一、基本畫圖

首先，給個簡單的例子：

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//?生成數(shù)據(jù)，畫出的是拋物線??

QVector<double>?x(101),?y(101);?//?initialize?with?entries?0..100??

for?(int?i=0;?i<101;?++i)??

{??

??x[i]?=?i/50.0?-?1;?//?x?goes?from?-1?to?1??

??y[i]?=?x[i]*x[i];?//?let's?plot?a?quadratic?function??

}??

//?添加數(shù)據(jù)曲線（一個圖像可以有多個數(shù)據(jù)曲線）??

customPlot->addGraph();??

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//?graph(0);可以獲取某個數(shù)據(jù)曲線（按添加先后排序）??

//?setData();為數(shù)據(jù)曲線關(guān)聯(lián)數(shù)據(jù)??

customPlot->graph(0)->setData(x,?y);??

//?為坐標(biāo)軸添加標(biāo)簽??

customPlot->xAxis->setLabel("x");??

customPlot->yAxis->setLabel("y");??

//?設(shè)置坐標(biāo)軸的范圍，以看到所有數(shù)據(jù)??

customPlot->xAxis->setRange(-1,?1);??

customPlot->yAxis->setRange(0,?1);??

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//?重畫圖像??

customPlot->replot();??

上面代碼生成的結(jié)果大致是這樣的：

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外觀??

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QCustomPlot的外觀由很多方面特性組成，都可以改變：??

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坐標(biāo)軸：??

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QCustomPlot有四個QCPAxis成員變量，分別代表四個坐標(biāo)軸：xAxis（下）yAxis（左）xAxis2（上）yAxis2（右）??

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QCPAxis有相應(yīng)的函數(shù)可以設(shè)置坐標(biāo)軸的刻度、間距、范圍等：??

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setTickStep(double?step);//設(shè)置刻度間距??

setTickVector(const?QVector<double>?&vec);//將坐標(biāo)軸刻度設(shè)置為vec??

setAutoTickStep(bool?on);//設(shè)置是否自動分配刻度間距??

setAutoTicks(bool?on);//設(shè)置是否自動分配刻度??

setAutoTickCount(int?approximateCount);//設(shè)置是否自動分配刻度數(shù)量??

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還有setBasePen、setTickPen、setTickLength、setSubTickLength、setSubTickPen、setTickLabelFont、setLabelFont、setTickLabelPadding、setLabelPadding、setRangeReversed等??

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等后面專門講QCPAxis的時候再詳細介紹??

曲線風(fēng)格：

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QCPGraph::setPen(const?QPen?&pen);??

曲線畫筆：

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QCPGraph::setLineStyle(LineStyle?ls);??

可以設(shè)置顏色、寬度、實虛等

曲線形狀：

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QCPGraph::setScatterStyle(QCPScatterStyle?&style);??

曲線形狀像*、+、x、o等等

填充曲線方式：

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QCPGraph::setBrush(const?QBrush?&brush);??

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QCPGraph::setChannelFillGraph(otherGraph);//設(shè)置與某之間曲線填充??

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QCPGraph::setBrush(Qt::NoBrush);//移除填充??

以上會等到專門將QCPGraph和QCPScatterStyle類的時候再細講網(wǎng)格：

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customPlot->yAxis->grid();??

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setPen、setZeroLinePen、setSubGridVisible等??

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等講QCPGrid類再細講??

二、高級畫圖

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1、多曲線與多風(fēng)格??

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<pre?name="code"?class="cpp">customPlot->setLocale(QLocale(QLocale::English,?QLocale::UnitedKingdom));?//?period?as?decimal?separator?and?comma?as?thousand?separator??

customPlot->legend->setVisible(true);??

QFont?legendFont?=?font();??//?start?out?with?MainWindow's?font..??

legendFont.setPointSize(9);?//?and?make?a?bit?smaller?for?legend??

customPlot->legend->setFont(legendFont);??

customPlot->legend->setBrush(QBrush(QColor(255,255,255,230)));??

//?by?default,?the?legend?is?in?the?inset?layout?of?the?main?axis?rect.?So?this?is?how?we?access?it?to?change?legend?placement:??

customPlot->axisRect()->insetLayout()->setInsetAlignment(0,?Qt::AlignBottom|Qt::AlignRight);??

???

//?setup?for?graph?0:?key?axis?left,?value?axis?bottom??

//?will?contain?left?maxwell-like?function??

customPlot->addGraph(customPlot->yAxis,?customPlot->xAxis);??

customPlot->graph(0)->setPen(QPen(QColor(255,?100,?0)));??

customPlot->graph(0)->setBrush(QBrush(QPixmap("./dali.png")));?//?fill?with?texture?of?specified?png-image??

customPlot->graph(0)->setLineStyle(QCPGraph::lsLine);??

customPlot->graph(0)->setScatterStyle(QCPScatterStyle(QCPScatterStyle::ssDisc,?5));??

customPlot->graph(0)->setName("Left?maxwell?function");??

???

//?setup?for?graph?1:?key?axis?bottom,?value?axis?left?(those?are?the?default?axes)??

//?will?contain?bottom?maxwell-like?function??

customPlot->addGraph();??

customPlot->graph(1)->setPen(QPen(Qt::red));??

customPlot->graph(1)->setBrush(QBrush(QPixmap("./dali.png")));?//?same?fill?as?we?used?for?graph?0??

customPlot->graph(1)->setLineStyle(QCPGraph::lsStepCenter);??

customPlot->graph(1)->setScatterStyle(QCPScatterStyle(QCPScatterStyle::ssCircle,?Qt::red,?Qt::white,?7));??

customPlot->graph(1)->setErrorType(QCPGraph::etValue);??

customPlot->graph(1)->setName("Bottom?maxwell?function");??

???

//?setup?for?graph?2:?key?axis?top,?value?axis?right??

//?will?contain?high?frequency?sine?with?low?frequency?beating:??

customPlot->addGraph(customPlot->xAxis2,?customPlot->yAxis2);??

customPlot->graph(2)->setPen(QPen(Qt::blue));??

customPlot->graph(2)->setName("High?frequency?sine");??

???

//?setup?for?graph?3:?same?axes?as?graph?2??

//?will?contain?low?frequency?beating?envelope?of?graph?2??

customPlot->addGraph(customPlot->xAxis2,?customPlot->yAxis2);??

QPen?blueDotPen;??

blueDotPen.setColor(QColor(30,?40,?255,?150));??

blueDotPen.setStyle(Qt::DotLine);??

blueDotPen.setWidthF(4);??

customPlot->graph(3)->setPen(blueDotPen);??

customPlot->graph(3)->setName("Sine?envelope");??

???

//?setup?for?graph?4:?key?axis?right,?value?axis?top??

//?will?contain?parabolically?distributed?data?points?with?some?random?perturbance??

customPlot->addGraph(customPlot->yAxis2,?customPlot->xAxis2);??

customPlot->graph(4)->setPen(QColor(50,?50,?50,?255));??

customPlot->graph(4)->setLineStyle(QCPGraph::lsNone);??

customPlot->graph(4)->setScatterStyle(QCPScatterStyle(QCPScatterStyle::ssCircle,?4));??

customPlot->graph(4)->setName("Some?random?data?around\na?quadratic?function");??

???

//?generate?data,?just?playing?with?numbers,?not?much?to?learn?here:??

QVector<double>?x0(25),?y0(25);??

QVector<double>?x1(15),?y1(15),?y1err(15);??

QVector<double>?x2(250),?y2(250);??

QVector<double>?x3(250),?y3(250);??

QVector<double>?x4(250),?y4(250);??

for?(int?i=0;?i<25;?++i)?//?data?for?graph?0??

{??

??x0[i]?=?3*i/25.0;??

??y0[i]?=?exp(-x0[i]*x0[i]*0.8)*(x0[i]*x0[i]+x0[i]);??

}??

for?(int?i=0;?i<15;?++i)?//?data?for?graph?1??

{??

??x1[i]?=?3*i/15.0;;??

??y1[i]?=?exp(-x1[i]*x1[i])*(x1[i]*x1[i])*2.6;??

??y1err[i]?=?y1[i]*0.25;??

}??

for?(int?i=0;?i<250;?++i)?//?data?for?graphs?2,?3?and?4??

{??

??x2[i]?=?i/250.0*3*M_PI;??

??x3[i]?=?x2[i];??

??x4[i]?=?i/250.0*100-50;??

??y2[i]?=?sin(x2[i]*12)*cos(x2[i])*10;??

??y3[i]?=?cos(x3[i])*10;??

??y4[i]?=?0.01*x4[i]*x4[i]?+?1.5*(rand()/(double)RAND_MAX-0.5)?+?1.5*M_PI;??

}??

???

//?pass?data?points?to?graphs:??

customPlot->graph(0)->setData(x0,?y0);??

customPlot->graph(1)->setDataValueError(x1,?y1,?y1err);??

customPlot->graph(2)->setData(x2,?y2);??

customPlot->graph(3)->setData(x3,?y3);??

customPlot->graph(4)->setData(x4,?y4);??

//?activate?top?and?right?axes,?which?are?invisible?by?default:??

customPlot->xAxis2->setVisible(true);??

customPlot->yAxis2->setVisible(true);??

//?set?ranges?appropriate?to?show?data:??

customPlot->xAxis->setRange(0,?2.7);??

customPlot->yAxis->setRange(0,?2.6);??

customPlot->xAxis2->setRange(0,?3.0*M_PI);??

customPlot->yAxis2->setRange(-70,?35);??

//?set?pi?ticks?on?top?axis:??

QVector<double>?piTicks;??

QVector<QString>?piLabels;??

piTicks?<<?0??<<?0.5*M_PI?<<?M_PI?<<?1.5*M_PI?<<?2*M_PI?<<?2.5*M_PI?<<?3*M_PI;??

piLabels?<<?"0"?<<?QString::fromUtf8("?π")?<<?QString::fromUtf8("π")?<<?QString::fromUtf8("1?π")?<<?QString::fromUtf8("2π")?<<?QString::fromUtf8("2?π")?<<?QString::fromUtf8("3π");??

customPlot->xAxis2->setAutoTicks(false);??

customPlot->xAxis2->setAutoTickLabels(false);??

customPlot->xAxis2->setTickVector(piTicks);??

customPlot->xAxis2->setTickVectorLabels(piLabels);??

//?add?title?layout?element:??

customPlot->plotLayout()->insertRow(0);??

customPlot->plotLayout()->addElement(0,?0,?new?QCPPlotTitle(customPlot,?"Way?too?many?graphs?in?one?plot"));??

//?set?labels:??

customPlot->xAxis->setLabel("Bottom?axis?with?outward?ticks");??

customPlot->yAxis->setLabel("Left?axis?label");??

customPlot->xAxis2->setLabel("Top?axis?label");??

customPlot->yAxis2->setLabel("Right?axis?label");??

//?make?ticks?on?bottom?axis?go?outward:??

customPlot->xAxis->setTickLength(0,?5);??

customPlot->xAxis->setSubTickLength(0,?3);??

//?make?ticks?on?right?axis?go?inward?and?outward:??

customPlot->yAxis2->setTickLength(3,?3);??

customPlot->yAxis2->setSubTickLength(1,?1);??

效果圖：

2、日期和時間數(shù)據(jù)曲線

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//?set?locale?to?english,?so?we?get?english?month?names:??

??customPlot->setLocale(QLocale(QLocale::English,?QLocale::UnitedKingdom));??

??//?seconds?of?current?time,?we'll?use?it?as?starting?point?in?time?for?data:??

??double?now?=?QDateTime::currentDateTime().toTime_t();??

??srand(8);?//?set?the?random?seed,?so?we?always?get?the?same?random?data??

??//?create?multiple?graphs:??

??for?(int?gi=0;?gi<5;?++gi)??

??{??

????customPlot->addGraph();??

????QPen?pen;??

????pen.setColor(QColor(0,?0,?255,?200));??

????customPlot->graph()->setLineStyle(QCPGraph::lsLine);??

????customPlot->graph()->setPen(pen);??

????customPlot->graph()->setBrush(QBrush(QColor(255/4.0*gi,160,50,150)));??

????//?generate?random?walk?data:??

????QVector<double>?time(250),?value(250);??

????for?(int?i=0;?i<250;?++i)??

????{??

??????time[i]?=?now?+?24*3600*i;??

??????if?(i?==?0)??

????????value[i]?=?(i/50.0+1)*(rand()/(double)RAND_MAX-0.5);??

??????else??

????????value[i]?=?fabs(value[i-1])*(1+0.02/4.0*(4-gi))?+?(i/50.0+1)*(rand()/(double)RAND_MAX-0.5);??

????}??

????customPlot->graph()->setData(time,?value);??

??}??

??//?configure?bottom?axis?to?show?date?and?time?instead?of?number:??

??customPlot->xAxis->setTickLabelType(QCPAxis::ltDateTime);??

??customPlot->xAxis->setDateTimeFormat("MMMM\nyyyy");??

??//?set?a?more?compact?font?size?for?bottom?and?left?axis?tick?labels:??

??customPlot->xAxis->setTickLabelFont(QFont(QFont().family(),?8));??

??customPlot->yAxis->setTickLabelFont(QFont(QFont().family(),?8));??

??//?set?a?fixed?tick-step?to?one?tick?per?month:??

??customPlot->xAxis->setAutoTickStep(false);??

??customPlot->xAxis->setTickStep(2628000);?//?one?month?in?seconds??

??customPlot->xAxis->setSubTickCount(3);??

??//?apply?manual?tick?and?tick?label?for?left?axis:??

??customPlot->yAxis->setAutoTicks(false);??

??customPlot->yAxis->setAutoTickLabels(false);??

??customPlot->yAxis->setTickVector(QVector<double>()?<<?5?<<?55);??

??customPlot->yAxis->setTickVectorLabels(QVector<QString>()?<<?"Not?so\nhigh"?<<?"Very\nhigh");??

??//?set?axis?labels:??

??customPlot->xAxis->setLabel("Date");??

??customPlot->yAxis->setLabel("Random?wobbly?lines?value");??

??//?make?top?and?right?axes?visible?but?without?ticks?and?labels:??

??customPlot->xAxis2->setVisible(true);??

??customPlot->yAxis2->setVisible(true);??

??customPlot->xAxis2->setTicks(false);??

??customPlot->yAxis2->setTicks(false);??

??customPlot->xAxis2->setTickLabels(false);??

??customPlot->yAxis2->setTickLabels(false);??

??//?set?axis?ranges?to?show?all?data:??

??customPlot->xAxis->setRange(now,?now+24*3600*249);??

??customPlot->yAxis->setRange(0,?60);??

??//?show?legend:??

??customPlot->legend->setVisible(true);??

效果圖：

三、曲線、柱形圖、統(tǒng)計圖...

到目前為止，我們?yōu)閳D像添加曲線都是使用

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QCustomPlot::addGraph();??

QCustomPlot::graph();??

其實，除了 QCPGraph ，QCustomPlot 還提供了多個畫圖類：

QCPCurve：與QCPGraph 類似，差別在于它是用于展示參數(shù)化曲線，可以有循環(huán)。

QCPBars：柱形圖，如果有多個QCPBars ，可以依次重疊。

QCPStatisticalBox、QCPColorMap、QCPFinancial
與QCPGraph 不同的是，這些畫圖類在添加到QCustomPlot 的時候需要使用new創(chuàng)建一個實例，而不能直接

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<span?style="color:?rgb(53,?53,?53);?font-family:?monospace;?line-height:?19.5px;?background-color:?rgb(240,?240,?240);">addPlottable</span>();??

簡單例子如下：

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QCPBars?*myBars?=?new?QCPBars(customPlot->xAxis,?customPlot->yAxis);??

customPlot->addPlottable(myBars);??

//?now?we?can?modify?properties?of?myBars:??

myBars->setName("Bars?Series?1");??

QVector<double>?keyData;??

QVector<double>?valueData;??

keyData?<<?1?<<?2?<<?3;??

valueData?<<?2?<<?4?<<?8;??

myBars->setData(keyData,?valueData);??

customPlot->rescaleAxes();??

customPlot->replot();??

好吧，這篇就到這里。水平有限，如有出錯，敬請指出，互相學(xué)習(xí)。 與50位技術(shù)專家面對面20年技術(shù)見證，附贈技術(shù)全景圖

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