Added candidate wxDragImage implementation for wxMSW

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@2071 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/dragimag.h

@@ -0,0 +1,189 @@
+/////////////////////////////////////////////////////////////////////////////
+// Name:        dragimag.h
+// Purpose:     wxDragImage class: a kind of a cursor, that can cope
+//              with more sophisticated images
+// Author:      Julian Smart
+// Modified by:
+// Created:     08/04/99
+// RCS-ID:      $Id$
+// Copyright:   (c) Julian Smart
+// Licence:   	wxWindows licence
+/////////////////////////////////////////////////////////////////////////////
+
+#ifndef _WX_DRAGIMAG_H_
+#define _WX_DRAGIMAG_H_
+
+#ifdef __GNUG__
+#pragma interface "dragimag.h"
+#endif
+
+#include "wx/bitmap.h"
+#include "wx/icon.h"
+#include "wx/cursor.h"
+#include "wx/treectrl.h"
+#include "wx/listctrl.h"
+
+/*
+  To use this class, create a wxDragImage when you start dragging, for example:
+
+  void MyTreeCtrl::OnBeginDrag(wxTreeEvent& event)
+  {
+#ifdef __WXMSW__
+    ::UpdateWindow((HWND) GetHWND()); // We need to implement this in wxWindows
+#endif
+
+    CaptureMouse();
+
+    m_dragImage = new wxDragImage(* this, itemId);
+    m_dragImage->BeginDrag(wxPoint(0, 0), this);
+    m_dragImage->Move(pt, this);
+    m_dragImage->Show(this);
+    ...
+  }
+
+  In your OnMouseMove function, hide the image, do any display updating required,
+  then move and show the image again:
+
+  void MyTreeCtrl::OnMouseMove(wxMouseEvent& event)
+  {
+    if (m_dragMode == MY_TREE_DRAG_NONE)
+    {
+        event.Skip();
+        return;
+    }
+
+    // Prevent screen corruption by hiding the image
+    if (m_dragImage)
+        m_dragImage->Hide(this);
+
+    // Do some updating of the window, such as highlighting the drop target
+    ...
+
+#ifdef __WXMSW__
+    if (updateWindow)
+        ::UpdateWindow((HWND) GetHWND());
+#endif
+
+    // Move and show the image again
+    m_dragImage->Move(event.GetPosition(), this);
+    m_dragImage->Show(this);
+ }
+
+ Eventually we end the drag and delete the drag image.
+
+ void MyTreeCtrl::OnLeftUp(wxMouseEvent& event)
+ {
+    ...
+
+    // End the drag and delete the drag image
+    if (m_dragImage)
+    {
+        m_dragImage->EndDrag(this);
+        delete m_dragImage;
+        m_dragImage = NULL;
+    }
+    ReleaseMouse();
+ }
+*/
+
+/*
+ Notes for Unix version:
+ Can we simply use cursors instead, creating a cursor dynamically, setting it into the window
+ in BeginDrag, and restoring the old cursor in EndDrag?
+ For a really bog-standard implementation, we could simply use a normal dragging cursor
+ and ignore the image.
+*/
+
+/*
+ * wxDragImage
+ */
+
+class WXDLLEXPORT wxDragImage: public wxObject
+{
+    DECLARE_DYNAMIC_CLASS(wxDragImage)
+public:
+    
+    // Ctors & dtor
+    ////////////////////////////////////////////////////////////////////////////
+
+    wxDragImage();
+    wxDragImage(const wxBitmap& image, const wxCursor& cursor = wxNullCursor, const wxPoint& hotspot = wxPoint(0, 0))
+    {
+        m_hImageList = 0;
+        Create(image, cursor);
+    }
+    wxDragImage(const wxIcon& image, const wxCursor& cursor = wxNullCursor, const wxPoint& hotspot = wxPoint(0, 0))
+    {
+        m_hImageList = 0;
+        Create(image, cursor);
+    }
+    wxDragImage(const wxString& str, const wxCursor& cursor = wxNullCursor, const wxPoint& hotspot = wxPoint(0, 0))
+    {
+        m_hImageList = 0;
+        Create(str, cursor);
+    }
+    wxDragImage(const wxTreeCtrl& treeCtrl, wxTreeItemId& id)
+    {
+        m_hImageList = 0;
+        Create(treeCtrl, id);
+    }
+    wxDragImage(const wxListCtrl& listCtrl, long id)
+    {
+        m_hImageList = 0;
+        Create(listCtrl, id);
+    }
+    ~wxDragImage();
+    
+    // Attributes
+    ////////////////////////////////////////////////////////////////////////////
+    
+    // Operations
+    ////////////////////////////////////////////////////////////////////////////
+    
+    // Create a drag image from a bitmap and optional cursor
+    bool Create(const wxBitmap& image, const wxCursor& cursor = wxNullCursor, const wxPoint& hotspot = wxPoint(0, 0));
+    
+    // Create a drag image from an icon and optional cursor
+    bool Create(const wxIcon& image, const wxCursor& cursor = wxNullCursor, const wxPoint& hotspot = wxPoint(0, 0));
+    
+    // Create a drag image from a string and optional cursor
+    bool Create(const wxString& str, const wxCursor& cursor = wxNullCursor, const wxPoint& hotspot = wxPoint(0, 0));
+
+    // Create a drag image for the given tree control item
+    bool Create(const wxTreeCtrl& treeCtrl, wxTreeItemId& id);
+
+    // Create a drag image for the given list control item
+    bool Create(const wxListCtrl& listCtrl, long id);
+
+    // Begin drag. hotspot is the location of the drag position relative to the upper-left
+    // corner of the image.
+    bool BeginDrag(const wxPoint& hotspot, wxWindow* window);
+    
+    // End drag
+    bool EndDrag(wxWindow* window);
+    
+    // Move the image: call from OnMouseMove. Pt is in window client coordinates if window
+    // is non-NULL, or in screen coordinates if NULL.
+    bool Move(const wxPoint& pt, wxWindow* window);
+
+    // Show the image
+    bool Show(wxWindow* window);
+
+    // Hide the image
+    bool Hide(wxWindow* window);
+    
+    // Implementation
+    ////////////////////////////////////////////////////////////////////////////
+    
+    // Returns the native image list handle
+    inline WXHIMAGELIST GetHIMAGELIST() const { return m_hImageList; }
+    
+protected:
+    WXHIMAGELIST    m_hImageList;
+    wxCursor        m_cursor;
+    wxPoint         m_hotspot;
+    wxPoint         m_position;
+};
+
+#endif
+    // _WX_DRAGIMAG_H_