Implement justify-alignment=auto.

Closes #1125.

bindings/python/mapnik_text_placement.cpp

@@ -329,6 +329,7 @@ void export_text_placement()
         .value("LEFT",J_LEFT)
         .value("MIDDLE",J_MIDDLE)
         .value("RIGHT",J_RIGHT)
+        .value("AUTO", J_AUTO)
         ;
 
     enumeration_<text_transform_e>("text_transform")

include/mapnik/placement_finder.hpp

@@ -137,6 +137,7 @@ private:
     double first_line_space_;
     vertical_alignment_e valign_;
     horizontal_alignment_e halign_;
+    justify_alignment_e jalign_;
     std::vector<unsigned> line_breaks_;
     std::vector<std::pair<double, double> > line_sizes_;
     std::queue< box2d<double> > envelopes_;

include/mapnik/text_properties.hpp

@@ -110,6 +110,7 @@ enum justify_alignment
     J_LEFT = 0,
     J_MIDDLE,
     J_RIGHT,
+    J_AUTO,
     justify_alignment_MAX
 };
 

src/placement_finder.cpp

@@ -305,24 +305,48 @@ template <typename DetectorT>
 void placement_finder<DetectorT>::init_alignment()
 {
     valign_ = p.valign;
-    if (valign_ == V_AUTO) {
+    if (valign_ == V_AUTO)
+    {
         if (p.displacement.second > 0.0)
+        {
             valign_ = V_BOTTOM;
-        else if (p.displacement.second < 0.0)
+        } else if (p.displacement.second < 0.0)
+        {
             valign_ = V_TOP;
-        else
+        } else
+        {
             valign_ = V_MIDDLE;
         }
+    }
 
     halign_ = p.halign;
-    if (halign_ == H_AUTO) {
+    if (halign_ == H_AUTO)
+    {
         if (p.displacement.first > 0.0)
+        {
             halign_ = H_RIGHT;
-        else if (p.displacement.first < 0.0)
+        } else if (p.displacement.first < 0.0)
+        {
             halign_ = H_LEFT;
-        else
+        } else
+        {
             halign_ = H_MIDDLE;
         }
+    }
+
+    jalign_ = p.jalign;
+    if (jalign_ == J_AUTO)
+    {
+        if (p.displacement.first > 0.0)
+        {
+            jalign_ = J_LEFT;
+        } else if (p.displacement.first < 0.0)
+        {
+            jalign_ = J_RIGHT;
+        } else {
+            jalign_ = J_MIDDLE;
+        }
+    }
 }
 
 
@@ -389,9 +413,9 @@ void placement_finder<DetectorT>::find_point_placement(double label_x,
     if (info_.get_rtl()) y = -y;
 
     // adjust for desired justification
-    if (p.jalign == J_LEFT)
+    if (jalign_ == J_LEFT)
         x = -(string_width_ / 2.0);
-    else if (p.jalign == J_RIGHT)
+    else if (jalign_ == J_RIGHT)
         x = (string_width_ / 2.0) - line_width;
     else /* J_MIDDLE */
         x = -(line_width / 2.0);
@@ -420,9 +444,9 @@ void placement_finder<DetectorT>::find_point_placement(double label_x,
             }
 
             // reset to begining of line position
-            if (p.jalign == J_LEFT)
+            if (jalign_ == J_LEFT)
                 x = -(string_width_ / 2.0);
-            else if (p.jalign == J_RIGHT)
+            else if (jalign_ == J_RIGHT)
                 x = (string_width_ / 2.0) - line_width;
             else
                 x = -(line_width / 2.0);

src/text_properties.cpp

@@ -40,7 +40,7 @@ text_symbolizer_properties::text_symbolizer_properties() :
     displacement(0,0),
     label_placement(POINT_PLACEMENT),
     halign(H_AUTO),
-    jalign(J_MIDDLE),
+    jalign(J_AUTO),
     valign(V_AUTO),
     label_spacing(0),
     label_position_tolerance(0),

src/text_symbolizer.cpp

@@ -69,6 +69,7 @@ static const char * justify_alignment_strings[] = {
     "left",
     "center",
     "right",
+    "auto",
     ""
 };
 

tests/visual_tests/jalign-auto.xml

@@ -0,0 +1,30 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!DOCTYPE Map>
+<Map background-color="white" srs="+proj=latlong +datum=WGS84">
+
+    <Layer name="layer" srs="+proj=latlong +datum=WGS84">
+        <StyleName>My Style</StyleName>
+        <Datasource>
+            <Parameter name="type">shape</Parameter>
+            <Parameter name="file">points.shp</Parameter>
+        </Datasource>
+    </Layer>
+
+    <Style name="My Style">
+        <Rule>
+            <Filter>[nr] = '5'</Filter>
+            <PointSymbolizer/>
+            <TextSymbolizer face-name="DejaVu Sans Book" size="10" placement="point" dx="-30" dy="-30" justify-alignment="auto">'Text line 1&#10;line 2'</TextSymbolizer>
+            <TextSymbolizer face-name="DejaVu Sans Book" size="10" placement="point" dx="0" dy="-30" justify-alignment="auto">'Text line 1&#10;line 2'</TextSymbolizer>
+            <TextSymbolizer face-name="DejaVu Sans Book" size="10" placement="point" dx="30" dy="-30" justify-alignment="auto">'Text line 1&#10;line 2'</TextSymbolizer>
+            
+            <TextSymbolizer face-name="DejaVu Sans Book" size="10" placement="point" dx="30" dy="0" justify-alignment="auto">'Text line 1&#10;line 2'</TextSymbolizer>
+            <TextSymbolizer face-name="DejaVu Sans Book" size="10" placement="point" dx="-30" dy="0" justify-alignment="auto">'Text line 1&#10;line 2'</TextSymbolizer>
+
+            <TextSymbolizer face-name="DejaVu Sans Book" size="10" placement="point" dx="-30" dy="30" justify-alignment="auto">'Text line 1&#10;line 2'</TextSymbolizer>
+            <TextSymbolizer face-name="DejaVu Sans Book" size="10" placement="point" dx="0" dy="30" justify-alignment="auto">'Text line 1&#10;line 2'</TextSymbolizer>
+            <TextSymbolizer face-name="DejaVu Sans Book" size="10" placement="point" dx="30" dy="30" justify-alignment="auto">'Text line 1&#10;line 2'</TextSymbolizer>
+        </Rule>
+    </Style>
+
+</Map>

tests/visual_tests/test.py

@@ -28,7 +28,8 @@ files = [
     ("formating-4", 500),
     ("shieldsymbolizer-1", 490, 495, 497, 498, 499, 500, 501, 502, 505, 510),
     ("expressionformat", 500),
-    ("rtl-point", (200, 200))
+    ("rtl-point", (200, 200)),
+    ("jalign-auto", (200, 200))
     ]
 
 def render(filename, width, height=100):