Fix implementation of spell check underline styles

The QTextCharFormat documentation said that the used style is based on
QStyle::SH_SpellCheckUnderlineStyle style hint, however in fact the
implementation (drawTextItemDecoration in qpainter.cpp) uses
themeHint(QPlatformTheme::SpellCheckUnderlineStyle) instead since Qt 5
(see commit 1f9ae50457a3750f).

Make the documentation match that behavior, and update QPlatformTheme
to use the correct default value.

Also, switch Cocoa theme to use DotLine, as that is what native macOS
applications use.

Change-Id: I2a6bb3da6c7b0686dca87ed2c251b6abc006123c
Task-number: QTBUG-50499
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@qt.io>

4 files changed, 9 insertions, 7 deletions

diff --git a/src/gui/kernel/qplatformtheme.cpp b/src/gui/kernel/qplatformtheme.cpp
index ebf65eda12..cd3966fb47 100644
--- a/src/gui/kernel/qplatformtheme.cpp
+++ b/src/gui/kernel/qplatformtheme.cpp
@@ -531,7 +531,7 @@ QVariant QPlatformTheme::defaultThemeHint(ThemeHint hint)
     case UiEffects:
         return QVariant(int(0));
     case SpellCheckUnderlineStyle:
-        return QVariant(int(QTextCharFormat::SpellCheckUnderline));
+        return QVariant(int(QTextCharFormat::WaveUnderline));
     case TabFocusBehavior:
         return QVariant(int(Qt::TabFocusAllControls));
     case IconPixmapSizes:
diff --git a/src/gui/text/qtextformat.cpp b/src/gui/text/qtextformat.cpp
index 1653ac8c33..8fe474af2c 100644
--- a/src/gui/text/qtextformat.cpp
+++ b/src/gui/text/qtextformat.cpp
@@ -1333,9 +1333,9 @@ bool QTextFormat::operator==(const QTextFormat &rhs) const
     \value DashDotLine          Dashs and dots are drawn using Qt::DashDotLine.
     \value DashDotDotLine       Underlines draw drawn using Qt::DashDotDotLine.
     \value WaveUnderline        The text is underlined using a wave shaped line.
-    \value SpellCheckUnderline  The underline is drawn depending on the QStyle::SH_SpellCeckUnderlineStyle
-                                style hint of the QApplication style. By default this is mapped to
-                                WaveUnderline, on \macos it is mapped to DashDotLine.
+    \value SpellCheckUnderline  The underline is drawn depending on the SpellCheckUnderlineStyle
+                                theme hint of QPlatformTheme. By default this is mapped to
+                                WaveUnderline, on \macos it is mapped to DotLine.
 
     \sa Qt::PenStyle
 */
diff --git a/src/plugins/platforms/cocoa/qcocoatheme.mm b/src/plugins/platforms/cocoa/qcocoatheme.mm
index 04dce802f3..5239864ad8 100644
--- a/src/plugins/platforms/cocoa/qcocoatheme.mm
+++ b/src/plugins/platforms/cocoa/qcocoatheme.mm
@@ -55,6 +55,7 @@
 #include <QtGui/private/qguiapplication_p.h>
 #include <QtGui/private/qcoregraphics_p.h>
 #include <QtGui/qpainter.h>
+#include <QtGui/qtextformat.h>
 #include <QtFontDatabaseSupport/private/qcoretextfontdatabase_p.h>
 #include <QtThemeSupport/private/qabstractfileiconengine_p.h>
 #include <qpa/qplatformdialoghelper.h>
@@ -344,6 +345,8 @@ QVariant QCocoaTheme::themeHint(ThemeHint hint) const
         return QVariant(QChar(0x2022));
     case QPlatformTheme::UiEffects:
         return QVariant(int(HoverEffect));
+    case QPlatformTheme::SpellCheckUnderlineStyle:
+        return QVariant(int(QTextCharFormat::DotLine));
     default:
         break;
     }
diff --git a/src/widgets/styles/qstyle.cpp b/src/widgets/styles/qstyle.cpp
index 0350d5e1a5..faa5f1e67e 100644
--- a/src/widgets/styles/qstyle.cpp
+++ b/src/widgets/styles/qstyle.cpp
@@ -1840,9 +1840,8 @@ void QStyle::drawItemPixmap(QPainter *painter, const QRect &rect, int alignment,
 
     \value SH_UnderlineShortcut  Whether shortcuts are underlined.
 
-    \value SH_SpellCheckUnderlineStyle  A
-        QTextCharFormat::UnderlineStyle value that specifies the way
-        misspelled words should be underlined.
+    \value SH_SpellCheckUnderlineStyle  Obsolete. Use SpellCheckUnderlineStyle
+    hint in QPlatformTheme instead.
 
     \value SH_SpinBox_AnimateButton  Animate a click when up or down is
     pressed in a spin box.