新手求教，qwt画出的图形无法显示出全部数据

[禅悟人生]

用qt做一个界面，目的是画出频谱图，使用qwt库，发现导入数据后，不同窗口大小显示的数据不一样，比如默认窗口大小显示大小如下
拉大一点后，图像变成这样

放到最大，结果如下

而相同数据用matlab画出的图应该是这样

请问用什么办法使其显示出所有数据？
代码如下：
plot.h

#include <qwt_plot.h>
#include <qwt_plot_spectrogram.h>

class Plot : public QwtPlot
{
    Q_OBJECT

public:

    Plot(QWidget * = NULL);

    public slots:

private:
    QwtPlotSpectrogram *d_spectrogram;
};

plot.cpp

#include <qprinter.h>
#include <qprintdialog.h>
#include <qnumeric.h>
#include <qwt_color_map.h>
#include <qwt_plot_spectrogram.h>
#include <qwt_scale_widget.h>
#include <qwt_scale_draw.h>
#include <qwt_plot_zoomer.h>
#include <qwt_plot_panner.h>
#include <qwt_plot_layout.h>
#include <qwt_plot_renderer.h>
#include <qwt_matrix_raster_data.h>
#include "plot.h"
#include <QFile>
#include<QtAlgorithms>



class MyZoomer : public QwtPlotZoomer
{
public:
    MyZoomer(QWidget *canvas) :
        QwtPlotZoomer(canvas)
    {
        setTrackerMode(AlwaysOn);
    }

    virtual QwtText trackerTextF(const QPointF &pos) const
    {
        QColor bg(Qt::white);
        //设置背景透明度
        bg.setAlpha(20);
        //QwtPlotZoomer::trackerTextF返回x,y的坐标轴的刻度数
        QwtText text = QwtPlotZoomer::trackerTextF(pos);
        text.setBackgroundBrush(QBrush(bg));
        return text;
    }
};

class SpectrogramData : public QwtMatrixRasterData
{
public:
    SpectrogramData()
    {

		QFile data("H:/STUDY/Qtproject/spectromgramTest/est.bin");
		if (data.open(QFile::ReadOnly))
		{
			QDataStream instream(&data);
			QVector<double> rawData;
			double *temp = new double[10000 * 300];
			instream.readRawData((char*)temp, 10000 * 300 * sizeof(double));
			for (int i = 0; i < 10000; i++)
			{
				for (int j = 0; j < 300; j++)
				{
					rawData += temp[j * 10000 + i];
				}
			}
	
		setValueMatrix(rawData, 300);

		delete[] temp;
			}

        setInterval(Qt::XAxis, QwtInterval(0, 1));
        setInterval(Qt::YAxis, QwtInterval(0,10));
        setInterval(Qt::ZAxis, QwtInterval(0.0, 0.01));
    }

};

class LinearColorMapRGB : public QwtLinearColorMap
{
public:
    LinearColorMapRGB() :
        //首尾颜色
        QwtLinearColorMap(Qt::darkCyan, Qt::red, QwtColorMap::RGB)
    {
        addColorStop(0.0, Qt::black);
        addColorStop(0.6, Qt::green);
        addColorStop(0.75, Qt::white);
    }
};



Plot::Plot(QWidget *parent) :
QwtPlot(parent)
{
    d_spectrogram = new QwtPlotSpectrogram();
    // use system specific thread count
    //设置线程数和缓存，影响不大
    d_spectrogram->setRenderThreadCount(0);
    d_spectrogram->setCachePolicy(QwtPlotRasterItem::PaintCache);

    d_spectrogram->setData(new SpectrogramData());
    d_spectrogram->attach(this);

    //设置轮廓线的数量和层次（当值为多少时画一条轮廓线）
    QList<double> contourLevels;
    for ( double level =0.001; level <0.1; level += 0.002)
        contourLevels += level;//不是相加，是在其后面添加元素
    d_spectrogram->setContourLevels( contourLevels );

    const QwtInterval zInterval = d_spectrogram->data()->interval(Qt::ZAxis);

    // A color bar on the right axis
    QwtScaleWidget *rightAxis = axisWidget(QwtPlot::yRight);
    rightAxis->setTitle("Intensity");
    //仅设置这个还不行
    rightAxis->setColorBarEnabled(true);

    setAxisScale(QwtPlot::yRight, zInterval.minValue(), zInterval.maxValue());
    enableAxis(QwtPlot::yRight);//默认disabed

    //设置画布对齐到所有坐标轴
    plotLayout()->setAlignCanvasToScales(true);

    //设置为RGBColorMap
    d_spectrogram->setColorMap(new LinearColorMapRGB());
    rightAxis->setColorMap(zInterval, new LinearColorMapRGB());

    //设置显示模式
    d_spectrogram->setDisplayMode(QwtPlotSpectrogram::ContourMode,true);
    d_spectrogram->setDisplayMode( QwtPlotSpectrogram::ImageMode, false);

    //设置鼠标操作
    // LeftButton for the zooming
    // MidButton for the panning
    // RightButton: zoom out by 1
    // Ctrl+RighButton: zoom out to full size
    QwtPlotZoomer* zoomer = new MyZoomer(canvas());
    //修改某一操作，比如一步返回到不放大状态
    zoomer->setMousePattern(QwtEventPattern::MouseSelect2,
        Qt::RightButton, Qt::ControlModifier);
    zoomer->setMousePattern(QwtEventPattern::MouseSelect3,
        Qt::RightButton);
    const QColor c(Qt::red);
    //设置RubberBandPen选择框笔触
    zoomer->setRubberBandPen(c);
    //设置TrackerPen笔触
    zoomer->setTrackerPen(c);

    QwtPlotPanner *panner = new QwtPlotPanner(canvas());
    //移动绘图时候右边colorbar不需要自动改变刻度
    panner->setAxisEnabled(QwtPlot::yRight, false);
    panner->setMouseButton(Qt::MidButton);

    // Avoid jumping when labels with more/less digits
    // appear/disappear when scrolling vertically

    const QFontMetrics fm(axisWidget(QwtPlot::yLeft)->font());
    QwtScaleDraw *sd = axisScaleDraw(QwtPlot::yLeft);
    sd->setMinimumExtent(fm.width("100.00"));

}

[禅悟人生]

引用 2 楼 shihoongbo 的回复:

最好约定一下点的精确度，比如小数点后多少位就强制清零，应该就没问题了

请问怎么约束点的精度？还可以约束坐标轴上点的精度？？？

[未狂]

最好约定一下点的精确度，比如小数点后多少位就强制清零，应该就没问题了

[未狂]

没用过qwt 但是窗口拉大了，图的分辨率就会高，精确度也就越高，原来因为小数位太高被省略的点，就会因为小数位后延伸能保存足够小的数，所以显示出来小图没有显示的点……

[QQ_278397935]

/* 画布纵横比 */ QwtPlotRescaler *plotRescaler = new QwtPlotRescaler(ui->qwtPlotCurve->canvas(), ui->qwtPlotCurve->yLeft, QwtPlotRescaler::Expanding); plotRescaler->setExpandingDirection(QwtPlotRescaler::ExpandBoth);