QImage.setDevicePixelRatio(2) seemed to do the trick along with a Image that is twice as large and manual translation of the appropriate coordinates. QPainter does the rest.
Good to know. > On Mar 16, 2017, at 8:32 PM, Patrick Stinson <patrickk...@gmail.com> wrote: > > That’s a good setting to know about, so thank you for pointing it out. > > Unfortunately, this isn’t what I am trying to accomplish. I have a singleton > QGraphicsItem that acts as a canvas and is always resized to fit the view’s > viewport. This canvas item paints lines to a QImage buffer with each QPointF > that comes in from the pencil or mouse, and each call to paint() just paints > the QImage buffer. When the pencil or mouse is lifted, it produces a QPixmap > from the boundingRect of the drawn data and creates a QGraphicsPixmapItem to > contain it. Each pencil stroke is created in this way which works quite well > (undo/move/delete, etc.), except for the low-res rendering. > > The canvas item uses a QImage “double-buffer” not to speed up performance but > to contain the pixmap data that is used to produce the pencil stroke items. > > Make sense? > >> On Mar 16, 2017, at 8:21 PM, Ch'Gans <chg...@gna.org> wrote: >> >> On 17 March 2017 at 16:01, Patrick Stinson <patrickk...@gmail.com> wrote: >>> Hi there! >>> >>> I am implementing handwriting with the apple pencil and am double-buffering >>> each stroke on a QImage before passing the resulting pixmap and bounding >>> rect for the stroke to a QGraphicsItem. The problem is that painting to the >>> QImage is not at retina resolution which is what you get when you paint >>> directly to the scene via QGraphicsItem::paint. >>> >>> Does anyone have a suggestion for how to handle this? >>> >>> Should I just double the QImage size and then translate the coordinates >>> appropriately? Then half the target rect in QPainter::drawPixmap(const Rect >>> &target, const QPixmap &, const QSize &source)? Or is there a more elegant >>> way to do it? >>> >> >> Have you tried QGraphicsItem::DeviceCoordinateCache ? >> >> My 2 cents >> >>> Thanks! >>> -P >>> >>> >>> _______________________________________________ >>> Interest mailing list >>> Interest@qt-project.org >>> http://lists.qt-project.org/mailman/listinfo/interest > _______________________________________________ Interest mailing list Interest@qt-project.org http://lists.qt-project.org/mailman/listinfo/interest
