Make BufferView::singeParUpdate more robust

In some cases, it might happen that this method is called in cases
where no metrics is know for the current paragraph or where its
position is not set.

Take care of these cases to avoid assertions.

Remove setting of inset positions in the method, but make sure that
updateMetrics(false) is always called to get everything right.

In the new code, updateMetrics(bool) os the method that sets
everything right with minimal effort.

diff --git a/src/BufferView.cpp b/src/BufferView.cpp
index 67aa4944f6dc012aade397a81f7873a16aa40ab1..ce315a6f49ee0595a29cc9eb48e7672c1fd29814 100644 (file)
--- a/src/BufferView.cpp
+++ b/src/BufferView.cpp
@@ -567,7 +567,9 @@ void BufferView::processUpdateFlags(Update::flags flags)
         * correct metrics at cursor position.
         */
        else if ((flags & Update::SinglePar) && !(flags & Update::ForceDraw)) {
-               if (!singleParUpdate())
+               if (singleParUpdate())
+                       updateMetrics(false);
+               else
                        updateMetrics(true);
        }
        else if (flags & Update::ForceDraw)
@@ -3150,6 +3152,10 @@ bool BufferView::singleParUpdate()
        if (d->inlineCompletionPos_.fixIfBroken())
                d->inlineCompletionPos_ = DocIterator();
 
+       if (!tm.contains(pit)) {
+               LYXERR(Debug::PAINTING, "SinglePar optimization failed: no known metrics");
+               return false;
+       }
        /* Try to rebreak only the paragraph containing the cursor (if
         * this paragraph contains insets etc., rebreaking will
         * recursively descend). We need a full redraw if either
@@ -3167,18 +3173,19 @@ bool BufferView::singleParUpdate()
        tm.redoParagraph(pit);
        ParagraphMetrics & pm = tm.parMetrics(pit);
        if (pm.height() != old_dim.height()
-               || (pm.width() != old_dim.width() && old_dim.width() == tm.width())) {
+            || (pm.width() != old_dim.width() && old_dim.width() == tm.width())) {
                // Paragraph height or width has changed so we cannot proceed
                // to the singlePar optimisation.
-               LYXERR(Debug::PAINTING, "SinglePar optimization failed.");
+               LYXERR(Debug::PAINTING, "SinglePar optimization failed: paragraph metrics changed");
                return false;
        }
        // Since position() points to the baseline of the first row, we
        // may have to update it. See ticket #11601 for an example where
        // the height does not change but the ascent does.
-       pm.setPosition(pm.position() - old_dim.ascent() + pm.ascent());
-
-       tm.updatePosCache(pit);
+       if (pm.hasPosition())
+               pm.setPosition(pm.position() - old_dim.ascent() + pm.ascent());
+       else
+               LYXERR0("SinglePar optimization succeeded, but no position to update");
 
        LYXERR(Debug::PAINTING, "\ny1: " << pm.top() << " y2: " << pm.bottom()
                << " pit: " << pit << " singlepar: 1");