QPainter ouside of paintEvent with a pixmap

[bitChanger]

After trying some more things I'm confused as to why the following don't work in Qt 4.1.1
This is an application not using threads.

void MyType::paintEvent(QPaintEvent*)
{
  QPainter painter;
  someFunc(&painter);
 
  painter.begin(this);
  painter.drawPixmap(QPoint(0, 0), *pmap);
  painter.end();
}
 
void MyType::someFunc(QPainter *painter)
{
  painter->begin(pmap);
  painter->setPen(dark);
  painter->drawLine(0, 0, 50, 50);
  // .. do something useful
  painter->end();
}

void MyType::paintEvent(QPaintEvent*)
{
  QPainter painter;
  someFunc(&painter);

  painter.begin(this);
  painter.drawPixmap(QPoint(0, 0), *pmap);
  painter.end();
}

void MyType::someFunc(QPainter *painter)
{
  painter->begin(pmap);
  painter->setPen(dark);
  painter->drawLine(0, 0, 50, 50);
  // .. do something useful
  painter->end();
}

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[jacek]

How do you create that pmap pixmap?

[bitChanger]

class MyType : public QWidget
{
  public:
    // ... methods
 
  private:
    QPixmap* pmap;
    QImage* image;
    QColor* backgroundColor;
};
 
void MyType::createImage()
{
  image = new QImage(50, 50, QImage::Format_RGB32);
  image->fill(backgroundColor->rgb());
 
  for (int i=0; i<50; i++)
  {
    QRgb rgb = qRgb(i, i+25, i+50);
    for (int x=0; x<50; ++x)
      image->setPixel(x, i, rgb);
  }
 
  convertImage();
}
 
void MyType::convertImage()
{
  pmap = new QPixmap();
  pmap->fromImage(*image, Qt::PreferDither);
  update();
}

class MyType : public QWidget
{
  public:
    // ... methods

  private:
    QPixmap* pmap;
    QImage* image;
    QColor* backgroundColor;
};

void MyType::createImage()
{
  image = new QImage(50, 50, QImage::Format_RGB32);
  image->fill(backgroundColor->rgb());

  for (int i=0; i<50; i++)
  {
    QRgb rgb = qRgb(i, i+25, i+50);
    for (int x=0; x<50; ++x)
      image->setPixel(x, i, rgb);
  }

  convertImage();
}

void MyType::convertImage()
{
  pmap = new QPixmap();
  pmap->fromImage(*image, Qt::PreferDither);
  update();
}

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Hope this is enough sudo code for you.

[jacek]

QPixmap::fromImage() is static.

It should be something like:

void MyType::convertImage()
{
  pmap = new QPixmap( QPixmap::fromImage(*image, Qt::PreferDither) );
  update();
}

void MyType::convertImage()
{
  pmap = new QPixmap( QPixmap::fromImage(*image, Qt::PreferDither) );
  update();
}

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[bitChanger]

Good catch, now it makes sense. Since static member functions have no "this" pointer my usage was wrong. That fixed it.

Thanks again.