yaxis.java

这是一个十分有用的java图形工具包

package net.turbochen.graph;

import java.awt.*;
import net.turbochen.graph.util.*;

/**
 * 绘制纵坐标轴,刻度及其网格线.
 * @author Turbo Chen
 */
public class YAxis extends Axis
{
    
    public YAxis(YScale scale,int tickCount)
    {
        this.scale = scale;
        this.tickCount = tickCount;
    }
    
    public YAxis(YAxis peerAxis, YScale scale,int tickCount)
    {
        this(scale,tickCount);
        this.peerAxis = peerAxis;
    }
    /**
     * 绘制y轴线,刻度线及格线.
     * @see net.turbochen.graph.ChartWidget#draw(Graphics)
     */
    public void draw(Graphics g)
    {
        if ( ! (scale instanceof YScale) ) return;
        int ticks = getTickCount();       
        int tickDist = (int) 
            Math.abs((double)(scale.getScreenMax() - scale.getScreenMin())/(double)(ticks+1));
        int tickY = scale.getScreenMin();
        int tickX = peerAxis.getScale().getScreenMin(); 
        int gridLength = peerAxis.getScale().getScreenMax();
        int axisLength = scale.getScreenMax();
        g.setColor(axisColor);
        g.drawLine(tickX, tickY, tickX, axisLength);
        double vtickDist = (scale.getMax() - scale.getMin())/(ticks+1);
        for ( int i = 0 ; i < ticks; i++ )
        {
            tickY = scale.getScreenMin()-tickDist*(i+1);
            if ( isDrawGrid() )
            {
                g.setColor(gridColor);
                g.drawLine(tickX, tickY , gridLength, tickY );
            }
            g.setColor(axisColor);
            g.drawLine(tickX, tickY , tickX-tickLength, tickY);
            String tickLabel = MathUtil.format(scale.getMin()+vtickDist*(i+1),"#.0");
            int tickLabelWidth = 
                            g.getFontMetrics().stringWidth(tickLabel);
            g.drawString(tickLabel, 
                            tickX-tickLength-tickLabelWidth,
                            tickY);
        }


    }

    /* (non-Javadoc)
     * @see net.turbochen.graph.Axis#calculateTickLabelSize(java.awt.Graphics)
     */
    protected int calculateTickLabelSize(Graphics g)
    {
        int SPACE_WIDTH = 20;
        int tickW = 
            g.getFontMetrics().stringWidth(MathUtil.format(scale.max,"#.0"));
        return tickLength+tickW+SPACE_WIDTH;
    }

}