Move the QPalette::resolveMask into the private

With 64bits, the mask is exhausted with the 21 colors x 3 color groups
we have right now.

In order to support accent colors, we need more palette entries. By
moving the mask into the d-pointer, we can extend QPalette within
the Qt 6 series, without breaking binary compatibility.

The resolveMask/setResolveMask methods that take integers are
documented as internals, so we can change those signatures after
Qt 6.0 as well.

As a side effect, setting the resolve mask on a QPalette detaches now.
Setting a mask is in most cases done on the result of
QPalette::resolve, which is usually detached already. And the QPalette
default constructor will have to detach from the global application
palette if that palette has any colors set explicitly.

Task-number: QTBUG-82925
Change-Id: I1e70f1c4d0dd98303e353b91df5dba2b1fe8ba01
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

src/gui/kernel/qpalette.cpp

@@ -66,11 +66,13 @@ static_assert(bitPosition(QPalette::ColorGroup(QPalette::NColorGroups - 1),
                   < sizeof(QPalette::ResolveMask) * CHAR_BIT,
                   "The resolve mask type is not wide enough to fit the entire bit mask.");
 
-class QPalettePrivate {
+class QPalettePrivate
+{
 public:
     QPalettePrivate() : ref(1), ser_no(qt_palette_count++), detach_no(0) { }
     QAtomicInt ref;
     QBrush br[QPalette::NColorGroups][QPalette::NColorRoles];
+    QPalette::ResolveMask resolveMask = {0};
     int ser_no;
     int detach_no;
 };
@@ -559,10 +561,11 @@ QPalette::QPalette()
     if (QGuiApplicationPrivate::app_pal) {
         d = QGuiApplicationPrivate::app_pal->d;
         d->ref.ref();
+        setResolveMask(0);
     } else {
         init();
         qt_palette_from_color(*this, Qt::black);
-        data.resolveMask = 0;
+        d->resolveMask = 0;
     }
 }
 
@@ -692,7 +695,8 @@ QPalette::~QPalette()
 }
 
 /*!\internal*/
-void QPalette::init() {
+void QPalette::init()
+{
     d = new QPalettePrivate;
 }
 
@@ -799,7 +803,7 @@ void QPalette::setBrush(ColorGroup cg, ColorRole cr, const QBrush &b)
         d->br[cg][cr] = b;
     }
 
-    data.resolveMask |= ResolveMask(1) << bitPosition(cg, cr);
+    d->resolveMask |= ResolveMask(1) << bitPosition(cg, cr);
 }
 
 /*!
@@ -831,7 +835,7 @@ bool QPalette::isBrushSet(ColorGroup cg, ColorRole cr) const
         return false;
     }
 
-    return data.resolveMask & (ResolveMask(1) << bitPosition(cg, cr));
+    return d->resolveMask & (ResolveMask(1) << bitPosition(cg, cr));
 }
 
 /*!
@@ -845,6 +849,7 @@ void QPalette::detach()
             for(int role = 0; role < (int)NColorRoles; role++)
                 x->br[grp][role] = d->br[grp][role];
         }
+        x->resolveMask = d->resolveMask;
         if(!d->ref.deref())
             delete d;
         d = x;
@@ -937,10 +942,10 @@ qint64 QPalette::cacheKey() const
 */
 QPalette QPalette::resolve(const QPalette &other) const
 {
-    if ((*this == other && data.resolveMask == other.data.resolveMask)
-        || data.resolveMask == 0) {
+    if ((*this == other && d->resolveMask == other.d->resolveMask)
+        || d->resolveMask == 0) {
         QPalette o = other;
-        o.data.resolveMask = data.resolveMask;
+        o.d->resolveMask = d->resolveMask;
         return o;
     }
 
@@ -949,30 +954,40 @@ QPalette QPalette::resolve(const QPalette &other) const
 
     for (int role = 0; role < int(NColorRoles); ++role) {
         for (int grp = 0; grp < int(NColorGroups); ++grp) {
-            if (!(data.resolveMask & (ResolveMask(1) << bitPosition(ColorGroup(grp), ColorRole(role))))) {
+            if (!(d->resolveMask & (ResolveMask(1) << bitPosition(ColorGroup(grp), ColorRole(role))))) {
                 palette.d->br[grp][role] = other.d->br[grp][role];
             }
         }
     }
 
-    palette.data.resolveMask |= other.data.resolveMask;
+    palette.d->resolveMask |= other.d->resolveMask;
 
     return palette;
 }
 
 /*!
-    \fn QPalette::ResolveMask QPalette::resolveMask() const
     \internal
 */
+QPalette::ResolveMask QPalette::resolveMask() const
+{
+    return d->resolveMask;
+}
+
+/*!
+    \internal
+*/
+void QPalette::setResolveMask(QPalette::ResolveMask mask)
+{
+    if (mask == d->resolveMask)
+        return;
+
+    detach();
+    d->resolveMask = mask;
+}
 
 /*!
     \typedef ResolveMask
     \internal
-*/
-
-/*!
-    \fn void QPalette::setResolveMask(ResolveMask)
-    \internal
 
     A bit mask that stores which colors the palette instance explicitly defines,
     and which ones are inherited from a parent.
@@ -1110,10 +1125,10 @@ void QPalette::setColorGroup(ColorGroup cg, const QBrush &windowText, const QBru
     for (int cr = Highlight; cr <= LinkVisited; ++cr) {
         if (cg == All) {
             for (int group = Active; group < NColorGroups; ++group) {
-                data.resolveMask &= ~(ResolveMask(1) << bitPosition(ColorGroup(group), ColorRole(cr)));
+                d->resolveMask &= ~(ResolveMask(1) << bitPosition(ColorGroup(group), ColorRole(cr)));
             }
         } else {
-            data.resolveMask &= ~(ResolveMask(1) << bitPosition(ColorGroup(cg), ColorRole(cr)));
+            d->resolveMask &= ~(ResolveMask(1) << bitPosition(ColorGroup(cg), ColorRole(cr)));
         }
     }
 }

src/gui/kernel/qpalette.h

@@ -157,8 +157,8 @@ public:
     QPalette resolve(const QPalette &other) const;
 
     using ResolveMask = quint64;
-    inline ResolveMask resolveMask() const { return data.resolveMask; }
-    inline void setResolveMask(ResolveMask mask) { data.resolveMask = mask; }
+    ResolveMask resolveMask() const;
+    void setResolveMask(ResolveMask mask);
 
 private:
     void setColorGroup(ColorGroup cr, const QBrush &windowText, const QBrush &button,
@@ -183,7 +183,6 @@ private:
 
     QPalettePrivate *d;
     struct Data {
-        ResolveMask resolveMask{0};
         ColorGroup currentGroup{Active};
     };
     Data data;