Add button layout for dialogs on Android

It used macOS layout before, but it differs from the actual layout in
Android/Material Design: affirmative actions are on the right side,
dismissive actions are directly to the left of the affirmative actions
and neutral actions are on the left side.

[ChangeLog][Platform-specific Changes][Android] Android dialogs now have
more appropriate button layout, with affirmative actions on the right.

Task-number: QTBUG-58060
Change-Id: I0755f80261410c64cf4f854b7f2a72e2d959db28
Reviewed-by: BogDan Vatra <bogdan@kdab.com>
Reviewed-by: J-P Nurmi <jpnurmi@qt.io>

src/gui/kernel/qplatformdialoghelper.cpp

@@ -60,7 +60,7 @@ QT_BEGIN_NAMESPACE
 
 */
 
-static const int buttonRoleLayouts[2][5][14] =
+static const int buttonRoleLayouts[2][6][14] =
 {
     // Qt::Horizontal
     {
@@ -92,7 +92,15 @@ static const int buttonRoleLayouts[2][5][14] =
         // MacModelessLayout
         { QPlatformDialogHelper::ResetRole, QPlatformDialogHelper::ApplyRole, QPlatformDialogHelper::ActionRole, QPlatformDialogHelper::Stretch,
           QPlatformDialogHelper::HelpRole, QPlatformDialogHelper::EOL, QPlatformDialogHelper::EOL, QPlatformDialogHelper::EOL, QPlatformDialogHelper::EOL,
-          QPlatformDialogHelper::EOL, QPlatformDialogHelper::EOL, QPlatformDialogHelper::EOL, QPlatformDialogHelper::EOL, QPlatformDialogHelper::EOL }
+          QPlatformDialogHelper::EOL, QPlatformDialogHelper::EOL, QPlatformDialogHelper::EOL, QPlatformDialogHelper::EOL, QPlatformDialogHelper::EOL },
+
+          // AndroidLayout (neutral, stretch, dismissive, affirmative)
+          // https://material.io/guidelines/components/dialogs.html#dialogs-specs
+        { QPlatformDialogHelper::HelpRole, QPlatformDialogHelper::ResetRole, QPlatformDialogHelper::ApplyRole, QPlatformDialogHelper::ActionRole,
+          QPlatformDialogHelper::Stretch, QPlatformDialogHelper::RejectRole | QPlatformDialogHelper::Reverse,
+          QPlatformDialogHelper::NoRole | QPlatformDialogHelper::Reverse, QPlatformDialogHelper::DestructiveRole | QPlatformDialogHelper::Reverse,
+          QPlatformDialogHelper::AlternateRole | QPlatformDialogHelper::Reverse, QPlatformDialogHelper::AcceptRole | QPlatformDialogHelper::Reverse,
+          QPlatformDialogHelper::YesRole | QPlatformDialogHelper::Reverse, QPlatformDialogHelper::EOL, QPlatformDialogHelper::EOL }
     },
 
     // Qt::Vertical
@@ -120,10 +128,20 @@ static const int buttonRoleLayouts[2][5][14] =
         // MacModelessLayout
         { QPlatformDialogHelper::ActionRole, QPlatformDialogHelper::ApplyRole, QPlatformDialogHelper::ResetRole, QPlatformDialogHelper::Stretch,
           QPlatformDialogHelper::HelpRole, QPlatformDialogHelper::EOL, QPlatformDialogHelper::EOL, QPlatformDialogHelper::EOL, QPlatformDialogHelper::EOL,
-          QPlatformDialogHelper::EOL, QPlatformDialogHelper::EOL, QPlatformDialogHelper::EOL, QPlatformDialogHelper::EOL, QPlatformDialogHelper::EOL }
+          QPlatformDialogHelper::EOL, QPlatformDialogHelper::EOL, QPlatformDialogHelper::EOL, QPlatformDialogHelper::EOL, QPlatformDialogHelper::EOL },
+
+          // AndroidLayout
+          // (affirmative
+          //  dismissive
+          //  neutral)
+          // https://material.io/guidelines/components/dialogs.html#dialogs-specs
+        { QPlatformDialogHelper::YesRole, QPlatformDialogHelper::AcceptRole, QPlatformDialogHelper::AlternateRole, QPlatformDialogHelper::DestructiveRole,
+          QPlatformDialogHelper::NoRole, QPlatformDialogHelper::RejectRole, QPlatformDialogHelper::Stretch, QPlatformDialogHelper::ActionRole, QPlatformDialogHelper::ApplyRole,
+          QPlatformDialogHelper::ResetRole, QPlatformDialogHelper::HelpRole, QPlatformDialogHelper::EOL, QPlatformDialogHelper::EOL }
     }
 };
 
+
 QPlatformDialogHelper::QPlatformDialogHelper()
 {
     qRegisterMetaType<StandardButton>();
@@ -917,6 +935,8 @@ const int *QPlatformDialogHelper::buttonLayout(Qt::Orientation orientation, Butt
         policy = MacLayout;
 #elif defined (Q_OS_LINUX) || defined (Q_OS_UNIX)
         policy = KdeLayout;
+#elif defined (Q_OS_ANDROID)
+        policy = AndroidLayout;
 #else
         policy = WinLayout;
 #endif

src/gui/kernel/qplatformdialoghelper.h

@@ -141,13 +141,14 @@ public:
     Q_ENUM(ButtonRole)
 
     enum ButtonLayout {
-        // keep this in sync with QDialogButtonBox::ButtonLayout and QMessageBox::ButtonLayout
+        // keep this in sync with QDialogButtonBox::ButtonLayout
         UnknownLayout = -1,
         WinLayout,
         MacLayout,
         KdeLayout,
         GnomeLayout,
-        MacModelessLayout
+        MacModelessLayout,
+        AndroidLayout
     };
 
     QPlatformDialogHelper();

src/plugins/platforms/android/qandroidplatformdialoghelpers.cpp

@@ -103,11 +103,7 @@ bool QAndroidPlatformMessageDialogHelper::show(Qt::WindowFlags windowFlags
     if (!str.isEmpty())
         m_javaMessageDialog.callMethod<void>("setDetailedText", "(Ljava/lang/String;)V", QJNIObjectPrivate::fromString(str).object());
 
-    // http://developer.android.com/design/building-blocks/dialogs.html
-    // dismissive action on the left, affirmative on the right
-    // There don't seem to be more fine-grained rules, but the OS X layout
-    // at least conforms to this one rule and makes the rest deterministic.
-    const int * currentLayout = buttonLayout(Qt::Horizontal, MacLayout);
+    const int * currentLayout = buttonLayout(Qt::Horizontal, AndroidLayout);
     while (*currentLayout != QPlatformDialogHelper::EOL) {
         int role = (*currentLayout & ~QPlatformDialogHelper::Reverse);
         addButtons(opt, static_cast<ButtonRole>(role));

src/widgets/doc/src/widgets-and-layouts/stylesheet.qdoc

@@ -1793,8 +1793,9 @@
            a QMessageBox. The possible values are 0
            (\l{QDialogButtonBox::}{WinLayout}), 1
            (\l{QDialogButtonBox::}{MacLayout}), 2
-           (\l{QDialogButtonBox::}{KdeLayout}), and 3
-           (\l{QDialogButtonBox::}{GnomeLayout}).
+           (\l{QDialogButtonBox::}{KdeLayout}), 3
+           (\l{QDialogButtonBox::}{GnomeLayout}) and 5
+           (\l{QDialogButtonBox::}{AndroidLayout}).
 
            If this property is not specified, it defaults to the
            value specified by the current style for the

src/widgets/widgets/qdialogbuttonbox.cpp

@@ -577,6 +577,8 @@ QDialogButtonBox::~QDialogButtonBox()
     \value MacLayout Use a policy appropriate for applications on \macos.
     \value KdeLayout Use a policy appropriate for applications on KDE.
     \value GnomeLayout Use a policy appropriate for applications on GNOME.
+    \value AndroidLayout Use a policy appropriate for applications on Android.
+                            This enum value was added in Qt 5.10.
 
     The button layout is specified by the \l{style()}{current style}. However,
     on the X11 platform, it may be influenced by the desktop environment.

src/widgets/widgets/qdialogbuttonbox.h

@@ -108,11 +108,13 @@ public:
     Q_FLAG(StandardButtons)
 
     enum ButtonLayout {
-        // keep this in sync with QMessageBox::ButtonLayout and QPlatformDialogHelper::ButtonLayout
+        // keep this in sync with QPlatformDialogHelper::ButtonLayout
         WinLayout,
         MacLayout,
         KdeLayout,
-        GnomeLayout
+        GnomeLayout,
+        // MacModelessLayout,
+        AndroidLayout = GnomeLayout + 2 // ### Qt 6: reorder
     };
 
     QDialogButtonBox(QWidget *parent = Q_NULLPTR);