From 632abdd87be8d021984773580e46e30625e0f196 Mon Sep 17 00:00:00 2001
From: Thomas Geymayer <tomgey@gmail.com>
Date: Sat, 9 Feb 2013 12:09:43 +0100
Subject: [PATCH] Fix CanvasText horizontal alignment.

Don't reduce width of bounding box below character width
even if outline of rendered character is smaller. This
prevents trailing spaces from being ignored and also
fixes continuously chaging alignment (especially with
monospace fonts).
---
 simgear/canvas/elements/CanvasText.cxx | 66 ++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)

diff --git a/simgear/canvas/elements/CanvasText.cxx b/simgear/canvas/elements/CanvasText.cxx
index c92a9ecf..8c4028bf 100644
--- a/simgear/canvas/elements/CanvasText.cxx
+++ b/simgear/canvas/elements/CanvasText.cxx
@@ -44,6 +44,8 @@ namespace canvas
     protected:
 
       canvas::Text *_text_element;
+
+      virtual void computePositions(unsigned int contextID) const;
   };
 
   //----------------------------------------------------------------------------
@@ -175,6 +177,70 @@ namespace canvas
     return bb;
   }
 
+  //----------------------------------------------------------------------------
+  void Text::TextOSG::computePositions(unsigned int contextID) const
+  {
+    if( _textureGlyphQuadMap.empty() || _layout == VERTICAL )
+      return osgText::Text::computePositions(contextID);
+
+    // TODO check when it can be larger
+    assert( _textureGlyphQuadMap.size() == 1 );
+
+    const GlyphQuads& quads = _textureGlyphQuadMap.begin()->second;
+    const GlyphQuads::Glyphs& glyphs = quads._glyphs;
+    const GlyphQuads::Coords2& coords = quads._coords;
+    const GlyphQuads::LineNumbers& line_numbers = quads._lineNumbers;
+
+    float wr = _characterHeight / getCharacterAspectRatio();
+
+    size_t cur_line = static_cast<size_t>(-1);
+    for(size_t i = 0; i < glyphs.size(); ++i)
+    {
+      // Check horizontal offsets
+
+      bool first_char = cur_line != line_numbers[i];
+      cur_line = line_numbers[i];
+
+      bool last_char = (i + 1 == glyphs.size())
+                    || (cur_line != line_numbers[i + 1]);
+
+      if( first_char || last_char )
+      {
+        // From osg/src/osgText/Text.cpp:
+        //
+        // osg::Vec2 upLeft = local+osg::Vec2(0.0f-fHorizQuadMargin, ...);
+        // osg::Vec2 lowLeft = local+osg::Vec2(0.0f-fHorizQuadMargin, ...);
+        // osg::Vec2 lowRight = local+osg::Vec2(width+fHorizQuadMargin, ...);
+        // osg::Vec2 upRight = local+osg::Vec2(width+fHorizQuadMargin, ...);
+
+        float left = coords[i * 4].x(),
+              right = coords[i * 4 + 2].x(),
+              width = glyphs[i]->getWidth() * wr;
+
+        // (local + width + fHoriz) - (local - fHoriz) = width + 2*fHoriz | -width
+        float margin = 0.5f * (right - left - width),
+              cursor_x = left + margin
+                       - glyphs[i]->getHorizontalBearing().x() * wr;
+
+        if( first_char )
+        {
+          if( cur_line == 0 || cursor_x < _textBB._min.x() )
+            _textBB._min.x() = cursor_x;
+        }
+
+        if( last_char )
+        {
+          float cursor_w = cursor_x + glyphs[i]->getHorizontalAdvance() * wr;
+
+          if( cur_line == 0 || cursor_w > _textBB._max.x() )
+            _textBB._max.x() = cursor_w;
+        }
+      }
+    }
+
+    return osgText::Text::computePositions(contextID);
+  }
+
   //----------------------------------------------------------------------------
   Text::Text( const CanvasWeakPtr& canvas,
               const SGPropertyNode_ptr& node,
-- 
2.39.5