workbench/libs/datatypes/startdragselect.c

   1 /*
   2     Copyright © 1995-2001, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc:
   6     Lang: English
   7 */
   8 #include <proto/dos.h>
   9 #include <proto/utility.h>
  10 #include <proto/datatypes.h>
  11 #include "datatypes_intern.h"
  12
  13 /*****************************************************************************
  14
  15     NAME */
  16
  17         AROS_LH1(ULONG, StartDragSelect,
  18
  19 /*  SYNOPSIS */
  20         AROS_LHA(Object *, o, A0),
  21
  22 /*  LOCATION */
  23         struct Library *, DataTypesBase, 50, DataTypes)
  24
  25 /*  FUNCTION
  26
  27     Start drag-selection by the user; the drag selection will only start
  28     if the object in question supports DTM_SELECT, is in a window or
  29     requester and no layout-process is working on the object.
  30
  31     INPUTS
  32
  33     o   --  data type object in question; may be NULL
  34
  35     RESULT
  36
  37     TRUE if all went OK, FALSE otherwise. If FALSE, IoErr() gives further
  38     information:
  39
  40     ERROR_ACTION_NOT_KNOWN   --  the object doesn't support DTM_SELECT
  41     ERROR_OBJECT_IN_USE      --  the object is currently occupied
  42
  43     NOTES
  44
  45     EXAMPLE
  46
  47     BUGS
  48
  49     SEE ALSO
  50
  51     INTERNALS
  52
  53     HISTORY
  54
  55     6.8.99  SDuvan  implemented
  56
  57 *****************************************************************************/
  58 {
  59     AROS_LIBFUNC_INIT
  60
  61     struct DTSpecialInfo *dtsi;
  62     BOOL                  retval = TRUE;
  63
  64     if(o == NULL)
  65         return FALSE;
  66
  67     dtsi = ((struct Gadget *)o)->SpecialInfo;
  68
  69     /* Doesn't support drag selection? */
  70     if(FindMethod(GetDTMethods(o), DTM_SELECT) == NULL)
  71     {
  72         SetIoErr(ERROR_ACTION_NOT_KNOWN);
  73         return FALSE;
  74     }
  75
  76     ObtainSemaphore(&dtsi->si_Lock);
  77
  78     if(dtsi->si_Flags & DTSIF_LAYOUTPROC)
  79     {
  80         retval = FALSE;
  81         SetIoErr(ERROR_OBJECT_IN_USE);
  82     }
  83     else
  84         dtsi->si_Flags |= DTSIF_DRAGSELECT;
  85
  86     ReleaseSemaphore(&dtsi->si_Lock);
  87
  88     return retval;
  89
  90     AROS_LIBFUNC_EXIT
  91 } /* StartDragSelect */
  92