HARP-12581: Add PoiBuilder to create PoiInfo for marker techniques.

@here/harp-datasource-protocol/lib/DecodedTile.ts

@@ -258,7 +258,7 @@ export interface TextGeometry {
     positions: BufferAttribute;
     texts: number[];
     technique?: number;
-    stringCatalog?: Array<string | undefined>;
+    stringCatalog: Array<string | undefined>;
     objInfos?: AttributeMap[];
 }
 
@@ -274,7 +274,7 @@ export interface PoiGeometry {
      */
     imageTextures?: number[];
     technique?: number;
-    stringCatalog?: Array<string | undefined>;
+    stringCatalog: Array<string | undefined>;
     objInfos?: AttributeMap[];
     // Angle in degrees from north clockwise specifying the directions the icons can be shifted.
     offsetDirections?: number[];

@here/harp-mapview/lib/poi/PoiBuilder.ts

@@ -0,0 +1,147 @@
+/*
+ * Copyright (C) 2017-2020 HERE Europe B.V.
+ * Licensed under Apache 2.0, see full license in LICENSE
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import {
+    composeTechniqueTextureName,
+    Env,
+    getPropertyValue,
+    IndexedTechniqueParams,
+    LineMarkerTechnique,
+    MapEnv,
+    PoiTechnique
+} from "@here/harp-datasource-protocol";
+import { assert, LoggerManager } from "@here/harp-utils";
+
+import { ColorCache } from "../ColorCache";
+import { PoiInfo, TextElement } from "../text/TextElement";
+
+const logger = LoggerManager.instance.create("PoiBuilder");
+
+function getImageTexture(technique: PoiTechnique | LineMarkerTechnique, env: MapEnv | Env) {
+    return technique.imageTexture !== undefined
+        ? composeTechniqueTextureName(getPropertyValue(technique.imageTexture, env), technique)
+        : undefined;
+}
+
+/**
+ * Creates {@link TextElement} objects from the decoded tile and list of materials specified. The
+ * priorities of the {@link TextElement}s are updated to simplify label placement.
+ *
+ * @param tile - The {@link Tile} to create the testElements on.
+ * @param decodedTile - The {@link @here/harp-datasource-protocol#DecodedTile}.
+ * @param textFilter -: Optional filter. Should return true for any text technique that is
+ *      applicable.
+ */
+export class PoiBuilder {
+    private m_iconMinZoomLevel?: number;
+    private m_iconMaxZoomLevel?: number;
+    private m_textMinZoomLevel?: number;
+    private m_textMaxZoomLevel?: number;
+    private m_technique?: (PoiTechnique | LineMarkerTechnique) & IndexedTechniqueParams;
+    private m_imageTextureName?: string;
+    private m_shieldGroupIndex?: number;
+
+    constructor(private readonly m_env: MapEnv | Env) {}
+
+    withTechnique(technique: (PoiTechnique | LineMarkerTechnique) & IndexedTechniqueParams): this {
+        this.m_imageTextureName = getImageTexture(technique, this.m_env);
+
+        this.m_iconMinZoomLevel =
+            getPropertyValue(technique.iconMinZoomLevel ?? technique.minZoomLevel, this.m_env) ??
+            undefined;
+        this.m_iconMaxZoomLevel =
+            getPropertyValue(technique.iconMaxZoomLevel ?? technique.maxZoomLevel, this.m_env) ??
+            undefined;
+        this.m_textMinZoomLevel =
+            getPropertyValue(technique.textMinZoomLevel ?? technique.minZoomLevel, this.m_env) ??
+            undefined;
+        this.m_textMaxZoomLevel =
+            getPropertyValue(technique.textMaxZoomLevel ?? technique.maxZoomLevel, this.m_env) ??
+            undefined;
+
+        this.m_technique = technique;
+        return this;
+    }
+
+    withIcon(imageTextureName?: string, shieldGroupIndex?: number): this {
+        if (imageTextureName !== undefined) {
+            this.m_imageTextureName = imageTextureName;
+        }
+        this.m_shieldGroupIndex = shieldGroupIndex;
+        return this;
+    }
+
+    build(textElement: TextElement): PoiInfo | undefined {
+        assert(this.m_technique !== undefined);
+        const technique = this.m_technique!;
+        const env = this.m_env;
+        const imageTextureName = this.m_imageTextureName;
+
+        // The POI name to be used is taken from the data, since it will
+        // specify the name of the texture to use.
+
+        // The POI name in the technique may override the POI name from the
+        // data.
+        const poiName =
+            technique.poiTable !== undefined ? technique.poiName ?? imageTextureName : undefined;
+
+        if (imageTextureName !== undefined && poiName !== undefined) {
+            logger.warn(
+                "Possible duplicate POI icon definition via imageTextureName and poiTable!"
+            );
+        }
+
+        if (imageTextureName === undefined && poiName === undefined) {
+            // Select the smaller/larger one of the two min/max values, because the TextElement
+            // is a container for both.
+            if (textElement.minZoomLevel === undefined) {
+                textElement.minZoomLevel =
+                    getPropertyValue(technique.textMinZoomLevel, env) ?? undefined;
+            }
+
+            if (textElement.maxZoomLevel === undefined) {
+                textElement.maxZoomLevel =
+                    getPropertyValue(technique.textMaxZoomLevel, env) ?? undefined;
+            }
+            return undefined;
+        }
+
+        const textIsOptional = technique.textIsOptional === true;
+        const iconIsOptional = technique.iconIsOptional !== false;
+        const renderTextDuringMovements = !(technique.renderTextDuringMovements === false);
+        const iconMayOverlap = technique.iconMayOverlap ?? technique.textMayOverlap;
+
+        const iconReserveSpace = technique.iconReserveSpace ?? technique.textReserveSpace;
+        const iconColorRaw = getPropertyValue(technique.iconColor, env);
+        const iconColor =
+            iconColorRaw !== null ? ColorCache.instance.getColor(iconColorRaw) : undefined;
+
+        textElement.poiInfo = {
+            technique,
+            imageTextureName,
+            poiTableName: technique.poiTable,
+            poiName,
+            shieldGroupIndex: this.m_shieldGroupIndex,
+            textElement,
+            textIsOptional,
+            iconIsOptional,
+            renderTextDuringMovements,
+            mayOverlap: iconMayOverlap,
+            reserveSpace: iconReserveSpace,
+            featureId: textElement.featureId,
+            iconBrightness: technique.iconBrightness,
+            iconColor,
+            iconMinZoomLevel: this.m_iconMinZoomLevel,
+            iconMaxZoomLevel: this.m_iconMaxZoomLevel,
+            textMinZoomLevel: this.m_textMinZoomLevel,
+            textMaxZoomLevel: this.m_textMaxZoomLevel
+        };
+
+        textElement.updateMinMaxZoomLevelsFromPoiInfo();
+
+        return textElement.poiInfo;
+    }
+}