Coordinate systems for QGrpahicsView/Scene and QPainter

[jkwok678]

Is there any difference?
In my QPainter code I just did a drawImage(x,y,*image).

QGrpahicsView.

painter.setWindow(QRect(0, 0, canvasSizeX, canvasSizeY));
painter.setViewport(0, 0, canvasSizeX, canvasSizeY);

QGraphicsPixmapItem *straightPixmapItem = scene->addPixmap(*image);
straightPixmapItem->setPos(x,y);

But now when I do this, it never shows at the same location. Surely they should both output to the same location if the window size is the same?

[eyllanesc]

try:

view->setAlignment(Qt::AlignLeft | Qt::AlignTop);

Note: don't abuse dynamic memory, you don't need a QPixmap pointer:

void drawImage(qreal x, qreal y, const QPixmap & image){
   QGraphicsPixmapItem *straightPixmapItem = scene->addPixmap(image);
    straightPixmapItem->setPos(x,y); 
}.

[jkwok678]

@eyllanesc said in Coordinate systems for QGrpahicsView/Scene and QPainter:

view->setAlignment(Qt::AlignLeft | Qt::AlignTop);

Thanks, it works, but what exactly is that command and what does it do?

[mrjj]

@jkwok678

It tells how the view is "centered"

https://doc.qt.io/qt-5/qgraphicsview.html#alignment-prop

[jkwok678]

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