Add persistence support for groups of wxRadioButton controls

Allow to easily save and restore the selected radio button.

Closes #25530.

Makefile.in

@@ -3955,6 +3955,7 @@ COND_USE_GUI_1_ALL_GUI_HEADERS =  \
 	wx/persist.h \
 	wx/persist/bookctrl.h \
 	wx/persist/dataview.h \
+	wx/persist/radiobut.h \
 	wx/persist/splitter.h \
 	wx/persist/toplevel.h \
 	wx/persist/treebook.h \

build/bakefiles/files.bkl

@@ -1229,6 +1229,7 @@ IMPORTANT: please read docs/tech/tn0016.txt before modifying this file!
     wx/persist.h
     wx/persist/bookctrl.h
     wx/persist/dataview.h
+    wx/persist/radiobut.h
     wx/persist/splitter.h
     wx/persist/toplevel.h
     wx/persist/treebook.h

build/cmake/files.cmake

@@ -1130,6 +1130,7 @@ set(GUI_CMN_HDR
     wx/persist.h
     wx/persist/bookctrl.h
     wx/persist/dataview.h
+    wx/persist/radiobut.h
     wx/persist/splitter.h
     wx/persist/toplevel.h
     wx/persist/treebook.h

build/files

@@ -1158,6 +1158,7 @@ GUI_CMN_HDR =
     wx/persist/checkbox.h
     wx/persist/combobox.h
     wx/persist/dataview.h
+    wx/persist/radiobut.h
     wx/persist/splitter.h
     wx/persist/toplevel.h
     wx/persist/treebook.h

build/msw/wx_core.vcxproj

@@ -2049,6 +2049,7 @@
     <ClInclude Include="..\..\include\wx\progdlg.h" />
     <ClInclude Include="..\..\include\wx\quantize.h" />
     <ClInclude Include="..\..\include\wx\radiobox.h" />
+    <ClInclude Include="..\..\include\wx\persist\radiobut.h" />
     <ClInclude Include="..\..\include\wx\radiobut.h" />
     <ClInclude Include="..\..\include\wx\range.h" />
     <ClInclude Include="..\..\include\wx\rawbmp.h" />

build/msw/wx_core.vcxproj.filters

@@ -2086,6 +2086,9 @@
     <ClInclude Include="..\..\include\wx\persist\dataview.h">
       <Filter>Common Headers</Filter>
     </ClInclude>
+    <ClInclude Include="..\..\include\wx\persist\radiobut.h">
+      <Filter>Common Headers</Filter>
+    </ClInclude>
     <ClInclude Include="..\..\include\wx\persist\splitter.h">
       <Filter>Common Headers</Filter>
     </ClInclude>

include/wx/persist/radiobut.h

@@ -0,0 +1,113 @@
+///////////////////////////////////////////////////////////////////////////////
+// Name:        wx/persist/radiobut.h
+// Purpose:     Persistence support for wxRadioButton.
+// Author:      Vadim Zeitlin
+// Created:     2025-06-12
+// Copyright:   (c) 2025 Vadim Zeitlin
+// Licence:     wxWindows licence
+///////////////////////////////////////////////////////////////////////////////
+
+#ifndef _WX_PERSIST_RADIOBUT_H_
+#define _WX_PERSIST_RADIOBUT_H_
+
+#include "wx/persist/window.h"
+
+#include "wx/radiobut.h"
+
+#if wxUSE_RADIOBTN
+
+// ----------------------------------------------------------------------------
+// string constants used by wxPersistentRadioButton
+// ----------------------------------------------------------------------------
+
+#define wxPERSIST_RADIOBUTTON_KIND wxASCII_STR("RadioButton")
+
+#define wxPERSIST_RADIOBUTTON_VALUE wxASCII_STR("Value")
+
+// ----------------------------------------------------------------------------
+// wxPersistentRadioButton: supports saving/restoring radio buttons state
+// ----------------------------------------------------------------------------
+
+// This class should be always used with the first button in a group of radio
+// buttons and it saves its state as an integer indicating the offset of the
+// selected radio button in this group.
+//
+// Currently radio buttons with wxRB_SINGLE style are not supported. While it
+// wouldn't be very difficult to add support for them if anybody really needs
+// it, it seems relatively unlikely, so for now we don't bother to do it.
+
+class wxPersistentRadioButton : public wxPersistentWindow<wxRadioButton>
+{
+public:
+    explicit wxPersistentRadioButton(wxRadioButton* radiobutton)
+        : wxPersistentWindow<wxRadioButton>(radiobutton)
+    {
+        wxASSERT_MSG( !radiobutton->HasFlag(wxRB_SINGLE),
+                      "wxPersistentRadioButton doesn't support wxRB_SINGLE" );
+
+        wxASSERT_MSG( radiobutton->HasFlag(wxRB_GROUP),
+                      "wxPersistentRadioButton should be used with the first "
+                      "radio button in a group" );
+    }
+
+    virtual void Save() const override
+    {
+        const wxRadioButton* button = Get();
+        for ( int n = 0;; ++n )
+        {
+            if ( button->GetValue() )
+            {
+                // We found the selected button, save its index.
+                SaveValue(wxPERSIST_RADIOBUTTON_VALUE, n);
+                break;
+            }
+
+            button = button->GetNextInGroup();
+            if ( !button )
+            {
+                wxFAIL_MSG("Didn't find a selected radio button in the group?");
+                break;
+            }
+        }
+    }
+
+    virtual bool Restore() override
+    {
+        int value;
+        if ( !RestoreValue(wxPERSIST_RADIOBUTTON_VALUE, &value) )
+            return false;
+
+        wxRadioButton* button = Get();
+        for ( int n = 0;; ++n )
+        {
+            if ( n == value )
+            {
+                // We found the button with the saved index, set its value.
+                button->SetValue(true);
+                break;
+            }
+
+            button = button->GetNextInGroup();
+
+            if ( !button )
+            {
+                // The saved value is invalid, silently ignore it because there
+                // doesn't seem to be much else that we can do in this case.
+                break;
+            }
+        }
+
+        return true;
+    }
+
+    virtual wxString GetKind() const override { return wxPERSIST_RADIOBUTTON_KIND; }
+};
+
+inline wxPersistentObject *wxCreatePersistentObject(wxRadioButton* radiobutton)
+{
+    return new wxPersistentRadioButton(radiobutton);
+}
+
+#endif // wxUSE_RADIOBTN
+
+#endif // _WX_PERSIST_RADIOBUT_H_

interface/wx/persist/radiobut.h

@@ -0,0 +1,75 @@
+///////////////////////////////////////////////////////////////////////////////
+// Name:        wx/persist/radiobutton.h
+// Purpose:     Interface of wxPersistentRadioButton
+// Author:      Vadim Zeitlin
+// Created:     2025-06-15
+// Copyright:   (c) 2025 Vadim Zeitlin <vadim@wxwidgets.org>
+// Licence:     wxWindows licence
+///////////////////////////////////////////////////////////////////////////////
+
+/**
+    Persistence adapter for wxRadioButton controls.
+
+    This adapter saves and restores the index of the selected wxRadioButton in
+    a group of radio buttons, to allow to retain the selection across program
+    executions.
+
+    Example of using it:
+    @code
+    // Assume that all these controls are added to some sizer elsewhere.
+    auto* label = new wxStaticText(this, wxID_ANY, "Play with:");
+
+    auto* black = new wxRadioButton(this, wxID_ANY, "&Black",
+                                    wxDefaultPosition,
+                                    wxDefaultSize,
+                                    wxRB_GROUP);
+    auto* white = new wxRadioButton(this, wxID_ANY, "&White");
+
+    // We register the first radio button here, but all radio buttons in the
+    // same group are potentially affected by this call.
+    wxPersistentRegisterAndRestore(black);
+    @endcode
+
+    During the first program execution, black colour will be selected, but if
+    the user selects white pieces, this selection will be restored during the
+    subsequent run.
+
+    @since 3.3.0
+ */
+class wxPersistentRadioButton : public wxPersistentWindow<wxRadioButton>
+{
+public:
+    /**
+        Constructor.
+
+        Please note that the radio button must be the first one in the group,
+        i.e. have ::wxRB_GROUP style set, otherwise an assertion will be
+        triggered.
+
+        Also note that currently ::wxRB_SINGLE style is not supported.
+
+        @param radiobutton
+            The associated radiobutton.
+     */
+    explicit wxPersistentRadioButton(wxRadioButton *radiobutton);
+
+    /**
+        Save the currently selected button index.
+
+        The 0-based index of the selected radio button in the group is saved as
+        radio button value.
+     */
+    virtual void Save() const;
+
+    /**
+        Restore the previously saved selection.
+
+        If the saved index is valid, i.e. is positive and less than the number
+        of radio buttons in the group, the radio button with the corresponding
+        index will be selected.
+     */
+    virtual bool Restore();
+};
+
+/// Overload allowing persistence adapter creation for wxRadioButton objects.
+wxPersistentObject *wxCreatePersistentObject(wxRadioButton *radiobutton);

tests/allheaders.h

@@ -268,6 +268,7 @@
 #include <wx/persist/checkbox.h>
 #include <wx/persist/combobox.h>
 #include <wx/persist/dataview.h>
+#include <wx/persist/radiobut.h>
 #include <wx/persist/splitter.h>
 #include <wx/persist/toplevel.h>
 #include <wx/persist/treebook.h>