+package tim.prune.gui.map;
+
+import java.awt.Color;
+import java.awt.image.BufferedImage;
+
+/**
+ * Class to manage coordinate conversions and other stuff for maps
+ */
+public abstract class MapUtils
+{
+ /**
+ * Transform a longitude into an x coordinate
+ * @param inLon longitude in degrees
+ * @return scaled X value from 0 to 1
+ */
+ public static double getXFromLongitude(double inLon)
+ {
+ return (inLon + 180.0) / 360.0;
+ }
+
+ /**
+ * Transform a latitude into a y coordinate
+ * @param inLat latitude in degrees
+ * @return scaled Y value from 0 to 1
+ */
+ public static double getYFromLatitude(double inLat)
+ {
+ return (1 - Math.log(Math.tan(inLat * Math.PI / 180) + 1 / Math.cos(inLat * Math.PI / 180)) / Math.PI) / 2;
+ }
+
+ /**
+ * Transform an x coordinate into a longitude
+ * @param inX scaled X value from 0(-180deg) to 1(+180deg)
+ * @return longitude in degrees
+ */
+ public static double getLongitudeFromX(double inX)
+ {
+ // Ensure x is really between 0 and 1 (to wrap longitudes)
+ double x = ((inX % 1.0) + 1.0) % 1.0;
+ // Note: First %1.0 restricts range to (-1,1), then +1.0 shifts to (0,2)
+ // Finally, %1.0 to give (0,1)
+ return x * 360.0 - 180.0;
+ }
+
+ /**
+ * Transform a y coordinate into a latitude
+ * @param inY scaled Y value from 0 to 1
+ * @return latitude in degrees
+ */
+ public static double getLatitudeFromY(double inY)
+ {
+ double n = Math.PI * (1 - 2 * inY);
+ return 180 / Math.PI * Math.atan(0.5 * (Math.exp(n) - Math.exp(-n)));
+ }
+
+ /**
+ * Tests whether there are any dark pixels in the image within the specified x,y rectangle
+ * @param inImage image to test
+ * @param inX left X coordinate
+ * @param inY bottom Y coordinate
+ * @param inWidth width of rectangle
+ * @param inHeight height of rectangle
+ * @param inTextColour colour of text
+ * @return true if the rectangle overlaps stuff too close to the given colour
+ */
+ public static boolean overlapsPoints(BufferedImage inImage, int inX, int inY,
+ int inWidth, int inHeight, Color inTextColour)
+ {
+ // each of the colour channels must be further away than this to count as empty
+ final int BRIGHTNESS_LIMIT = 80;
+ final int textRGB = inTextColour.getRGB();
+ final int textLow = textRGB & 255;
+ final int textMid = (textRGB >> 8) & 255;
+ final int textHigh = (textRGB >> 16) & 255;
+ try
+ {
+ // loop over x coordinate of rectangle
+ for (int x=0; x<inWidth; x++)
+ {
+ // loop over y coordinate of rectangle
+ for (int y=0; y<inHeight; y++)
+ {
+ int pixelColor = inImage.getRGB(inX + x, inY - y);
+ // split into four components rgba
+ int pixLow = pixelColor & 255;
+ int pixMid = (pixelColor >> 8) & 255;
+ int pixHigh = (pixelColor >> 16) & 255;
+ //int fourthBit = (pixelColor >> 24) & 255; // alpha ignored
+ // If colours are too close in any channel then it's an overlap
+ if (Math.abs(pixLow-textLow) < BRIGHTNESS_LIMIT ||
+ Math.abs(pixMid-textMid) < BRIGHTNESS_LIMIT ||
+ Math.abs(pixHigh-textHigh) < BRIGHTNESS_LIMIT) {return true;}
+ }
+ }
+ }
+ catch (NullPointerException e) {
+ // ignore null pointers, just return false
+ }
+ return false;
+ }
+}