Backport adjusting cursorToX for trailing spaces from Qt 5

This is a backport of d07982b104de5dc2b54bef09c071500ce22cf539
from Qt 5 which fixes cursorToX() in some cases, e.g. when
a line filled with spaces is ended by a soft line break.

Task-number: QTBUG-27354
Change-Id: Ia88873aeb3c0620044fefe24fc6bb1310e3aa339
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
Reviewed-by: Andrew den Exter <andrew.den.exter@qinetic.com.au>

2 files changed, 10 insertions, 15 deletions

diff --git a/src/gui/text/qtextengine.cpp b/src/gui/text/qtextengine.cpp
index b368fd9..319829d 100644
--- a/src/gui/text/qtextengine.cpp
+++ b/src/gui/text/qtextengine.cpp
@@ -2826,13 +2826,7 @@ QFixed QTextEngine::leadingSpaceWidth(const QScriptLine &line)
         || !isRightToLeft())
         return QFixed();
 
-    int pos = line.length;
-    const HB_CharAttributes *attributes = this->attributes();
-    if (!attributes)
-        return QFixed();
-    while (pos > 0 && attributes[line.from + pos - 1].whiteSpace)
-        --pos;
-    return width(line.from + pos, line.length - pos);
+    return width(line.from + line.length, line.trailingSpaces);
 }
 
 QFixed QTextEngine::alignLine(const QScriptLine &line)
@@ -2842,14 +2836,12 @@ QFixed QTextEngine::alignLine(const QScriptLine &line)
     // if width is QFIXED_MAX that means we used setNumColumns() and that implicitly makes this line left aligned.
     if (!line.justified && line.width != QFIXED_MAX) {
         int align = option.alignment();
-        if (align & Qt::AlignLeft)
-            x -= leadingSpaceWidth(line);
         if (align & Qt::AlignJustify && isRightToLeft())
             align = Qt::AlignRight;
         if (align & Qt::AlignRight)
-            x = line.width - (line.textAdvance + leadingSpaceWidth(line));
+            x = line.width - (line.textAdvance);
         else if (align & Qt::AlignHCenter)
-            x = (line.width - line.textAdvance)/2 - leadingSpaceWidth(line);
+            x = (line.width - line.textAdvance)/2;
     }
     return x;
 }
diff --git a/src/gui/text/qtextlayout.cpp b/src/gui/text/qtextlayout.cpp
index 4b26eb5..bb216e9 100644
--- a/src/gui/text/qtextlayout.cpp
+++ b/src/gui/text/qtextlayout.cpp
@@ -2498,13 +2498,14 @@ qreal QTextLine::cursorToX(int *cursorPos, Edge edge) const
     bool lastLine = i >= eng->lines.size() - 1;
 
     QFixed x = line.x;
-    x += eng->alignLine(line);
+    x += eng->alignLine(line) - eng->leadingSpaceWidth(line);
 
     if (!i && !eng->layoutData->items.size()) {
         *cursorPos = 0;
         return x.toReal();
     }
 
+    int lineEnd = line.from + line.length + line.trailingSpaces;
     int pos = *cursorPos;
     int itm;
     const HB_CharAttributes *attributes = eng->attributes();
@@ -2512,9 +2513,9 @@ qreal QTextLine::cursorToX(int *cursorPos, Edge edge) const
         *cursorPos = 0;
         return x.toReal();
     }
-    while (pos < line.from + line.length && !attributes[pos].charStop)
+    while (pos < lineEnd && !attributes[pos].charStop)
         pos++;
-    if (pos == line.from + (int)line.length) {
+    if (pos == lineEnd) {
         // end of line ensure we have the last item on the line
         itm = eng->findItem(pos-1);
     }
@@ -2546,7 +2547,6 @@ qreal QTextLine::cursorToX(int *cursorPos, Edge edge) const
 
     bool reverse = eng->layoutData->items[itm].analysis.bidiLevel % 2;
 
-    int lineEnd = line.from + line.length;
 
     // add the items left of the cursor
 
@@ -2619,6 +2619,9 @@ qreal QTextLine::cursorToX(int *cursorPos, Edge edge) const
     if (eng->option.wrapMode() != QTextOption::NoWrap && x > line.x + line.width)
         x = line.x + line.width;
 
+    if (eng->option.wrapMode() != QTextOption::NoWrap && x < 0)
+        x = 0;
+
     *cursorPos = pos + si->position;
     return x.toReal();
 }