Add thumbnailAvailable property to PlasmaCore.WindowThumbnail

This property tells us whether a thumbnail is actually being rendered or it has
fallen back to the window icon

REVIEW: 120946
BUG: 336524

src/declarativeimports/core/windowthumbnail.cpp

@@ -65,6 +65,7 @@ WindowThumbnail::WindowThumbnail(QQuickItem *parent)
     , m_xcb(false)
     , m_winId(0)
     , m_paintedSize(QSizeF())
+    , m_thumbnailAvailable(false)
     , m_damaged(false)
     , m_depth(0)
 #if HAVE_XCB_COMPOSITE
@@ -151,6 +152,11 @@ qreal WindowThumbnail::paintedHeight() const
     return m_paintedSize.height();
 }
 
+bool WindowThumbnail::thumbnailAvailable() const
+{
+    return m_thumbnailAvailable;
+}
+
 QSGNode *WindowThumbnail::updatePaintNode(QSGNode *oldNode, UpdatePaintNodeData *updatePaintNodeData)
 {
     Q_UNUSED(updatePaintNodeData)
@@ -350,6 +356,7 @@ void WindowThumbnail::windowToTexture(WindowTextureNode *textureNode)
     if (m_pixmap == XCB_PIXMAP_NONE) {
         // create above failed
         iconToTexture(textureNode);
+        setThumbnailAvailable(false);
         return;
     }
     bool fallbackToIcon = true;
@@ -366,6 +373,7 @@ void WindowThumbnail::windowToTexture(WindowTextureNode *textureNode)
         // just for safety to not crash
         iconToTexture(textureNode);
     }
+    setThumbnailAvailable(!fallbackToIcon);
     textureNode->markDirty(QSGNode::DirtyForceUpdate);
 #else
     iconToTexture(textureNode);
@@ -615,4 +623,12 @@ void WindowThumbnail::discardPixmap()
 #endif
 }
 
+void WindowThumbnail::setThumbnailAvailable(bool thumbnailAvailable)
+{
+    if (m_thumbnailAvailable != thumbnailAvailable) {
+        m_thumbnailAvailable = thumbnailAvailable;
+        emit thumbnailAvailableChanged();
+    }
+}
+
 } // namespace

src/declarativeimports/core/windowthumbnail.h

@@ -78,6 +78,7 @@ class WindowThumbnail : public QQuickItem, public QAbstractNativeEventFilter
     Q_PROPERTY(uint winId READ winId WRITE setWinId NOTIFY winIdChanged)
     Q_PROPERTY(qreal paintedWidth READ paintedWidth NOTIFY paintedSizeChanged)
     Q_PROPERTY(qreal paintedHeight READ paintedHeight NOTIFY paintedSizeChanged)
+    Q_PROPERTY(bool thumbnailAvailable READ thumbnailAvailable NOTIFY thumbnailAvailableChanged)
 
 public:
     WindowThumbnail(QQuickItem *parent = 0);
@@ -90,10 +91,12 @@ public:
 
     qreal paintedWidth() const;
     qreal paintedHeight() const;
+    bool thumbnailAvailable() const;
 
 Q_SIGNALS:
     void winIdChanged();
     void paintedSizeChanged();
+    void thumbnailAvailableChanged();
 
 private:
     void iconToTexture(WindowTextureNode *textureNode);
@@ -102,9 +105,12 @@ private:
     void stopRedirecting();
     void resetDamaged();
     void discardPixmap();
+    void setThumbnailAvailable(bool thumbnailAvailable);
+
     bool m_xcb;
     uint32_t m_winId;
     QSizeF m_paintedSize;
+    bool m_thumbnailAvailable;
     bool m_damaged;
     int m_depth;
 #if HAVE_XCB_COMPOSITE