Ensure surface textures are deleted from the render thread.

Keep a reference to the QWaylandBuffer in QSGTexture instances
wrapping that buffer and destroy the texture in their destructor
to ensure it is also deleted in the render thread rather than
whereever the last reference to QWaylandBuffer expires.

Change-Id: Id83d40b6fea7c679d638b9209cdd1a3bdd37e741

src/compositor/compositor_api/qwaylandquicksurface.cpp

@@ -53,6 +53,40 @@
 
 QT_BEGIN_NAMESPACE
 
+class QWaylandSurfaceTexture : public QSGTexture
+{
+public:
+    QWaylandSurfaceTexture(const QWaylandBufferRef &ref, QWaylandQuickSurface *surface)
+        : m_bufferRef(ref)
+        , m_textureSize(surface->size())
+        , m_textureId(m_bufferRef.createTexture())
+        , m_hasAlphaChannel(surface->useTextureAlpha())
+    {
+    }
+
+    ~QWaylandSurfaceTexture()
+    {
+        m_bufferRef.destroyTexture();
+    }
+
+    int textureId() const { return m_textureId; }
+    QSize textureSize() const { return m_textureSize; }
+    bool hasAlphaChannel() const { return m_hasAlphaChannel; }
+    bool hasMipmaps() const { return false; }
+
+    void bind()
+    {
+        glBindTexture(GL_TEXTURE_2D, m_textureId);
+        updateBindOptions();
+    }
+
+private:
+    QWaylandBufferRef m_bufferRef;
+    QSize m_textureSize;
+    int m_textureId;
+    bool m_hasAlphaChannel;
+};
+
 class BufferAttacher : public QWaylandBufferAttacher
 {
 public:
@@ -89,11 +123,7 @@ class BufferAttacher : public QWaylandBufferAttacher
             if (bufferRef.isShm()) {
                 texture = window->createTextureFromImage(bufferRef.image());
             } else {
-                QQuickWindow::CreateTextureOptions opt = 0;
-                if (surface->useTextureAlpha()) {
-                    opt |= QQuickWindow::TextureHasAlphaChannel;
-                }
-                texture = window->createTextureFromId(bufferRef.createTexture(), surface->size(), opt);
+                texture = new QWaylandSurfaceTexture(bufferRef, surface);
             }
             texture->bind();
         }