It turns out that the wrong base class was used for the chart.
QQuickWidget can only be used on desktop, not in a mobile UI.
Therefore, turn this into a QQuickItem and move the container
QQuickWidget into desktop-only code.
Currently, this code is insane: The chart is rendered onto a
QGraphicsScene (as it was before), which is then rendered into
a QImage, which is transformed into a QSGTexture, which is then
projected onto the device. This is performed on every mouse
move event, since these events in general change the position
of the info-box.
The plan is to slowly convert elements such as the info-box into
QQuickItems. Browsing the QtQuick documentation, this will
not be much fun.
Also note that the rendering currently tears, flickers and has
antialiasing artifacts, most likely owing to integer (QImage)
to floating point (QGraphicsScene, QQuickItem) conversion
problems. The data flow is
QGraphicsScene (float) -> QImage (int) -> QQuickItem (float).
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
Dirk says rounded corners look better. This now looks a bit
extreme to me and probably the border size should be increased.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
For some chart (e.g. pie charts or stacked bar charts), we want
to display a legend. QtCharts' legend interface happens to be
private and therefore is of no use.
This introduces a legend box which is implemented using
QGraphicItems, which can be placed on top of QCharts. It's very
unfancy, but works for now. If there are too many items, not
all are shown. Currently, the legend is configured to fill
at most half of the width and half of the height of the chart.
This might need some optimization.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
