Potentially fix slowness issue with Selection. Cache the Selection status when the data is changed.

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@20622 a592a061-630c-0410-9148-cb99ea01b6c8

src/frontends/qt4/GuiSelection.cpp

@@ -30,6 +30,16 @@ using std::endl;
 namespace lyx {
 namespace frontend {
 
+GuiSelection::GuiSelection()
+	: selection_supported_(qApp->clipboard()->supportsSelection())
+{
+	connect(qApp->clipboard(), SIGNAL(dataChanged()),
+		this, SLOT(on_dataChanged()));
+	// initialize clipboard status.
+	on_dataChanged();
+}
+
+
 void GuiSelection::haveSelection(bool own)
 {
 	if (!qApp->clipboard()->supportsSelection())
@@ -78,13 +88,22 @@ void GuiSelection::put(docstring const & str)
 }
 
 
+void GuiSelection::on_dataChanged()
+{
+	text_selection_empty_ = qApp->clipboard()->
+		text(QClipboard::Selection).isEmpty();
+}
+
+
 bool GuiSelection::empty() const
 {
-	if (!qApp->clipboard()->supportsSelection())
+	if (!selection_supported_)
 		return true;
 
-	return qApp->clipboard()->text(QClipboard::Selection).isEmpty();
+	return text_selection_empty_;
 }
 
 } // namespace frontend
 } // namespace lyx
+
+#include "GuiSelection_moc.cpp"

src/frontends/qt4/GuiSelection.h

@@ -16,15 +16,19 @@
 
 #include "frontends/Selection.h"
 
+#include <QObject>
+
 namespace lyx {
 namespace frontend {
 
 /**
  * The Qt4 version of the Selection.
  */
-class GuiSelection : public Selection
+class GuiSelection : public QObject, public Selection
 {
+	Q_OBJECT
 public:
+	GuiSelection();
 	virtual ~GuiSelection() {}
 
 	/** Selection overloaded methods
@@ -35,6 +39,13 @@ public:
 	void put(docstring const & str);
 	bool empty() const;
 	//@}
+
+private Q_SLOTS:
+	void on_dataChanged();
+
+private:
+	bool text_selection_empty_;
+	bool const selection_supported_;
 };
 
 } // namespace frontend

src/frontends/qt4/Makefile.am

@@ -119,7 +119,6 @@ NOMOCHEADER = \
 	ButtonController.h \
 	GuiFontLoader.h \
 	GuiFontMetrics.h \
-	GuiSelection.h \
 	GuiImage.h \
 	GuiPainter.h \
 	qt_helpers.h
@@ -171,6 +170,7 @@ MOCHEADER = \
 	GuiPrint.h \
 	GuiRef.h \
 	GuiSearch.h \
+	GuiSelection.h \
 	GuiSelectionManager.h \
 	GuiSendto.h \
 	GuiSetBorder.h \