Simplify TAB order code in wxStdDialogButtonSizer::Realize()

No real changes, just add a helper class to avoid repeating the same
sequence of lines many times in this function.

This aims to slightly improve 42e9eb7ce8.

See #17940.

Closes https://github.com/wxWidgets/wxWidgets/pull/539

src/common/sizer.cpp

@@ -2764,25 +2764,47 @@ void wxStdDialogButtonSizer::SetCancelButton( wxButton *button )
 
 void wxStdDialogButtonSizer::Realize()
 {
-    wxButton* lastAdded = NULL;
+    // Helper used to move the most recently added button after the previously
+    // added one in TAB order.
+    class TabOrderUpdater
+    {
+    public:
+        TabOrderUpdater()
+            : m_lastAdded(NULL)
+        {
+        }
+
+        void Add(wxButton* btn)
+        {
+            if ( m_lastAdded )
+            {
+                // Button should follow previous one in the keyboard navigation
+                // order.
+                btn->MoveAfterInTabOrder(m_lastAdded);
+            }
+
+            m_lastAdded = btn;
+        }
+
+    private:
+        wxButton* m_lastAdded;
+    };
+
+    TabOrderUpdater tabOrder;
+
 #ifdef __WXMAC__
         Add(0, 0, 0, wxLEFT, 6);
         if (m_buttonHelp)
         {
             Add((wxWindow*)m_buttonHelp, 0, wxALIGN_CENTRE | wxLEFT | wxRIGHT, 6);
-            lastAdded = m_buttonHelp;
+            tabOrder.Add(m_buttonHelp);
         }
 
         if (m_buttonNegative){
             // HIG POLICE BULLETIN - destructive buttons need extra padding
             // 24 pixels on either side
             Add((wxWindow*)m_buttonNegative, 0, wxALIGN_CENTRE | wxLEFT | wxRIGHT, 12);
-            // Button should follow previous one in the keyboard navigation order.
+            tabOrder.Add(m_buttonNegative);
-            if ( lastAdded )
-            {
-                m_buttonNegative->MoveAfterInTabOrder(lastAdded);
-            }
-            lastAdded = m_buttonNegative;
         }
 
         // extra whitespace between help/negative and cancel/ok buttons
@@ -2793,12 +2815,7 @@ void wxStdDialogButtonSizer::Realize()
             // Cancel or help should be default
             // m_buttonCancel->SetDefaultButton();
 
-            // Button should follow previous one in the keyboard navigation order.
+            tabOrder.Add(m_buttonCancel);
-            if ( lastAdded )
-            {
-                m_buttonCancel->MoveAfterInTabOrder(lastAdded);
-            }
-            lastAdded = m_buttonCancel;
         }
 
         // Ugh, Mac doesn't really have apply dialogs, so I'll just
@@ -2806,12 +2823,7 @@ void wxStdDialogButtonSizer::Realize()
         if (m_buttonApply)
         {
             Add((wxWindow*)m_buttonApply, 0, wxALIGN_CENTRE | wxLEFT | wxRIGHT, 6);
-            // Button should follow previous one in the keyboard navigation order.
+            tabOrder.Add(m_buttonApply);
-            if ( lastAdded )
-            {
-                m_buttonApply->MoveAfterInTabOrder(lastAdded);
-            }
-            lastAdded = m_buttonApply;
         }
 
         if (m_buttonAffirmative){
@@ -2823,11 +2835,7 @@ void wxStdDialogButtonSizer::Realize()
                 if (m_buttonNegative)
                     m_buttonNegative->SetLabel(_("Don't Save"));
             }
-            // Button should follow previous one in the keyboard navigation order.
+            tabOrder.Add(m_buttonAffirmative);
-            if ( lastAdded )
-            {
-                m_buttonAffirmative->MoveAfterInTabOrder(lastAdded);
-            }
         }
 
         // Extra space around and at the right
@@ -2848,7 +2856,7 @@ void wxStdDialogButtonSizer::Realize()
         if (m_buttonHelp)
         {
             Add(m_buttonHelp, flagsBtn);
-            lastAdded = m_buttonHelp;
+            tabOrder.Add(m_buttonHelp);
         }
 
         // Align the rest of the buttons to the right.
@@ -2857,44 +2865,25 @@ void wxStdDialogButtonSizer::Realize()
         if (m_buttonNegative)
         {
             Add(m_buttonNegative, flagsBtn);
-            // Button should follow previous one in the keyboard navigation order.
+            tabOrder.Add(m_buttonNegative);
-            if ( lastAdded )
-            {
-                m_buttonNegative->MoveAfterInTabOrder(lastAdded);
-            }
-            lastAdded = m_buttonNegative;
         }
 
         if (m_buttonApply)
         {
             Add(m_buttonApply, flagsBtn);
-            // Button should follow previous one in the keyboard navigation order.
+            tabOrder.Add(m_buttonApply);
-            if ( lastAdded )
-            {
-                m_buttonApply->MoveAfterInTabOrder(lastAdded);
-            }
-            lastAdded = m_buttonApply;
         }
 
         if (m_buttonCancel)
         {
             Add(m_buttonCancel, flagsBtn);
-            // Button should follow previous one in the keyboard navigation order.
+            tabOrder.Add(m_buttonCancel);
-            if ( lastAdded )
-            {
-                m_buttonCancel->MoveAfterInTabOrder(lastAdded);
-            }
-            lastAdded = m_buttonCancel;
         }
 
         if (m_buttonAffirmative)
         {
             Add(m_buttonAffirmative, flagsBtn);
-            // Button should follow previous one in the keyboard navigation order.
+            tabOrder.Add(m_buttonAffirmative);
-            if ( lastAdded )
-            {
-                m_buttonAffirmative->MoveAfterInTabOrder(lastAdded);
-            }
         }
 
         // Ensure that the right margin is 12 as well.
@@ -2907,48 +2896,29 @@ void wxStdDialogButtonSizer::Realize()
 
         if (m_buttonAffirmative){
             Add((wxWindow*)m_buttonAffirmative, 0, wxALIGN_CENTRE | wxLEFT | wxRIGHT, m_buttonAffirmative->ConvertDialogToPixels(wxSize(2, 0)).x);
-            lastAdded = m_buttonAffirmative;
+            tabOrder.Add(m_buttonAffirmative);
         }
 
         if (m_buttonNegative){
             Add((wxWindow*)m_buttonNegative, 0, wxALIGN_CENTRE | wxLEFT | wxRIGHT, m_buttonNegative->ConvertDialogToPixels(wxSize(2, 0)).x);
-            // Button should follow previous one in the keyboard navigation order.
+            tabOrder.Add(m_buttonNegative);
-            if ( lastAdded )
-            {
-                m_buttonNegative->MoveAfterInTabOrder(lastAdded);
-            }
-            lastAdded = m_buttonNegative;
         }
 
         if (m_buttonCancel){
             Add((wxWindow*)m_buttonCancel, 0, wxALIGN_CENTRE | wxLEFT | wxRIGHT, m_buttonCancel->ConvertDialogToPixels(wxSize(2, 0)).x);
-            // Button should follow previous one in the keyboard navigation order.
+            tabOrder.Add(m_buttonCancel);
-            if ( lastAdded )
-            {
-                m_buttonCancel->MoveAfterInTabOrder(lastAdded);
-            }
-            lastAdded = m_buttonCancel;
         }
 
         if (m_buttonApply)
         {
             Add((wxWindow*)m_buttonApply, 0, wxALIGN_CENTRE | wxLEFT | wxRIGHT, m_buttonApply->ConvertDialogToPixels(wxSize(2, 0)).x);
-            // Button should follow previous one in the keyboard navigation order.
+            tabOrder.Add(m_buttonApply);
-            if ( lastAdded )
-            {
-                m_buttonApply->MoveAfterInTabOrder(lastAdded);
-            }
-            lastAdded = m_buttonApply;
         }
 
         if (m_buttonHelp)
         {
             Add((wxWindow*)m_buttonHelp, 0, wxALIGN_CENTRE | wxLEFT | wxRIGHT, m_buttonHelp->ConvertDialogToPixels(wxSize(2, 0)).x);
-            // Button should follow previous one in the keyboard navigation order.
+            tabOrder.Add(m_buttonHelp);
-            if ( lastAdded )
-            {
-                m_buttonHelp->MoveAfterInTabOrder(lastAdded);
-            }
         }
 #else
         // GTK+1 and any other platform
@@ -2957,7 +2927,7 @@ void wxStdDialogButtonSizer::Realize()
         if (m_buttonHelp)
         {
             Add((wxWindow*)m_buttonHelp, 0, wxALIGN_CENTRE | wxLEFT | wxRIGHT, m_buttonHelp->ConvertDialogToPixels(wxSize(4, 0)).x);
-            lastAdded = m_buttonHelp;
+            tabOrder.Add(m_buttonHelp);
         }
 
         // extra whitespace between help and cancel/ok buttons
@@ -2966,43 +2936,24 @@ void wxStdDialogButtonSizer::Realize()
         if (m_buttonApply)
         {
             Add((wxWindow*)m_buttonApply, 0, wxALIGN_CENTRE | wxLEFT | wxRIGHT, m_buttonApply->ConvertDialogToPixels(wxSize(4, 0)).x);
-            // Button should follow previous one in the keyboard navigation order.
+            tabOrder.Add(m_buttonApply);
-            if ( lastAdded )
-            {
-                m_buttonApply->MoveAfterInTabOrder(lastAdded);
-            }
-            lastAdded = m_buttonApply;
         }
 
         if (m_buttonAffirmative){
             Add((wxWindow*)m_buttonAffirmative, 0, wxALIGN_CENTRE | wxLEFT | wxRIGHT, m_buttonAffirmative->ConvertDialogToPixels(wxSize(4, 0)).x);
-            // Button should follow previous one in the keyboard navigation order.
+            tabOrder.Add(m_buttonAffirmative);
-            if ( lastAdded )
-            {
-                m_buttonAffirmative->MoveAfterInTabOrder(lastAdded);
-            }
-            lastAdded = m_buttonAffirmative;
         }
 
         if (m_buttonNegative){
             Add((wxWindow*)m_buttonNegative, 0, wxALIGN_CENTRE | wxLEFT | wxRIGHT, m_buttonNegative->ConvertDialogToPixels(wxSize(4, 0)).x);
-            // Button should follow previous one in the keyboard navigation order.
+            tabOrder.Add(m_buttonNegative);
-            if ( lastAdded )
-            {
-                m_buttonNegative->MoveAfterInTabOrder(lastAdded);
-            }
-            lastAdded = m_buttonNegative;
         }
 
         if (m_buttonCancel){
             Add((wxWindow*)m_buttonCancel, 0, wxALIGN_CENTRE | wxLEFT | wxRIGHT, m_buttonCancel->ConvertDialogToPixels(wxSize(4, 0)).x);
             // Cancel or help should be default
             // m_buttonCancel->SetDefaultButton();
-            // Button should follow previous one in the keyboard navigation order.
+            tabOrder.Add(m_buttonCancel);
-            if ( lastAdded )
-            {
-                m_buttonCancel->MoveAfterInTabOrder(lastAdded);
-            }
         }
 
 #endif