branch: externals/osm
commit d27892f63a5356ba1a406de0b26af1185e096131
Author: Daniel Mendler <m...@daniel-mendler.de>
Commit: Daniel Mendler <m...@daniel-mendler.de>
Add some utility functions
---
osm.el | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/osm.el b/osm.el
index 3da392f61d..413b080246 100644
--- a/osm.el
+++ b/osm.el
@@ -219,14 +219,22 @@ We need two distinct images which are not `eq' for the
display properties.")
(setq lat (* lat (/ float-pi 180.0)))
(- 0.5 (/ (log (+ (tan lat) (/ 1 (cos lat)))) float-pi 2)))
+(defun osm--x-to-lon (x zoom)
+ "Return longitude in degrees for X/ZOOM."
+ (- (/ (* x 360.0) 256.0 (expt 2.0 zoom)) 180.0))
+
+(defun osm--y-to-lat (y zoom)
+ "Return latitude in degrees for Y/ZOOM."
+ (setq y (* float-pi (- 1 (* 2 (/ y 256.0 (expt 2.0 zoom))))))
+ (/ (* 180 (atan (/ (- (exp y) (exp (- y))) 2))) float-pi))
+
(defun osm--lon ()
"Return longitude in degrees."
- (- (/ (* osm--x 360.0) 256.0 (expt 2.0 osm--zoom)) 180.0))
+ (osm--x-to-lon osm--x osm--zoom))
(defun osm--lat ()
"Return latitude in degrees."
- (let ((y (* float-pi (- 1 (* 2 (/ osm--y 256.0 (expt 2.0 osm--zoom)))))))
- (/ (* 180 (atan (/ (- (exp y) (exp (- y))) 2))) float-pi)))
+ (osm--y-to-lat osm--y osm--zoom))
(defun osm--lon-to-x (lon zoom)
"Convert LON/ZOOM to x coordinate in pixel."
