From 4de97522a1267854384dae3480d00f13e93531ee Mon Sep 17 00:00:00 2001
From: Le Tan <tamlokveer@gmail.com>
Date: Mon, 28 May 2018 20:34:33 +0800
Subject: [PATCH] bug-fix: VTextEdit::visibleBlockRange() may get wrong range
 before updating document size after preview

---
 src/vpreviewmanager.cpp |  9 +++++++++
 src/vtextedit.cpp       | 13 +++++++++++++
 src/vtextedit.h         |  2 ++
 3 files changed, 24 insertions(+)

diff --git a/src/vpreviewmanager.cpp b/src/vpreviewmanager.cpp
index 36546a59..36c7d74d 100644
--- a/src/vpreviewmanager.cpp
+++ b/src/vpreviewmanager.cpp
@@ -590,4 +590,13 @@ void VPreviewManager::relayoutEditor(const OrderedIntSet &p_blocks)
     }
 
     m_editor->relayout(bs);
+
+    // We may get the wrong visible block range before relayout() updating the document size.
+    OrderedIntSet after;
+    int afterFirst = m_editor->firstVisibleBlockNumber();
+    for (int i = afterFirst; i < first; ++i) {
+        after.insert(i, QMapDummyValue());
+    }
+
+    m_editor->relayout(after);
 }
diff --git a/src/vtextedit.cpp b/src/vtextedit.cpp
index 175c977e..4de52a9d 100644
--- a/src/vtextedit.cpp
+++ b/src/vtextedit.cpp
@@ -277,6 +277,13 @@ void VTextEdit::updateLineNumberArea()
     }
 }
 
+int VTextEdit::firstVisibleBlockNumber() const
+{
+    VTextDocumentLayout *layout = getLayout();
+    Q_ASSERT(layout);
+    return layout->findBlockByPosition(QPointF(0, -contentOffsetY()));
+}
+
 QTextBlock VTextEdit::firstVisibleBlock() const
 {
     VTextDocumentLayout *layout = getLayout();
@@ -317,6 +324,8 @@ void VTextEdit::clearBlockImages()
 void VTextEdit::relayout(const OrderedIntSet &p_blocks)
 {
     getLayout()->relayout(p_blocks);
+
+    updateLineNumberArea();
 }
 
 void VTextEdit::relayoutVisibleBlocks()
@@ -330,6 +339,8 @@ void VTextEdit::relayoutVisibleBlocks()
     }
 
     getLayout()->relayout(blocks);
+
+    updateLineNumberArea();
 }
 
 bool VTextEdit::containsImage(const QString &p_imageName) const
@@ -419,6 +430,8 @@ void VTextEdit::setCursorLineBlockBg(const QColor &p_bg)
 void VTextEdit::relayout()
 {
     getLayout()->relayout();
+
+    updateLineNumberArea();
 }
 
 void VTextEdit::setDisplayScaleFactor(qreal p_factor)
diff --git a/src/vtextedit.h b/src/vtextedit.h
index daba93b3..e7ea94ff 100644
--- a/src/vtextedit.h
+++ b/src/vtextedit.h
@@ -33,6 +33,8 @@ public:
 
     void setLineNumberColor(const QColor &p_foreground, const QColor &p_background);
 
+    int firstVisibleBlockNumber() const;
+
     QTextBlock firstVisibleBlock() const;
 
     QTextBlock lastVisibleBlock() const;