diff -r e21306fce501 dw/textblock.cc
--- a/dw/textblock.cc	Sun Dec 20 19:02:02 2009 +0000
+++ b/dw/textblock.cc	Tue Dec 22 00:59:00 2009 +0000
@@ -329,6 +329,48 @@
    //DBG_MSG_END (widget);
 }
 
+/*
+ * Determine the Y offset for a word of the given style and dimensions
+ * in the line.
+ */
+int Textblock::wordYOffsetLine(Line *line, int ascent, int descent,
+                               core::style::Style *style)
+{
+   int y = 0;
+
+   if (style->valign == core::style::VALIGN_TOP) {
+      MSG("valign top\n");
+   } else if (style->valign == core::style::VALIGN_TEXT_TOP) {
+      y = line->ascent - style->font->ascent;
+      MSG("valign text-top\n");
+   } else if (style->valign == core::style::VALIGN_MIDDLE) {
+      /* It is supposed to be centered at xHeight/2, i.e., something more
+       * like the "center of mass" than the midpoint of the Line.
+       */
+      y =  line->ascent - (style->font->ascent - style->font->descent +
+            (ascent + descent)) / 2;
+      MSG("valign middle\n");
+   } else {
+      y = line->ascent - ascent;
+
+      if (style->valign == core::style::VALIGN_BASELINE) {
+      } else if (style->valign == core::style::VALIGN_BOTTOM) {
+         y += line->descent - descent;
+         MSG("valign bottom\n");
+      } else if (style->valign == core::style::VALIGN_TEXT_BOTTOM) {
+         y += style->font->descent - descent;
+         MSG("valign text-bottom\n");
+      } else if (style->valign == core::style::VALIGN_SUPER) {
+         y -= style->font->ascent / 2;
+         MSG("valign super\n");
+      } else if (style->valign == core::style::VALIGN_SUB) {
+         y += style->font->ascent / 3;
+         MSG("valign sub\n");
+      }
+   }
+   return y;
+}
+
 
 void Textblock::sizeAllocateImpl (core::Allocation *allocation)
 {
@@ -359,17 +401,10 @@
          case core::Content::WIDGET:
             /** \todo Justification within the line is done here. */
             childAllocation.x = xCursor + allocation->x;
-            /* align=top:
-               childAllocation.y = line->top + allocation->y;
-            */
-
-            /* align=bottom (base line) */
-            /* Commented lines break the n2 and n3 test cases at
-             * http://www.dillo.org/test/img/ */
-            childAllocation.y =
-               lineYOffsetCanvasAllocation (line, allocation)
-               + (line->ascent - word->size.ascent);
-               // - word->content.widget->getStyle()->margin.top;
+            childAllocation.y = lineYOffsetCanvasAllocation(line, allocation) +
+                                wordYOffsetLine(line, word->size.ascent,
+                                                word->size.descent,
+                                                word->style);
             childAllocation.width = word->size.width;
             childAllocation.ascent = word->size.ascent;
                // + word->content.widget->getStyle()->margin.top;
@@ -861,6 +896,90 @@
 }
 
 /*
+ * Update the line's ascent and descent to accommodate the word.
+ */
+void Textblock::calcLineAscentDescent(const Word *word, Line *line,
+                                      int lineIndex)
+{
+   int wordAscent;
+   int wordDescent;
+
+   switch (word->style->valign) {
+      case core::style::VALIGN_BASELINE:
+         wordAscent = word->size.ascent;
+         wordDescent = word->size.descent;
+         break;
+      case core::style::VALIGN_SUPER:
+         wordAscent = word->size.ascent + word->style->font->ascent / 2;
+         wordDescent = word->size.descent;
+         break;
+      case core::style::VALIGN_SUB:
+         wordAscent = word->size.ascent;
+         wordDescent = word->size.descent + word->style->font->ascent / 3;
+         break;
+      case core::style::VALIGN_TOP:
+      case core::style::VALIGN_BOTTOM:
+      {
+         /* \todo This needs to be more sophisticated, since a word later in
+          * the line could provide more room, but for now let's stretch out the
+          * line if we need more room.
+          */
+         int extra = word->size.ascent + word->size.descent -
+                     (line->ascent + line->descent);
+
+         wordAscent = line->ascent;
+         wordDescent = line->descent;
+
+         if (extra > 0) {
+            int extraDescent = extra * word->size.descent /
+                               (word->size.ascent + word->size.descent);
+            wordDescent += extraDescent;
+            wordAscent += extra - extraDescent;
+         }
+         break;
+      }
+      case core::style::VALIGN_MIDDLE:
+         wordAscent = (word->style->font->ascent - word->style->font->descent +
+                       word->size.ascent + word->size.descent) / 2;
+         wordDescent = word->size.ascent + word->size.descent - wordAscent;
+         break;
+      case core::style::VALIGN_TEXT_TOP:
+         wordAscent = word->style->font->ascent;
+         wordDescent = word->size.ascent + word->size.descent - wordAscent;
+         break;
+      case core::style::VALIGN_TEXT_BOTTOM:
+         wordDescent = word->style->font->descent;
+         wordAscent = word->size.ascent + word->size.descent - wordDescent;
+         break;
+      default:
+         misc::assertNotReached ();
+   }
+   line->ascent = misc::max (line->ascent, wordAscent);
+   line->descent = misc::max (line->descent, wordDescent);
+
+   if (word->content.type == core::Content::WIDGET) {
+      line->marginDescent =
+         misc::max (line->marginDescent,
+                    wordDescent +
+                    word->content.widget->getStyle()->margin.bottom);
+
+      /* If the widget is not in the first line of the paragraph, its top
+       * margin may make the line higher.
+       */
+      if (lineIndex > 0) {
+         /* Here, we know already what the break and the bottom margin
+          * contributed to the space before this line.
+          */
+         line->ascent =
+            misc::max (line->ascent,
+                       wordAscent
+                       + word->content.widget->getStyle()->margin.top);
+      }
+   } else
+      line->marginDescent = misc::max (line->marginDescent, line->descent);
+}
+
+/*
  * This method is called in two cases: (i) when a word is added (by
  * Dw_page_add_word), and (ii) when a page has to be (partially)
  * rewrapped. It does word wrap, and adds new lines, if necessary.
@@ -948,41 +1067,7 @@
    }
 
    lastLine->lastWord = wordIndex;
-   lastLine->ascent = misc::max (lastLine->ascent, (int) word->size.ascent);
-   lastLine->descent = misc::max (lastLine->descent, (int) word->size.descent);
-
-   //DBG_OBJ_ARRSET_NUM (page, "lines.%d.ascent", page->num_lines - 1,
-   //                    lastLine->ascent);
-   //DBG_OBJ_ARRSET_NUM (page, "lines.%d.descent", page->num_lines - 1,
-   //                    lastLine->descent);
-
-   if (word->content.type == core::Content::WIDGET) {
-      lastLine->marginDescent =
-         misc::max (lastLine->marginDescent,
-                    word->size.descent +
-                    word->content.widget->getStyle()->margin.bottom);
-
-      //DBG_OBJ_ARRSET_NUM (page, "lines.%d.descent", page->num_lines - 1,
-      //                    lastLine->descent);
-
-      /* If the widget is not in the first line of the paragraph, its top
-       * margin may make the line higher.
-       */
-      if (lines->size () > 1) {
-         /* Here, we know already what the break and the bottom margin
-          * contributed to the space before this line.
-          */
-         lastLine->ascent =
-            misc::max (lastLine->ascent,
-                       word->size.ascent
-                       + word->content.widget->getStyle()->margin.top);
-
-         //DBG_OBJ_ARRSET_NUM (page, "lines.%d.ascent", page->num_lines - 1,
-         //                    lastLine->ascent);
-      }
-   } else
-      lastLine->marginDescent =
-         misc::max (lastLine->marginDescent, lastLine->descent);
+   calcLineAscentDescent(word, lastLine, lines->size() - 1);
 
    getWordExtremes (word, &wordExtremes);
    lastSpace = (wordIndex > 0) ? words->getRef(wordIndex - 1)->origSpace : 0;
@@ -1216,23 +1301,23 @@
  */
 void Textblock::decorateText(core::View *view, core::style::Style *style,
                              core::style::Color::Shading shading,
-                             int x, int yBase, int width)
+                             int x, int y, int width)
 {
-   int y;
+   int y2;
 
-   if (style->textDecoration & core::style::TEXT_DECORATION_UNDERLINE) {
-      y = yBase + 1;
-      view->drawLine (style->color, shading, x, y, x + width - 1, y);
-   }
    if (style->textDecoration & core::style::TEXT_DECORATION_OVERLINE) {
-      y = yBase - style->font->ascent + 1;
-      view->drawLine (style->color, shading, x, y, x + width - 1, y);
+      y2 = y + 1;
+      view->drawLine (style->color, shading, x, y2, x + width - 1, y2);
    }
    if (style->textDecoration & core::style::TEXT_DECORATION_LINE_THROUGH) {
       int height = 1 + style->font->xHeight / 10;
 
-      y = yBase + (style->font->descent - style->font->ascent) / 2;
-      view->drawRectangle (style->color, shading, true, x, y, width, height);
+      y2 = y + (style->font->ascent + style->font->descent) / 2;
+      view->drawRectangle (style->color, shading, true, x, y2, width, height);
+   }
+   if (style->textDecoration & core::style::TEXT_DECORATION_UNDERLINE) {
+      y2 = y + style->font->ascent + 1;
+      view->drawLine (style->color, shading, x, y2, x + width - 1, y2);
    }
 }
 
@@ -1240,34 +1325,27 @@
  * Draw a word of text.
  */
 void Textblock::drawText(int wordIndex, core::View *view,core::Rectangle *area,
-                         int xWidget, int yWidgetBase)
+                         int xWidget, int yWidget)
 {
    Word *word = words->getRef(wordIndex);
    int xWorld = allocation.x + xWidget;
    core::style::Style *style = word->style;
-   int yWorldBase;
-
-   /* Adjust the text baseline if the word is <SUP>-ed or <SUB>-ed. */
-   if (style->valign == core::style::VALIGN_SUB)
-      yWidgetBase += style->font->ascent / 3;
-   else if (style->valign == core::style::VALIGN_SUPER) {
-      yWidgetBase -= style->font->ascent / 2;
-   }
-   yWorldBase = yWidgetBase + allocation.y;
+   int yWorld = yWidget + allocation.y;
 
    /* Draw background (color, image), when given. */
    if (style->hasBackground ())
       drawBox (
-         view, style, area, xWidget, yWidgetBase - style->font->ascent,
+         view, style, area, xWidget, yWidget,
          word->size.width, style->font->ascent + style->font->descent, false);
 
    view->drawText (style->font, style->color,
-                   core::style::Color::SHADING_NORMAL, xWorld, yWorldBase,
-                   word->content.text, strlen (word->content.text));
+                   core::style::Color::SHADING_NORMAL, xWorld,
+                   yWorld + style->font->ascent, word->content.text,
+                   strlen (word->content.text));
 
    if (style->textDecoration)
       decorateText(view, style, core::style::Color::SHADING_NORMAL, xWorld,
-                   yWorldBase, word->size.width);
+                   yWorld, word->size.width);
 
    for (int layer = 0; layer < core::HIGHLIGHT_NUM_LAYERS; layer++) {
       if (hlStart[layer].index <= wordIndex &&
@@ -1303,18 +1381,18 @@
             /* Draw background for highlighted text. */
             view->drawRectangle (
                wordBgColor, core::style::Color::SHADING_INVERSE, true, xStart,
-               yWorldBase - style->font->ascent, width,
-               style->font->ascent + style->font->descent);
+               yWorld, width, style->font->ascent + style->font->descent);
 
             /* Highlight the text. */
             view->drawText (style->font, style->color,
                             core::style::Color::SHADING_INVERSE, xStart,
-                            yWorldBase, word->content.text + firstCharIdx,
+                            yWorld + style->font->ascent,
+                            word->content.text + firstCharIdx,
                             lastCharIdx - firstCharIdx);
 
             if (style->textDecoration)
                decorateText(view, style, core::style::Color::SHADING_INVERSE,
-                            xStart, yWorldBase, width);
+                            xStart, yWorld, width);
          }
       }
    }
@@ -1324,22 +1402,14 @@
  * Draw a space.
  */
 void Textblock::drawSpace(int wordIndex, core::View *view,
-                          core::Rectangle *area, int xWidget, int yWidgetBase)
+                          core::Rectangle *area, int xWidget, int yWidget)
 {
    Word *word = words->getRef(wordIndex);
    int xWorld = allocation.x + xWidget;
-   int yWorldBase;
+   int yWorld = allocation.y + yWidget;
    core::style::Style *style = word->spaceStyle;
    bool highlight = false;
 
-   /* Adjust the space baseline if it is <SUP>-ed or <SUB>-ed */
-   if (style->valign == core::style::VALIGN_SUB)
-      yWidgetBase += style->font->ascent / 3;
-   else if (style->valign == core::style::VALIGN_SUPER) {
-      yWidgetBase -= style->font->ascent / 2;
-   }
-   yWorldBase = allocation.y + yWidgetBase;
-
    for (int layer = 0; layer < core::HIGHLIGHT_NUM_LAYERS; layer++) {
       if (hlStart[layer].index <= wordIndex &&
           hlEnd[layer].index > wordIndex) {
@@ -1355,13 +1425,13 @@
 
       view->drawRectangle (
          spaceBgColor, core::style::Color::SHADING_INVERSE, true, xWorld,
-         yWorldBase - style->font->ascent, word->effSpace,
+         yWorld, word->effSpace,
          style->font->ascent + style->font->descent);
    } else {
       /* Draw space background (color, image), when given. */
       if (style->hasBackground ())
          drawBox (
-            view, style, area, xWidget, yWidgetBase - style->font->ascent,
+            view, style, area, xWidget, yWidget,
             word->effSpace, style->font->ascent + style->font->descent, false);
    }
    if (style->textDecoration) {
@@ -1369,7 +1439,7 @@
          core::style::Color::SHADING_INVERSE :
          core::style::Color::SHADING_NORMAL;
 
-      decorateText(view, style, shading, xWorld, yWorldBase, word->effSpace);
+      decorateText(view, style, shading, xWorld, yWorld, word->effSpace);
    }
 }
 
@@ -1382,7 +1452,7 @@
 void Textblock::drawLine (Line *line, core::View *view, core::Rectangle *area)
 {
    int xWidget = lineXOffsetWidget(line);
-   int yWidgetBase = lineYOffsetWidget (line) + line->ascent;
+   int yWidget = lineYOffsetWidget (line);
 
    /* Here's an idea on how to optimize this routine to minimize the number
     * of drawing calls:
@@ -1400,6 +1470,7 @@
       if (xWidget + word->size.width + word->effSpace >= area->x) {
          if (word->content.type == core::Content::TEXT ||
              word->content.type == core::Content::WIDGET) {
+            int yOffset;
 
             if (word->size.width > 0) {
                if (word->content.type == core::Content::WIDGET) {
@@ -1409,14 +1480,20 @@
                   if (child->intersects (area, &childArea))
                      child->draw (view, &childArea);
                } else {
-                  drawText(wordIndex, view, area, xWidget, yWidgetBase);
+                  yOffset = wordYOffsetLine(line, word->style->font->ascent,
+                                            word->style->font->descent,
+                                            word->style);
+                  drawText(wordIndex, view, area, xWidget, yWidget + yOffset);
                }
             }
             if (word->effSpace > 0 && wordIndex < line->lastWord &&
                 words->getRef(wordIndex + 1)->content.type !=
                                                         core::Content::BREAK) {
+               yOffset = wordYOffsetLine(line, word->spaceStyle->font->ascent,
+                                         word->spaceStyle->font->descent,
+                                         word->spaceStyle);
                drawSpace(wordIndex, view, area, xWidget + word->size.width,
-                         yWidgetBase);
+                         yWidget + yOffset);
             }
 
          }
@@ -1582,17 +1659,8 @@
    size->width = layout->textWidth (style->font, text, len);
    size->ascent = style->font->ascent;
    size->descent = style->font->descent;
-
-   /* 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 += (size->ascent / 3);
-   else if (style->valign == core::style::VALIGN_SUPER)
-      size->ascent += (size->ascent / 2);
 }
 
-
 /**
  * Add a word to the page structure. Stashes the argument pointer in
  * the page data structure so that it will be deallocated on destroy.
diff -r e21306fce501 dw/textblock.hh
--- a/dw/textblock.hh	Sun Dec 20 19:02:02 2009 +0000
+++ b/dw/textblock.hh	Tue Dec 22 00:59:00 2009 +0000
@@ -260,6 +260,7 @@
    void markChange (int ref);
    void justifyLine (Line *line, int availWidth);
    void addLine (int wordInd, bool newPar);
+   void calcLineAscentDescent (const Word *word, Line *line, int lineIndex);
    void calcWidgetSize (core::Widget *widget, core::Requisition *size);
    void rewrap ();
    void decorateText(core::View *view, core::style::Style *style,
@@ -339,6 +340,8 @@
    {
       return lineYOffsetCanvas (lines->getRef (lineIndex));
    }
+   int wordYOffsetLine(Line *line, int ascent, int descent,
+                       core::style::Style *style);
 
    bool sendSelectionEvent (core::SelectionState::EventType eventType,
                             core::MousePositionEvent *event);