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  1. 26th May 2011, 13:42 #5
    Troudhyl
    Troudhyl is offline Novice
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    Default Re: x-bottom scale div linked to pixels even if resizing

    Ok so, my code is cleaner using the right class. But it "flashes" again and I know why. I set the step size with setAxisScale at each new value, but when i call replot(), it auto-adjust the step size, then I set it again with the next value, then replot(), etc. Is there a way to fix this ?

    This is my code, from a simple graphical QWidget project (with ui) if you want to test the behavior.

    Widget.ui
    Qt Code: 
    1. <ui version="4.0">
    2.  <class>Widget</class>
    3.  <widget class="QWidget" name="Widget">
    4.   <property name="geometry">
    5.    <rect>
    6.     <x>0</x>
    7.     <y>0</y>
    8.     <width>706</width>
    9.     <height>366</height>
    10.    </rect>
    11.   </property>
    12.   <property name="windowTitle">
    13.    <string>Widget</string>
    14.   </property>
    15.   <layout class="QHBoxLayout" name="horizontalLayout">
    16.    <item>
    17.     <layout class="QVBoxLayout" name="verticalLayout">
    18.      <property name="spacing">
    19.       <number>0</number>
    20.      </property>
    21.      <item>
    22.       <widget class="QPushButton" name="reset">
    23.        <property name="text">
    24.         <string>Stop</string>
    25.        </property>
    26.       </widget>
    27.      </item>
    28.     </layout>
    29.    </item>
    30.   </layout>
    31.  </widget>
    32.  <layoutdefault spacing="6" margin="11"/>
    33.  <resources/>
    34.  <connections/>
    35. </ui>
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    Widget.h
    Qt Code: 
    1. #ifndef WIDGET_H
    2. #define WIDGET_H
    3.  
    4. #include <QWidget>
    5. #include <QTimer>
    6.  
    7. namespace Ui {
    8.     class Widget;
    9. }
    10.  
    11. class QSizeGrip;
    12. class QwtPlot;
    15. class PlotZoomer;
    18. class QwtPlotRescaler;
    19.  
    20. class Widget : public QWidget
    21. {
    22.     Q_OBJECT
    23.  
    24. public:
    25.     explicit Widget(QWidget *parent = 0);
    26.     ~Widget();
    27.  
    28. private:
    29.     Ui::Widget *ui;
    30.  
    31.     QVector<QPointF> points;
    32.     qreal curX;
    33.     QTimer timer;
    34.  
    35.     QSizeGrip* m_pSizeGrip;
    36.     QwtPlot* m_pPlot;
    37.     QwtPlotCurve* m_pCurve;
    38.     QwtPlotGrid* m_pGrid;
    39.     int stepSize;
    40.     PlotZoomer* m_pZoomer;
    41.     QwtPlotMagnifier* m_pMagnifier;
    42.     QwtPlotPanner* m_pPanner;
    43.     QwtPlotRescaler* m_pRescaler;
    44.  
    45.     void resizeEvent(QResizeEvent *e);
    46.  
    47. private slots:
    48.     void newValue();
    49.     void playPause();
    50. };
    51.  
    52. #endif // WIDGET_H
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    Widget.cpp
    Qt Code: 
    1. #include "Widget.h"
    2. #include "ui_Widget.h"
    3.  
    4. #include <QTime>
    5. #include <QSizeGrip>
    6. #include <QResizeEvent>
    7. #include <qmath.h>
    8.  
    9. #include <qwt_plot.h>
    10. #include <qwt_plot_grid.h>
    11. #include <qwt_plot_curve.h>
    12. #include <qwt_plot_canvas.h>
    13. #include <qwt_plot_layout.h>
    14. #include <qwt_plot_zoomer.h>
    15. #include <qwt_plot_panner.h>
    16. #include <qwt_plot_magnifier.h>
    17. #include <qwt_plot_rescaler.h>
    18. #include <qwt_scale_draw.h>
    19.  
    20. class PlotZoomer : public QwtPlotZoomer
    21. {
    22. public:
    23.     explicit PlotZoomer(QwtPlotCanvas *canvas);
    24.  
    25.     void setZoomBase( const QRectF &base );
    26. };
    27.  
    28. PlotZoomer::PlotZoomer(QwtPlotCanvas *canvas) :
    29.     QwtPlotZoomer(canvas)
    30. {
    31. }
    32.  
    33. void PlotZoomer::setZoomBase(const QRectF &base)
    34. {
    35.     if ( !plot() )
    36.         return;
    37.  
    38.     int currentIndex = zoomRectIndex();
    39.     QStack<QRectF> stack = zoomStack();
    40.     stack.replace(0, base);
    41.     setZoomStack(stack, 0);
    42.     zoom(currentIndex);
    43. }
    44.  
    45. Widget::Widget(QWidget *parent) :
    46.     QWidget(parent),
    47.     ui(new Ui::Widget),
    48.     m_pSizeGrip(new QSizeGrip(this)),
    49.     curX( 0 ),
    50.     stepSize( 50 ),
    51.     m_pPlot( new QwtPlot( this ) ),
    52.     m_pCurve( new QwtPlotCurve ),
    53.     m_pGrid( new QwtPlotGrid )
    54. {
    55.     ui->setupUi(this);
    56.  
    57.     m_pPlot->canvas()->setPaintAttribute(QwtPlotCanvas::BackingStore, false);
    58.     m_pPlot->setCanvasBackground(Qt::black);
    59.     m_pPlot->setWindowFlags( m_pPlot->windowFlags() | Qt::SubWindow );
    60.     m_pPlot->plotLayout()->setAlignCanvasToScales(true);
    61.  
    62.     m_pRescaler = new QwtPlotRescaler(m_pPlot->canvas());
    63.     m_pRescaler->setAspectRatio(QwtPlot::yLeft, 0.0);
    64.  
    65.     m_pSizeGrip->resize(12,12);
    66.     m_pSizeGrip->move(width()-12,height()-12);
    67.  
    68.     m_pCurve->setPen(QColor(Qt::green));
    69.     m_pCurve->setRenderHint(QwtPlotItem::RenderAntialiased);
    70.     m_pCurve->attach(m_pPlot);
    71.  
    72.     m_pGrid->setPen(QColor(Qt::white));
    73.     m_pGrid->attach(m_pPlot);
    74.  
    75.     m_pZoomer = new PlotZoomer( m_pPlot->canvas() );
    76.     m_pZoomer->setRubberBandPen(QColor(Qt::red));
    77.     m_pZoomer->setTrackerPen( QColor( Qt::red ) );
    78.     m_pZoomer->setTrackerFont( QFont( "Helvetica [Cronyx]", 12, QFont::Bold ) );
    79.     m_pZoomer->setTrackerMode( PlotZoomer::AlwaysOn );
    80.     m_pZoomer->setMousePattern( QwtEventPattern::MouseSelect2, Qt::RightButton, Qt::ControlModifier );
    81.     m_pZoomer->setMousePattern( QwtEventPattern::MouseSelect3, Qt::RightButton );
    82.  
    83.     m_pMagnifier = new QwtPlotMagnifier( m_pPlot->canvas() );
    84.     m_pMagnifier->setMouseButton( Qt::MidButton );
    85.  
    86.     m_pPanner = new QwtPlotPanner( m_pPlot->canvas() );
    87.     m_pPanner->setMouseButton( Qt::LeftButton, Qt::ControlModifier );
    88.  
    89.     ui->verticalLayout->addWidget( m_pPlot );
    90.  
    91.     connect( &timer, SIGNAL( timeout() ), SLOT( newValue() ) );
    92.     connect( ui->reset, SIGNAL( clicked() ), SLOT( playPause() ) );
    93.  
    94.     qsrand( QTime::currentTime().msec() );
    95.     playPause();
    96. }
    97.  
    98. Widget::~Widget()
    99. {
    100.     delete ui;
    101. }
    102.  
    103. void Widget::newValue()
    104. {
    105.     points << QPointF(curX++, qSin(curX/30)*100);//qrand()%201 - 100);
    106.  
    107.     if (points.size() > m_pPlot->canvas()->width()) {
    108.         m_pRescaler->setExpandingDirection(QwtPlotRescaler::ExpandDown);
    109.         points.remove(0);
    110.     }
    111.  
    112.     int left (curX > points.size() ? curX - points.size() : 0);
    113.     m_pPlot->setAxisScale(QwtPlot::xBottom, left, left + m_pPlot->canvas()->width(), stepSize);
    114.  
    115.     m_pCurve->setSamples(points);
    116.     m_pPlot->replot();
    117. }
    118.  
    119. void Widget::playPause() {
    120.     bool wasActive(timer.isActive());
    121.  
    122.     m_pZoomer->setEnabled(wasActive);
    123.     m_pMagnifier->setEnabled(wasActive);
    124.     m_pPanner->setEnabled(wasActive);
    125.     m_pPlot->axisScaleDraw(QwtPlot::xBottom)->enableComponent(QwtAbstractScaleDraw::Labels, wasActive);
    126.  
    127.     if (!wasActive) {
    128.         m_pZoomer->zoom(0);
    129.         ui->reset->setText("Stop");
    130.         points.clear();
    131.         curX = 0;
    132.         m_pPlot->setAxisScale(QwtPlot::xBottom, 0, m_pPlot->canvas()->width(), stepSize);
    133.         m_pPlot->setAxisScale(QwtPlot::yLeft, 0, 0, 0);
    134.         m_pPlot->setAxisAutoScale(QwtPlot::yLeft);
    135.         m_pPlot->setContentsMargins(0,0,0,15);
    136.         timer.start(20);
    137.     } else {
    138.         timer.stop();
    139.         ui->reset->setText("Start");
    140.         m_pZoomer->setZoomBase(QRectF(m_pPlot->axisScaleDiv(QwtPlot::xBottom)->lowerBound(), m_pPlot->axisScaleDiv(QwtPlot::yLeft)->lowerBound(), m_pPlot->axisScaleDiv(QwtPlot::xBottom)->range(), m_pPlot->axisScaleDiv(QwtPlot::yLeft)->range()));
    141.         m_pPlot->setContentsMargins(0,0,0,0);
    142.         m_pPlot->replot();
    143.     }
    144. }
    145.  
    146. void Widget::resizeEvent(QResizeEvent *e) {
    147.     QWidget::resizeEvent(e);
    148.     if (m_pPlot->isVisible()) {
    149.         QSize oldSize(e->oldSize());
    150.         QSize size(e->size());
    151.  
    152.         if (points.size() >= m_pPlot->canvas()->width() && size.width() < oldSize.width()) {
    153.             m_pRescaler->setExpandingDirection(QwtPlotRescaler::ExpandDown);
    154.             points.remove(0, oldSize.width() - size.width());
    155.         } else {
    156.             m_pRescaler->setExpandingDirection(QwtPlotRescaler::ExpandUp);
    157.         }
    158.     }
    159.  
    160.     m_pSizeGrip->move(width()-12, height()-12);
    161. }
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    Another strange behavior: after zooming with a box (when it is paused), unzooming with right click one more time than the 0 level do a one-pixel horizontal shift... A way to avoid this ?

    Edit: And I can't reduce the vertical size as much as I want...
    Last edited by Troudhyl; 26th May 2011 at 15:39. Reason: nicer code
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