Rendering programmatically generated data

[Guest]

I have generated a color-bar pattern and stored it in a buffer.
How do i render/display this buffer data onto my application.

[jsulm]

@sankar-110 See http://doc.qt.io/qt-5/qwidget.html#paintEvent
Example: http://doc.qt.io/qt-5/qtwidgets-widgets-analogclock-example.html

[mrjj]

Hi
While a custom Widget with a paintEvent is the right way, there is also the
alternative to paint on pixmap and show the image on a QLabel.
Note that you are only allowed to paint on an image this way.
Painting directly to screen will not work.
Has to be inside paintEvent then.

void MainWindow::on_pushButton_released() {

  int h = ui->label->height();
  int w = ui->label->width();

  QPixmap pix(w, h);
  QPainter paint(&pix);
  pix.fill( Qt::white );
  paint.setPen(QColor(0, 0, 0, 255));


  int y = 0;
  int x = 0;

  int bw = 10; // bar width
  for (int barcount = 0; barcount < 12; ++barcount) {
    paint.setBrush(QColor(255 - x, 34 + x, 255, 255));
    paint.drawRect(x, h - GetBarHeight(h),  bw, h );
    x += bw + 4;
  }
  paint.end();
  ui->label->setPixmap(pix);
}