Fix print layers when opacity background layer is a layer group

src/map/LayerHelper.js

@@ -4,7 +4,7 @@
 import googAsserts from 'goog/asserts.js';
 import * as olArray from 'ol/array.js';
 import olFormatWMTSCapabilities from 'ol/format/WMTSCapabilities.js';
-import olLayerGroup from 'ol/layer/Group.js';
+import OlLayerGroup from 'ol/layer/Group.js';
 import olLayerImage from 'ol/layer/Image.js';
 import olLayerTile from 'ol/layer/Tile.js';
 import * as olObj from 'ol/obj.js';
@@ -241,7 +241,7 @@ exports.prototype.createWMTSLayerFromCapabilititesObj = function(
  * @export
  */
 exports.prototype.createBasicGroup = function(opt_layers) {
-  const group = new olLayerGroup();
+  const group = new OlLayerGroup();
   if (opt_layers) {
     group.setLayers(opt_layers);
   }
@@ -287,26 +287,44 @@ exports.prototype.getGroupFromMap = function(map, groupName) {
  * @export
  */
 exports.prototype.getFlatLayers = function(layer) {
-  return this.getFlatLayers_(layer, []);
+  if (layer instanceof OlLayerGroup) {
+    const sublayers = layer.getLayers().getArray();
+    const hasGroupLayer = sublayers.some(sublayer => sublayer instanceof OlLayerGroup);
+    if (!hasGroupLayer) {
+      return sublayers.slice();
+    }
+  }
+  return this.getFlatLayers_(layer, [], undefined);
 };
 
 
 /**
  * Get an array of all layers in a group. The group can contain multiple levels
- * of others groups.
+ * of others groups. When we flatten a group, we get the child layers.
+ * If opacity is defined on the group, this value is lost.
+ * Computed opacity is a custom 'back-up' value that contains
+ * the calculated value of all ancestors and the given layer.
  * @param {ol.layer.Base} layer The base layer, mostly a group of layers.
  * @param {Array.<ol.layer.Base>} array An array to add layers.
+ * @param {number|undefined} computedOpacity Opacity inherited from ancestor layer groups.
  * @return {Array.<ol.layer.Layer>} Layers.
  * @private
  */
-exports.prototype.getFlatLayers_ = function(layer, array) {
-  if (layer instanceof olLayerGroup) {
+exports.prototype.getFlatLayers_ = function(layer, array, computedOpacity) {
+  const opacity = layer.getOpacity();
+  if (computedOpacity !== undefined) {
+    computedOpacity *= opacity;
+  } else {
+    computedOpacity = opacity;
+  }
+  if (layer instanceof OlLayerGroup) {
     const sublayers = layer.getLayers();
     sublayers.forEach((l) => {
-      this.getFlatLayers_(l, array);
+      this.getFlatLayers_(l, array, computedOpacity);
     });
   } else {
     if (array.indexOf(layer) < 0) {
+      layer.set('inheritedOpacity', computedOpacity, true);
       array.push(layer);
     }
   }
@@ -326,7 +344,7 @@ exports.prototype.getFlatLayers_ = function(layer, array) {
 exports.prototype.getLayerByName = function(layerName, layers) {
   let found = null;
   layers.some((layer) => {
-    if (layer instanceof olLayerGroup) {
+    if (layer instanceof OlLayerGroup) {
       const sublayers = layer.getLayers().getArray();
       found = this.getLayerByName(layerName, sublayers);
     } else if (layer.get('layerNodeName') === layerName) {
@@ -440,7 +458,7 @@ exports.prototype.refreshWMSLayer = function(layer) {
  * @param {number} ZIndex The ZIndex for children element.
  */
 exports.prototype.setZIndexToFirstLevelChildren = function(element, ZIndex) {
-  if (!(element instanceof olLayerGroup)) {
+  if (!(element instanceof OlLayerGroup)) {
     return;
   }
   const innerGroupLayers = element.getLayers();

src/print/Service.js

@@ -238,19 +238,19 @@ exports.prototype.encodeImageWmsLayer_ = function(arr, layer) {
   const url = source.getUrl();
   if (url !== undefined) {
     this.encodeWmsLayer_(
-      arr, layer.getOpacity(), url, source.getParams());
+      arr, layer, url, source.getParams());
   }
 };
 
 
 /**
  * @param {Array.<MapFishPrintLayer>} arr Array.
- * @param {number} opacity Opacity of the layer.
+ * @param {ol.layer.Image} layer The layer.
  * @param {string} url Url of the WMS server.
  * @param {Object} params Url parameters
  * @private
  */
-exports.prototype.encodeWmsLayer_ = function(arr, opacity, url, params) {
+exports.prototype.encodeWmsLayer_ = function(arr, layer, url, params) {
   if (url.startsWith('//')) {
     url = window.location.protocol  + url;
   }
@@ -280,7 +280,7 @@ exports.prototype.encodeWmsLayer_ = function(arr, opacity, url, params) {
     customParams: customParams,
     serverType: params['SERVERTYPE'],
     type: 'wms',
-    opacity: opacity,
+    opacity: this.getOpacityOrInherited_(layer),
     version: params['VERSION'],
     useNativeAngle: this.printNativeAngle_,
   });
@@ -360,7 +360,7 @@ exports.prototype.encodeTileWmtsLayer_ = function(arr, layer) {
     layer: source.getLayer(),
     matrices: matrices,
     matrixSet: source.getMatrixSet(),
-    opacity: layer.getOpacity(),
+    opacity: this.getOpacityOrInherited_(layer),
     requestEncoding: source.getRequestEncoding(),
     style: source.getStyle(),
     type: 'WMTS',
@@ -383,7 +383,7 @@ exports.prototype.encodeTileWmsLayer_ = function(arr, layer) {
   googAsserts.assertInstanceof(source, olSourceTileWMS);
 
   this.encodeWmsLayer_(
-    arr, layer.getOpacity(), source.getUrls()[0], source.getParams());
+    arr, layer, source.getUrls()[0], source.getParams());
 };
 
 
@@ -399,6 +399,18 @@ exports.prototype.getWmtsUrl_ = function(source) {
   return exports.getAbsoluteUrl_(urls[0]);
 };
 
+/**
+ * Return an opacity value for the specified layer.
+ * @param {ol.layer.Base} layer Layer.
+ * @returns {number} opacity Opacity value.
+ * @private
+ */
+exports.prototype.getOpacityOrInherited_ = function(layer) {
+  if (layer.get('inheritedOpacity') !== undefined) {
+    return layer.get('inheritedOpacity');
+  }
+  return layer.getOpacity();
+};
 
 /**
  * Send a create report request to the MapFish Print service.