d54cf7ff13
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@52014 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
96 lines
3.7 KiB
C
96 lines
3.7 KiB
C
/////////////////////////////////////////////////////////////////////////////
|
|
// Name: dnd.h
|
|
// Purpose: topic overview
|
|
// Author: wxWidgets team
|
|
// RCS-ID: $Id$
|
|
// Licence: wxWindows license
|
|
/////////////////////////////////////////////////////////////////////////////
|
|
|
|
/*!
|
|
|
|
@page overview_dnd Drag and drop overview
|
|
|
|
Classes: #wxDataObject, #wxTextDataObject, #wxDropSource, #wxDropTarget,
|
|
#wxTextDropTarget, #wxFileDropTarget
|
|
|
|
Note that @c wxUSE_DRAG_AND_DROP must be defined in @c setup.h in order
|
|
to use drag and drop in wxWidgets.
|
|
|
|
See also: @ref overview_dataobject and @ref samplednd_overview.
|
|
|
|
It may be noted that data transfer to and from the clipboard is quite
|
|
similar to data transfer with drag and drop and the code to implement
|
|
these two types is almost the same. In particular, both data transfer
|
|
mechanisms store data in some kind of #wxDataObject and identify its format(s)
|
|
using the #wxDataFormat class.
|
|
|
|
To be a @e drag source, i.e. to provide the data which may be dragged by
|
|
the user elsewhere, you should implement the following steps:
|
|
|
|
@li @b Preparation: First of all, a data object must be created and
|
|
initialized with the data you wish to drag. For example:
|
|
|
|
@code
|
|
wxTextDataObject my_data("This text will be dragged.");
|
|
@endcode
|
|
|
|
@li <b>Drag start</b>: To start the dragging process (typically in response to a
|
|
mouse click) you must call wxDropSource::DoDragDrop like this:
|
|
|
|
@code
|
|
wxDropSource dragSource( this );
|
|
dragSource.SetData( my_data );
|
|
wxDragResult result = dragSource.DoDragDrop( true );
|
|
@endcode
|
|
|
|
@li @b Dragging: The call to DoDragDrop() blocks the program until the user releases
|
|
the mouse button (unless you override the #GiveFeedback function to do something
|
|
special). When the mouse moves in a window of a program which understands the
|
|
same drag-and-drop protocol (any program under Windows or any program supporting
|
|
the XDnD protocol under X Windows), the corresponding #wxDropTarget methods
|
|
are called - see below.
|
|
|
|
@li <b>Processing the result</b>: DoDragDrop() returns an @e effect code which
|
|
is one of the values of @c wxDragResult enum (explained #here):
|
|
|
|
@code
|
|
switch (result)
|
|
{
|
|
case wxDragCopy:
|
|
// copy the data
|
|
break;
|
|
case wxDragMove:
|
|
// move the data
|
|
break;
|
|
default:
|
|
// do nothing
|
|
break;
|
|
}
|
|
@endcode
|
|
|
|
|
|
To be a @e drop target, i.e. to receive the data dropped by the user you should
|
|
follow the instructions below:
|
|
|
|
@li @b Initialization: For a window to be a drop target, it needs to have
|
|
an associated #wxDropTarget object. Normally, you will call wxWindow::SetDropTarget
|
|
during window creation associating your drop target with it. You must derive a class from
|
|
wxDropTarget and override its pure virtual methods. Alternatively, you may
|
|
derive from #wxTextDropTarget or #wxFileDropTarget and override their OnDropText()
|
|
or OnDropFiles() method.
|
|
|
|
@li @b Drop: When the user releases the mouse over a window, wxWidgets
|
|
asks the associated wxDropTarget object if it accepts the data. For this,
|
|
a #wxDataObject must be associated with the drop target and this data object will
|
|
be responsible for the format negotiation between the drag source and the drop target.
|
|
If all goes well, then #OnData will get called and the wxDataObject belonging to
|
|
the drop target can get filled with data.
|
|
|
|
@li <b>The end</b>: After processing the data, DoDragDrop() returns either
|
|
wxDragCopy or wxDragMove depending on the state of the keys Ctrl, Shift
|
|
and Alt at the moment of the drop. There is currently no way for the drop
|
|
target to change this return code.
|
|
|
|
*/
|
|
|