X-Git-Url: https://git.gag.com/?a=blobdiff_plain;f=altoslib%2FAltosMapTransform.java;h=b8f2910760baa6f22d09840ad80739d52e562cd6;hb=master;hp=ba9d1ae46121ca5ce72895562dd13ec736e88a38;hpb=76b288f8d02e0a48f04de9455a2dd0b77e48bd63;p=fw%2Faltos

diff --git a/altoslib/AltosMapTransform.java b/altoslib/AltosMapTransform.java
index ba9d1ae4..3f8f290c 100644
--- a/altoslib/AltosMapTransform.java
+++ b/altoslib/AltosMapTransform.java
@@ -29,6 +29,8 @@ public class AltosMapTransform {
 
 	double	offset_x, offset_y;
 
+	int	width, height;
+
 	public AltosLatLon lat_lon (AltosPointDouble point) {
 		double lat, lon;
 		double rads;
@@ -110,6 +112,39 @@ public class AltosMapTransform {
 		return screen(point(lat, lon));
 	}
 
+	/* Return first longitude value which ends up on-screen */
+	public double first_lon(double lon) {
+		/* Find a longitude left of the screen */
+		for (;;) {
+			double x = lon * scale_x - offset_x;
+			if (x < 0)
+				break;
+			lon -= 360.0;
+		}
+		/* Find the first longitude on the screen */
+		for (;;) {
+			double x = lon * scale_x - offset_x;
+			if (x >= 0)
+				break;
+			lon += 360.0;
+		}
+		return lon;
+	}
+
+	/* Return last longitude value which ends up on-screen */
+	public double last_lon(double lon) {
+		lon = first_lon(lon);
+
+		for(;;) {
+			double next_lon = lon + 360.0;
+			double next_x = next_lon * scale_x - offset_x;
+			if (next_x >= width)
+				break;
+			lon = next_lon;
+		}
+		return lon;
+	}
+
 	private boolean has_location;
 
 	public boolean has_location() {
@@ -120,6 +155,9 @@ public class AltosMapTransform {
 		scale_x = 256/360.0 * Math.pow(2, zoom);
 		scale_y = 256/(2.0*Math.PI) * Math.pow(2, zoom);
 
+		this.width = width;
+		this.height = height;
+
 		AltosPointDouble centre_pt = point(centre_lat_lon);
 
 		has_location = (centre_lat_lon.lat != 0 || centre_lat_lon.lon != 0);