Question

I have a little question about how to implement some sort of graphics editor.
For drawing I use this method:
first I check if left mouse button is clicked, then I draw one pixel at event->pos() on my QPixmap, and after that I call update(); to redraw it. I also paint lines on QPixmap between two dots if the mouse is moved with pressed button(because without it it will just some dots). It works pretty well, but I want to know if there’s more optimized method to do this. Here’s some code(I’ve skipped parts with zooming, joining missing pixels between to pixels etc.)

void Editor::paintEvent(QPaintEvent *event)
{
    painter.drawPixmap(QRect(0, 0, image.width() * zoom , image.height() * zoom),
                             image);
}

void Editor::mousePressEvent(QMouseEvent *event)
{

    if(event->button() == Qt::LeftButton)
    {
        setImagePixel(event->pos());
    }

}

void Editor::mouseMoveEvent(QMouseEvent *event)
{
    if(event->buttons() & Qt::LeftButton)
    {
        setImagePixel(event->pos(), true);
    }
}

void Editor::setImagePixel(const QPoint &pos)
{

    QPainter painter(&image);
    if(image.rect().contains(i, j))
    {
        painter.begin(&image);
        painter.setPen(primaryColor);
        painter.drawPoint(i, j);
        painter.end();
    }
}

Answer 1

Yes, I would use QPainterPath and its API to draw hand-made shapes. Look at its methods : moveTo() and lineTo(), which will let you get rid of the drawing logic (missing pixels, etc). It is also very easy to combine with mouse events.

Hope this helps.