QImage display sharp pixels - c++

Question

I have a matrix with boolean values that I'm trying to plot with QImage. I have imported the image from a uchar vector with 0 and 255 values for false and true respectively. I would like to have black and white squares representing the different values, but instead I get blur between the pixels as shown in the picture here. Could you please let me know how to get rid of the blur and display larger pixels?
The code is as follows:
for(int i=0; i<world.size(); ++i) {
if(world[i] == true)
world_uchar[i] = 255;
else
world_uchar[i] = 0;
}
QImage img(world_uchar, cols, rows, QImage::Format_Indexed8);
QLabel myLabel;
myLabel.setPixmap(QPixmap::fromImage(img));
myLabel.setScaledContents(true);
myLabel.show();

Answer 1

Instead of using setScaledContents I draw a resized image every times that the window size changes, or on the image change. See an example below (on that example I've used QMainWindow):
class MainWindow : public QMainWindow
{
Q_OBJECT
...
private:
QPixmap pixmap;
};
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
ui->label->setAlignment(Qt::AlignCenter);
//SetMinminumSize to ensure that the QLabel
//can be resized
ui->label->setMinimumSize(10, 10);
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::on_pushButton_clicked()
{
QBitArray world(256, false);
uchar *world_uchar = new uchar[world.size()];
int cols, rows;
cols = rows = (int)qSqrt(world.size());
for (int i = 0; i < world.size(); i += 2)
world.setBit(i, (qrand() % ((1 + 1) - 0) + 0));
for (int i = 0; i < world.size(); i++)
{
if (world[i])
world_uchar[i] = 255;
else
world_uchar[i] = 0;
}
QImage img(world_uchar, cols, rows, QImage::Format_Indexed8);
pixmap = QPixmap::fromImage(img);
OnResize();
}
void MainWindow::resizeEvent(QResizeEvent *)
{
OnResize();
}
void MainWindow::OnResize()
{
if (!pixmap.isNull())
ui->label->setPixmap(pixmap.scaled(ui->label->size(), Qt::KeepAspectRatio, Qt::FastTransformation));
}