tim/prune/gui/map/ScaleBar.java

   1 package tim.prune.gui.map;
   2
   3 import java.awt.Color;
   4 import java.awt.Dimension;
   5 import java.awt.Graphics;
   6 import javax.swing.JPanel;
   7
   8 import tim.prune.Config;
   9 import tim.prune.I18nManager;
  10
  11 /**
  12  * Class to show a scale bar on the main map of Prune
  13  */
  14 public class ScaleBar extends JPanel
  15 {
  16         /** zoom level */
  17         private int _zoomLevel = -1;
  18         /** y tile number */
  19         private int _yTile = -1;
  20
  21         // Dimensions
  22         /** Offset from left side in pixels */
  23         private static final int LEFT_OFFSET = 20;
  24         /** Offset from top in pixels */
  25         private static final int Y_OFFSET = 10;
  26         /** Tick height in pixels */
  27         private static final int TICK_HEIGHT = 5;
  28         /** Margin between bar and end text in pixels */
  29         private static final int MARGIN_WIDTH = 8;
  30
  31         /** metric scales for each zoom level */
  32         private static final int[] _metricScales = {10000, 5000, 2000, 2000, 1000, 500, 200, 100,
  33                 50, 20, 10, 5, 2, 2, 1, -2, -5, -10, -20, -50, -100, -200};
  34         /** pixel counts for each zoom level (metric) */
  35         private static final int[] _metricPixels = {64, 64, 51, 102, 102, 102, 81, 81,
  36                 81, 65, 65, 65, 52, 105, 105, 105, 83, 83, 83, 67, 67, 67};
  37         /** imperial scales for each zoom level (num miles) */
  38         private static final int[] _mileScales = {10000, 10000, 5000, 2000, 2000, 1000, 500, 200,
  39                 100, 50, 20, 10, 5, 2, 1, -2, -2, -5, -10, -20, -50, -100};
  40         /** pixel counts for each zoom level (miles) */
  41         private static final int[] _milePixels = {79, 79, 79, 64, 127, 127, 127, 102,
  42                 102, 102, 81, 81, 81, 65, 65, 65, 130, 104, 104, 104, 104, 83, 83};
  43
  44
  45         /**
  46          * Constructor
  47          */
  48         public ScaleBar()
  49         {
  50                 super();
  51                 setOpaque(false);
  52                 setPreferredSize(new Dimension(100, 20));
  53         }
  54
  55         /**
  56          * Paint method to override display
  57          * @param inG graphics object
  58          */
  59         public void paint(Graphics inG)
  60         {
  61                 super.paint(inG);
  62                 if (_zoomLevel > -1)
  63                 {
  64                         try {
  65                                 boolean useMetric = Config.getConfigBoolean(Config.KEY_METRIC_UNITS);
  66                                 int rightSide = LEFT_OFFSET + (useMetric?_metricPixels[_zoomLevel]:_milePixels[_zoomLevel]);
  67                                 int scale = (useMetric?_metricScales[_zoomLevel]:_mileScales[_zoomLevel]);
  68
  69                                 // work out cos(latitude) from y tile and zoom, and apply to scale
  70                                 final double n = Math.pow(2, _zoomLevel);
  71                                 final double angle = Math.PI * (1 - 2.0*_yTile/n);
  72                                 final double lat = Math.atan(Math.sinh(angle));
  73                                 final double cosLat = Math.cos(lat);
  74                                 rightSide = (int) (rightSide / cosLat);
  75                                 // Adjust if scale is too large
  76                                 while (rightSide > 300)
  77                                 {
  78                                         rightSide /= 2;
  79                                         scale /= 2;
  80                                         // Abort if scale is now less than 1 unit (shouldn't ever be)
  81                                         if (scale < 1) {return;}
  82                                 }
  83
  84                                 // horizontal
  85                                 inG.setColor(Color.BLACK);
  86                                 inG.drawLine(LEFT_OFFSET, Y_OFFSET, rightSide, Y_OFFSET);
  87                                 inG.drawLine(LEFT_OFFSET, Y_OFFSET+1, rightSide, Y_OFFSET+1);
  88                                 // 0 tick
  89                                 inG.drawLine(LEFT_OFFSET, Y_OFFSET, LEFT_OFFSET, Y_OFFSET-TICK_HEIGHT);
  90                                 inG.drawLine(LEFT_OFFSET+1, Y_OFFSET, LEFT_OFFSET+1, Y_OFFSET-TICK_HEIGHT);
  91                                 // end tick
  92                                 inG.drawLine(rightSide, Y_OFFSET, rightSide, Y_OFFSET-TICK_HEIGHT);
  93                                 inG.drawLine(rightSide+1, Y_OFFSET, rightSide+1, Y_OFFSET-TICK_HEIGHT);
  94                                 // text
  95                                 String text = (scale>0?(""+scale):("1/"+(-scale))) + " " + I18nManager.getText(useMetric?"units.kilometres.short":"units.miles.short");
  96                                 inG.drawString(text, rightSide+MARGIN_WIDTH, Y_OFFSET);
  97                         }
  98                         catch (ArrayIndexOutOfBoundsException ai) {}
  99                 }
 100         }
 101
 102         /**
 103          * Update the scale level
 104          * @param inZoom new zoom level
 105          */
 106         public void updateScale(int inZoom, int inYtile)
 107         {
 108                 _zoomLevel = inZoom;
 109                 _yTile = inYtile;
 110         }
 111 }