JavaFX 2.x：Y 轴上的对数刻度

Question

正如这里这篇非常好的文章一样

Java FX 2 中的对数刻度

我已经更改了此类以获取 Y 轴上的对数刻度，并且工作正常。我遇到的唯一问题是水平网格线很少，并且比例始终从 0 或接近零开始。

这是我得到的

我希望在数据系列的最小和最大范围内也有刻度值网格，在本例中 min = 19,35 max = 20,35；截至目前，所有 10 条水平网格线均绘制在该范围之外。

如何做到这一点？

谢谢大家，这是我的 Y 轴日志代码

import java.text.NumberFormat;
import java.util.ArrayList;
import java.util.List;
import javafx.beans.binding.DoubleBinding;
import javafx.beans.property.DoubleProperty;
import javafx.beans.property.SimpleDoubleProperty;
import javafx.scene.chart.ValueAxis;

//http://blog.dooapp.com/logarithmic-scale-strikes-back-in-javafx-20        
public class LogarithmicAxis extends ValueAxis<Number> {

//Create our LogarithmicAxis class that extends ValueAxis<Number> and define two properties that will represent the log lower and upper bounds of our axis.     
private final DoubleProperty logUpperBound = new SimpleDoubleProperty();
private final DoubleProperty logLowerBound = new SimpleDoubleProperty();
//

//we bind our properties with the default bounds of the value axis. But before, we should verify the given range according to the mathematic logarithmic interval definition.
public LogarithmicAxis() {
    super(1, 100);
    bindLogBoundsToDefaultBounds();
}

public LogarithmicAxis(double lowerBound, double upperBound) {
    super(lowerBound, upperBound);
try {
    validateBounds(lowerBound, upperBound);
    bindLogBoundsToDefaultBounds();
} catch (IllegalLogarithmicRangeException e) {
    }
}

/**
 * Bind our logarithmic bounds with the super class bounds, consider the base 10 logarithmic scale.
 */
private void bindLogBoundsToDefaultBounds() {
    logLowerBound.bind(new DoubleBinding() {
        {
            super.bind(lowerBoundProperty());
        }

        @Override
        protected double computeValue() {
            return Math.log10(lowerBoundProperty().get());
        }
    });
    logUpperBound.bind(new DoubleBinding() {
        {
            super.bind(upperBoundProperty());
        }

        @Override
        protected double computeValue() {
            return Math.log10(upperBoundProperty().get());
        }
    });
}

/**
 * Validate the bounds by throwing an exception if the values are not conform to the mathematics log interval:
 * ]0,Double.MAX_VALUE]
 *
 * @param lowerBound
 * @param upperBound
 * @throws IllegalLogarithmicRangeException
 */
private void validateBounds(double lowerBound, double upperBound) throws IllegalLogarithmicRangeException {
    if (lowerBound < 0 || upperBound < 0 || lowerBound > upperBound) {
        throw new IllegalLogarithmicRangeException(
                "The logarithmic range should be include to ]0,Double.MAX_VALUE] and the lowerBound should be less than the upperBound");
    }
}

//Now we have to implement all abstract methods of the ValueAxis class.
//The first one, calculateMinorTickMarks is used to get the list of minor tick marks position that you want to display on the axis. You could find my definition below. It's based on the number of minor tick and the logarithmic formula.
@Override
protected List<Number> calculateMinorTickMarks() {
    Number[] range = getRange();
    List<Number> minorTickMarksPositions = new ArrayList<>();
    if (range != null) {

        Number lowerBound = range[0];
        Number upperBound = range[1];
        double logUpperBound = Math.log10(upperBound.doubleValue());
        double logLowerBound = Math.log10(lowerBound.doubleValue());

        int minorTickMarkCount = getMinorTickCount();

        for (double i = logLowerBound; i <= logUpperBound; i += 1) {
            for (double j = 0; j <= 10; j += (1. / minorTickMarkCount)) {
                double value = j * Math.pow(10, i);
                minorTickMarksPositions.add(value);
            }
        }
    }
    return minorTickMarksPositions;
}

//Then, the calculateTickValues method is used to calculate a list of all the data values for each tick mark in range, represented by the second parameter. The formula is the same than previously but here we want to display one tick each power of 10.
@Override
protected List<Number> calculateTickValues(double length, Object range) {
    List<Number> tickPositions = new ArrayList<Number>();
    if (range != null) {
        Number lowerBound = ((Number[]) range)[0];
        Number upperBound = ((Number[]) range)[1];
        double logLowerBound = Math.log10(lowerBound.doubleValue());
        double logUpperBound = Math.log10(upperBound.doubleValue());
        System.out.println("lower bound is: " + lowerBound.doubleValue());

        for (double i = logLowerBound; i <= logUpperBound; i += 1) {
            for (double j = 1; j <= 10; j++) {
                double value = (j * Math.pow(10, i));
                tickPositions.add(value);
            }
        }
    }
    return tickPositions;
}

//The getRange provides the current range of the axis. A basic implementation is to return an array of the lowerBound and upperBound properties defined into the ValueAxis class.
@Override
protected Number[] getRange() {
    return new Number[] { lowerBoundProperty().get(), upperBoundProperty().get() };
}

//The getTickMarkLabel is only used to convert the number value to a string that will be displayed under the tickMark. Here I choose to use a number formatter.
@Override
protected String getTickMarkLabel(Number value) {
    NumberFormat formatter = NumberFormat.getInstance();
    formatter.setMaximumIntegerDigits(6);
    formatter.setMinimumIntegerDigits(1);
    return formatter.format(value);
}

//The method setRange is used to update the range when data are added into the chart. There is two possibilities, the axis is animated or not. The simplest case is to set the lower and upper bound properties directly with the new values.
@Override    
protected void setRange(Object range, boolean animate) {
    if (range != null) {
        Number lowerBound = ((Number[]) range)[0];
        Number upperBound = ((Number[]) range)[1];
        try {
            validateBounds(lowerBound.doubleValue(), upperBound.doubleValue());
        } catch (IllegalLogarithmicRangeException e) {
        }

        lowerBoundProperty().set(lowerBound.doubleValue());
        upperBoundProperty().set(upperBound.doubleValue());
    }
}

//We are almost done but we forgot to override 2 important methods that are used to perform the matching between data and the axis (and the reverse).
@Override
public Number getValueForDisplay(double displayPosition) {
    double delta = logUpperBound.get() - logLowerBound.get();
    if (getSide().isVertical()) {
        return Math.pow(10, (((displayPosition - getHeight()) / -getHeight()) * delta) + logLowerBound.get());
    } else {
        return Math.pow(10, (((displayPosition / getWidth()) * delta) + logLowerBound.get()));
    }
}

@Override
public double getDisplayPosition(Number value) {
    double delta = logUpperBound.get() - logLowerBound.get();
    double deltaV = Math.log10(value.doubleValue()) - logLowerBound.get();
    if (getSide().isVertical()) {
        return (1. - ((deltaV) / delta)) * getHeight();
    } else {
        return ((deltaV) / delta) * getWidth();
    }
}

/**
 * Exception to be thrown when a bound value isn't supported by the logarithmic axis<br>
 *
 *
 * @author Kevin Senechal mailto: kevin.senechal@dooapp.com
 *
 */
public class IllegalLogarithmicRangeException extends Exception {
/**
 * @param string
 */
    public IllegalLogarithmicRangeException(String message) {
        super(message);
    }
}
}

Answer 1

我认为你的问题是这样的：

    super(1, 100);

从文档中：

Create a non-auto-ranging ValueAxis with the given upper & lower bound

尝试使用不带参数的构造函数，这将使边界自动调整范围。

您最终应该得到一个如下所示的构造函数：

public LogarithmicAxis() {
    // was: super(1, 100);
    super();
    bindLogBoundsToDefaultBounds();
}