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BangleApps
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use linear projection/interpolation in openseachart.js

master
marko 2022-02-17 17:26:44 -05:00
parent 3b1e964166
commit 0870c9a639
1 changed files with 7 additions and 12 deletions
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19
apps/openseachart/openseachart.js
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@ -23,7 +23,7 @@ function center() {
*/
var map = require("Storage").readJSON("openseachart.json");
map.center = Bangle.project({lat:map.lat,lon:map.lon});
map.center = {lat:map.lat, lon:map.lon} // save original center
exports.map = map;
exports.lat = map.lat; // actual position of middle of screen
exports.lon = map.lon; // actual position of middle of screen
@ -33,9 +33,8 @@ exports.draw = function() {
var s = require("Storage");
var cx = g.getWidth()/2;
var cy = g.getHeight()/2;
var p = Bangle.project({lat:m.lat,lon:m.lon});
var ix = (p.x-map.center.x)/map.scale + (map.imgx/2) - cx;
var iy = (map.center.y-p.y)/map.scale + (map.imgy/2) - cy;
var ix = (map.lon-map.center.lon)/map.dlonpx + (map.imgx/2) - cx;
var iy = (map.center.lat-map.lat)/map.dlatpx + (map.imgy/2) - cy;
//console.log(ix,iy);
var tx = 0|(ix/map.tilesize);
var ty = 0|(iy/map.tilesize);
@ -52,20 +51,16 @@ exports.draw = function() {
/// Convert lat/lon to pixels on the screen
exports.latLonToXY = function(lat, lon) {
var p = Bangle.project({lat:m.lat,lon:m.lon});
var q = Bangle.project({lat:lat, lon:lon});
var cx = g.getWidth()/2;
var cy = g.getHeight()/2;
return {
x : (q.x-p.x)/map.scale + cx,
y : cy - (q.y-p.y)/map.scale
x : cx + (lon-m.lon)/max.dlonpx,
y : cy - (lat-m.lat)/map.dlatpx
};
};
/// Given an amount to scroll in pixels on the screen, adjust the lat/lon of the map to match
exports.scroll = function(x,y) {
var a = Bangle.project({lat:this.lat,lon:this.lon});
var b = Bangle.project({lat:this.lat+1,lon:this.lon+1});
this.lon += x * this.map.scale / (a.x-b.x);
this.lat -= y * this.map.scale / (a.y-b.y);
this.lon += x * this.map.dlonpx;
this.lat -= y * this.map.dlatpx;
};