Qwt 自定义坐标轴tick

Interval and all tick positions of a scale are stored in a QwtScaleDiv object. 

You can manually create a QwtScaleDiv and assign it to a plot axis (QwtPlot::setAxisScaleDiv()) , or you can use a QwtScaleEngine ( QwtPlot has one for each axis), that calculates it for you. When autoscaling ( QwtPlot::setAxisAutoScale() ) is enabled, the interval for the calculation of the scale is taken from the bounding rectangle of the plot items ( f.e. curves ), otherwise interval/step size are passed with QwtPlot::setAxisScale().

The default scale engines try to calculate ticks for linear decimal scales, what doesn't need to be the right thing for date/time scales. ( QwtDateTimeScaleEngine is on my TODO list ). To improve your scale divisions you can derive and assign ( QwtPlot::setAxisScaleEngine()) your own scale engine or simply use QwtPlot::setAxisScaleDiv instead.