Use QFontMetrics information for underlines (and friends) width and position

The width of the line is now dependent on the font size.

This new computation is applied to: underline, strikeout, double underline.

src/frontends/FontMetrics.h

@@ -65,6 +65,14 @@ public:
 	virtual Dimension const defaultDimension() const = 0;
 	/// return the em size
 	virtual int em() const = 0;
+	/// return the width of a line for underlining
+	virtual int lineWidth() const = 0;
+	/// return the distance from the base line to where an underline
+	/// should be drawn.
+	virtual int underlinePos() const = 0;
+	/// return the distance from the base line to where the strike out line
+	/// should be drawn.
+	virtual int strikeoutPos() const = 0;
 
 	/// return the width of the char in the font
 	virtual int width(char_type c) const = 0;

src/frontends/qt4/GuiFontMetrics.cpp

@@ -78,6 +78,24 @@ int GuiFontMetrics::em() const
 }
 
 
+int GuiFontMetrics::lineWidth() const
+{
+	return metrics_.lineWidth();
+}
+
+
+int GuiFontMetrics::underlinePos() const
+{
+	return metrics_.underlinePos();
+}
+
+
+int GuiFontMetrics::strikeoutPos() const
+{
+	return metrics_.strikeOutPos();
+}
+
+
 int GuiFontMetrics::lbearing(char_type c) const
 {
 	if (!is_utf16(c))

src/frontends/qt4/GuiFontMetrics.h

@@ -36,6 +36,9 @@ public:
 	virtual int maxDescent() const;
 	virtual Dimension const defaultDimension() const;
 	virtual int em() const;
+	virtual int lineWidth() const;
+	virtual int underlinePos() const;
+	virtual int strikeoutPos() const;
 	virtual int width(char_type c) const;
 	virtual int ascent(char_type c) const;
 	virtual int descent(char_type c) const;

src/frontends/qt4/GuiPainter.cpp

@@ -570,42 +570,37 @@ int GuiPainter::preeditText(int x, int y, char_type c,
 }
 
 
-void GuiPainter::doubleUnderline(FontInfo const & f, int x, int y, int width)
+void GuiPainter::underline(FontInfo const & f, int x, int y, int width,
+                           line_style ls)
 {
 	FontMetrics const & fm = theFontMetrics(f);
+	int const pos = fm.underlinePos();
 
-	int const below = max(fm.maxDescent() / 2, 2);
-
-	line(x, y + below, x + width, y + below, f.realColor());
-	line(x, y + below - 2, x + width, y + below - 2, f.realColor());
-}
-
-
-void GuiPainter::underline(FontInfo const & f, int x, int y, int width)
-{
-	FontMetrics const & fm = theFontMetrics(f);
-
-	int const below = max(fm.maxDescent() / 2, 2);
-	int const height = max((fm.maxDescent() / 4) - 1, 1);
-
-	if (height < 2)
-		line(x, y + below, x + width, y + below, f.realColor());
-	else
-		fillRectangle(x, y + below, width, below + height, f.realColor());
+	line(x, y + pos, x + width, y + pos,
+	     f.realColor(), ls, fm.lineWidth());
 }
 
 
 void GuiPainter::strikeoutLine(FontInfo const & f, int x, int y, int width)
 {
 	FontMetrics const & fm = theFontMetrics(f);
+	int const pos = fm.strikeoutPos();
 
-	int const middle = max((fm.maxHeight() / 4), 1);
-	int const height =  middle/3;
+	line(x, y - pos, x + width, y - pos,
+	     f.realColor(), line_solid, fm.lineWidth());
+}
 
-	if (height < 2)
-		line(x, y - middle, x + width, y - middle, f.realColor());
-	else
-		fillRectangle(x, y - middle, width, height, f.realColor());
+
+void GuiPainter::doubleUnderline(FontInfo const & f, int x, int y, int width)
+{
+	FontMetrics const & fm = theFontMetrics(f);
+	int const pos1 = fm.underlinePos() + fm.lineWidth();
+	int const pos2 = fm.underlinePos() - fm.lineWidth() + 1;
+
+	line(x, y + pos1, x + width, y + pos1,
+		 f.realColor(), line_solid, fm.lineWidth());
+	line(x, y + pos2, x + width, y + pos2,
+		 f.realColor(), line_solid, fm.lineWidth());
 }
 
 

src/frontends/qt4/GuiPainter.h

@@ -147,7 +147,7 @@ public:
 private:
 	/// check the font, and if set, draw an underline
 	void underline(FontInfo const & f,
-		int x, int y, int width);
+	               int x, int y, int width, line_style ls = line_solid);
 
 	/// check the font, and if set, draw an dashed underline
 	void dashedUnderline(FontInfo const & f,