Qt5 eglfs QWT6.1 Empty Plot region

[shriramrs31]

Hallo,

I have Qt5.1.0 working with my custom board with AM3359 processor. linaro toolchain was used for cross compiling (came by default with AM335x SDK6 from TI). the tool chain is with hardfp. I cross compiled QWT6.1.0 successfully yesterday and have been trying to get the examples running.

Unfortunately plots are not displayed in eglfs platform. The plot region is empty. With "-platform linuxfb" the plots are working fine.

This is the output when running the program in eglfs mode

root@am335x-evm:~# ./oscilloscope -platform eglfs
QIconvCodec::convertFromUnicode: using Latin-1 for conversion, iconv_open failed
QIconvCodec::convertToUnicode: using Latin-1 for conversion, iconv_open failed
evdevtouch: Using device /dev/input/event0
min X: 0 max X: 800
min Y: 0 max Y: 480
min pressure: 0 max pressure: 0
device name: ft5x0x_ts
Protocol type A
EGLFS: Unable to query physical screen size, defaulting to 100 dpi.
EGLFS: To override, set QT_QPA_EGLFS_PHYSICAL_WIDTH and QT_QPA_EGLFS_PHYSICAL_HEIGHT (in millimeters).
This plugin does not support propagateSizeHints()
void QWidgetPrivate::setMask_sys(const QRegion&): Not supported on eglfs.

The dials and text are getting rendered properly. Only the plots are empty. The result is same for any example / custom application that uses plot. Even just a simple plot with no real time data update is empty.

If I use linuxfb, the plots are working fine. This is the output when i run with linuxfb platform :

root@am335x-evm:~# ./oscilloscope -platform linuxfb
QIconvCodec::convertFromUnicode: using Latin-1 for conversion, iconv_open failed
QIconvCodec::convertToUnicode: using Latin-1 for conversion, iconv_open failed
This plugin does not support propagateSizeHints()
void QWidgetPrivate::setMask_sys(const QRegion&): Not supported on linuxfb.
void QWidgetPrivate::setMask_sys(const QRegion&): Not supported on linuxfb.

Has anyone experience something similar ? or point me in the right direction to solve this ?

Thanks a lot.

Ram

[Uwe]

Only the plots are empty. The result is same for any example / custom application that uses plot.

Please try the simple_plot example as it is it does absolutely nothing special - no overlays etc.

What happens, when you disable the internal backing store of the canvas:

QwtPlotCanvas *canvas = new QwPlotCanvas();
canvas->setPaintAttribute( QwtPlotCanvas::BackingStore, false );
plot->setCanvas( canvas );

QwtPlotCanvas *canvas = new QwPlotCanvas();
canvas->setPaintAttribute( QwtPlotCanvas::BackingStore, false );
plot->setCanvas( canvas );

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Uwe

[shriramrs31]

Hi Uwe,

Thanks a lot for your quick response.

Yes I tried simple plot also and with the same result. Scale and Axis are being displayed. I can see a half of the orange dot at 0,0 but the reminder of plot is not there. with -platform linuxfb i see the full plot.

I also tried the simple plot with your backing store option suggestion like below :

#include <qapplication.h>
#include <qwt_plot.h>
#include <qwt_plot_canvas.h>
#include <qwt_plot_curve.h>
#include <qwt_plot_grid.h>
#include <qwt_symbol.h>
#include <qwt_legend.h>
 
int main( int argc, char **argv )
{
    QApplication a( argc, argv );
 
    QwtPlot plot;
 
    QwtPlotCanvas *canvas = new QwtPlotCanvas();
    canvas->setPaintAttribute(QwtPlotCanvas::BackingStore, false);
    plot.setCanvas( canvas );
 
    plot.setTitle( "Plot Demo" );
    plot.setCanvasBackground( Qt::white );
    plot.setAxisScale( QwtPlot::yLeft, 0.0, 10.0 );
    plot.insertLegend( new QwtLegend() );
 
    QwtPlotGrid *grid = new QwtPlotGrid();
    grid->attach( &plot );
 
    QwtPlotCurve *curve = new QwtPlotCurve();
    curve->setTitle( "Some Points" );
    curve->setPen( Qt::blue, 4 ),
    curve->setRenderHint( QwtPlotItem::RenderAntialiased, true );
 
    QwtSymbol *symbol = new QwtSymbol( QwtSymbol::Ellipse,
        QBrush( Qt::yellow ), QPen( Qt::red, 2 ), QSize( 8, 8 ) );
    curve->setSymbol( symbol );
 
    QPolygonF points;
    points << QPointF( 0.0, 4.4 ) << QPointF( 1.0, 3.0 )
        << QPointF( 2.0, 4.5 ) << QPointF( 3.0, 6.8 )
        << QPointF( 4.0, 7.9 ) << QPointF( 5.0, 7.1 );
    curve->setSamples( points );
 
    curve->attach( &plot );
 
    plot.resize( 600, 400 );
    plot.show();
    plot.replot();
 
    return a.exec();
}

#include <qapplication.h>
#include <qwt_plot.h>
#include <qwt_plot_canvas.h>
#include <qwt_plot_curve.h>
#include <qwt_plot_grid.h>
#include <qwt_symbol.h>
#include <qwt_legend.h>

int main( int argc, char **argv )
{
    QApplication a( argc, argv );

    QwtPlot plot;

    QwtPlotCanvas *canvas = new QwtPlotCanvas();
    canvas->setPaintAttribute(QwtPlotCanvas::BackingStore, false);
    plot.setCanvas( canvas );

    plot.setTitle( "Plot Demo" );
    plot.setCanvasBackground( Qt::white );
    plot.setAxisScale( QwtPlot::yLeft, 0.0, 10.0 );
    plot.insertLegend( new QwtLegend() );

    QwtPlotGrid *grid = new QwtPlotGrid();
    grid->attach( &plot );

    QwtPlotCurve *curve = new QwtPlotCurve();
    curve->setTitle( "Some Points" );
    curve->setPen( Qt::blue, 4 ),
    curve->setRenderHint( QwtPlotItem::RenderAntialiased, true );

    QwtSymbol *symbol = new QwtSymbol( QwtSymbol::Ellipse,
        QBrush( Qt::yellow ), QPen( Qt::red, 2 ), QSize( 8, 8 ) );
    curve->setSymbol( symbol );

    QPolygonF points;
    points << QPointF( 0.0, 4.4 ) << QPointF( 1.0, 3.0 )
        << QPointF( 2.0, 4.5 ) << QPointF( 3.0, 6.8 )
        << QPointF( 4.0, 7.9 ) << QPointF( 5.0, 7.1 );
    curve->setSamples( points );

    curve->attach( &plot );

    plot.resize( 600, 400 );
    plot.show();
    plot.replot();

    return a.exec();
}

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Still no plot.

I know that eglfs can render only one single surface and only in fullscreen mode. Can this be anything to do with this ?

Ram

[Uwe]

What exactly do you see:

1. Scales: yes,
2. legend: no
3. title: ?
4. canvas background: ?
5. canvas frame ?
6. curve: ?
7. grid: ?

Uwe

[shriramrs31]

Hallo Uwe,

Hope these pictures help

eglfs.jpglinuxfb.jpg

Thanks.

Ram

[Uwe]

The left picture is not the simple_plot example - there are no scales from 0-100. Don't know what this application is, but it probably has no items attached. Should be a problem on your side - eglfs is not to blame.

The second one shows the simple_plot example - everything seems to be o.k. there, beside that it is not in fullscreen mode and you see some "noise" from the previous application left in your graphics memory in the area, that is not covered by the application.

Uwe

[shriramrs31]

Hi Uwe,

Both the pictures are from executing the same code binary : "simpleplot example". Just executed with different platforms in argument.

The left pic was executed with "./simpleplot -platform eglfs". The right picture was result of execution "./simpleplot -platform linuxfb".

linuxfb does not cover the full screen and also does not react to touch. Some settings might be missing here. But, I dont want to use linuxfb for my end application. It was just a test to see what happens with other platforms in argument.

I have eglfs qt5.0 and qwt 6.1rc3 working for another board. I want to port this application here.

Thanks a lot and best regards.

Ram

[Uwe]

The left image has scales from 0-100 - this is neither a default nor somehow related to application code. I don't see how this somehow depends on your platform plugin.

I recommend to start your debugger to check where the 100 is from.

Uwe