add text attribute horizontal-alignment="adjust"

include/mapnik/symbolizer_enumerations.hpp

@@ -158,6 +158,7 @@ enum horizontal_alignment_enum
     H_MIDDLE,
     H_RIGHT,
     H_AUTO,
+    H_ADJUST,
     horizontal_alignment_enum_MAX
 };
 

include/mapnik/text/placement_finder_impl.hpp

@@ -67,6 +67,8 @@ bool placement_finder::find_line_placements(T & path, bool points)
                 {
                     continue;
                 }
+
+            layouts_.adjust(pp.length(), scale_factor_);
         }
 
         double spacing = get_spacing(pp.length(), points ? 0. : layouts_.width());
@@ -74,7 +76,7 @@ bool placement_finder::find_line_placements(T & path, bool points)
         //horizontal_alignment_e halign = layouts_.back()->horizontal_alignment();
 
         // halign == H_LEFT -> don't move
-        if (horizontal_alignment_ == H_MIDDLE || horizontal_alignment_ == H_AUTO)
+        if (horizontal_alignment_ == H_MIDDLE || horizontal_alignment_ == H_AUTO || horizontal_alignment_ == H_ADJUST)
         {
             if (!pp.forward(spacing / 2.0)) continue;
         }

include/mapnik/text/text_layout.hpp

@@ -110,6 +110,10 @@ public:
 
     void evaluate_properties(feature_impl const& feature, attributes const& attr);
 
+    text_line const& longest_line() const;
+
+    void set_character_spacing(double spacing, double scale_factor);
+
 private:
     void break_line(text_line & line, double wrap_width, unsigned text_ratio, bool wrap_before);
     void break_line(text_line & line, char wrap_char,
@@ -186,6 +190,8 @@ public:
     inline double width() const { return bounds_.width(); }
     inline double height() const { return bounds_.height(); }
 
+    void adjust(double width, double scale_factor);
+
 private:
     text_layout_vector layouts_;
 

include/mapnik/text/text_line.hpp

@@ -52,6 +52,8 @@ public:
     // Iterator beyond last glyph.
     const_iterator end() const;
 
+    // Width of all glyphs without character spacing.
+    double glyphs_width() const { return glyphs_width_; }
     // Width of all glyphs including character spacing.
     double width() const { return width_; }
     // Real line height. For first line: max_char_height(), for all others: line_height().
@@ -75,14 +77,21 @@ public:
 
     // Number of glyphs.
     unsigned size() const;
+
+    unsigned space_count() const { return space_count_; }
+
+    void set_character_spacing(double character_spacing, double scale_factor);
+
 private:
     glyph_vector glyphs_;
     double line_height_; // Includes line spacing (returned by freetype)
     double max_char_height_; // Height of 'X' character of the largest font in this run. //TODO: Initialize this!
     double width_;
+    double glyphs_width_;
     unsigned first_char_;
     unsigned last_char_;
     bool first_line_;
+    unsigned space_count_;
 };
 
 } //namespace mapnik

src/symbolizer_enumerations.cpp

@@ -137,6 +137,7 @@ static const char * horizontal_alignment_strings[] = {
     "middle",
     "right",
     "auto",
+    "adjust",
     ""
 };
 

src/text/placement_finder.cpp

@@ -36,6 +36,7 @@
 
 // stl
 #include <vector>
+#include <functional>
 
 namespace mapnik
 {
@@ -192,6 +193,7 @@ bool placement_finder::single_line_placement(vertex_cache &pp, text_upright_e or
         pixel_position const& layout_displacement = layout.displacement();
         double sign = (real_orientation == UPRIGHT_LEFT) ? -1 : 1;
         double offset = layout_displacement.y + 0.5 * sign * layout.height();
+        bool move_by_length = layout.horizontal_alignment() == H_ADJUST;
 
         for (auto const& line : layout)
         {
@@ -209,12 +211,14 @@ bool placement_finder::single_line_placement(vertex_cache &pp, text_upright_e or
             double angle;
             rotation rot;
             double last_glyph_spacing = 0.;
+            std::function<bool(double)> glyph_move_method = std::bind(
+                move_by_length ? &vertex_cache::move : &vertex_cache::move_to_distance, &off_pp, std::placeholders::_1);
 
             for (auto const& glyph : line)
             {
                 if (current_cluster != static_cast<int>(glyph.char_index))
                 {
-                    if (!off_pp.move_to_distance(sign * (layout.cluster_width(current_cluster) + last_glyph_spacing)))
+                    if (!glyph_move_method(sign * (layout.cluster_width(current_cluster) + last_glyph_spacing)))
                     {
                         return false;
                     }

src/text/text_layout.cpp

@@ -415,6 +415,31 @@ double text_layout::jalign_offset(double line_width) const
     return 0;
 }
 
+text_line const& text_layout::longest_line() const
+{
+    if (lines_.empty())
+    {
+        throw std::runtime_error("longest_line: Text layout has no lines.");
+    }
+    text_layout::const_iterator longest = lines_.begin();
+    for (text_layout::const_iterator line = longest + 1; line != lines_.end(); ++line)
+    {
+        if (line->glyphs_width() > longest->glyphs_width())
+        {
+            longest = line;
+        }
+    }
+    return *longest;
+}
+
+void text_layout::set_character_spacing(double spacing, double scale_factor)
+{
+    for (auto & line : lines_)
+    {
+        line.set_character_spacing(spacing, scale_factor);
+    }
+}
+
 void layout_container::add(text_layout_ptr layout)
 {
     text_ += layout->text();
@@ -461,5 +486,20 @@ void layout_container::clear()
     line_count_ = 0;
 }
 
-
+void layout_container::adjust(double width, double scale_factor)
+{
+    for (auto & layout_ptr : layouts_)
+    {
+        text_layout & layout = *layout_ptr;
+        if (layout.horizontal_alignment() == H_ADJUST)
+        {
+            text_line const& longest_line = layout.longest_line();
+            double character_spacing = ((width - longest_line.glyphs_width()) / longest_line.space_count()) / scale_factor;
+            if (character_spacing >= .0)
+            {
+                layout.set_character_spacing(character_spacing, scale_factor);
+            }
+        }
+    }
+}
 } //ns mapnik

src/text/text_line.cpp

@@ -31,9 +31,11 @@ text_line::text_line(unsigned first_char, unsigned last_char)
       line_height_(0.0),
       max_char_height_(0.0),
       width_(0.0),
+      glyphs_width_(0.0),
       first_char_(first_char),
       last_char_(last_char),
-      first_line_(false)
+      first_line_(false),
+      space_count_(0)
 {}
 
 void text_line::add_glyph(glyph_info const& glyph, double scale_factor_)
@@ -43,11 +45,15 @@ void text_line::add_glyph(glyph_info const& glyph, double scale_factor_)
     if (glyphs_.empty())
     {
         width_ = advance;
+        glyphs_width_ = advance;
+        space_count_ = 0;
     }
     else if (advance)
     {
         // Only add character spacing if the character is not a zero-width part of a cluster.
         width_ += advance + glyphs_.back().format->character_spacing  * scale_factor_;
+        glyphs_width_ += advance;
+        space_count_++;
     }
     glyphs_.push_back(glyph);
 }
@@ -99,4 +105,23 @@ unsigned text_line::size() const
     return glyphs_.size();
 }
 
+void text_line::set_character_spacing(double character_spacing, double scale_factor)
+{
+    bool first = true;
+    for (auto const& glyph : glyphs_)
+    {
+        glyph.format->character_spacing = character_spacing;
+        double advance = glyph.advance();
+        if (first)
+        {
+            width_ = advance;
+            first = false;
+        }
+        else if (advance)
+        {
+            width_ += advance + character_spacing * scale_factor;
+        }
+    }
+}
+
 } // end namespace mapnik