nakarte

commit 6052331e8078776bc10148dd0b40ad21bb6f3e6f
parent e81ef8983b1cfe20e1136e1e5129da497edea69b
Author: Sergej Orlov <wladimirych@gmail.com>
Date:   Sun, 19 Mar 2017 17:06:26 +0300

[print/grid overlay] true (earth surface) scale for grid

Diffstat:
M
src/lib/leaflet.control.printPages/decoration.grid.js
 | 
67
++++++++++++++++++++++++++++++++++++++++++++++++++++++++-----------

1 file changed, 56 insertions(+), 11 deletions(-)
diff --git a/src/lib/leaflet.control.printPages/decoration.grid.js b/src/lib/leaflet.control.printPages/decoration.grid.js
@@ -1,4 +1,10 @@
 import {PrintStaticLayer} from './decorations';
+import L from 'leaflet';
+
+
+function radians(degrees) {
+    return degrees * Math.PI / 180;
+}
 
 class Grid extends PrintStaticLayer {
     lineThicknessMm = 0.2;
@@ -11,10 +17,10 @@ class Grid extends PrintStaticLayer {
     intervals = [1, 1.5, 2, 3.3, 5, 7.5,
         10, 15, 20, 33, 50, 75,
         100, 150, 200, 333, 500, 750,
-        1000, 1500, 2000, 3333, 5000, 7500,
-        10000, 15000, 20000, 33333, 50000, 75000,
-        100000, 150000, 200000, 333333, 500000, 750000,
-        1000000, 1500000, 2000000, 3333333, 5000000, 7500000];
+        1000, 1500, 2000, 4000, 5000, 7500,
+        10000, 15000, 20000, 40000, 50000, 75000,
+        100000, 150000, 200000, 400000, 500000, 750000,
+        1000000, 1500000, 2000000, 4000000, 5000000, 7500000];
 
     getGridInterval(printOptions) {
         const minGridIntervalM = this.minGridIntervalMm / 10 * printOptions.scale;
@@ -24,7 +30,7 @@ class Grid extends PrintStaticLayer {
                 break
             }
         }
-        return {intervalM, intervalMm: intervalM / printOptions.scale * 10};
+        return intervalM;
     }
 
     formatDistance(x) {
@@ -42,23 +48,62 @@ class Grid extends PrintStaticLayer {
     }
 
     _drawRaster(canvas, printOptions) {
+        const metersPerDegree = L.Projection.SphericalMercator.R * Math.PI / 180;
         const ctx = canvas.getContext('2d');
         ctx.beginPath();
         const lineThickness = this.lineThicknessMm / 25.4 * printOptions.resolution;
-        const {intervalMm, intervalM} = this.getGridInterval(printOptions);
-        const intervalPx = intervalMm / 25.4 * printOptions.resolution;
         ctx.lineWidth = lineThickness;
         ctx.strokeStyle = '#ccc';
+
+        const intervalM = this.getGridInterval(printOptions);
         const width = printOptions.destPixelSize.x;
         const height = printOptions.destPixelSize.y;
-        for (let x = 0; x <= width; x += intervalPx) {
-            ctx.moveTo(x, 0);
-            ctx.lineTo(x, height);
+        const mercatorBounds = L.bounds(
+            L.Projection.SphericalMercator.project(printOptions.latLngBounds.getNorthWest()),
+            L.Projection.SphericalMercator.project(printOptions.latLngBounds.getSouthEast())
+        );
+        const canvasToMercatorScale = mercatorBounds.getSize().unscaleBy(printOptions.destPixelSize);
+        const rows = [];
+        let y = height;
+        while (true) {
+            let yMerc = mercatorBounds.max.y - y * canvasToMercatorScale.y;
+            let lat = L.Projection.SphericalMercator.unproject(L.point(0, yMerc)).lat;
+            rows.push({lat, y});
+            if (y < 0) {
+                break
+            }
+            let lat2 = lat + intervalM / metersPerDegree;
+            let yMerc2 = L.Projection.SphericalMercator.project(L.latLng(lat2, 0)).y;
+            y = (mercatorBounds.max.y - yMerc2) / canvasToMercatorScale.y;
         }
-        for (let y = height; y >= 0; y -= intervalPx) {
+        for ({y} of rows) {
             ctx.moveTo(0, y);
             ctx.lineTo(width, y);
         }
+        const pageCanvasCenterX = printOptions.destPixelSize.x / 2;
+        for (let direction of [-1, 1]) {
+            let colN = 0;
+            while (true) {
+                let firstRow = true;
+                let hasPointInPage = false;
+                for (let {lat, y} of rows) {
+                    let dx = colN * intervalM / Math.cos(radians(lat)) / canvasToMercatorScale.x;
+                    if (dx < pageCanvasCenterX) {
+                        hasPointInPage = true;
+                    }
+                    if (firstRow) {
+                        ctx.moveTo(pageCanvasCenterX + dx * direction, y);
+                    } else {
+                        ctx.lineTo(pageCanvasCenterX + dx * direction, y);
+                    }
+                    firstRow = false;
+                }
+                if (!hasPointInPage) {
+                    break
+                }
+                colN += 1;
+            }
+        }
         ctx.stroke();
 
         const caption = 'Grid ' + this.formatDistance(intervalM);