QPlainTextEdit scrolling issue with folded paragraphs

With Qt Creator, we could reproduce scrolling problems when paragraphs
were folded away. Effectively the first "visible" block could be an
invisible one, resulting in firstVisibleBlock() returning something bogus.
The result were drawing errors.

Reviewed-by: con

1 files changed, 7 insertions, 3 deletions

diff --git a/src/gui/widgets/qplaintextedit.cpp b/src/gui/widgets/qplaintextedit.cpp
index 89fe7b8..028ffe8 100644
--- a/src/gui/widgets/qplaintextedit.cpp
+++ b/src/gui/widgets/qplaintextedit.cpp
@@ -684,8 +684,12 @@ void QPlainTextEditPrivate::ensureVisible(int position, bool center, bool forceC
 
         qreal h = center ? line.naturalTextRect().center().y() : line.naturalTextRect().bottom();
 
+        QTextBlock previousVisibleBlock = block;
         while (h < height && block.previous().isValid()) {
-            block = block.previous();
+            previousVisibleBlock = block;
+            do {
+                block = block.previous();
+            } while (!block.isVisible() && block.previous().isValid());
             h += q->blockBoundingRect(block).height();
         }
 
@@ -699,8 +703,8 @@ void QPlainTextEditPrivate::ensureVisible(int position, bool center, bool forceC
             ++l;
         }
 
-        if (block.next().isValid() && l >= lineCount) {
-            block = block.next();
+        if (l >= lineCount) {
+            block = previousVisibleBlock;
             l = 0;
         }
         setTopBlock(block.blockNumber(), l);