Polygon label position enhancements (#204), closes #80

resources/rendertheme.xsd

@@ -145,7 +145,8 @@
         <xs:attribute name="stroke-width" default="0" type="tns:nonNegativeFloat" use="optional" />
         <!-- priority for label placement, 0 = highest priority -->
         <xs:attribute name="priority" default="0" type="xs:integer" use="optional" />
-
+        <!-- polygon area expressed as a ratio to tile area, e.g. 0.1 for 10% of tile area -->
+        <xs:attribute name="area-size" default="0" type="tns:nonNegativeFloat" use="optional" />
         <!-- symbol src name in atlas -->
         <xs:attribute name="symbol" type="tns:src" use="optional" />
     </xs:complexType>

vtm-themes/resources/assets/styles/default.xml

@@ -260,6 +260,7 @@
                 -->
                 <m v="parking" zoom-min="15">
                     <area fill="#f4f4f4" stroke="#d4d4d4" stroke-width="0.2" />
+                    <symbol src="assets:symbols/transport/parking.svg" />
                 </m>
                 <m closed="yes" v="fountain">
                     <area fill="#b4cbdc" stroke="#000080" stroke-width="0.15" />
@@ -401,6 +402,7 @@
     <m e="way">
         <m closed="yes" k="natural" v="water">
             <area use="water" />
+            <caption k="name" fill="#777744" size="16" stroke="#aaffffff" stroke-width="2.0" area-size="0.4" />
             <!--<line use="water:outline" />-->
         </m>
 
@@ -521,7 +523,18 @@
         <!-- runways areas -->
         <m k="aeroway">
             <m closed="yes" v="aerodrome">
-                <area fill="#e8ecde" />
+                <m zoom-min="12">
+                    <area fill="#e8ecde" />
+                </m>
+                <m zoom-min="12">
+                    <caption dy="18" fill="#000000" k="name" priority="5" size="19" stroke="#ffffff"
+                        stroke-width="2.0" area-size="0.1"/>
+                </m>
+                <m zoom-max="11">
+                    <caption dy="18" fill="#000000" k="ref" priority="5" size="19" stroke="#ffffff"
+                        stroke-width="2.0" />
+                </m>
+                <symbol src="assets:symbols/transport/airport.svg" />
             </m>
             <!-- A place where planes are parked -->
             <m v="apron">
@@ -554,7 +567,7 @@
             <m zoom-min="17">
                 <caption style="bold" fill="#4040ff" k="name" priority="9" size="14"
                     stroke="#ffffff" stroke-width="2.0" />
-                <caption style="bold" fill="#606060" k="addr:housenumber" priority="10" size="10"
+                <caption style="bold" fill="#606060" k="addr:housenumber" priority="10" size="16"
                     stroke="#ffffff" stroke-width="2.0" />
             </m>
         </m>
@@ -929,7 +942,7 @@
         </m>
 
         <m k="highway" v="track">
-            <m k="areay" v="yes">
+            <m k="area" v="yes">
                 <area fill="#aaff0000" />
             </m>
         </m>
@@ -984,6 +997,7 @@
 
         <!-- place -->
         <m k="place">
+            <circle radius="5.0" fill="#ff0000"/>
             <m v="suburb" zoom-max="14">
                 <caption style="italic" fill="#606060" k="name" priority="4" size="17"
                     stroke="#ffffff" stroke-width="2.0" />
@@ -998,7 +1012,7 @@
             </m>
             <m v="town">
                 <caption dy="14" fill="#000000" k="name" priority="2" size="19" stroke="#ffffff"
-                    stroke-width="2.0" symbol="assets:symbols/dot_white.svg" />
+                    stroke-width="2.0" />
             </m>
             <m v="city">
                 <m zoom-min="7">
@@ -1039,7 +1053,7 @@
             <m k="aeroway" v="helipad" zoom-min="16">
                 <symbol src="assets:symbols/transport/helicopter_pad.svg" />
             </m>
-            <m k="aeroway" v="aerodrome|airport">
+            <m k="aeroway" v="aerodrome|airport" zoom-min="9">
                 <symbol src="assets:symbols/transport/airport.svg" />
             </m>
         </m>

vtm/src/org/oscim/core/GeometryBuffer.java

@@ -1,5 +1,6 @@
 /*
  * Copyright 2013 Hannes Janetzek
+ * Copyright 2016 Andrey Novikov
  *
  * This file is part of the OpenScienceMap project (http://www.opensciencemap.org).
  *
@@ -411,6 +412,27 @@ public class GeometryBuffer {
         }
     }
 
+    /**
+     * Calculates geometry area, only polygon outer ring is taken into account.
+     *
+     * @return polygon area, 0 for other geometries
+     */
+    public float area() {
+        if (isPoint() || isLine() || getNumPoints() < 3)
+            return 0f;
+
+        float area = 0f;
+        // use only outer ring
+        int n = index[0];
+
+        for (int i = 0; i < n - 2; i += 2) {
+            area = area + (points[i] * points[i+3]) - (points[i+1] * points[i+2]);
+        }
+        area = area + (points[n-2] * points[1]) - (points[n-1] * points[0]);
+
+        return 0.5f * area;
+    }
+
     public String toString() {
         StringBuffer sb = new StringBuffer();
         int o = 0;

vtm/src/org/oscim/core/MapElement.java

@@ -33,6 +33,8 @@ public class MapElement extends GeometryBuffer {
 
     public final TagSet tags = new TagSet();
 
+    public PointF labelPosition;
+
     public MapElement() {
         super(1024, 16);
     }
@@ -45,6 +47,10 @@ public class MapElement extends GeometryBuffer {
         this.layer = layer;
     }
 
+    public void setLabelPosition(float x, float y) {
+        labelPosition = new PointF(x, y);
+    }
+
     @Override
     public MapElement clear() {
         layer = 5;

vtm/src/org/oscim/layers/tile/vector/labeling/LabelTileLoaderHook.java

@@ -1,5 +1,6 @@
 /*
  * Copyright 2016 devemux86
+ * Copyright 2016 Andrey Novikov
  *
  * This file is part of the OpenScienceMap project (http://www.opensciencemap.org).
  *
@@ -18,6 +19,7 @@ package org.oscim.layers.tile.vector.labeling;
 
 import org.oscim.core.MapElement;
 import org.oscim.core.PointF;
+import org.oscim.core.Tile;
 import org.oscim.layers.tile.MapTile;
 import org.oscim.layers.tile.vector.VectorTileLayer.TileLoaderThemeHook;
 import org.oscim.renderer.bucket.RenderBuckets;
@@ -26,6 +28,7 @@ import org.oscim.renderer.bucket.TextItem;
 import org.oscim.theme.styles.RenderStyle;
 import org.oscim.theme.styles.SymbolStyle;
 import org.oscim.theme.styles.TextStyle;
+import org.oscim.utils.geom.PolyLabel;
 
 import static org.oscim.core.GeometryBuffer.GeometryType.LINE;
 import static org.oscim.core.GeometryBuffer.GeometryType.POINT;
@@ -70,23 +73,25 @@ public class LabelTileLoaderHook implements TileLoaderThemeHook {
                     offset += length;
                 }
             } else if (element.type == POLY) {
-                // TODO place somewhere on polygon
                 String value = element.tags.getValue(text.textKey);
                 if (value == null || value.length() == 0)
                     return false;
 
-                float x = 0;
+                if (text.areaSize > 0f) {
-                float y = 0;
+                    float area = element.area();
-                int n = element.index[0];
+                    float ratio = area / (Tile.SIZE * Tile.SIZE); // we can't use static as it's recalculated based on dpi
-
+                    if (ratio < text.areaSize)
-                for (int i = 0; i < n; ) {
+                        return false;
-                    x += element.points[i++];
-                    y += element.points[i++];
                 }
-                x /= (n / 2);
-                y /= (n / 2);
 
-                ld.labels.push(TextItem.pool.get().set(x, y, value, text));
+                PointF label = element.labelPosition;
+                if (label == null)
+                    label = PolyLabel.get(element, 5f);
+
+                if (label.x < 0 || label.x > Tile.SIZE || label.y < 0 || label.y > Tile.SIZE)
+                    return false;
+
+                ld.labels.push(TextItem.pool.get().set(label.x, label.y, value, text));
             } else if (element.type == POINT) {
                 String value = element.tags.getValue(text.textKey);
                 if (value == null || value.length() == 0)
@@ -97,7 +102,7 @@ public class LabelTileLoaderHook implements TileLoaderThemeHook {
                     ld.labels.push(TextItem.pool.get().set(p.x, p.y, value, text));
                 }
             }
-        } else if ((element.type == POINT) && (style instanceof SymbolStyle)) {
+        } else if (style instanceof SymbolStyle) {
             SymbolStyle symbol = (SymbolStyle) style;
 
             if (symbol.bitmap == null && symbol.texture == null)
@@ -105,14 +110,32 @@ public class LabelTileLoaderHook implements TileLoaderThemeHook {
 
             LabelTileData ld = get(tile);
 
-            for (int i = 0, n = element.getNumPoints(); i < n; i++) {
+            if (element.type == POINT) {
-                PointF p = element.getPoint(i);
+                for (int i = 0, n = element.getNumPoints(); i < n; i++) {
+                    PointF p = element.getPoint(i);
+
+                    SymbolItem it = SymbolItem.pool.get();
+                    if (symbol.bitmap != null)
+                        it.set(p.x, p.y, symbol.bitmap, true);
+                    else
+                        it.set(p.x, p.y, symbol.texture, true);
+                    ld.symbols.push(it);
+                }
+            } else if (element.type == LINE) {
+                //TODO: implement
+            } else if (element.type == POLY) {
+                PointF centroid = element.labelPosition;
+                if (centroid == null)
+                    return false;
+
+                if (centroid.x < 0 || centroid.x > Tile.SIZE || centroid.y < 0 || centroid.y > Tile.SIZE)
+                    return false;
 
                 SymbolItem it = SymbolItem.pool.get();
                 if (symbol.bitmap != null)
-                    it.set(p.x, p.y, symbol.bitmap, true);
+                    it.set(centroid.x, centroid.y, symbol.bitmap, true);
                 else
-                    it.set(p.x, p.y, symbol.texture, true);
+                    it.set(centroid.x, centroid.y, symbol.texture, true);
                 ld.symbols.push(it);
             }
         }

vtm/src/org/oscim/theme/XmlThemeBuilder.java

@@ -3,6 +3,7 @@
  * Copyright 2013 Hannes Janetzek
  * Copyright 2016 devemux86
  * Copyright 2016 Longri
+ * Copyright 2016 Andrey Novikov
  *
  * This file is part of the OpenScienceMap project (http://www.opensciencemap.org).
  *
@@ -863,6 +864,9 @@ public class XmlThemeBuilder extends DefaultHandler {
             else if ("priority".equals(name))
                 b.priority = Integer.parseInt(value);
 
+            else if ("area-size".equals(name))
+                b.areaSize = Float.parseFloat(value);
+
             else if ("dy".equals(name))
                 // NB: minus..
                 b.dy = -Float.parseFloat(value) * CanvasAdapter.dpi / 160;

vtm/src/org/oscim/theme/styles/TextStyle.java

@@ -1,6 +1,7 @@
 /*
  * Copyright 2013 Hannes Janetzek
  * Copyright 2016 devemux86
+ * Copyright 2016 Andrey Novikov
  *
  * This file is part of the OpenScienceMap project (http://www.opensciencemap.org).
  *
@@ -36,6 +37,7 @@ public final class TextStyle extends RenderStyle<TextStyle> {
         public boolean caption;
         public float dy;
         public int priority;
+        public float areaSize;
         public Bitmap bitmap;
         public TextureRegion texture;
         public FontFamily fontFamily;
@@ -49,6 +51,7 @@ public final class TextStyle extends RenderStyle<TextStyle> {
             fontSize = 0;
             caption = false;
             priority = Integer.MAX_VALUE;
+            areaSize = 0f;
             bitmap = null;
             texture = null;
             fillColor = Color.BLACK;
@@ -98,6 +101,11 @@ public final class TextStyle extends RenderStyle<TextStyle> {
             return self();
         }
 
+        public T areaSize(float areaSize) {
+            this.areaSize = areaSize;
+            return self();
+        }
+
         public T bitmap(Bitmap bitmap) {
             this.bitmap = bitmap;
             return self();
@@ -126,6 +134,7 @@ public final class TextStyle extends RenderStyle<TextStyle> {
             fontSize = other.fontSize;
             caption = other.caption;
             priority = other.priority;
+            areaSize = other.areaSize;
             bitmap = other.bitmap;
             texture = other.texture;
             fillColor = other.fillColor;
@@ -141,6 +150,7 @@ public final class TextStyle extends RenderStyle<TextStyle> {
             this.caption = style.caption;
             this.dy = style.dy;
             this.priority = style.priority;
+            this.areaSize = style.areaSize;
             this.bitmap = style.bitmap;
             this.texture = style.texture;
             this.fillColor = style.paint.getColor();
@@ -159,6 +169,7 @@ public final class TextStyle extends RenderStyle<TextStyle> {
         this.caption = tb.caption;
         this.dy = tb.dy;
         this.priority = tb.priority;
+        this.areaSize = tb.areaSize;
         this.bitmap = tb.bitmap;
         this.texture = tb.texture;
 
@@ -193,6 +204,7 @@ public final class TextStyle extends RenderStyle<TextStyle> {
     public final boolean caption;
     public final float dy;
     public final int priority;
+    public final float areaSize;
 
     public float fontHeight;
     public float fontDescent;

vtm/src/org/oscim/tiling/source/mapfile/MapDatabase.java

@@ -2,6 +2,7 @@
  * Copyright 2010, 2011, 2012 mapsforge.org
  * Copyright 2013, 2014 Hannes Janetzek
  * Copyright 2016 devemux86
+ * Copyright 2016 Andrey Novikov
  *
  * This file is part of the OpenScienceMap project (http://www.opensciencemap.org).
  *
@@ -840,9 +841,11 @@ public class MapDatabase implements ITileDataSource {
                     e.tags.add(new Tag(Tag.KEY_REF, str, false));
                 }
             }
-            if ((featureByte & WAY_FEATURE_LABEL_POSITION) != 0)
+
-                // labelPosition =
+            int[] labelPosition = null;
-                readOptionalLabelPosition();
+            if ((featureByte & WAY_FEATURE_LABEL_POSITION) != 0) {
+                labelPosition = readOptionalLabelPosition();
+            }
 
             if ((featureByte & WAY_FEATURE_DATA_BLOCKS_BYTE) != 0) {
                 wayDataBlocks = mReadBuffer.readUnsignedInt();
@@ -870,6 +873,8 @@ public class MapDatabase implements ITileDataSource {
                     continue;
                 }
 
+                if (labelPosition != null && wayDataBlock == 0)
+                    e.setLabelPosition(e.points[0] + labelPosition[0], e.points[1] + labelPosition[1]);
                 mTileProjection.project(e);
 
                 if (!e.tags.containsKey("building"))
@@ -879,6 +884,7 @@ public class MapDatabase implements ITileDataSource {
                 e.simplify(1, true);
 
                 e.setLayer(layer);
+
                 mapDataSink.process(e);
             }
         }
@@ -886,14 +892,14 @@ public class MapDatabase implements ITileDataSource {
         return true;
     }
 
-    private float[] readOptionalLabelPosition() {
+    private int[] readOptionalLabelPosition() {
-        float[] labelPosition = new float[2];
+        int[] labelPosition = new int[2];
 
         /* get the label position latitude offset (VBE-S) */
-        labelPosition[1] = mTileLatitude + mReadBuffer.readSignedInt();
+        labelPosition[1] = mReadBuffer.readSignedInt();
 
         /* get the label position longitude offset (VBE-S) */
-        labelPosition[0] = mTileLongitude + mReadBuffer.readSignedInt();
+        labelPosition[0] = mReadBuffer.readSignedInt();
 
         return labelPosition;
     }
@@ -1021,6 +1027,10 @@ public class MapDatabase implements ITileDataSource {
                     indices[idx] = (short) cnt;
                 }
             }
+            if (e.labelPosition != null) {
+                e.labelPosition.x = projectLon(e.labelPosition.x);
+                e.labelPosition.y = projectLat(e.labelPosition.y);
+            }
         }
     }
 }

vtm/src/org/oscim/utils/geom/PolyLabel.java

@@ -0,0 +1,198 @@
+/**
+ * Copyright 2016 Andrey Novikov
+ * Java implementation of
+ * https://github.com/mapbox/polylabel
+ *
+ * ISC License
+ * Copyright (c) 2016 Mapbox
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any purpose
+ * with or without fee is hereby granted, provided that the above copyright notice
+ * and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH REGARD TO
+ * THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
+ * IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA
+ * OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
+ * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
+ * SOFTWARE.
+ */
+package org.oscim.utils.geom;
+
+import org.oscim.core.GeometryBuffer;
+import org.oscim.core.PointF;
+
+import java.util.Comparator;
+import java.util.PriorityQueue;
+
+public class PolyLabel {
+    private static float SQRT2 = (float) Math.sqrt(2);
+
+    /**
+     * Returns pole of inaccessibility, the most distant internal point from the polygon outline.
+     * @param polygon polygon geometry
+     * @param precision calculation precision
+     * @return optimal label placement point
+     */
+    public static PointF get(GeometryBuffer polygon, float precision) {
+        // find the bounding box of the outer ring
+        float minX = Float.MAX_VALUE, minY = Float.MAX_VALUE, maxX = Float.MIN_VALUE, maxY = Float.MIN_VALUE;
+
+        int n = polygon.index[0];
+
+        for (int i = 0; i < n; ) {
+            float x = polygon.points[i++];
+            float y = polygon.points[i++];
+            if (x < minX) minX = x;
+            if (y < minY) minY = y;
+            if (x > maxX) maxX = x;
+            if (y > maxY) maxY = y;
+        }
+
+        float width = maxX - minX;
+        float height = maxY - minY;
+        float cellSize = Math.min(width, height);
+        float h = cellSize / 2;
+
+        // a priority queue of cells in order of their "potential" (max distance to polygon)
+        PriorityQueue<Cell> cellQueue = new PriorityQueue<>(1, new MaxComparator());
+
+        // cover polygon with initial cells
+        for (float x = minX; x < maxX; x += cellSize) {
+            for (float y = minY; y < maxY; y += cellSize) {
+                cellQueue.add(new Cell(x + h, y + h, h, polygon));
+            }
+        }
+
+        // take centroid as the first best guess
+        Cell bestCell = getCentroidCell(polygon);
+
+        // special case for rectangular polygons
+        Cell bboxCell = new Cell(minX + width / 2, minY + height / 2, 0, polygon);
+        if (bboxCell.d > bestCell.d) bestCell = bboxCell;
+
+        while (!cellQueue.isEmpty()) {
+            // pick the most promising cell from the queue
+            Cell cell = cellQueue.remove();
+
+            // update the best cell if we found a better one
+            if (cell.d > bestCell.d)
+                bestCell = cell;
+
+            // do not drill down further if there's no chance of a better solution
+            if (cell.max - bestCell.d <= precision) continue;
+
+            // split the cell into four cells
+            h = cell.h / 2;
+            cellQueue.add(new Cell(cell.x - h, cell.y - h, h, polygon));
+            cellQueue.add(new Cell(cell.x + h, cell.y - h, h, polygon));
+            cellQueue.add(new Cell(cell.x - h, cell.y + h, h, polygon));
+            cellQueue.add(new Cell(cell.x + h, cell.y + h, h, polygon));
+        }
+
+        return new PointF(bestCell.x, bestCell.y);
+    }
+
+    private static class MaxComparator implements Comparator<Cell>
+    {
+        @Override
+        public int compare(Cell a, Cell b) {
+            return Float.compare(b.max, a.max);
+        }
+    }
+
+    private static class Cell {
+        final float x;
+        final float y;
+        final float h;
+        final float d;
+        final float max;
+
+        Cell(float x, float y, float h, GeometryBuffer polygon) {
+            this.x = x; // cell center x
+            this.y = y; // cell center y
+            this.h = h; // half the cell size
+            this.d = pointToPolygonDist(x, y, polygon); // distance from cell center to polygon
+            this.max = this.d + this.h * SQRT2; // max distance to polygon within a cell
+        }
+    }
+
+    // signed distance from point to polygon outline (negative if point is outside)
+    private static float pointToPolygonDist(float x, float y, GeometryBuffer polygon) {
+        boolean inside = false;
+        float minDistSq = Float.POSITIVE_INFINITY;
+
+        int pos = 0;
+
+        for (int k = 0; k < polygon.index.length; k++) {
+            if (polygon.index[k] < 0)
+                break;
+            if (polygon.index[k] == 0)
+                continue;
+
+            for (int i = 0, n = polygon.index[k], j = n - 2; i < n; j = i, i += 2) {
+                float ax = polygon.points[pos+i];
+                float ay = polygon.points[pos+i+1];
+                float bx = polygon.points[pos+j];
+                float by = polygon.points[pos+j+1];
+
+                if (((ay > y) ^ (by > y)) &&
+                        (x < (bx - ax) * (y - ay) / (by - ay) + ax)) inside = !inside;
+
+                minDistSq = Math.min(minDistSq, getSegDistSq(x, y, ax, ay, bx, by));
+            }
+
+            pos += polygon.index[k];
+        }
+
+        return (float) ((inside ? 1 : -1) * Math.sqrt(minDistSq));
+    }
+
+    // get polygon centroid
+    private static Cell getCentroidCell(GeometryBuffer polygon) {
+        float area = 0f;
+        float x = 0f;
+        float y = 0f;
+
+        for (int i = 0, n = polygon.index[0], j = n - 2; i < n; j = i, i += 2) {
+            float ax = polygon.points[i];
+            float ay = polygon.points[i+1];
+            float bx = polygon.points[j];
+            float by = polygon.points[j+1];
+            float f = ax * by - bx * ay;
+            x += (ax + bx) * f;
+            y += (ay + by) * f;
+            area += f * 3;
+        }
+        return new Cell(x / area, y / area, 0f, polygon);
+    }
+
+    // get squared distance from a point to a segment
+    private static float getSegDistSq(float px, float py, float ax, float ay, float bx, float by) {
+
+        float x = ax;
+        float y = ay;
+        float dx = bx - x;
+        float dy = by - y;
+
+        if (dx != 0f || dy != 0f) {
+
+            float t = ((px - x) * dx + (py - y) * dy) / (dx * dx + dy * dy);
+
+            if (t > 1) {
+                x = bx;
+                y = by;
+
+            } else if (t > 0) {
+                x += dx * t;
+                y += dy * t;
+            }
+        }
+
+        dx = px - x;
+        dy = py - y;
+
+        return dx * dx + dy * dy;
+    }
+}