The processEvents / screen update recursion bug fix.

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@9931 a592a061-630c-0410-9148-cb99ea01b6c8

src/BufferView_pimpl.C

@@ -617,12 +617,20 @@ void BufferView::Pimpl::update(bool fitcursor, bool forceupdate)
 	if (buffer_) {
 		// Update macro store
 		buffer_->buildMacros();
-		// First drawing step
 
 		CoordCache backup;
 		std::swap(theCoords, backup);
+		
+		// This call disallows cursor blink to call
+		// processEvents. It is necessary to prevent screen
+		// redraw being called recursively.
+		screen().unAllowSync();
+		// This, together with doneUpdating(), verifies (using
+		// asserts) that screen redraw is not called from 
+		// within itself.
 		theCoords.startUpdating();
 
+		// First drawing step
 		ViewMetricsInfo vi = metrics();
 
 		if (fitcursor && fitCursor()) {
@@ -633,7 +641,8 @@ void BufferView::Pimpl::update(bool fitcursor, bool forceupdate)
 			// Second drawing step
 			screen().redraw(*bv_, vi);
 		} else {
-			// Abort updating of the coord cache - just restore the old one
+			// Abort updating of the coord
+			// cache - just restore the old one
 			std::swap(theCoords, backup);
 		}
 	} else

src/ChangeLog

@@ -1,3 +1,8 @@
+2005-05-11  Martin Vermeer  <martin.vermeer@hut.fi>
+
+	* BufferView_pimpl.C (update): fix processEvents -caused update
+	recursion bug
+
 2005-05-09  Georg Baum  <Georg.Baum@post.rwth-aachen.de>
 
 	* cursor.h (undispatched, noUpdate): add comments from André

src/frontends/ChangeLog

@@ -1,3 +1,8 @@
+2005-05-11  Martin Vermeer  <martin.vermeer@hut.fi>
+
+	* screen.[hC]: fix processEvents -caused screen update recursion
+	bug
+
 2005-04-25  Angus Leeming  <leeming@lyx.org>
 
 	* LyXView.C:

src/frontends/qt2/ChangeLog

@@ -1,3 +1,11 @@
+2005-05-11  Martin Vermeer  <martin.vermeer@hut.fi>
+
+	* lyx_gui.C (sync_events):
+	* QDialogView.h (update, build):
+	* QLPopupMenu.C (fire):
+	* QMathDialog.C (resizeEvent, showingPanel): fix processEvent
+	-caused update recursion bug
+
 2005-05-06  Michael Schmitt  <michael.schmitt@teststep.org>
 
 	* ui/*.ui: remove captions: they are unused and pollute the po

src/frontends/qt2/QDialogView.h

@@ -126,10 +126,8 @@ void QView<GUIDialog>::update()
 
 	// protect the BC from unwarranted state transitions
 
-	qApp->processEvents();
 	updating_ = true;
 	update_contents();
-	qApp->processEvents();
 	updating_ = false;
 
 	form()->setUpdatesEnabled(true);
@@ -142,10 +140,8 @@ void QView<GUIDialog>::build()
 {
 	// protect the BC from unwarranted state transitions
 
-	qApp->processEvents();
 	updating_ = true;
 	build_dialog();
-	qApp->processEvents();
 	updating_ = false;
 }
 

src/frontends/qt2/QLPopupMenu.C

@@ -88,7 +88,6 @@ QLPopupMenu::QLPopupMenu(QLMenubar * owner,
 
 void QLPopupMenu::fire(int index)
 {
-	qApp->processEvents();
 #ifdef Q_WS_MACX
 	if (index >= indexOffset) {
 		MenuItem mi = owner_->backend().getMenu("LyX")[index - indexOffset];

src/frontends/qt2/QMathDialog.C

@@ -52,8 +52,7 @@ protected:
 			return;
 
 		w_->resize(viewport()->width(), w_->height());
-		// force the resize to get accurate scrollbars
-		qApp->processEvents();
+		// force the resize to get accurate scrollbar
 		resizeContents(w_->width(), w_->height());
 	}
 private:
@@ -156,9 +155,6 @@ void QMathDialog::showingPanel(int num)
 
 	addPanel(num);
 
-	// Qt needs to catch up. Dunno why.
-	qApp->processEvents();
-
 	panel_initialised[num] = true;
 }
 

src/frontends/qt2/lyx_gui.C

@@ -252,6 +252,10 @@ void start(string const & batch, vector<string> const & files)
 
 void sync_events()
 {
+	// This is the ONLY place where processEvents may be called.
+	// During screen update/ redraw, this method is disabled to 
+	// prevent keyboard events being handed to the LyX core, where
+	// they could cause re-entrant calls to screen update.
 	qApp->processEvents();
 }
 

src/frontends/screen.C

@@ -122,7 +122,7 @@ SplashScreen::SplashScreen()
 
 
 LyXScreen::LyXScreen()
-	: greyed_out_(true), cursor_visible_(false)
+	: greyed_out_(true), cursor_visible_(false), sync_allowed_(true)
 {
 	// Start loading the pixmap as soon as possible
 	if (lyxrc.show_banner) {
@@ -147,15 +147,19 @@ void LyXScreen::checkAndGreyOut()
 
 void LyXScreen::showCursor(BufferView & bv)
 {
-	// You are not expected to understand this. This forces Qt
-	// (the problem case) to deal with its event queue. This is
-	// necessary when holding down a key such as 'page down' or
-	// just typing: without this processing of the event queue,
-	// the cursor gets ahead of itself without a selection or
-	// workarea redraw having a chance to keep up. If you think
-	// you can remove this, try selecting text with the mouse
-	// in Qt, or holding Page Down on the User's Guide.
-	lyx_gui::sync_events();
+	// This code is currently meaningful only for the Qt frontend.
+	// This is the place (like below in hideCursor) where
+	// processEvents is being called, and things like keystrokes and
+	// mouse clicks are being handed to the LyX core, once every 
+	// cursor blink. 
+	// THERE IS NOT SUPPOSED TO BE ANY OTHER CALL TO processEvents 
+	// ANYWHERE ELSE.
+	// in BufferView::Pimpl::update() and here, the sync_allowed_
+	// guard is set/cleared which is used here to prevent recursive
+	// calls to screen update. startUpdating() and doneUpdating() in
+	// coordcache again contain asserts to detect such recursion.
+	if (sync_allowed_)
+		lyx_gui::sync_events();
 
 	if (cursor_visible_)
 		return;
@@ -202,6 +206,9 @@ void LyXScreen::showCursor(BufferView & bv)
 
 void LyXScreen::hideCursor()
 {
+	if (sync_allowed_)
+		lyx_gui::sync_events();
+
 	if (!cursor_visible_)
 		return;
 
@@ -223,13 +230,12 @@ void LyXScreen::redraw(BufferView & bv, ViewMetricsInfo const & vi)
 {
 	greyed_out_ = false;
 	workarea().getPainter().start();
-	hideCursor();
 	paintText(bv, vi);
 	lyxerr[Debug::DEBUG] << "Redraw screen" << endl;
 	expose(0, 0, workarea().workWidth(), workarea().workHeight());
 	workarea().getPainter().end();
 	theCoords.doneUpdating();
-	showCursor(bv);
+	sync_allowed_ = true;
 }
 
 

src/frontends/screen.h

@@ -54,6 +54,9 @@ public:
 	/// toggle the cursor's visibility
 	void toggleCursor(BufferView & bv);
 
+	///
+	void unAllowSync() { sync_allowed_ = false; };
+
 protected:
 	/// cause the display of the given area of the work area
 	virtual void expose(int x, int y, int w, int h) = 0;
@@ -86,6 +89,9 @@ private:
 
 	/// is the cursor currently displayed
 	bool cursor_visible_;
+
+	///
+	bool sync_allowed_;
 };
 
 #endif // SCREEN_H