interface/wx/mousemanager.h

   1 ///////////////////////////////////////////////////////////////////////////////
   2 // Name:        wx/mousemanager.h
   3 // Purpose:     documentation of wxMouseEventsManager class
   4 // Author:      Vadim Zeitlin
   5 // Created:     2009-04-20
   6 // RCS-ID:      $Id$
   7 // Copyright:   (c) 2009 Vadim Zeitlin <vadim@wxwidgets.org>
   8 // Licence:     wxWindows licence
   9 ///////////////////////////////////////////////////////////////////////////////
  10
  11 /**
  12     @class wxMouseEventsManager
  13
  14     Helper for handling mouse input events in windows containing multiple
  15     items.
  16
  17     This class handles mouse events and synthesizes high-level notifications
  18     such as clicks and drag events from low level mouse button presses and
  19     mouse movement events. It is useful because handling the mouse events is
  20     less obvious than might seem at a first glance: for example, clicks on an
  21     object should only be generated if the mouse was both pressed and released
  22     over it and not just released (so it requires storing the previous state)
  23     and dragging shouldn't start before the mouse moves away far enough.
  24
  25     This class encapsulates all these dull details for controls containing
  26     multiple items which can be identified by a positive integer index and you
  27     just need to implement its pure virtual functions to use it.
  28
  29     Notice that this class supposes that all items can be identified by an
  30     integer "index" but it doesn't need to be an ordinal index of the item
  31     (although this is the most common case) -- it can be any value which can
  32     be used to uniquely identify an item.
  33
  34     @library{core}
  35     @category{events}
  36  */
  37 class wxMouseEventsManager : public wxEvtHandler
  38 {
  39 public:
  40     /**
  41         Constructor creates the manager for the window.
  42
  43         A mouse event manager is always associated with a window and must be
  44         destroyed by the window when it is destroyed (it doesn't need to be
  45         allocated on the heap however).
  46      */
  47     wxMouseEventsManager(wxWindow *win);
  48
  49 protected:
  50     /**
  51         Must be overridden to return the item at the given position.
  52
  53         @param pos
  54             The position to test, in physical coordinates.
  55         @return
  56             The index of the item at the given position or wxNOT_FOUND if there
  57             is no item there.
  58      */
  59     virtual int MouseHitTest(const wxPoint& pos) = 0;
  60
  61     /**
  62         Must be overridden to react to mouse clicks.
  63
  64         This method is called when the user clicked (i.e. pressed and released
  65         mouse over the @e same item) and should normally generate a
  66         notification about this click and return true if it was handled or
  67         false otherwise, determining whether the original mouse event is
  68         skipped or not.
  69
  70         @param item
  71             The item which was clicked.
  72         @return
  73             @true if the mouse event was processed and @false otherwise.
  74      */
  75     virtual bool MouseClicked(int item) = 0;
  76
  77     /**
  78         Must be overridden to allow or deny dragging of the item.
  79
  80         This method is called when the user attempts to start dragging the
  81         given item.
  82
  83         @param item
  84             The item which is going to be dragged.
  85         @param pos
  86             The position from where it is being dragged.
  87         @return
  88             @true to allow the item to be dragged (in which case
  89             MouseDragging() and MouseDragEnd() will be called later, unless
  90             MouseDragCancelled() is called instead) or @false to forbid it.
  91      */
  92     virtual bool MouseDragBegin(int item, const wxPoint& pos) = 0;
  93
  94     /**
  95         Must be overridden to provide feed back while an item is being dragged.
  96
  97         This method is called while the item is being dragged and should
  98         normally update the feedback shown on screen (usually this is done
  99         using wxOverlay).
 100
 101         Notice that this method will never be called for the items for which
 102         MouseDragBegin() returns @false. Consequently, if MouseDragBegin()
 103         always returns @false you can do nothing in this method.
 104
 105         @param item
 106             The item being dragged.
 107         @param pos
 108             The current position of the item.
 109
 110         @see MouseDragEnd()
 111      */
 112     virtual void MouseDragging(int item, const wxPoint& pos) = 0;
 113
 114     /**
 115         Must be overridden to handle item drop.
 116
 117         This method is called when the mouse is released after dragging the
 118         item. Normally the item should be positioned at the new location.
 119
 120         @param item
 121             The item which was dragged and now dropped.
 122         @param pos
 123             The position at which the item was dropped.
 124
 125         @see MouseDragBegin(), MouseDragging()
 126      */
 127     virtual void MouseDragEnd(int item, const wxPoint& pos) = 0;
 128
 129     /**
 130         Must be overridden to handle cancellation of mouse dragging.
 131
 132         This method is called when mouse capture is lost while dragging the
 133         item and normally should remove the visual feedback drawn by
 134         MouseDragging() as well as reset any internal variables set in
 135         MouseDragBegin().
 136
 137         @see wxMouseCaptureLostEvent
 138      */
 139     virtual void MouseDragCancelled(int item) = 0;
 140
 141
 142     /**
 143         May be overridden to update the state of an item when it is pressed.
 144
 145         This method is called when the item is becomes pressed and can be used
 146         to change its appearance when this happens. It is mostly useful for
 147         button-like items and doesn't need to be overridden if the items
 148         shouldn't change their appearance when pressed.
 149
 150         @param item
 151             The item being pressed.
 152      */
 153     virtual void MouseClickBegin(int item);
 154
 155     /**
 156         Must be overridden to reset the item appearance changed by
 157         MouseClickBegin().
 158
 159         This method is called if the mouse capture was lost while the item was
 160         pressed and must be overridden to restore the default item appearance
 161         if it was changed in MouseClickBegin().
 162
 163         @see MouseDragCancelled(), wxMouseCaptureLostEvent
 164      */
 165     virtual void MouseClickCancelled(int item);
 166 };