src/gtk/clipbrd.cpp

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        src/gtk/clipbrd.cpp
   3 // Purpose:     wxClipboard implementation for wxGTK
   4 // Author:      Robert Roebling, Vadim Zeitlin
   5 // Id:          $Id$
   6 // Copyright:   (c) 1998 Robert Roebling
   7 //              (c) 2007 Vadim Zeitlin
   8 // Licence:     wxWindows licence
   9 /////////////////////////////////////////////////////////////////////////////
  10
  11 // ============================================================================
  12 // declarations
  13 // ============================================================================
  14
  15 // ----------------------------------------------------------------------------
  16 // headers
  17 // ----------------------------------------------------------------------------
  18
  19 // For compilers that support precompilation, includes "wx.h".
  20 #include "wx/wxprec.h"
  21
  22 #if wxUSE_CLIPBOARD
  23
  24 #include "wx/clipbrd.h"
  25
  26 #ifndef WX_PRECOMP
  27     #include "wx/app.h"
  28     #include "wx/log.h"
  29     #include "wx/utils.h"
  30     #include "wx/dataobj.h"
  31 #endif
  32
  33 #include "wx/scopedarray.h"
  34 #include "wx/scopeguard.h"
  35 #include "wx/evtloop.h"
  36
  37 #include "wx/gtk/private.h"
  38
  39 typedef wxScopedArray<wxDataFormat> wxDataFormatArray;
  40
  41 // ----------------------------------------------------------------------------
  42 // data
  43 // ----------------------------------------------------------------------------
  44
  45 static GdkAtom  g_clipboardAtom   = 0;
  46 static GdkAtom  g_targetsAtom     = 0;
  47 static GdkAtom  g_timestampAtom   = 0;
  48
  49 #if wxUSE_UNICODE
  50 extern GdkAtom g_altTextAtom;
  51 #endif
  52
  53 // the trace mask we use with wxLogTrace() - call
  54 // wxLog::AddTraceMask(TRACE_CLIPBOARD) to enable the trace messages from here
  55 // (there will be a *lot* of them!)
  56 #define TRACE_CLIPBOARD wxT("clipboard")
  57
  58 // ----------------------------------------------------------------------------
  59 // wxClipboardSync: used to perform clipboard operations synchronously
  60 // ----------------------------------------------------------------------------
  61
  62 // constructing this object on stack will wait wait until the latest clipboard
  63 // operation is finished on block exit
  64 //
  65 // notice that there can be no more than one such object alive at any moment,
  66 // i.e. reentrancies are not allowed
  67 class wxClipboardSync
  68 {
  69 public:
  70     wxClipboardSync(wxClipboard& clipboard)
  71     {
  72         wxASSERT_MSG( !ms_clipboard, wxT("reentrancy in clipboard code") );
  73         ms_clipboard = &clipboard;
  74     }
  75
  76     ~wxClipboardSync()
  77     {
  78 #if wxUSE_CONSOLE_EVENTLOOP
  79         // ensure that there is a running event loop: this might not be the
  80         // case if we're called before the main event loop startup
  81         wxEventLoopGuarantor ensureEventLoop;
  82 #endif
  83         while (ms_clipboard)
  84             wxEventLoopBase::GetActive()->YieldFor(wxEVT_CATEGORY_CLIPBOARD);
  85     }
  86
  87     // this method must be called by GTK+ callbacks to indicate that we got the
  88     // result for our clipboard operation
  89     static void OnDone(wxClipboard * WXUNUSED_UNLESS_DEBUG(clipboard))
  90     {
  91         wxASSERT_MSG( clipboard == ms_clipboard,
  92                         wxT("got notification for alien clipboard") );
  93
  94         ms_clipboard = NULL;
  95     }
  96
  97     // this method should be called if it's possible that no async clipboard
  98     // operation is currently in progress (like it can be the case when the
  99     // clipboard is cleared but not because we asked about it), it should only
 100     // be called if such situation is expected -- otherwise call OnDone() which
 101     // would assert in this case
 102     static void OnDoneIfInProgress(wxClipboard *clipboard)
 103     {
 104         if ( ms_clipboard )
 105             OnDone(clipboard);
 106     }
 107
 108 private:
 109     static wxClipboard *ms_clipboard;
 110
 111     wxDECLARE_NO_COPY_CLASS(wxClipboardSync);
 112 };
 113
 114 wxClipboard *wxClipboardSync::ms_clipboard = NULL;
 115
 116 // ============================================================================
 117 // clipboard callbacks implementation
 118 // ============================================================================
 119
 120 //-----------------------------------------------------------------------------
 121 // "selection_received" for targets
 122 //-----------------------------------------------------------------------------
 123
 124 extern "C" {
 125 static void
 126 targets_selection_received( GtkWidget *WXUNUSED(widget),
 127                             GtkSelectionData *selection_data,
 128                             guint32 WXUNUSED(time),
 129                             wxClipboard *clipboard )
 130 {
 131     if ( !clipboard )
 132         return;
 133
 134     wxON_BLOCK_EXIT1(wxClipboardSync::OnDone, clipboard);
 135
 136     if ( !selection_data || selection_data->length <= 0 )
 137         return;
 138
 139     // make sure we got the data in the correct form
 140     GdkAtom type = selection_data->type;
 141     if ( type != GDK_SELECTION_TYPE_ATOM )
 142     {
 143         if ( strcmp(wxGtkString(gdk_atom_name(type)), "TARGETS") != 0 )
 144         {
 145             wxLogTrace( TRACE_CLIPBOARD,
 146                         wxT("got unsupported clipboard target") );
 147
 148             return;
 149         }
 150     }
 151
 152     // it's not really a format, of course, but we can reuse its GetId() method
 153     // to format this atom as string
 154     wxDataFormat clip(selection_data->selection);
 155     wxLogTrace( TRACE_CLIPBOARD,
 156                 wxT("Received available formats for clipboard %s"),
 157                 clip.GetId().c_str() );
 158
 159     // the atoms we received, holding a list of targets (= formats)
 160     const GdkAtom * const atoms = (GdkAtom *)selection_data->data;
 161     for ( size_t i = 0; i < selection_data->length/sizeof(GdkAtom); i++ )
 162     {
 163         const wxDataFormat format(atoms[i]);
 164
 165         wxLogTrace(TRACE_CLIPBOARD, wxT("\t%s"), format.GetId().c_str());
 166
 167         if ( clipboard->GTKOnTargetReceived(format) )
 168             return;
 169     }
 170 }
 171 }
 172
 173 bool wxClipboard::GTKOnTargetReceived(const wxDataFormat& format)
 174 {
 175     if ( format != m_targetRequested )
 176         return false;
 177
 178     m_formatSupported = true;
 179     return true;
 180 }
 181
 182 //-----------------------------------------------------------------------------
 183 // "selection_received" for the actual data
 184 //-----------------------------------------------------------------------------
 185
 186 extern "C" {
 187 static void
 188 selection_received( GtkWidget *WXUNUSED(widget),
 189                     GtkSelectionData *selection_data,
 190                     guint32 WXUNUSED(time),
 191                     wxClipboard *clipboard )
 192 {
 193     if ( !clipboard )
 194         return;
 195
 196     wxON_BLOCK_EXIT1(wxClipboardSync::OnDone, clipboard);
 197
 198     if ( !selection_data || selection_data->length <= 0 )
 199         return;
 200
 201     clipboard->GTKOnSelectionReceived(*selection_data);
 202 }
 203 }
 204
 205 //-----------------------------------------------------------------------------
 206 // "selection_clear"
 207 //-----------------------------------------------------------------------------
 208
 209 extern "C" {
 210 static gint
 211 selection_clear_clip( GtkWidget *WXUNUSED(widget), GdkEventSelection *event )
 212 {
 213     wxClipboard * const clipboard = wxTheClipboard;
 214     if ( !clipboard )
 215         return TRUE;
 216
 217     // notice the use of OnDoneIfInProgress() here instead of just OnDone():
 218     // it's perfectly possible that we're receiving this notification from GTK+
 219     // even though we hadn't cleared the clipboard ourselves but because
 220     // another application (or even another window in the same program)
 221     // acquired it
 222     wxON_BLOCK_EXIT1(wxClipboardSync::OnDoneIfInProgress, clipboard);
 223
 224     wxClipboard::Kind kind;
 225     if (event->selection == GDK_SELECTION_PRIMARY)
 226     {
 227         wxLogTrace(TRACE_CLIPBOARD, wxT("Lost primary selection" ));
 228
 229         kind = wxClipboard::Primary;
 230     }
 231     else if (event->selection == g_clipboardAtom)
 232     {
 233         wxLogTrace(TRACE_CLIPBOARD, wxT("Lost clipboard" ));
 234
 235         kind = wxClipboard::Clipboard;
 236     }
 237     else // some other selection, we're not concerned
 238     {
 239         return FALSE;
 240     }
 241
 242     // the clipboard is no longer in our hands, we don't need data any more
 243     clipboard->GTKClearData(kind);
 244
 245     return TRUE;
 246 }
 247 }
 248
 249 //-----------------------------------------------------------------------------
 250 // selection handler for supplying data
 251 //-----------------------------------------------------------------------------
 252
 253 extern "C" {
 254 static void
 255 selection_handler( GtkWidget *WXUNUSED(widget),
 256                    GtkSelectionData *selection_data,
 257                    guint WXUNUSED(info),
 258                    guint WXUNUSED(time),
 259                    gpointer signal_data )
 260 {
 261     wxClipboard * const clipboard = wxTheClipboard;
 262     if ( !clipboard )
 263         return;
 264
 265     wxDataObject * const data = clipboard->GTKGetDataObject();
 266     if ( !data )
 267         return;
 268
 269     // ICCCM says that TIMESTAMP is a required atom.
 270     // In particular, it satisfies Klipper, which polls
 271     // TIMESTAMP to see if the clipboards content has changed.
 272     // It shall return the time which was used to set the data.
 273     if (selection_data->target == g_timestampAtom)
 274     {
 275         guint timestamp = GPOINTER_TO_UINT (signal_data);
 276         gtk_selection_data_set(selection_data,
 277                                GDK_SELECTION_TYPE_INTEGER,
 278                                32,
 279                                (guchar*)&(timestamp),
 280                                sizeof(timestamp));
 281         wxLogTrace(TRACE_CLIPBOARD,
 282                    wxT("Clipboard TIMESTAMP requested, returning timestamp=%u"),
 283                    timestamp);
 284         return;
 285     }
 286
 287     wxDataFormat format( selection_data->target );
 288
 289     wxLogTrace(TRACE_CLIPBOARD,
 290                wxT("clipboard data in format %s, GtkSelectionData is target=%s type=%s selection=%s timestamp=%u"),
 291                format.GetId().c_str(),
 292                wxString::FromAscii(wxGtkString(gdk_atom_name(selection_data->target))).c_str(),
 293                wxString::FromAscii(wxGtkString(gdk_atom_name(selection_data->type))).c_str(),
 294                wxString::FromAscii(wxGtkString(gdk_atom_name(selection_data->selection))).c_str(),
 295                GPOINTER_TO_UINT( signal_data )
 296                );
 297
 298     if ( !data->IsSupportedFormat( format ) )
 299         return;
 300
 301     int size = data->GetDataSize( format );
 302     if ( !size )
 303         return;
 304
 305     wxCharBuffer buf(size - 1); // it adds 1 internally (for NUL)
 306
 307     // text data must be returned in UTF8 if format is wxDF_UNICODETEXT
 308     if ( !data->GetDataHere(format, buf.data()) )
 309         return;
 310
 311     // use UTF8_STRING format if requested in Unicode build but just plain
 312     // STRING one in ANSI or if explicitly asked in Unicode
 313 #if wxUSE_UNICODE
 314     if (format == wxDataFormat(wxDF_UNICODETEXT))
 315     {
 316         gtk_selection_data_set_text(
 317             selection_data,
 318             (const gchar*)buf.data(),
 319             size );
 320     }
 321     else
 322 #endif // wxUSE_UNICODE
 323     {
 324         gtk_selection_data_set(
 325             selection_data,
 326             GDK_SELECTION_TYPE_STRING,
 327             8*sizeof(gchar),
 328             (const guchar*)buf.data(),
 329             size );
 330     }
 331 }
 332 }
 333
 334 void wxClipboard::GTKOnSelectionReceived(const GtkSelectionData& sel)
 335 {
 336     wxCHECK_RET( m_receivedData, wxT("should be inside GetData()") );
 337
 338     const wxDataFormat format(sel.target);
 339     wxLogTrace(TRACE_CLIPBOARD, wxT("Received selection %s"),
 340                format.GetId().c_str());
 341
 342     if ( !m_receivedData->IsSupportedFormat(format) )
 343         return;
 344
 345     m_receivedData->SetData(format, sel.length, sel.data);
 346     m_formatSupported = true;
 347 }
 348
 349 //-----------------------------------------------------------------------------
 350 // asynchronous "selection_received" for targets
 351 //-----------------------------------------------------------------------------
 352
 353 extern "C" {
 354 static void
 355 async_targets_selection_received( GtkWidget *WXUNUSED(widget),
 356                             GtkSelectionData *selection_data,
 357                             guint32 WXUNUSED(time),
 358                             wxClipboard *clipboard )
 359 {
 360     if ( !clipboard ) // Assert?
 361         return;
 362
 363     if (!clipboard->m_sink)
 364         return;
 365
 366     wxClipboardEvent *event = new wxClipboardEvent(wxEVT_CLIPBOARD_CHANGED);
 367     event->SetEventObject( clipboard );
 368
 369     if ( !selection_data || selection_data->length <= 0 )
 370     {
 371         clipboard->m_sink->QueueEvent( event );
 372         clipboard->m_sink.Release();
 373         return;
 374     }
 375
 376     // make sure we got the data in the correct form
 377     GdkAtom type = selection_data->type;
 378     if ( type != GDK_SELECTION_TYPE_ATOM )
 379     {
 380         if ( strcmp(wxGtkString(gdk_atom_name(type)), "TARGETS") != 0 )
 381         {
 382             wxLogTrace( TRACE_CLIPBOARD,
 383                         wxT("got unsupported clipboard target") );
 384
 385             clipboard->m_sink->QueueEvent( event );
 386             clipboard->m_sink.Release();
 387             return;
 388         }
 389     }
 390
 391     // it's not really a format, of course, but we can reuse its GetId() method
 392     // to format this atom as string
 393     wxDataFormat clip(selection_data->selection);
 394     wxLogTrace( TRACE_CLIPBOARD,
 395                 wxT("Received available formats for clipboard %s"),
 396                 clip.GetId().c_str() );
 397
 398     // the atoms we received, holding a list of targets (= formats)
 399     const GdkAtom * const atoms = (GdkAtom *)selection_data->data;
 400     for ( size_t i = 0; i < selection_data->length/sizeof(GdkAtom); i++ )
 401     {
 402         const wxDataFormat format(atoms[i]);
 403
 404         wxLogTrace(TRACE_CLIPBOARD, wxT("\t%s"), format.GetId().c_str());
 405
 406         event->AddFormat( format );
 407     }
 408
 409     clipboard->m_sink->QueueEvent( event );
 410     clipboard->m_sink.Release();
 411 }
 412 }
 413
 414 // ============================================================================
 415 // wxClipboard implementation
 416 // ============================================================================
 417
 418 // ----------------------------------------------------------------------------
 419 // wxClipboard ctor/dtor
 420 // ----------------------------------------------------------------------------
 421
 422 IMPLEMENT_DYNAMIC_CLASS(wxClipboard,wxObject)
 423
 424 wxClipboard::wxClipboard()
 425 {
 426     m_open = false;
 427
 428     m_dataPrimary =
 429     m_dataClipboard =
 430     m_receivedData = NULL;
 431
 432     m_formatSupported = false;
 433     m_targetRequested = 0;
 434
 435     // we use m_targetsWidget to query what formats are available
 436     m_targetsWidget = gtk_window_new( GTK_WINDOW_POPUP );
 437     gtk_widget_realize( m_targetsWidget );
 438
 439     g_signal_connect (m_targetsWidget, "selection_received",
 440                       G_CALLBACK (targets_selection_received), this);
 441
 442     // we use m_targetsWidgetAsync to query what formats are available asynchronously
 443     m_targetsWidgetAsync = gtk_window_new( GTK_WINDOW_POPUP );
 444     gtk_widget_realize( m_targetsWidgetAsync );
 445
 446     g_signal_connect (m_targetsWidgetAsync, "selection_received",
 447                       G_CALLBACK (async_targets_selection_received), this);
 448
 449     // we use m_clipboardWidget to get and to offer data
 450     m_clipboardWidget = gtk_window_new( GTK_WINDOW_POPUP );
 451     gtk_widget_realize( m_clipboardWidget );
 452
 453     g_signal_connect (m_clipboardWidget, "selection_received",
 454                       G_CALLBACK (selection_received), this);
 455
 456     g_signal_connect (m_clipboardWidget, "selection_clear_event",
 457                       G_CALLBACK (selection_clear_clip), NULL);
 458
 459     // initialize atoms we use if not done yet
 460     if ( !g_clipboardAtom )
 461         g_clipboardAtom = gdk_atom_intern( "CLIPBOARD", FALSE );
 462     if ( !g_targetsAtom )
 463         g_targetsAtom = gdk_atom_intern ("TARGETS", FALSE);
 464     if ( !g_timestampAtom )
 465         g_timestampAtom = gdk_atom_intern ("TIMESTAMP", FALSE);
 466 }
 467
 468 wxClipboard::~wxClipboard()
 469 {
 470     Clear();
 471
 472     gtk_widget_destroy( m_clipboardWidget );
 473     gtk_widget_destroy( m_targetsWidget );
 474 }
 475
 476 // ----------------------------------------------------------------------------
 477 // wxClipboard helper functions
 478 // ----------------------------------------------------------------------------
 479
 480 GdkAtom wxClipboard::GTKGetClipboardAtom() const
 481 {
 482     return m_usePrimary ? (GdkAtom)GDK_SELECTION_PRIMARY
 483                         : g_clipboardAtom;
 484 }
 485
 486 void wxClipboard::GTKClearData(Kind kind)
 487 {
 488     wxDataObject *&data = Data(kind);
 489     wxDELETE(data);
 490 }
 491
 492 bool wxClipboard::SetSelectionOwner(bool set)
 493 {
 494     bool rc = gtk_selection_owner_set
 495               (
 496                 set ? m_clipboardWidget : NULL,
 497                 GTKGetClipboardAtom(),
 498                 (guint32)GDK_CURRENT_TIME
 499               );
 500
 501     if ( !rc )
 502     {
 503         wxLogTrace(TRACE_CLIPBOARD, wxT("Failed to %sset selection owner"),
 504                    set ? wxT("") : wxT("un"));
 505     }
 506
 507     return rc;
 508 }
 509
 510 void wxClipboard::AddSupportedTarget(GdkAtom atom)
 511 {
 512     gtk_selection_add_target
 513     (
 514         m_clipboardWidget,
 515         GTKGetClipboardAtom(),
 516         atom,
 517         0 // info (same as client data) unused
 518     );
 519 }
 520
 521 bool wxClipboard::IsSupportedAsync(wxEvtHandler *sink)
 522 {
 523     if (m_sink.get())
 524         return false;  // currently busy, come back later
 525
 526     wxCHECK_MSG( sink, false, wxT("no sink given") );
 527
 528     m_sink = sink;
 529     gtk_selection_convert( m_targetsWidgetAsync,
 530                            GTKGetClipboardAtom(),
 531                            g_targetsAtom,
 532                            (guint32) GDK_CURRENT_TIME );
 533
 534     return true;
 535 }
 536
 537 bool wxClipboard::DoIsSupported(const wxDataFormat& format)
 538 {
 539     wxCHECK_MSG( format, false, wxT("invalid clipboard format") );
 540
 541     wxLogTrace(TRACE_CLIPBOARD, wxT("Checking if format %s is available"),
 542                format.GetId().c_str());
 543
 544     // these variables will be used by our GTKOnTargetReceived()
 545     m_targetRequested = format;
 546     m_formatSupported = false;
 547
 548     // block until m_formatSupported is set from targets_selection_received
 549     // callback
 550     {
 551         wxClipboardSync sync(*this);
 552
 553         gtk_selection_convert( m_targetsWidget,
 554                                GTKGetClipboardAtom(),
 555                                g_targetsAtom,
 556                                (guint32) GDK_CURRENT_TIME );
 557     }
 558
 559     return m_formatSupported;
 560 }
 561
 562 // ----------------------------------------------------------------------------
 563 // wxClipboard public API implementation
 564 // ----------------------------------------------------------------------------
 565
 566 void wxClipboard::Clear()
 567 {
 568     gtk_selection_clear_targets( m_clipboardWidget, GTKGetClipboardAtom() );
 569
 570     if ( gdk_selection_owner_get(GTKGetClipboardAtom()) ==
 571             m_clipboardWidget->window )
 572     {
 573         wxClipboardSync sync(*this);
 574
 575         // this will result in selection_clear_clip callback being called and
 576         // it will free our data
 577         SetSelectionOwner(false);
 578     }
 579
 580     m_targetRequested = 0;
 581     m_formatSupported = false;
 582 }
 583
 584 bool wxClipboard::Open()
 585 {
 586     wxCHECK_MSG( !m_open, false, wxT("clipboard already open") );
 587
 588     m_open = true;
 589
 590     return true;
 591 }
 592
 593 bool wxClipboard::SetData( wxDataObject *data )
 594 {
 595     wxCHECK_MSG( m_open, false, wxT("clipboard not open") );
 596
 597     wxCHECK_MSG( data, false, wxT("data is invalid") );
 598
 599     Clear();
 600
 601     return AddData( data );
 602 }
 603
 604 bool wxClipboard::AddData( wxDataObject *data )
 605 {
 606     wxCHECK_MSG( m_open, false, wxT("clipboard not open") );
 607
 608     wxCHECK_MSG( data, false, wxT("data is invalid") );
 609
 610     // we can only store one wxDataObject so clear the old one
 611     Clear();
 612
 613     Data() = data;
 614
 615     // get formats from wxDataObjects
 616     const size_t count = data->GetFormatCount();
 617     wxDataFormatArray formats(new wxDataFormat[count]);
 618     data->GetAllFormats(formats.get());
 619
 620     // always provide TIMESTAMP as a target, see comments in selection_handler
 621     // for explanation
 622     AddSupportedTarget(g_timestampAtom);
 623
 624     for ( size_t i = 0; i < count; i++ )
 625     {
 626         const wxDataFormat format(formats[i]);
 627
 628         wxLogTrace(TRACE_CLIPBOARD, wxT("Adding support for %s"),
 629                    format.GetId().c_str());
 630
 631         AddSupportedTarget(format);
 632     }
 633
 634     g_signal_connect (m_clipboardWidget, "selection_get",
 635                       G_CALLBACK (selection_handler),
 636                       GUINT_TO_POINTER (gtk_get_current_event_time()) );
 637
 638     // tell the world we offer clipboard data
 639     return SetSelectionOwner();
 640 }
 641
 642 void wxClipboard::Close()
 643 {
 644     wxCHECK_RET( m_open, wxT("clipboard not open") );
 645
 646     m_open = false;
 647 }
 648
 649 bool wxClipboard::IsOpened() const
 650 {
 651     return m_open;
 652 }
 653
 654 bool wxClipboard::IsSupported( const wxDataFormat& format )
 655 {
 656     if ( DoIsSupported(format) )
 657         return true;
 658
 659 #if wxUSE_UNICODE
 660     if ( format == wxDF_UNICODETEXT )
 661     {
 662         // also with plain STRING format
 663         return DoIsSupported(g_altTextAtom);
 664     }
 665 #endif // wxUSE_UNICODE
 666
 667     return false;
 668 }
 669
 670 bool wxClipboard::GetData( wxDataObject& data )
 671 {
 672     wxCHECK_MSG( m_open, false, wxT("clipboard not open") );
 673
 674     // get all supported formats from wxDataObjects: notice that we are setting
 675     // the object data, so we need them in "Set" direction
 676     const size_t count = data.GetFormatCount(wxDataObject::Set);
 677     wxDataFormatArray formats(new wxDataFormat[count]);
 678     data.GetAllFormats(formats.get(), wxDataObject::Set);
 679
 680     for ( size_t i = 0; i < count; i++ )
 681     {
 682         const wxDataFormat format(formats[i]);
 683
 684         // is this format supported by clipboard ?
 685         if ( !DoIsSupported(format) )
 686             continue;
 687
 688         wxLogTrace(TRACE_CLIPBOARD, wxT("Requesting format %s"),
 689                    format.GetId().c_str());
 690
 691         // these variables will be used by our GTKOnSelectionReceived()
 692         m_receivedData = &data;
 693         m_formatSupported = false;
 694
 695         {
 696             wxClipboardSync sync(*this);
 697
 698             gtk_selection_convert(m_clipboardWidget,
 699                                   GTKGetClipboardAtom(),
 700                                   format,
 701                                   (guint32) GDK_CURRENT_TIME );
 702         } // wait until we get the results
 703
 704         /*
 705            Normally this is a true error as we checked for the presence of such
 706            data before, but there are applications that may return an empty
 707            string (e.g. Gnumeric-1.6.1 on Linux if an empty cell is copied)
 708            which would produce a false error message here, so we check for the
 709            size of the string first. With ANSI, GetDataSize returns an extra
 710            value (for the closing null?), with unicode, the exact number of
 711            tokens is given (that is more than 1 for non-ASCII characters)
 712            (tested with Gnumeric-1.6.1 and OpenOffice.org-2.0.2)
 713          */
 714 #if wxUSE_UNICODE
 715         if ( format != wxDF_UNICODETEXT || data.GetDataSize(format) > 0 )
 716 #else // !UNICODE
 717         if ( format != wxDF_TEXT || data.GetDataSize(format) > 1 )
 718 #endif // UNICODE / !UNICODE
 719         {
 720             wxCHECK_MSG( m_formatSupported, false,
 721                          wxT("error retrieving data from clipboard") );
 722         }
 723
 724         return true;
 725     }
 726
 727     wxLogTrace(TRACE_CLIPBOARD, wxT("GetData(): format not found"));
 728
 729     return false;
 730 }
 731
 732 #endif // wxUSE_CLIPBOARD