Qt antialiasing sets different pen widths - c++

Question

I have a qt app which has a big QGraphicsView where I draw a grid.
This grid reacts on mouse clicks. Basically, if you click on some box -> the box is made red. And if you double click on it -> it goes back to its original state (its white).
This is the implementation of my QGraphicsView:
#include "mapview.h"
// Constructors
mapview::mapview()
{
setUpGui();
}
mapview::mapview(QWidget *parent) : QGraphicsView(parent)
{
setUpGui();
}
// GUI setup
void mapview::setUpGui()
{
scene = new QGraphicsScene(this);
this->setScene(scene);
this->setRenderHint(QPainter::Antialiasing);
// this->setRenderHint(QPainter::HighQualityAntialiasing);
}
// Events
void mapview::mousePressEvent(QMouseEvent *event)
{
if (event->button() == Qt::LeftButton) {
lastPoint = event->pos();
scribbling = true;
}
}
void mapview::mouseMoveEvent(QMouseEvent *event)
{
if ((event->buttons() & Qt::LeftButton) && scribbling)
{
drawWall(event->pos());
}
}
void mapview::mouseReleaseEvent(QMouseEvent *event)
{
if (event->button() == Qt::LeftButton && scribbling)
{
drawWall(event->pos());
scribbling = false;
}
}
void mapview::mouseDoubleClickEvent(QMouseEvent *event)
{
removeWall(event->pos());
}
// Drawing methods
void mapview::drawGrid(const int box_count)
{
scene->clear();
auto x = 0.0;
auto y = 0.0;
this->margin = 20.0;
_width = this->width() - 2 * margin;
_height = this->height() - 2 * margin;
if (fabs(_width - _height) >= std::numeric_limits<double>::epsilon())
{
// qDebug() << "width (" << width << ") != height (" << height << ")";
return;
}
this->box_count = box_count;
this->box_size = _width / box_count;
// Horizontal
for (auto i = 0; i <= box_count; i++)
{
QGraphicsLineItem *line = new QGraphicsLineItem(x, y, x + _width, y);
QPen pen;
pen.setColor(Qt::black);
line->setPen(pen);
// scene->addLine(x, y, x + _width, y);
scene->addItem(line);
y += box_size;
}
y = 0.0;
// Vertical
for (auto i = 0; i <= box_count; i++)
{
scene->addLine(x, y, x, y + _height);
x += box_size;
}
}
void mapview::drawWall(const QPointF &endPoint)
{
auto x = endPoint.x() - margin;
auto y = endPoint.y() - margin;
x = static_cast<int>(x / box_size) * box_size;
y = static_cast<int>(y / box_size) * box_size;
QGraphicsRectItem* rect = new QGraphicsRectItem(x, y, this->box_size, this->box_size);
rect->setBrush(QBrush(Qt::red));
rect->setPen(QPen());
scene->addItem(rect);
}
void mapview::removeWall(const QPointF &point)
{
auto x = point.x() - margin;
auto y = point.y() - margin;
x = static_cast<int>(x / box_size) * box_size;
y = static_cast<int>(y / box_size) * box_size;
QGraphicsRectItem* rect = new QGraphicsRectItem(x, y, this->box_size, this->box_size);
rect->setBrush(QBrush(Qt::white));
rect->setPen(QPen());
scene->addItem(rect);
}
As you can see at the top, I set up antialiasing. The problem is, that when I set it up, it somehow changes the view of my drawing:
This is the view of an untouched grid:
Now for the box 1x1 (indexed from 0) I've clicked it (made it red) and then I double clicked it (so it got back to its original state). The problem is, as you can see, the border of this box is kinda thicker:
Funny thing is, that it's only thicker on this view. If I zoom it in, there's no difference between its border and the borders of other boxes. The other thing is, if I set Qt::HighQualityAntialiasing -> the border is the same, but then the zooming gets laggy, I guess it has to do more heavy computations or something like this.
So my question here would be: Is there a way, to make the antialiasing not change the thickness of the border? (I mean, I know it doesn't really change it, but you can definitely see a difference here)