【小计】QWT类的一些使用方法

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鼠标滚轮放大缩小：

QwtPlotMagnifier *PM = new QwtPlotMagnifier( ui->qwtPlot->canvas() );

鼠标左键拖动波形：

QwtPlotPanner *PQ= new QwtPlotPanner(  ui->qwtPlot->canvas() );

鼠标左键选择区域放大：（右键还原）

QwtPlotZoomer* zoomer = new QwtPlotZoomer( ui->qwtPlot->canvas() );
zoomer->setRubberBandPen( QColor( Qt::black ) );
zoomer->setTrackerPen( QColor( Qt::black ) );
zoomer->setMousePattern(QwtEventPattern::MouseSelect2,Qt::RightButton, Qt::ControlModifier );
zoomer->setMousePattern(QwtEventPattern::MouseSelect3,Qt::RightButton );

设置X轴下面标识：

ui->qwtPlot->setAxisTitle(QwtPlot::xBottom, "x -->" );

设置X轴取值范围：

ui->qwtPlot->setAxisScale(QwtPlot::xBottom, 0.0, 30.0);

设置Y轴左边标识（竖着显示）：

ui->qwtPlot->setAxisTitle(QwtPlot::yLeft, "y -->");

设置Y轴取值范围：

ui->qwtPlot->setAxisScale(QwtPlot::yLeft, -1.0, 1.0);

创建一个sin()曲线：

QwtPlotCurve *cSin = new QwtPlotCurve("y = sin(x)");
cSin->setRenderHint(QwtPlotItem::RenderAntialiased);
cSin->setLegendAttribute(QwtPlotCurve::LegendShowLine, true);
cSin->setPen(QPen(Qt::blue));
 cSin->attach(ui->qwtPlot);
cSin->setData(new FunctionData(::sin));

其中FunctionData为：

class FunctionData: public QwtSyntheticPointData { public: FunctionData(double(*y)(double)): QwtSyntheticPointData(100), d_y(y) { } virtual double y(double x) const { return d_y(x); } private: double(*d_y)(double); };

class FunctionData: public QwtSyntheticPointData
{
public:
    FunctionData(double(*y)(double)):
        QwtSyntheticPointData(100),
        d_y(y)
    {
    }
    virtual double y(double x) const
    {
        return d_y(x);
    }
private:
    double(*d_y)(double);
};

创建波形标识：（Y=0） QwtPlotMarker *mY = new QwtPlotMarker(); mY->setLabel(QString::fromLatin1("y = 0")); mY->setLabelAlignment(Qt::AlignRight|Qt::AlignTop); mY->setLineStyle(QwtPlotMarker::HLine); mY->setYValue(0.0); mY->attach(ui->qwtPlot);

QwtPlotMarker *mY = new QwtPlotMarker();
    mY->setLabel(QString::fromLatin1("y = 0"));
    mY->setLabelAlignment(Qt::AlignRight|Qt::AlignTop);
    mY->setLineStyle(QwtPlotMarker::HLine);
    mY->setYValue(0.0);
    mY->attach(ui->qwtPlot);

创建波形标识：（X=PI/2） QwtPlotMarker *mX = new QwtPlotMarker(); mX->setLabel(QString::fromLatin1("x = PI/2")); mX->setLabelAlignment(Qt::AlignLeft | Qt::AlignBottom); mX->setLabelOrientation(Qt::Vertical); mX->setLineStyle(QwtPlotMarker::VLine); mX->setLinePen(QPen(Qt::black, 1, Qt::DashDotDotLine)); mX->setXValue(M_PI/2); mX->attach(ui->qwtPlot);

QwtPlotMarker *mX = new QwtPlotMarker();
    mX->setLabel(QString::fromLatin1("x = PI/2"));
    mX->setLabelAlignment(Qt::AlignLeft | Qt::AlignBottom);
    mX->setLabelOrientation(Qt::Vertical);
    mX->setLineStyle(QwtPlotMarker::VLine);
    mX->setLinePen(QPen(Qt::black, 1, Qt::DashDotDotLine));
    mX->setXValue(M_PI/2);
    mX->attach(ui->qwtPlot);

设置qwtPlot的画布:（圆角矩形） ui->qwtPlot->canvas()->setLineWidth( 1 ); ui->qwtPlot->canvas()->setFrameStyle( QFrame::Box | QFrame::Plain ); ui->qwtPlot->canvas()->setBorderRadius( 15 );

ui->qwtPlot->canvas()->setLineWidth( 1 );
    ui->qwtPlot->canvas()->setFrameStyle( QFrame::Box | QFrame::Plain );
    ui->qwtPlot->canvas()->setBorderRadius( 15 );

设置qwtPlot的画布：（白色填充） QPalette canvasPalette( Qt::white ); canvasPalette.setColor( QPalette::Foreground, QColor( 133, 190, 232 ) ); ui->qwtPlot->canvas()->setPalette( canvasPalette );

QPalette canvasPalette( Qt::white );
    canvasPalette.setColor( QPalette::Foreground, QColor( 133, 190, 232 ) );
    ui->qwtPlot->canvas()->setPalette( canvasPalette );

设置整个界面的颜色： QPalette pal = palette(); const QColor buttonColor = pal.color( QPalette::Button ); QLinearGradient gradient( 0, 0, 0, 1 ); gradient.setCoordinateMode( QGradient::StretchToDeviceMode ); gradient.setColorAt( 0.0, Qt::white ); gradient.setColorAt( 0.7, buttonColor ); gradient.setColorAt( 1.0, buttonColor ); pal.setBrush( QPalette::Window, gradient ); setPalette( pal );

QPalette pal = palette();
    const QColor buttonColor = pal.color( QPalette::Button );
    QLinearGradient gradient( 0, 0, 0, 1 );
    gradient.setCoordinateMode( QGradient::StretchToDeviceMode );
    gradient.setColorAt( 0.0, Qt::white );
    gradient.setColorAt( 0.7, buttonColor );
    gradient.setColorAt( 1.0, buttonColor );
    pal.setBrush( QPalette::Window, gradient );
    setPalette( pal );