info.monitorenter.gui.chart.axis.scalepolicy
Class AxisScalePolicyAutomaticBestFit

java.lang.Object
  info.monitorenter.gui.chart.axis.scalepolicy.AxisScalePolicyAutomaticBestFit

All Implemented Interfaces:

IAxisScalePolicy

public class AxisScalePolicyAutomaticBestFit
extends java.lang.Object
implements IAxisScalePolicy

Very basic and fast scale policy implementation that ensures the following:

• Every scale tick is a minor or major tick of the corresponding axis.
• If a scale tick was found that matches a major and a minor tick it is judged as major tick.
• Every major tick is a multiple of minor ticks: It is not possible for the sum minor ticks to "skip" a major tick.
• There is no guarantee that the labels of ticks will overwrite each others.
• There is no guarantee that the major and minor ticks of the axis are chosen in a reasonable manner: You could get no labels at all if the values are too high or thousands of labels with a weird output.

Author:

Achim Westermann

Field Summary

protected double

m_power Internally used for rounding to ticks, calculated once per paint iteration.

Constructor Summary

AxisScalePolicyAutomaticBestFit()

Method Summary

protected java.util.List<LabeledValue>	getLabels(double resolution, IAxis<?> axis) Returns the labels for this axis.
java.util.List<LabeledValue>	getScaleValues(java.awt.Graphics g2d, IAxis<?> axis) Returns the array of labeled values that will be used by the Chart2D to paint labels.
void	initPaintIteration(IAxis<?> axis) Performs expensive calculations for various values that are used by many calls throughout a paint iterations.
protected LabeledValue	roundToTicks(double value, boolean floor, boolean findMajorTick, IAxis<?> axis) Internal rounding routine.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

m_power

protected double m_power

Internally used for rounding to ticks, calculated once per paint iteration.

Constructor Detail

AxisScalePolicyAutomaticBestFit

public AxisScalePolicyAutomaticBestFit()

Method Detail

getScaleValues

public java.util.List<LabeledValue> getScaleValues(java.awt.Graphics g2d,
                                                   IAxis<?> axis)

Description copied from interface: IAxisScalePolicy

Returns the array of labeled values that will be used by the Chart2D to paint labels.

Specified by:

getScaleValues in interface IAxisScalePolicy

Parameters:

g2d - Provides information about the graphic context (e.g. font metrics).

axis - the axis to work for.

Returns:

the labeled values that will be used by the Chart2D to paint labels.

initPaintIteration

public void initPaintIteration(IAxis<?> axis)

Description copied from interface: IAxisScalePolicy

Performs expensive calculations for various values that are used by many calls throughout a paint iterations.

These values are constant throughout a paint iteration by the contract that no point is added removed or changed in this period. Because these values are used from many methods it is impossible to calculate them at a "transparent" method that may perform this caching over a paint period without knowledge from outside. The first method called in a paint iteration is called several further times in the iteration. So this is the common hook to invoke before painting a chart.

Specified by:

initPaintIteration in interface IAxisScalePolicy

Parameters:

axis - the axis to read data from.

See Also:

IAxisScalePolicy.initPaintIteration(info.monitorenter.gui.chart.IAxis)

getLabels

protected java.util.List<LabeledValue> getLabels(double resolution,
                                                 IAxis<?> axis)

Returns the labels for this axis.

The labels will have at least the given argument resolution as distance in the value domain of the chart.

Parameters:

resolution - the distance in the value domain of the chart that has to be at least between to labels.

Returns:

the labels for the axis.

roundToTicks

protected LabeledValue roundToTicks(double value,
                                    boolean floor,
                                    boolean findMajorTick,
                                    IAxis<?> axis)

Internal rounding routine.

Arguments are not chosen to be "understandable" or "usable" but optimized for performance.

The findMajorTick argument may be used e.g. to force labels to start from a major tick.

Parameters:

value - the value to round.

floor - if true, rounding goes to floor else to ceiling.

findMajorTick - if true the returned value will be a major tick (which might be fare more away from the given value than the next major tick).

Returns:

the value rounded to minor or major ticks.