Qt Drawing pixel by pixel zoomed - c++

Question

I tried to find some helps around internet, i had some codes to test but none works like i want.
I would draw with Qt something pixel by pixel.
I tried with a QImage within a QLabel with the protected event mousePressEvent it worked, but the pixels are too small to see them.
I tried to scale my Image, it's much better, but the position X, Y are not the same position of the pixels now or they're not synchronized with the pixels locations.
Here a screenshot of what i want do, if someone has an idea to recreate this...
If i can exactly done this via Qt i'll save a lots of time, just a basic drawing pixel by pixel, i created this example with Paint, Black and White format zoomed to 800%.
Thanks.

Answer 1

This is a solution hard-coded for a specific size - just implement relative coordinate mapping between pixmap and draw widget and you are set.
class Widget : public QWidget
{
Q_OBJECT
public:
Widget(QWidget *parent = 0) : QWidget(parent), pressed(0) {
color = Qt::black;
pixmap = new QPixmap("h:/small.png");
resize(240, 240);
}
~Widget() { if (pixmap) delete pixmap; }
protected:
void paintEvent(QPaintEvent *) {
QPainter painter(this);
painter.drawPixmap(0, 0, pixmap->scaled(240, 240));
painter.drawPixmap(0, 0, *pixmap);
}
void mousePressEvent(QMouseEvent *e) {
if (e->button() == Qt::RightButton)
color = color == Qt::black ? Qt::white : Qt::black;
else {
pressed = 1;
draw(e);
}
}
void mouseReleaseEvent(QMouseEvent *) { pressed = 0; }
void mouseMoveEvent(QMouseEvent *e) { draw(e); }
private:
void draw(QMouseEvent *e) {
if (pressed) {
QPainter painter(pixmap);
painter.setPen(color);
int x = e->pos().x() / 12;
int y = e->pos().y() / 12;
painter.drawPoint(x, y);
repaint();
}
}
QColor color;
QPixmap *pixmap;
bool pressed;
};