-// Called to create a short code for the short link.
-function makeShortCode(map) {
- var zoom = map.getZoom(),
- str = '',
- char_array = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_~",
- x = Math.round((map.getCenter().lng + 180.0) * ((1 << 30) / 90.0)),
- y = Math.round((map.getCenter().lat + 90.0) * ((1 << 30) / 45.0)),
- // JavaScript only has to keep 32 bits of bitwise operators, so this has to be
- // done in two parts. each of the parts c1/c2 has 30 bits of the total in it
- // and drops the last 4 bits of the full 64 bit Morton code.
- c1 = interlace(x >>> 17, y >>> 17), c2 = interlace((x >>> 2) & 0x7fff, (y >>> 2) & 0x7fff);
-
- for (var i = 0; i < Math.ceil((zoom + 8) / 3.0) && i < 5; ++i) {
- digit = (c1 >> (24 - 6 * i)) & 0x3f;
- str += char_array.charAt(digit);
- }
- for (i = 5; i < Math.ceil((zoom + 8) / 3.0); ++i) {
- digit = (c2 >> (24 - 6 * (i - 5))) & 0x3f;
- str += char_array.charAt(digit);
- }
- for (i = 0; i < ((zoom + 8) % 3); ++i) str += "-";
-
- // Called to interlace the bits in x and y, making a Morton code.
- function interlace(x, y) {
- x = (x | (x << 8)) & 0x00ff00ff;
- x = (x | (x << 4)) & 0x0f0f0f0f;
- x = (x | (x << 2)) & 0x33333333;
- x = (x | (x << 1)) & 0x55555555;
- y = (y | (y << 8)) & 0x00ff00ff;
- y = (y | (y << 4)) & 0x0f0f0f0f;
- y = (y | (y << 2)) & 0x33333333;
- y = (y | (y << 1)) & 0x55555555;
- return (x << 1) | y;
- }
-
- return str;