Fix vertical alignment of inline images

Inline images can have 4 different alignments. Unfortunately,
AlignTop and AlignBottom can only be set once we have laid out
the whole line and know the total height of the line, as one
could otherwise end up with lines that are too high.

To fix this, position the images for these cases in a second loop
after we have calculated the length of the line and the maximal
image height in that line.

Task-number: QTBUG-59310
Change-Id: I1fd4cd39e43a13d1967b9f5c9ce8270a99269cd9
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>

2 files changed, 63 insertions, 15 deletions

diff --git a/src/gui/text/qtextdocumentlayout.cpp b/src/gui/text/qtextdocumentlayout.cpp
index a9227f0171..9aeea44dd3 100644
--- a/src/gui/text/qtextdocumentlayout.cpp
+++ b/src/gui/text/qtextdocumentlayout.cpp
@@ -3049,18 +3049,12 @@ void QTextDocumentLayout::resizeInlineObject(QTextInlineObject item, int posInDo
     QSizeF inlineSize = (pos == QTextFrameFormat::InFlow ? intrinsic : QSizeF(0, 0));
     item.setWidth(inlineSize.width());
 
-    QFontMetrics m(f.font());
-    switch (f.verticalAlignment())
-    {
-    case QTextCharFormat::AlignMiddle:
-        item.setDescent(inlineSize.height() / 2);
-        item.setAscent(inlineSize.height() / 2);
-        break;
-    case QTextCharFormat::AlignBaseline:
-        item.setDescent(m.descent());
-        item.setAscent(inlineSize.height() - m.descent());
-        break;
-    default:
+    if (f.verticalAlignment() == QTextCharFormat::AlignMiddle) {
+        QFontMetrics m(f.font());
+        qreal halfX = m.xHeight()/2.;
+        item.setAscent((inlineSize.height() + halfX) / 2.);
+        item.setDescent((inlineSize.height() - halfX) / 2.);
+    } else {
         item.setDescent(0);
         item.setAscent(inlineSize.height());
     }
diff --git a/src/gui/text/qtextlayout.cpp b/src/gui/text/qtextlayout.cpp
index ca6866d836..be306ed224 100644
--- a/src/gui/text/qtextlayout.cpp
+++ b/src/gui/text/qtextlayout.cpp
@@ -1823,6 +1823,9 @@ void QTextLine::layout_helper(int maxGlyphs)
     lbh.logClusters = eng->layoutData->logClustersPtr;
     lbh.previousGlyph = 0;
 
+    bool hasInlineObject = false;
+    QFixed maxInlineObjectHeight = 0;
+
     while (newItem < eng->layoutData->items.size()) {
         lbh.resetRightBearing();
         lbh.softHyphenWidth = 0;
@@ -1851,8 +1854,11 @@ void QTextLine::layout_helper(int maxGlyphs)
         lbh.tmpData.leading = qMax(lbh.tmpData.leading + lbh.tmpData.ascent,
                                    current.leading + current.ascent) - qMax(lbh.tmpData.ascent,
                                                                             current.ascent);
-        lbh.tmpData.ascent = qMax(lbh.tmpData.ascent, current.ascent);
-        lbh.tmpData.descent = qMax(lbh.tmpData.descent, current.descent);
+        if (current.analysis.flags != QScriptAnalysis::Object) {
+            // objects need some special treatment as they can special alignment or be floating
+            lbh.tmpData.ascent = qMax(lbh.tmpData.ascent, current.ascent);
+            lbh.tmpData.descent = qMax(lbh.tmpData.descent, current.descent);
+        }
 
         if (current.analysis.flags == QScriptAnalysis::Tab && (alignment & (Qt::AlignLeft | Qt::AlignRight | Qt::AlignCenter | Qt::AlignJustify))) {
             lbh.whiteSpaceOrObject = true;
@@ -1900,9 +1906,18 @@ void QTextLine::layout_helper(int maxGlyphs)
 
             if (eng->block.docHandle()) {
                 QTextInlineObject inlineObject(item, eng);
-                eng->docLayout()->positionInlineObject(inlineObject, eng->block.position() + current.position, inlineObject.format());
+                QTextFormat f = inlineObject.format();
+                eng->docLayout()->positionInlineObject(inlineObject, eng->block.position() + current.position, f);
+                QTextCharFormat::VerticalAlignment valign = f.toCharFormat().verticalAlignment();
+                if (valign != QTextCharFormat::AlignTop && valign != QTextCharFormat::AlignBottom) {
+                    lbh.tmpData.ascent = qMax(lbh.tmpData.ascent, current.ascent);
+                    lbh.tmpData.descent = qMax(lbh.tmpData.descent, current.descent);
+                }
             }
 
+            hasInlineObject = true;
+            maxInlineObjectHeight = qMax(maxInlineObjectHeight, current.ascent + current.descent);
+
             lbh.tmpData.textWidth += current.width;
 
             newItem = item + 1;
@@ -2038,6 +2053,43 @@ found:
         line += lbh.tmpData;
     }
 
+    if (hasInlineObject && eng->block.docHandle()) {
+        // position top/bottom aligned inline objects
+        if (maxInlineObjectHeight > line.ascent + line.descent) {
+            // extend line height if required
+            QFixed toAdd = (maxInlineObjectHeight - line.ascent - line.descent)/2;
+            line.ascent += toAdd;
+            line.descent = maxInlineObjectHeight - line.ascent;
+        }
+        int startItem = eng->findItem(line.from);
+        int endItem = eng->findItem(line.from + line.length);
+        if (endItem < 0)
+            endItem = eng->layoutData->items.size();
+        for (int item = startItem; item < endItem; ++item) {
+            QScriptItem &current = eng->layoutData->items[item];
+            if (current.analysis.flags == QScriptAnalysis::Object) {
+                QTextInlineObject inlineObject(item, eng);
+                QTextCharFormat::VerticalAlignment align = inlineObject.format().toCharFormat().verticalAlignment();
+                QFixed height = current.ascent + current.descent;
+                switch (align) {
+                case QTextCharFormat::AlignTop:
+                    current.ascent = line.ascent;
+                    current.descent = height - line.ascent;
+                    break;
+                case QTextCharFormat::AlignBottom:
+                    current.descent = line.descent;
+                    current.ascent = height - line.descent;
+                    break;
+                default:
+                    break;
+                }
+                Q_ASSERT(line.ascent >= current.ascent);
+                Q_ASSERT(line.descent >= current.descent);
+            }
+        }
+    }
+
+
     LB_DEBUG("line length = %d, ascent=%f, descent=%f, textWidth=%f (spacew=%f)", line.length, line.ascent.toReal(),
            line.descent.toReal(), line.textWidth.toReal(), lbh.spaceData.width.toReal());
     LB_DEBUG("        : '%s'", eng->layoutData->string.mid(line.from, line.length).toUtf8().data());
@@ -2511,6 +2563,8 @@ void QTextLine::draw(QPainter *p, const QPointF &pos, const QTextLayout::FormatR
                     QFixed itemY = y - si.ascent;
                     if (format.verticalAlignment() == QTextCharFormat::AlignTop) {
                         itemY = y - lineBase;
+                    } else if (format.verticalAlignment() == QTextCharFormat::AlignBottom) {
+                        itemY = y + line.descent - si.ascent - si.descent;
                     }
 
                     QRectF itemRect(iterator.x.toReal(), itemY.toReal(), iterator.itemWidth.toReal(), si.height().toReal());