Polygon label position (#204), #80

- Fix infinite recursion on invalid polygons
- Allow setting area-size for text styles
- Skip unnecessary calculations if label is outside of visible area

resources/rendertheme.xsd

@@ -143,10 +143,10 @@
         <xs:attribute name="fill" default="#000000" type="tns:color" use="optional" />
         <xs:attribute name="stroke" default="#000000" type="tns:color" use="optional" />
         <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" />
+        <!-- priority for label placement, 0 = highest priority -->
+        <xs:attribute name="priority" default="0" type="xs:integer" use="optional" />
         <!-- symbol src name in atlas -->
         <xs:attribute name="symbol" type="tns:src" use="optional" />
     </xs:complexType>
@@ -220,6 +220,8 @@
         <xs:attribute name="stroke" default="#000000" type="tns:color" use="optional" />
         <xs:attribute name="stroke-width" default="0" type="tns:nonNegativeFloat" use="optional" />
         <xs:attribute name="caption" default="false" type="xs:boolean" 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" />
         <!-- priority for label placement, 0 = highest priority -->
         <xs:attribute name="priority" default="0" type="xs:integer" use="optional" />
     </xs:complexType>

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

@@ -77,6 +77,11 @@ public class LabelTileLoaderHook implements TileLoaderThemeHook {
                 if (value == null || value.length() == 0)
                     return false;
 
+                PointF label = element.labelPosition;
+                // skip unnecessary calculations if label is outside of visible area
+                if (label != null && (label.x < 0 || label.x > Tile.SIZE || label.y < 0 || label.y > Tile.SIZE))
+                    return false;
+
                 if (text.areaSize > 0f) {
                     float area = element.area();
                     float ratio = area / (Tile.SIZE * Tile.SIZE); // we can't use static as it's recalculated based on dpi
@@ -84,13 +89,9 @@ public class LabelTileLoaderHook implements TileLoaderThemeHook {
                         return false;
                 }
 
-                PointF label = element.labelPosition;
                 if (label == null)
                     label = PolyLabel.get(element);
 
-                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);

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

@@ -43,6 +43,13 @@ public class PolyLabel {
         // 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;
 
+        // take centroid as the first best guess
+        Cell bestCell = getCentroidCell(polygon);
+
+        // if polygon is clipped to a line, return invalid label point
+        if (Float.isNaN(bestCell.x) || Float.isNaN(bestCell.y))
+            return new PointF(-1f, -1f);
+
         int n = polygon.index[0];
 
         for (int i = 0; i < n; ) {
@@ -69,9 +76,6 @@ public class PolyLabel {
             }
         }
 
-        // 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;