for VALIGN_SUB and VALIGN_SUPER only increase line-height if necessary

For cases like

<div style="line-height:1.7">
dillo dillo dillo dillo dillo dillo
dillo dillo dillo dillo dillo dillo
dillo dillo dillo dillo dillo dillo
dillo dillo dillo dillo dillo <sup>dillo</sup>
dillo dillo dillo dillo dillo dillo
dillo dillo dillo dillo dillo dillo
dillo dillo dillo dillo dillo <sub>dillo</sub>
dillo dillo dillo dillo dillo dillo
dillo dillo dillo dillo dillo dillo
</div>

this gives equally spaced lines and also seems to
replicate firefox behaviour.

1 files changed, 9 insertions, 4 deletions

diff --git a/dw/textblock.cc b/dw/textblock.cc
index 1d486083..cd301871 100644
--- a/dw/textblock.cc
+++ b/dw/textblock.cc
@@ -1447,6 +1447,8 @@ void Textblock::calcTextSize (const char *text, size_t len,
                               core::style::Style *style,
                               core::Requisition *size, bool isStart, bool isEnd)
 {
+   int requiredAscent, requiredDescent;
+
    size->width = textWidth (text, 0, len, style, isStart, isEnd);
    size->ascent = style->font->ascent;
    size->descent = style->font->descent;
@@ -1485,10 +1487,13 @@ void Textblock::calcTextSize (const char *text, size_t len,
    /* In case of a sub or super script we increase the word's height and
     * potentially the line's height.
     */
-   if (style->valign == core::style::VALIGN_SUB)
-      size->descent += (style->font->ascent / 3);
-   else if (style->valign == core::style::VALIGN_SUPER)
-      size->ascent += (style->font->ascent / 2);
+   if (style->valign == core::style::VALIGN_SUB) {
+      requiredDescent = style->font->descent + style->font->ascent / 3;
+      size->descent = misc::max (size->descent, requiredDescent);
+   } else if (style->valign == core::style::VALIGN_SUPER) {
+      requiredAscent = style->font->ascent + style->font->ascent / 2;
+      size->ascent = misc::max (size->ascent, requiredAscent);
+   }
 }
 
 /**