (m_parentView->position() + m_parentView->parentPosition()) : QPointF(); }
+
 private:
     friend class WindowCompositor;
     GLuint m_texture;
     QPointF m_position;
     QWaylandShellSurface *m_shellSurface;
+    WindowCompositorView *m_parentView;
 };
 
 class WindowCompositor : public QWaylandCompositor
@@ -114,6 +119,9 @@ private slots:
     void onSetTransient(QWaylandSurface *parentSurface, const QPoint &relativeToParent, QWaylandShellSurface::FocusPolicy focusPolicy);
     void onSetPopup(QWaylandInputDevice *inputDevice, QWaylandSurface *parent, const QPoint &relativeToParent);
 
+    void onSubsurfaceChanged(QWaylandSurface *child, QWaylandSurface *parent);
+    void onSubsurfacePositionChanged(const QPoint &position);
+
     void updateCursor();
 private:
     WindowCompositorView *findView(const QWaylandSurface *s) const;
diff --git a/examples/wayland/subsurface/main.qml b/examples/wayland/subsurface/main.qml
index fa71d4b6b..8d221401b 100644
--- a/examples/wayland/subsurface/main.qml
+++ b/examples/wayland/subsurface/main.qml
@@ -69,4 +69,22 @@ Rectangle {
         anchors.horizontalCenter: parent.horizontalCenter
         text: syncStatus.sync ? "sync mode" : "de-sync mode"
     }
+
+    // If you can see these rectangles, something's not right
+    Rectangle {
+        //Child at (150, 70, 100, 100)
+        color: "yellow"
+        x: 150
+        y: 70
+        width:100
+        height:100
+    }
+    Rectangle {
+        //Shm at (30, 30, 50, 50)
+        color: "yellow"
+        x: 30
+        y: 30
+        width: 50
+        height: 50
+    }
 }