From 26d14f81d50ae4784a925120e32a20b82e6d33f4 Mon Sep 17 00:00:00 2001
From: Le Tan <tamlokveer@gmail.com>
Date: Sat, 16 Sep 2017 15:07:31 +0800
Subject: [PATCH] bug-fix: findFirstVisibleBlock() return invalid block when
 fails

A huge block as the last block may lead to failure to find first visible
block.
---
 src/vedit.cpp | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/vedit.cpp b/src/vedit.cpp
index 3199b672..720e21d1 100644
--- a/src/vedit.cpp
+++ b/src/vedit.cpp
@@ -1021,6 +1021,10 @@ void VEdit::lineNumberAreaPaintEvent(QPaintEvent *p_event)
     QAbstractTextDocumentLayout *layout = document()->documentLayout();
 
     QTextBlock block = firstVisibleBlock();
+    if (!block.isValid()) {
+        return;
+    }
+
     int blockNumber = block.blockNumber();
     int offsetY = contentOffsetY();
     QRectF rect = layout->blockBoundingRect(block);
@@ -1196,8 +1200,7 @@ QTextBlock VEdit::firstVisibleBlock()
         block = block.next();
     }
 
-    Q_ASSERT(false);
-    return doc->begin();
+    return QTextBlock();
 }
 
 int LineNumberArea::calculateWidth() const