这个小部件类，对于QCustomPlot的所有方面都有所体现
下面阅读它的函数：
函数组织顺序为: 基本设置---添加图线---删除图线---添加额外Item---层次管理---坐标轴管理----导出图表
QCustomPlot (QWidget *parent=0) void setViewport (const QRect &rect)//视口设置，通常就是本部件所在的长宽 void setBackground (const QPixmap &pm)//在整个视口的最底层绘制图片，用作背景 void setBackground (const QPixmap &pm, bool scaled, Qt::AspectRatioMode mode=Qt::KeepAspectRatioByExpanding) void setBackground (const QBrush &brush) void setBackgroundScaled (bool scaled)//设置setBackground 所绘的图是否进行缩放以适应Viewport void setBackgroundScaledMode (Qt::AspectRatioMode mode)//有Qt::IgnoreAspectRatio（忽略比例，缩放至适应视口），Qt::KeepAspectRatio（保持长宽比，直到一边最大至视口边缘）Qt::KeepAspectRatioByExpanding（保持长宽比，缩放至充满视口） void setAntialiasedElements (const QCP::AntialiasedElements &antialiasedElements)//抗锯齿效果，对于各对象，都有默认设置，可通过本函数，改变默认不抗锯齿的元素，使它也抗。 void setAntialiasedElement (QCP::AntialiasedElement antialiasedElement, bool enabled=true)//更方便的开关 void setNotAntialiasedElements (const QCP::AntialiasedElements ¬AntialiasedElements)//设置不抗 void setNotAntialiasedElement (QCP::AntialiasedElement notAntialiasedElement, bool enabled=true) void setAutoAddPlottableToLegend (bool on)//是否自动添加图形到图例，默认是 void setInteraction (const QCP::Interaction &interaction, bool enabled=true)//设置交互方式，如是否可拖动或缩放轴，是否可选中轴或图例等。 void setInteractions (const QCP::Interactions &interactions) void setSelectionTolerance (int pixels)//选择公差设置，在多少像素中能选中某个元素 void setNoAntialiasingOnDrag (bool enabled)//拖动时是否也抗锯齿 void setPlottingHint (QCP::PlottingHint hint, bool enabled=true)//设置其它参数，如快速绘制线（损失质量），缓存轴的lable(提高效率) void setPlottingHints (const QCP::PlottingHints &hints) void setMultiSelectModifier (Qt::KeyboardModifier modifier)//要多选时的按键，默认Qt::ControlModifier，即ctrl QRect viewport () const//与上述大致对应 QPixmap background () const bool backgroundScaled () const Qt::AspectRatioMode backgroundScaledMode () const QCPLayoutGrid * plotLayout () const QCP::AntialiasedElements antialiasedElements () const QCP::AntialiasedElements notAntialiasedElements () const bool autoAddPlottableToLegend () const const QCP::Interactions interactions () const int selectionTolerance () const bool noAntialiasingOnDrag () const QCP::PlottingHints plottingHints () const Qt::KeyboardModifier multiSelectModifier () const QCPAbstractPlottable * plottable (int index)//所有添加的图线都自动加了索引，按先后顺序 QCPAbstractPlottable * plottable () bool addPlottable (QCPAbstractPlottable *plottable)//添加除graph线外的其它种类型的曲线或图 bool removePlottable (QCPAbstractPlottable *plottable) bool removePlottable (int index) int clearPlottables () int plottableCount () const QList< QCPAbstractPlottable * > selectedPlottables () const//返回选中的线 QCPAbstractPlottable * plottableAt (const QPointF &pos, bool onlySelectable=false) const//返回某个点是否有图线 bool hasPlottable (QCPAbstractPlottable *plottable) const QCPGraph * addGraph (QCPAxis *keyAxis=0, QCPAxis *valueAxis=0)//为Graph线留的特殊接口，因Graph是最常用的 bool removeGraph (QCPGraph *graph) bool removeGraph (int index) QCPGraph * graph (int index) const QCPGraph * graph () const int clearGraphs () int graphCount () const QList< QCPGraph * > selectedGraphs () const bool addItem (QCPAbstractItem *item)//添加一些附加item，如箭头等 bool removeItem (QCPAbstractItem *item) bool removeItem (int index) int clearItems () int itemCount () const QCPAbstractItem * item (int index) const QCPAbstractItem * item () const QList< QCPAbstractItem * > selectedItems () const QCPAbstractItem * itemAt (const QPointF &pos, bool onlySelectable=false) const bool hasItem (QCPAbstractItem *item) const QCPLayoutElement * layoutElementAt (const QPointF &pos) const QCPLayer * layer (const QString &name) const//QCustomPlot分层的实现与管理 QCPLayer * layer (int index) const QCPLayer * currentLayer () const bool setCurrentLayer (const QString &name) bool setCurrentLayer (QCPLayer *layer) int layerCount () const bool addLayer (const QString &name, QCPLayer *otherLayer=0, LayerInsertMode insertMode=limAbove) bool removeLayer (QCPLayer *layer) bool moveLayer (QCPLayer *layer, QCPLayer *otherLayer, LayerInsertMode insertMode=limAbove) QCPAxisRect * axisRect (int index=0) const QList< QCPAxisRect * > axisRects () const QList< QCPAxis * > selectedAxes () const QList< QCPLegend * > selectedLegends () const int axisRectCount () const bool savePdf (const QString &fileName, bool noCosmeticPen=false, int width=0, int height=0, const QString &pdfCreator="", const QString &pdfTitle="")//将图表导出成各种格式 bool savePng (const QString &fileName, int width=0, int height=0, double scale=1.0, int quality=-1) bool saveJpg (const QString &fileName, int width=0, int height=0, double scale=1.0, int quality=-1) bool saveBmp (const QString &fileName, int width=0, int height=0, double scale=1.0) bool saveRastered (const QString &fileName, int width, int height, double scale, const char *format, int quality=-1) QPixmap toPixmap (int width=0, int height=0, double scale=1.0) void toPainter (QCPPainter *painter, int width=0, int height=0) //三个槽 Q_SLOT void replot (QCustomPlot::RefreshPriority refreshPriority=QCustomPlot::rpHint)//重新生成图表 Q_SLOT void rescaleAxes (bool onlyVisiblePlottables=false) Q_SLOT void deselectAll ()//取消选择