[script] Use a compact representation for horizontal offsets between glyphs

Kerning is quite frequent, that is to apply a horizontal but no vertical
offset to a glyph. For instance by discarding the vertical coordinate
where it remains the same and only encoding the horizontal offset we
reduce the file size by ~12.5% when tracing poppler.

1 files changed, 16 insertions, 6 deletions

diff --git a/util/cairo-script/cairo-script-operators.c b/util/cairo-script/cairo-script-operators.c
index 5247682f..6a6279dd 100644
--- a/util/cairo-script/cairo-script-operators.c
+++ b/util/cairo-script/cairo-script-operators.c
@@ -2351,7 +2351,7 @@ _glyph_string (csi_t *ctx,
 	       cairo_scaled_font_t *scaled_font,
 	       cairo_glyph_t *glyphs)
 {
-    double x,y;
+    double x,y, dx;
     csi_integer_t nglyphs, i, j;
     struct glyph_advance_cache *cache;
     cairo_status_t status;
@@ -2448,12 +2448,22 @@ _glyph_string (csi_t *ctx,
 	}
 
 	case CSI_OBJECT_TYPE_INTEGER:
-	case CSI_OBJECT_TYPE_REAL: /* dx */
-	    x = csi_number_get_value (obj);
-	    if (++i == array->stack.len)
+	case CSI_OBJECT_TYPE_REAL: /* dx or x*/
+	    dx = csi_number_get_value (obj);
+	    if (i+1 == array->stack.len)
 		break;
-	    y = csi_number_get_value (&array->stack.objects[i]);
-	    break;
+
+	    switch ((int) csi_object_get_type (&array->stack.objects[i+1])) {
+	    case CSI_OBJECT_TYPE_INTEGER:
+	    case CSI_OBJECT_TYPE_REAL: /* y */
+		y = csi_number_get_value (&array->stack.objects[i+1]);
+		x = dx;
+		i++;
+		break;
+
+	    default:
+		x += dx;
+	    }
 	}
     }