Better control of default view

fix #40

Let the user choose the map behaviour to define default view:

- saved center and zoom: current behaviour, and default
- bounds: will compute the view to fit all the map data, useful for
  having the same view in different sized devices (mobile…)
- latest feature: useful in some situation, where the map tracks some
  progress (travel…), this will certainly needs a bit more iterations,
  mainly to have an explicit default datalayer
- user location: this option used to exist but was then removed, I
  can remember when and why

Note: when there is a URL hash, the hash will be used

umap/static/umap/js/umap.forms.js

@@ -417,7 +417,16 @@ L.FormBuilder.DataLayerSwitcher = L.FormBuilder.Select.extend({
   },
 })
 
-L.FormBuilder.onLoadPanel = L.FormBuilder.Select.extend({
+L.FormBuilder.DefaultView = L.FormBuilder.Select.extend({
+  selectOptions: [
+    ['center', L._('Saved center and zoom')],
+    ['bounds', L._('Layers bounds')],
+    ['latest', L._('Latest feature')],
+    ['locate', L._('User location')],
+  ],
+})
+
+L.FormBuilder.OnLoadPanel = L.FormBuilder.Select.extend({
   selectOptions: [
     ['none', L._('None')],
     ['caption', L._('Caption')],
@@ -1008,9 +1017,13 @@ L.U.FormBuilder = L.FormBuilder.extend({
       label: L._('Do you want to display the scale control?'),
     },
     onLoadPanel: {
-      handler: 'onLoadPanel',
+      handler: 'OnLoadPanel',
       label: L._('Do you want to display a panel on load?'),
     },
+    defaultView: {
+      handler: 'DefaultView',
+      label: L._('Default view'),
+    },
     displayPopupFooter: {
       handler: 'Switch',
       label: L._('Do you want to display popup footer?'),

umap/static/umap/js/umap.js

@@ -144,18 +144,6 @@ L.U.Map.include({
       // Certainly IE8, which has a limited version of defineProperty
     }
 
-    if (this.options.hash) this.addHash()
-    this.initCenter()
-    this.handleLimitBounds()
-
-    this.initTileLayers(this.options.tilelayers)
-
-    // Global storage for retrieving datalayers and features
-    this.datalayers = {}
-    this.datalayers_index = []
-    this.dirty_datalayers = []
-    this.features_index = {}
-
     // Retrocompat
     if (
       this.options.slideshow &&
@@ -164,9 +152,17 @@ L.U.Map.include({
     )
       this.options.slideshow.active = true
 
-    this.initControls()
+    // Global storage for retrieving datalayers and features
+    this.datalayers = {}
+    this.datalayers_index = []
+    this.dirty_datalayers = []
+    this.features_index = {}
 
-    // create datalayers
+    if (this.options.hash) this.addHash()
+    this.initControls()
+    this.initCenter()
+    this.handleLimitBounds()
+    this.initTileLayers(this.options.tilelayers)
     this.initDatalayers()
 
     if (this.options.displayCaptionOnLoad) {
@@ -636,10 +632,16 @@ L.U.Map.include({
     if (this.options.hash && this._hash.parseHash(location.hash)) {
       // FIXME An invalid hash will cause the load to fail
       this._hash.update()
-    } else if (this.options.locate && this.options.locate.setView) {
-      // Prevent from making two setViews at init
-      // which is not very fluid...
-      this.locate(this.options.locate)
+    } else if (this.options.defaultView === 'locate' && !this.options.noControl) {
+      this._controls.locate.start()
+    } else if (this.options.defaultView === 'bounds') {
+      this.onceDataLoaded(() => this.fitBounds(this.getLayersBounds()))
+    } else if (this.options.defaultView === 'latest') {
+      this.onceDataLoaded(() => {
+        const datalayer = this.defaultDataLayer(),
+          feature = datalayer.getFeatureByIndex(-1)
+        if (feature) feature.zoomTo()
+      })
     } else {
       this.options.center = this.latLng(this.options.center)
       this.setView(this.options.center, this.options.zoom)
@@ -1036,6 +1038,7 @@ L.U.Map.include({
     'miniMap',
     'displayPopupFooter',
     'onLoadPanel',
+    'defaultView',
     'tilelayersControl',
     'name',
     'description',
@@ -1273,6 +1276,9 @@ L.U.Map.include({
     }
   },
 
+  // TODO: allow to control the default datalayer
+  // (edit and viewing)
+  // cf https://github.com/umap-project/umap/issues/585
   defaultDataLayer: function () {
     let datalayer, fallback
     datalayer = this.lastUsedDataLayer
@@ -1314,6 +1320,7 @@ L.U.Map.include({
       'options.miniMap',
       'options.scaleControl',
       'options.onLoadPanel',
+      'options.defaultView',
       'options.displayPopupFooter',
       'options.captionBar',
       'options.captionMenus',
@@ -2098,4 +2105,13 @@ L.U.Map.include({
   getAdvancedFilterKeys: function () {
     return (this.options.advancedFilterKey || '').split(',')
   },
+
+  getLayersBounds: function () {
+    const bounds = new L.latLngBounds()
+    this.eachBrowsableDataLayer((d) => {
+      if (d.isVisible()) bounds.extend(d.layer.getBounds())
+    })
+    return bounds
+  },
+
 })