libshell|Client|LineWrapping: Determining content index at a width

The ILineWrapping interface now contains methods that allow
determining which content index is at a given width in a range.

FontLineWrapping also now correctly uses advance width when suitable.
Visible width is only used for determining the actual wrapping points.

doomsday/client/include/ui/widgets/fontlinewrapping.h

@@ -42,6 +42,8 @@ class FontLineWrapping : public de::shell::ILineWrapping
     de::shell::WrappedLine line(int index) const;
     int width() const;
     int height() const;
+    int rangeWidth(de::shell::Range const &range) const;
+    int indexAtWidth(de::shell::Range const &range, int width) const;
 
     /**
      * Calculates the total height of the wrapped lined in pixels, taking into

doomsday/client/src/ui/widgets/fontlinewrapping.cpp

@@ -34,14 +34,23 @@ DENG2_PIMPL_NOREF(FontLineWrapping)
         return text.substr(range.start, range.size());
     }
 
-    int rangeWidth(Range const &range) const
+    int rangeVisibleWidth(Range const &range) const
     {
         if(font)
         {
             return font->measure(rangeText(range)).width();
         }
         return 0;
     }
+
+    int rangeAdvanceWidth(Range const &range) const
+    {
+        if(font)
+        {
+            return font->advanceWidth(rangeText(range));
+        }
+        return 0;
+    }
 };
 
 FontLineWrapping::FontLineWrapping() : d(new Instance)
@@ -89,7 +98,7 @@ void FontLineWrapping::wrapTextToWidth(String const &text, int maxWidth)
     forever
     {
         // Quick check: does the remainder fit?
-        if(d->rangeWidth(Range(begin, text.size())) <= maxWidth)
+        if(d->rangeVisibleWidth(Range(begin, text.size())) <= maxWidth)
         {
             d->lines.append(WrappedLine(Range(begin, text.size())));
             break;
@@ -102,7 +111,7 @@ void FontLineWrapping::wrapTextToWidth(String const &text, int maxWidth)
         {
             ++end;
 
-            if(d->rangeWidth(Range(begin, end)) > maxWidth)
+            if(d->rangeVisibleWidth(Range(begin, end)) > maxWidth)
             {
                 // Went too far.
                 wrapPosMax = --end;
@@ -136,10 +145,10 @@ void FontLineWrapping::wrapTextToWidth(String const &text, int maxWidth)
         }
         else
         {
-            //if(text.at(end).isSpace()) ++end;
+            while(text.at(end).isSpace()) ++end;
             d->lines.append(WrappedLine(Range(begin, end)));
             begin = end;
-            while(text.at(begin).isSpace()) ++begin;
+            //while(text.at(begin).isSpace()) ++begin;
         }
     }
 
@@ -161,7 +170,7 @@ int FontLineWrapping::width() const
     for(int i = 0; i < d->lines.size(); ++i)
     {
         WrappedLine const &span = d->lines[i];
-        w = de::max(w, d->rangeWidth(span.range));
+        w = de::max(w, d->rangeVisibleWidth(span.range));
     }
     return w;
 }
@@ -171,6 +180,33 @@ int FontLineWrapping::height() const
     return d->lines.size();
 }
 
+int FontLineWrapping::rangeWidth(Range const &range) const
+{
+    return d->rangeAdvanceWidth(range);
+}
+
+int FontLineWrapping::indexAtWidth(Range const &range, int width) const
+{
+    int prevWidth = 0;
+
+    for(int i = range.start; i < range.end; ++i)
+    {
+        int const rw = d->rangeAdvanceWidth(Range(range.start, i));
+        if(rw >= width)
+        {
+            // Which is closer, this or the previous char?
+            if(de::abs(rw - width) <= de::abs(prevWidth - width))
+            {
+                qDebug() << "this" << i;
+                return i;
+            }
+            return i - 1;
+        }
+        prevWidth = rw;
+    }
+    return range.end;
+}
+
 int FontLineWrapping::totalHeightInPixels() const
 {
     if(!d->font) return 0;
@@ -197,7 +233,8 @@ Vector2i FontLineWrapping::charTopLeftInPixels(int line, int charIndex)
     Range const range(span.range.start, de::min(span.range.end, span.range.start + charIndex));
 
     Vector2i cp;
-    cp.x = d->font->measure(d->rangeText(range)).width();
+    cp.x = d->font->advanceWidth(d->rangeText(range));
     cp.y = line * d->font->lineSpacing().valuei();
+
     return cp;
 }

doomsday/libshell/include/de/shell/libshell.h

@@ -54,7 +54,7 @@ struct LIBSHELL_PUBLIC Range
     }
 };
 
-/// Word wrapping.
+/// Line of word-wrapped text.
 struct LIBSHELL_PUBLIC WrappedLine
 {
     Range range;
@@ -73,8 +73,19 @@ class LIBSHELL_PUBLIC ILineWrapping
     virtual void clear() = 0;
     virtual void wrapTextToWidth(String const &text, int maxWidth) = 0;
     virtual WrappedLine line(int index) const = 0;
+
+    /// Determines the visible maximum width of the wrapped content.
     virtual int width() const = 0;
+
+    /// Determines the number of lines in the wrapped content.
     virtual int height() const = 0;
+
+    /// Returns the advance width of the range.
+    virtual int rangeWidth(Range const &range) const = 0;
+
+    /// Calculates which index in the provided content range occupies a
+    /// character at a given width.
+    virtual int indexAtWidth(Range const &range, int width) const = 0;
 };
 
 } // namespace shell

doomsday/libshell/include/de/shell/monospacelinewrapping.h

@@ -52,6 +52,8 @@ class LIBSHELL_PUBLIC MonospaceLineWrapping : public ILineWrapping
     WrappedLine line(int index) const { return _lines[index]; }
     int width() const;
     int height() const;
+    int rangeWidth(Range const &range) const;
+    int indexAtWidth(Range const &range, int width) const;
 
 private:
     QList<WrappedLine> _lines;

doomsday/libshell/src/monospacelinewrapping.cpp

@@ -107,5 +107,19 @@ int MonospaceLineWrapping::height() const
     return _lines.size();
 }
 
+int MonospaceLineWrapping::rangeWidth(Range const &range) const
+{
+    return range.size();
+}
+
+int MonospaceLineWrapping::indexAtWidth(Range const &range, int width) const
+{
+    if(width <= range.size())
+    {
+        return range.start + width;
+    }
+    return range.end;
+}
+
 } // namespace shell
 } // namespace de