From a5f9baa9a3aa9d2fe134d6cef3280f7836e9a3e9 Mon Sep 17 00:00:00 2001
From: Benjamin Gerber <benjamin.gerber@camptocamp.com>
Date: Fri, 9 Feb 2024 13:43:15 +0100
Subject: [PATCH] Add getExtent utils and constants

---
 CHANGES.md           |  1 +
 src/VectorEncoder.ts |  2 +-
 src/constants.ts     | 13 +++++++++++++
 src/utils.ts         | 23 ++++++++++++++++++++---
 test.js              |  5 +++--
 5 files changed, 38 insertions(+), 6 deletions(-)
 create mode 100644 src/constants.ts

diff --git a/CHANGES.md b/CHANGES.md
index b2e8cf2..e48cf66 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,6 +1,7 @@
 # @geoblocks/geoblocks changes
 
 ## 0.2.3
+- Add utility functions.
 - In `BaseCustomizer`, the printExtent can be now set and get/set are dedicated methods.
 - `pdfA` (allow transparency) is now a spec.map optional param.
 - spec.attributes are now partial and `datasources` attribute is removed.
diff --git a/src/VectorEncoder.ts b/src/VectorEncoder.ts
index 85d897c..7660ee9 100644
--- a/src/VectorEncoder.ts
+++ b/src/VectorEncoder.ts
@@ -81,7 +81,7 @@ export default class VectorEncoder {
     }
     console.assert(source instanceof VectorSource);
 
-    const features = source.getFeaturesInExtent(this.customizer_.printExtent);
+    const features = source.getFeaturesInExtent(this.customizer_.getPrintExtent());
 
     const geojsonFeatures: GeoJSONFeature[] = [];
     const mapfishStyleObject: MFPVectorStyle = {
diff --git a/src/constants.ts b/src/constants.ts
new file mode 100644
index 0000000..cc1ca20
--- /dev/null
+++ b/src/constants.ts
@@ -0,0 +1,13 @@
+export const Constants = {
+  /** "Standardized rendering pixel size" is defined as 0.28 mm, see http://www.opengeospatial.org/standards/wmts */
+  WMTS_PIXEL_SIZE: 0.28e-3,
+  /** Standard PPI */
+  POINTS_PER_INCH: 72,
+  /** According to the "international yard" definition 1 inch is defined as exactly 2.54 cm. */
+  METERS_PER_INCH: 0.0254,
+};
+
+export const CalculatedConstants = {
+  /** Default to PPI / METERS per Inch */
+  POINTS_PER_DISTANCE_UNIT: () => Constants.POINTS_PER_INCH / Constants.METERS_PER_INCH,
+};
diff --git a/src/utils.ts b/src/utils.ts
index 9d51631..e956dc5 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -2,9 +2,26 @@ import WMTSTileGrid from 'ol/tilegrid/WMTS.js';
 import {toSize} from 'ol/size.js';
 import type {MFPReportResponse, MFPSpec, MFPStatusResponse, MFPWmtsMatrix} from './types';
 import type {WMTS} from 'ol/source.js';
+import type {Extent} from 'ol/extent';
+import {Constants, CalculatedConstants} from './constants';
 
-// "Standardized rendering pixel size" is defined as 0.28 mm, see http://www.opengeospatial.org/standards/wmts
-const WMTS_PIXEL_SIZE_ = 0.28e-3;
+/**
+ * @param mapPageSize The page size (width, height)
+ * @param center The coordinate of the extent's center.
+ * @param scale The scale to calculate the extent width.
+ * @returns an extent that fit the page size. Calculated with POINTS_PER_DISTANCE_UNIT (by default using meters)
+ */
+export function getPrintExtent(mapPageSize: number[], center: number[], scale: number): Extent {
+  const [mapPageWidthMeters, mapPageHeightMeters] = mapPageSize.map(
+    (side) => ((side / CalculatedConstants.POINTS_PER_DISTANCE_UNIT()) * scale) / 2,
+  );
+  return [
+    center[0] - mapPageWidthMeters,
+    center[1] - mapPageHeightMeters,
+    center[0] + mapPageWidthMeters,
+    center[1] + mapPageHeightMeters,
+  ];
+}
 
 /**
  * Takes a hex value and prepends a zero if it's a single digit.
@@ -51,7 +68,7 @@ export function getWmtsMatrices(source: WMTS): MFPWmtsMatrix[] {
     const resolutionMeters = tileGrid.getResolution(i) * metersPerUnit;
     wmtsMatrices.push({
       identifier: matrixIds[i],
-      scaleDenominator: resolutionMeters / WMTS_PIXEL_SIZE_,
+      scaleDenominator: resolutionMeters / Constants.WMTS_PIXEL_SIZE,
       tileSize: toSize(tileGrid.getTileSize(i)),
       topLeftCorner: tileGrid.getOrigin(i),
       matrixSize: [tileRange.maxX - tileRange.minX, tileRange.maxY - tileRange.minY],
diff --git a/test.js b/test.js
index be340c0..8c5c755 100644
--- a/test.js
+++ b/test.js
@@ -25,7 +25,7 @@ test('Empty map', async (t) => {
     dpi: 300,
     layout: 'landscape_a4',
     format: 'pdf',
-    customAttributes: {},
+    customAttributes: {title: 'My title'},
     customizer: customizer,
   });
   assert.deepEqual(result, {
@@ -38,6 +38,7 @@ test('Empty map', async (t) => {
         rotation: 0,
         scale: 1,
       },
+      title: 'My title',
     },
     format: 'pdf',
     layout: 'landscape_a4',
@@ -45,7 +46,7 @@ test('Empty map', async (t) => {
 });
 
 test('OSM map', async (t) => {
-  const MFP_URL = 'https://geomapfish-demo-2-5.camptocamp.com/printproxy';
+  const MFP_URL = 'https://geomapfish-demo-2-8.camptocamp.com/printproxy';
   const layout = '1 A4 portrait'; // better take from MFP
   const map = new Map({
     target: 'map',