[twin-font] Clean up font data by joining lines and closing paths

Two changes here:

  * Replace move_to;line_to;move_to;line_to sequences with
    move_to;line_to;line_to when feasible.

  * Close paths for round glyphs.

Both improve the stroke rendering of the joint.

The first change also saves 3 bytes per joint (33 such joints).
Which we have just left unused for now.  To reclaim them one need
to update the charset table.  Something for a lazy Sunday afternoon
scripting task.

In the saving department, we can save further by:

  - Getting rid of the left/ascent/descent values as we compute
    glyph bounding box automatically.  Then we can liberally use
    the right value to adjust glyph advance width.  Saves three
    bytes per glyph (there's 96 glyphs in the font).

  - First operation is always a move_to.  So we can remove the 'm'
    for that.  Ugly though.

And the charset has zeros for the first 32 entries.  Can get rid of
that too at the expense of handling it in the code...

In total, combining the above we can save some 500 bytes.  The font
currently takes about 3.7kb.

1 files changed, 14 insertions, 4 deletions

diff --git a/src/cairo-font-face-twin.c b/src/cairo-font-face-twin.c
index 86e083df..75669a54 100644
--- a/src/cairo-font-face-twin.c
+++ b/src/cairo-font-face-twin.c
@@ -125,6 +125,9 @@ twin_scaled_font_render_glyph (cairo_scaled_font_t  *scaled_font,
 
     for (;;) {
 	switch (*g++) {
+	case 'M':
+	    cairo_close_path (cr);
+	    /* fall through */
 	case 'm':
 	    x1 = FX(*g++);
 	    y1 = FY(*g++);
@@ -135,6 +138,9 @@ twin_scaled_font_render_glyph (cairo_scaled_font_t  *scaled_font,
 	    }
 	    cairo_move_to (cr, x1, y1);
 	    continue;
+	case 'L':
+	    cairo_close_path (cr);
+	    /* fall through */
 	case 'l':
 	    x1 = FX(*g++);
 	    y1 = FY(*g++);
@@ -145,6 +151,9 @@ twin_scaled_font_render_glyph (cairo_scaled_font_t  *scaled_font,
 	    }
 	    cairo_line_to (cr, x1, y1);
 	    continue;
+	case 'C':
+	    cairo_close_path (cr);
+	    /* fall through */
 	case 'c':
 	    x1 = FX(*g++);
 	    y1 = FY(*g++);
@@ -163,18 +172,19 @@ twin_scaled_font_render_glyph (cairo_scaled_font_t  *scaled_font,
 	    }
 	    cairo_curve_to (cr, x1, y1, x2, y2, x3, y3);
 	    continue;
-	case 'o':
+	case 'E':
 	    cairo_close_path (cr);
-	    break;
+	    /* fall through */
 	case 'e':
 	    cairo_stroke (cr);
 	    break;
+	case 'X':
+	    /* filler */
+	    continue;
 	}
 	break;
     }
 
-    cairo_stroke (cr);
-
     metrics->x_advance = FX(twin_glyph_right(b)) + cairo_get_line_width (cr);
     metrics->x_advance +=  cairo_get_line_width (cr)/* XXX 2*x.margin */;
     if (info.snap)