QTextEngine::layoutData is nullptr

QTextEdit*  mytext = new QTextEdit(parent);

setAcceptRichText(false);
setReadOnly(true);
setUndoRedoEnabled(false);

setTextColor(lineColor);

append("14:41:51: 开始读取数据计算数据(v:2.8.3)，请等待...");

When the above code append, layoutData is a null pointer at the following location, causing the program to crash

inline bool ensureSpace(int nGlyphs) const

{         if (layoutData->glyphLayout.numGlyphs - layoutData->used < nGlyphs)             return layoutData->reallocate((((layoutData->used + nGlyphs)*3/2 + 15) >> 4) << 4);         return true;     }

Also in QTextLineItemIterator: : next () collapse, layoutData is also a null pointer.

 

• The crash caused by layoutData being a null pointer is accidental.

 
eg:

class MsgListener
{
public:
    MsgListener(){};
    virtual ~MsgListener() {}

    virtual void showMsg(const QString & qsMsg, int nType) = 0;
};

---------------------------------------------------------------------
static QList<MsgListener *>   MsgListeners;
class MsgManage
{
public:
    ~MsgManage();
    static void Register_Listener(MsgListener * pListener);
    static void Unregister_Listener(MsgListener * pListener);
    static bool ShowMsg( const QString & qsMsg,int nType = -1 )
    {
        for (int i = 0; i < MsgListeners.size(); ++i)

{             MsgListener * listener = MsgListeners[i];            listener->showMsg(qsMsg, nType);         }

    }

    private:
        MsgManage();    
    };
---------------------------------------------------------------------
    DockMsgOutput : public QDockWidget,MsgListener

{         m_editMsg = new QTextEdit(parent);         m_editMsg->setAcceptRichText(false);         m_editMsg->setReadOnly(true);         m_editMsg->setUndoRedoEnabled(false);         DockMsgOutput->setWidget(m_editMsg);     }

   
    void DockMsgOutput::showMsg(const QString & qsMsg, int nType)

{         ...         m_editMsg->setTextColor(color);         m_editMsg->append(msg);           m_editMsg->ensureCursorVisible();     }

---------------------------------------------------------------------

    callback(qsMsg,type)

{         MsgManage::showMsg(qsMsg,type)     }