How to draw a cruve with increasing data?

[anson97209]

Painting incrementally doesn't depend on what is painted. You wrote, that the realtime example works - so it's obviously a problem in your application code.

Uwe

when I enable Qt::WA_PaintOutsidePaintEvent, it will run faster, but it can't display anything unless I left-clicked mouse in the canvas, it is the same in the realtime_plot example not only just in my application code.

[Uwe]

when I enable Qt::WA_PaintOutsidePaintEvent, it will run faster, but it can't display anything unless I left-clicked mouse in the canvas,

No surprise, when it doesn't paint anything.

... it is the same in the realtime_plot example not only just in my application code.

I explicitely asked if it is working ...

I checked the example with Qt 4.3 on X11 with success - so I guess you are running Qt Embedded ( I also asked you which Qt you are using ... ). On Qt Embedded Qt::WA_PaintOutsidePaintEvent is not supported and of course nothing will be painted ( clicking in the canvas triggers a repaint ).

The strategy on platforms, where the raster paint engine is used, is that each drawCurve posts a dummy event and paints inside the paint event. You have the penalty of posting/processing the paint event, but you don't need to paint anything beside the additional points. There is no way to get around this limitation of Qt4 ( Qt3 should be faster ).

You didn't write how many points you want to paint in which time and I have no idea how fast your arm board is. But with the realtime example you can try to find out what is possible.

One more hint: fixing performance issues of the raster paint engine was one of the main features of Qt 4.5. If painting is too slow you could try to upgrade from Qt 4.3 ( AFAIR you might have something about 20-30%).

Uwe

[anson97209]

Thank you very much!

[sumit@sofomo.co.in]

Thank you very much!

Hi anson97209,

I'm also trying to plot running data and have referred curveplot1, curveplot2, realtimeplot and so on example but was unable to make it up to the mark.
Can you upload your complete plotting code or mail me to sumit@sofomo.co.in?

Thank You.

Regards,
Sumit