Add wxCursor::GetHotSpot() and implement it for wxMSW and wxGTK.

Allow retrieving the coordinates of the cursor hot spot, at least for the
ports for which we know how to do it.

Closes #16539.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@78134 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/changes.txt

@@ -60,6 +60,7 @@ All (GUI):
 - Allow customizing window shown by wxBusyInfo.
 - Make results of wxDC::DrawEllipticArc() consistent across all platforms.
 - XRC handler for wxAuiToolBar added (Kinaou Hervé, David Hart).
+- Add wxCursor::GetHotSpot().
 - Add wxFD_NO_FOLLOW style for wxFileDialog (Luca Bacci).
 - Add support for embedding bitmaps in generated SVG in wxSVGFileDC (iwbnwif).
 - Add support for sorting wxDataViewCtrl by multiple columns (Trigve).

include/wx/cursor.h

@@ -39,6 +39,8 @@ public:
     wxCursor(int id) { InitFromStock((wxStockCursor)id); }
 #endif
 */
+
+    virtual wxPoint GetHotSpot() const { return wxDefaultPosition; }
 };
 
 #if defined(__WXMSW__)

include/wx/gtk/cursor.h

@@ -36,6 +36,9 @@ public:
               int hotSpotX = -1, int hotSpotY = -1,
               const char maskBits[] = NULL,
               const wxColour* fg = NULL, const wxColour* bg = NULL);
+
+    virtual wxPoint GetHotSpot() const wxOVERRIDE;
+
     virtual ~wxCursor();
 
     // implementation

include/wx/msw/cursor.h

@@ -27,6 +27,9 @@ public:
 #if WXWIN_COMPATIBILITY_2_8
     wxCursor(int id) { InitFromStock((wxStockCursor)id); }
 #endif
+
+    virtual wxPoint GetHotSpot() const wxOVERRIDE;
+
     virtual ~wxCursor();
 
     // implementation only

interface/wx/cursor.h

@@ -214,6 +214,19 @@ public:
     */
     virtual bool IsOk() const;
 
+    /**
+        Returns the coordinates of the cursor hot spot.
+
+        The hot spot is the point at which the mouse is actually considered to
+        be when this cursor is used.
+
+        This method is currently only implemented in wxMSW and wxGTK2+ and
+        simply returns ::wxDefaultPosition in the other ports.
+
+        @since 3.1.0
+     */
+    wxPoint GetHotSpot() const;
+
     /**
         Assignment operator, using @ref overview_refcount "reference counting".
     */

src/gtk/cursor.cpp

@@ -170,6 +170,35 @@ wxCursor::~wxCursor()
 {
 }
 
+wxPoint wxCursor::GetHotSpot() const
+{
+#if GTK_CHECK_VERSION(2,8,0)
+    if (GetCursor())
+    {
+        if (gtk_check_version(2,8,0) == NULL)
+        {
+            GdkPixbuf *pixbuf = gdk_cursor_get_image(GetCursor());
+            if (pixbuf)
+            {
+		wxPoint hotSpot = wxDefaultPosition;
+                const gchar* opt_xhot = gdk_pixbuf_get_option(pixbuf, "x_hot");
+                const gchar* opt_yhot = gdk_pixbuf_get_option(pixbuf, "y_hot");
+                if (opt_xhot && opt_yhot)
+                {
+		    const int xhot = atoi(opt_xhot);
+		    const int yhot = atoi(opt_yhot);
+		    hotSpot = wxPoint(xhot, yhot);
+                }
+                g_object_unref(pixbuf);
+                return hotSpot;
+            }
+        }
+    }
+#endif
+
+    return wxDefaultPosition;
+}
+
 void wxCursor::InitFromStock( wxStockCursor cursorId )
 {
     m_refData = new wxCursorRefData();

src/msw/cursor.cpp

@@ -275,6 +275,18 @@ wxCursor::wxCursor(const wxString& filename,
     }
 }
 
+wxPoint wxCursor::GetHotSpot() const
+{
+    if ( !GetGDIImageData() )
+        return wxDefaultPosition;
+
+    AutoIconInfo ii;
+    if ( !ii.GetFrom((HICON)GetGDIImageData()->m_hCursor) )
+        return wxDefaultPosition;
+
+    return wxPoint(ii.xHotspot, ii.yHotspot);
+}
+
 namespace
 {