Add wxImageList::Destroy()

This will be useful in wxMSW implementation and seems to make sense to
have as a public function, as long as we have Create().

include/wx/generic/imaglist.h

@@ -26,6 +26,7 @@ public:
     wxGenericImageList( int width, int height, bool mask = true, int initialCount = 1 );
     virtual ~wxGenericImageList();
     bool Create( int width, int height, bool mask = true, int initialCount = 1 );
+    void Destroy();
 
     virtual int GetImageCount() const;
     virtual bool GetSize( int index, int &width, int &height ) const;

include/wx/msw/imaglist.h

@@ -58,6 +58,9 @@ public:
   // initialNumber is the initial number of images to reserve.
   bool Create(int width, int height, bool mask = true, int initialNumber = 1);
 
+  // Destroys the image list, Create() may then be called again later.
+  void Destroy();
+
   // Adds a bitmap, and optionally a mask bitmap.
   // Note that wxImageList creates *new* bitmaps, so you may delete
   // 'bitmap' and 'mask' after calling Add.

interface/wx/imaglist.h

@@ -124,11 +124,29 @@ public:
     int Add(const wxIcon& icon);
 
     /**
-        Initializes the list. See wxImageList() for details.
+        Initializes the list.
+
+        See wxImageList() for details.
+
+        This function can be called only once after creating the object using
+        its default ctor or after calling Destroy().
     */
     bool Create(int width, int height, bool mask = true,
                 int initialCount = 1);
 
+    /**
+        Destroys the current list.
+
+        This function resets the object to its initial state and does more than
+        just RemoveAll() in the native wxMSW version.
+
+        After calling it, Create() may be called again to recreate the image
+        list, e.g. using a different size.
+
+        @since 3.1.6
+     */
+    void Destroy();
+
     /**
         Draws a specified image onto a device context.
 

src/generic/imaglist.cpp

@@ -39,9 +39,16 @@ wxGenericImageList::wxGenericImageList( int width, int height, bool mask, int in
     (void)Create(width, height, mask, initialCount);
 }
 
-wxGenericImageList::~wxGenericImageList()
+void wxGenericImageList::Destroy()
 {
     (void)RemoveAll();
+
+    // Make it invalid.
+    m_size = wxSize(0, 0);
+}
+
+wxGenericImageList::~wxGenericImageList()
+{
 }
 
 int wxGenericImageList::GetImageCount() const

src/msw/imaglist.cpp

@@ -100,7 +100,7 @@ bool wxImageList::Create(int width, int height, bool mask, int initial)
     return m_hImageList != 0;
 }
 
-wxImageList::~wxImageList()
+void wxImageList::Destroy()
 {
     if ( m_hImageList )
     {
@@ -109,6 +109,11 @@ wxImageList::~wxImageList()
     }
 }
 
+wxImageList::~wxImageList()
+{
+    Destroy();
+}
+
 // ----------------------------------------------------------------------------
 // wxImageList attributes
 // ----------------------------------------------------------------------------