Memory Leak in Qt 4.10.0

[ndiwan]

HI All,

I am getting memory leak in my c++ code written in Qt 4.10.0.
I am not Sure where the leak is.
I correct few things like doing cleanup whenever using setFont. Also confirmed that all dynamic memory allocations are getting cleaned in destructor.
Now I am not ure where the issue is. Could you please help me with how I can detect memory leak.

Thanks
Nitin

[JonB]

@ndiwan
Use valgrind to detect memory leakages.

[J.Hilk]

@ndiwan there is no such thing as Qt 4.10.0

[ndiwan]

Thanks For Reply.
bolded text

Attached is the valgrid plugin in my Qt creator. Do I need to use this. Sorry but I am new in Qt.
It say External Application.

Thanks

[jsulm]

@ndiwan said in Memory Leak in Qt 4.10.0:

Do I need to use this.

Yes, the "Valgrind Memory Analyzer"

[ndiwan]

Thanks.
Do you find any issue here relelated to memory leak in my paintEvent:

void CSkateRetarder::paintEvent(QPaintEvent * )
{
    QPainter painter(this);
    painter.setRenderHint(QPainter::Antialiasing);
    QPainterPath m_SelectedPath = QPainterPath();
    m_SelectedPath.addRect(0,0, getRectWidth()+10, getRectHeight()+10);
    QPen pen = QPen(m_qcRetarderColor,2);
    QFont::cleanup();
    QFont font("Arial", 10);
    font.setBold(true);
    painter.setFont(font);
    painter.setPen(pen);

    if(m_state == SKATE_POS_OPEN || m_state == SKATE_POS_OOC_OPEN || (m_state == SKATE_POS_COMM_LOST && m_PrevState == -1) || m_PrevState == SKATE_POS_OPEN || m_PrevState == SKATE_POS_OOC_OPEN)
    {
        painter.setBrush(QBrush(Qt::transparent));
        QPainterPath path;
        path.addRoundedRect(QRectF(5, 5, getRectWidth(), getRectHeight()), 5, 5);
        painter.drawPath(path);
        painter.setBrush(QBrush(m_qcRetarderColor));
        QPainterPath upperCurve;
        upperCurve.moveTo(10, 5);
        upperCurve.lineTo(getRectWidth(), 5);
        upperCurve.lineTo(getRectWidth()-5, 10);
        upperCurve.lineTo(getRectWidth()-10, 5);
        upperCurve.lineTo(getRectWidth()-15, 10);
        upperCurve.lineTo(getRectWidth()-20, 5);
        upperCurve.lineTo(getRectWidth()-25, 10);
        upperCurve.lineTo(getRectWidth()-30, 5);
        upperCurve.lineTo(getRectWidth()-35, 10);
        upperCurve.lineTo(getRectWidth()-40, 5);
        upperCurve.lineTo(getRectWidth()-45, 10);
        upperCurve.lineTo(getRectWidth()-50, 5);
        painter.drawPath(upperCurve);
        QPainterPath lowerCurve;
        lowerCurve.moveTo(10, getRectHeight()+5);
        lowerCurve.lineTo(getRectWidth(), getRectHeight()+5);
        lowerCurve.lineTo(getRectWidth()-5, getRectHeight());
        lowerCurve.lineTo(getRectWidth()-10, getRectHeight()+5);
        lowerCurve.lineTo(getRectWidth()-15, getRectHeight());
        lowerCurve.lineTo(getRectWidth()-20, getRectHeight()+5);
        lowerCurve.lineTo(getRectWidth()-25, getRectHeight());
        lowerCurve.lineTo(getRectWidth()-30, getRectHeight()+5);
        lowerCurve.lineTo(getRectWidth()-35, getRectHeight());
        lowerCurve.lineTo(getRectWidth()-40, getRectHeight()+5);
        lowerCurve.lineTo(getRectWidth()-45, getRectHeight());
        lowerCurve.lineTo(getRectWidth()-50, getRectHeight()+5);
        painter.drawPath(lowerCurve);
        painter.setBackgroundMode(Qt::TransparentMode);
        painter.setPen(QPen(Qt::white, 2));
        painter.drawText(5,5, getRectWidth(), getRectHeight(), Qt::AlignHCenter | Qt::AlignVCenter, "OPEN");
    }
    else if(m_state == SKATE_POS_CLOSE || m_state == SKATE_POS_OOC_CLOSE || m_PrevState == SKATE_POS_CLOSE || m_PrevState == SKATE_POS_OOC_CLOSE)
    {
        painter.setBrush(QBrush(m_qcRetarderColor));
        QPainterPath path;
        path.addRoundedRect(QRectF(5, 10, getRectWidth(), getRectHeight()-10), 5, 5);
        painter.drawPath(path);
        painter.setBackgroundMode(Qt::TransparentMode);
        painter.setPen(QPen(Qt::white, 2));
        QPainterPath MiddleLine;
        MiddleLine.moveTo(5, getRectHeight()/2+5);
        MiddleLine.lineTo(10, getRectHeight()/2);
        MiddleLine.lineTo(15, getRectHeight()/2+10);
        MiddleLine.lineTo(20, getRectHeight()/2);
        MiddleLine.lineTo(25, getRectHeight()/2+10);
        MiddleLine.lineTo(30, getRectHeight()/2);
        MiddleLine.lineTo(35, getRectHeight()/2+10);
        MiddleLine.lineTo(40, getRectHeight()/2);
        MiddleLine.lineTo(45, getRectHeight()/2+10);
        MiddleLine.lineTo(50, getRectHeight()/2);
        MiddleLine.lineTo(55, getRectHeight()/2+10);
        MiddleLine.lineTo(60, getRectHeight()/2);
        MiddleLine.lineTo(65, getRectHeight()/2+5);
        painter.drawPath(MiddleLine);
    }
    else
    {
        painter.setBrush(QBrush(Qt::transparent));
        QPainterPath path;
        path.addRoundedRect(QRectF(5, 5, getRectWidth(), getRectHeight()), 5, 5);
        painter.drawPath(path);
        painter.setBrush(QBrush(m_qcRetarderColor));
        QPainterPath upperCurve;
        upperCurve.moveTo(10, 5);
        upperCurve.lineTo(getRectWidth(), 5);
        upperCurve.lineTo(getRectWidth()-5, 10);
        upperCurve.lineTo(getRectWidth()-10, 5);
        upperCurve.lineTo(getRectWidth()-15, 10);
        upperCurve.lineTo(getRectWidth()-20, 5);
        upperCurve.lineTo(getRectWidth()-25, 10);
        upperCurve.lineTo(getRectWidth()-30, 5);
        upperCurve.lineTo(getRectWidth()-35, 10);
        upperCurve.lineTo(getRectWidth()-40, 5);
        upperCurve.lineTo(getRectWidth()-45, 10);
        upperCurve.lineTo(getRectWidth()-50, 5);
        painter.drawPath(upperCurve);
        QPainterPath lowerCurve;
        lowerCurve.moveTo(10, getRectHeight()+5);
        lowerCurve.lineTo(getRectWidth(), getRectHeight()+5);
        lowerCurve.lineTo(getRectWidth()-5, getRectHeight());
        lowerCurve.lineTo(getRectWidth()-10, getRectHeight()+5);
        lowerCurve.lineTo(getRectWidth()-15, getRectHeight());
        lowerCurve.lineTo(getRectWidth()-20, getRectHeight()+5);
        lowerCurve.lineTo(getRectWidth()-25, getRectHeight());
        lowerCurve.lineTo(getRectWidth()-30, getRectHeight()+5);
        lowerCurve.lineTo(getRectWidth()-35, getRectHeight());
        lowerCurve.lineTo(getRectWidth()-40, getRectHeight()+5);
        lowerCurve.lineTo(getRectWidth()-45, getRectHeight());
        lowerCurve.lineTo(getRectWidth()-50, getRectHeight()+5);
        painter.drawPath(lowerCurve);
        painter.setBackgroundMode(Qt::TransparentMode);
        painter.setPen(QPen(Qt::white, 2));

    }
    if(m_isHighlight)
    {
        painter.setBrush(Qt::transparent);
        painter.setPen(QPen(Qt::green,3));
        painter.drawPath(m_SelectedPath);
    }
    if(m_isPulse)
    {
        painter.setBrush(Qt::transparent);
        painter.setPen(QPen(Qt::yellow,3));
        painter.drawPath(m_SelectedPath);
    }
    QRect rect = m_SelectedPath.boundingRect().toRect();
    QRegion Mask(rect);
    setMask(Mask);
    QFont::cleanup();
    painter.end();
}

---

Edit: added code tags, to make it readable [jhilk]

[jsulm]

@ndiwan said in Memory Leak in Qt 4.10.0:

m_SelectedPath.addRect(0,0, getRectWidth()+10, getRectHeight()+10);

Do you ever remove rects from m_SelectedPath?

[ndiwan]

No. How to remove rect from QPainterPath ?

Thanks

[jsulm]

@ndiwan Why do you actually add a rect each time paintEvent is called?

[J.Hilk]

@ndiwan should actually not be necessary , m_SelectedPath is, despite its name, a local (scoped) variable:

void CSkateRetarder::paintEvent(QPaintEvent * )
{
   QPainter painter(this);
   painter.setRenderHint(QPainter::Antialiasing);
   QPainterPath m_SelectedPath = QPainterPath();
   m_SelectedPath.addRect(0,0, getRectWidth()+10, getRectHeight()+10);
...

so it should get cleaned up when the function returns

[jsulm]

@J-Hilk Ah, you're right, didn't notice this.

[ndiwan]

I am drawing a rectangular widget. That's why addign rectangle. Did you still see any memory leakage related issue in paintEvent ?

Thanks

[jsulm]

@ndiwan said in Memory Leak in Qt 4.10.0:

Did you still see any memory leakage related issue in paintEvent ?

No
Did you run Valgrind as suggested to find memory leaks?

[ndiwan]

Sorry, But I am not sure how to use that in Window Qt. I know ho to use valgrind in Linux

Actually my application runs with a login dialog. Do I need to provided user id and passoword in arguments here ?
Also kit drop down is diable.

Thanks

[jsulm]

@ndiwan said in Memory Leak in Qt 4.10.0:

Do I need to provided user id and passoword in arguments here ?

No

"Also kit drop down is diable" - what do you mean?

[ndiwan]

Kit dropdown is disable.

Thansks

[jsulm]

@ndiwan said in Memory Leak in Qt 4.10.0:

Kit dropdown is disable

This is the same what I asked about. Can you please explain what dropdown you mean? Maybe a screen-shot?

[ndiwan]

In the above screenshot Kit combo dropdown is disable. If I click manage , I can see this:

[jsulm]

@ndiwan Do you have Valgrind? Check in Analyzer/Valgrind. You need to set the path to Valgrind executable.

[Christian Ehrlicher]

@jsulm Since when does valgrind run on windows?