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  5. QDateTimeAxis

QDateTimeAxis 类

The QDateTimeAxis class adds dates and times to a chart's axis. 更多...

头： #include <QDateTimeAxis>
实例化： DateTimeAxis
继承： QAbstractAxis

特性

公共函数

QDateTimeAxis (QObject * parent = nullptr)
virtual ~QDateTimeAxis ()
QString format () const
QDateTime max () const
QDateTime min () const
void setFormat (QString format )
void setMax (QDateTime max )
void setMin (QDateTime min )
void setRange (QDateTime min , QDateTime max )
void setTickCount (int count )
int tickCount () const

重实现公共函数

virtual QAbstractAxis::AxisType type () const override

信号

void formatChanged (QString format )
void maxChanged (QDateTime max )
void minChanged (QDateTime min )
void rangeChanged (QDateTime min , QDateTime max )
void tickCountChanged (int tickCount )

详细描述

QDateTimeAxis can be set up to show an axis line with tick marks, grid lines, and shades. The labels can be configured by setting an appropriate DateTime format. QDateTimeAxis works correctly with dates from 4714 BCE to 287396 CE. For other limitiations related to QDateTime ，见 QDateTime 文档编制。

注意： QDateTimeAxis is disabled on platforms that define qreal as float.

QDateTimeAxis can be used with any QXYSeries . To add a data point to the series, QDateTime::toMSecsSinceEpoch () is used: 

QLineSeries *series = new QLineSeries;
QDateTime xValue;
xValue.setDate(QDate(2012, 1 , 18));
xValue.setTime(QTime(9, 34));
qreal yValue = 12;
series->append(xValue.toMSecsSinceEpoch(), yValue);
xValue.setDate(QDate(2013, 5 , 11));
xValue.setTime(QTime(11, 14));
qreal yValue = 22;
series->append(xValue.toMSecsSinceEpoch(), yValue);

The following code snippet illustrates adding the series to the chart and setting up QDateTimeAxis: 

QChartView *chartView = new QChartView;
chartView->chart()->addSeries(series);
// ...
QDateTimeAxis *axisX = new QDateTimeAxis;
axisX->setFormat("dd-MM-yyyy h:mm");
chartView->chart()->setAxisX(axisX, series);

特性文档编制

format : QString

This property holds the format string that is used when creating the label for the axis out of a QDateTime 对象。

见 QDateTime documentation for information on how the string should be defined.

访问函数：

QString format () const
void setFormat (QString format )

通知程序信号：

void formatChanged (QString format )

另请参阅 QChart::locale .

max : QDateTime

此特性保持轴的最大值。

When setting this property, the minimum value is adjusted if necessary, to ensure that the range remains valid.

访问函数：

QDateTime max () const
void setMax (QDateTime max )

通知程序信号：

void maxChanged (QDateTime max )

min : QDateTime

此特性保持轴的最小值。

When setting this property, the maximum value is adjusted if necessary, to ensure that the range remains valid.

访问函数：

QDateTime min () const
void setMin (QDateTime min )

通知程序信号：

void minChanged (QDateTime min )

tickCount : int

This property holds the number of tick marks on the axis.

访问函数：

int tickCount () const
void setTickCount (int count )

通知程序信号：

void tickCountChanged (int tickCount )

成员函数文档编制

QDateTimeAxis:: QDateTimeAxis ( QObject * parent = nullptr)

Constructs an axis object that is a child of parent .

[signal] void QDateTimeAxis:: formatChanged ( QString format )

此信号发射当 format of the axis changes.

注意： 通知程序信号对于特性 format .

[signal] void QDateTimeAxis:: maxChanged ( QDateTime max )

This signal is emitted when the maximum value of the axis, specified by max ，改变。

注意： 通知程序信号对于特性 max .

[signal] void QDateTimeAxis:: minChanged ( QDateTime min )

This signal is emitted when the minimum value of the axis, specified by min ，改变。

注意： 通知程序信号对于特性 min .

[signal] void QDateTimeAxis:: rangeChanged ( QDateTime min , QDateTime max )

This signal is emitted when the minimum or maximum value of the axis, specified by min and max ，改变。

[signal] void QDateTimeAxis:: tickCountChanged ( int tickCount )

This signal is emitted when the number of tick marks on the axis, specified by tickCount ，改变。

注意： 通知程序信号对于特性 tickCount .

[虚拟] QDateTimeAxis:: ~QDateTimeAxis ()

销毁对象。

void QDateTimeAxis:: setRange ( QDateTime min , QDateTime max )

Sets the range on the axis from min to max 。若 min 大于 max ，此函数返回不做任何改变。

void QDateTimeAxis:: setTickCount ( int count )

Sets the number of tick marks on the axis to count .

注意： setter 函数对于特性 tickCount .

另请参阅 tickCount ().

int QDateTimeAxis:: tickCount () const

Returns the number of tick marks on the axis.

注意： Getter function for property tickCount.

另请参阅 setTickCount ().

[override virtual] QAbstractAxis::AxisType QDateTimeAxis:: type () const

重实现： QAbstractAxis::type () const.

返回轴的类型。

内容