windows/dce.c

   1 /*
   2  * USER DCE functions
   3  *
   4  * Copyright 1993 Alexandre Julliard
   5  *           1996,1997 Alex Korobka
   6  *
   7  * This library is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * This library is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with this library; if not, write to the Free Software
  19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  20  *
  21  *
  22  * Note: Visible regions of CS_OWNDC/CS_CLASSDC window DCs
  23  * have to be updated dynamically.
  24  *
  25  * Internal DCX flags:
  26  *
  27  * DCX_DCEEMPTY    - dce is uninitialized
  28  * DCX_DCEBUSY     - dce is in use
  29  * DCX_DCEDIRTY    - ReleaseDC() should wipe instead of caching
  30  * DCX_KEEPCLIPRGN - ReleaseDC() should not delete the clipping region
  31  * DCX_WINDOWPAINT - BeginPaint() is in effect
  32  */
  33
  34 #include <assert.h>
  35 #include "dce.h"
  36 #include "win.h"
  37 #include "gdi.h"
  38 #include "user.h"
  39 #include "wine/debug.h"
  40 #include "windef.h"
  41 #include "wingdi.h"
  42 #include "wine/winbase16.h"
  43 #include "wine/winuser16.h"
  44
  45 WINE_DEFAULT_DEBUG_CHANNEL(dc);
  46
  47 static DCE *firstDCE;
  48 static HDC defaultDCstate;
  49
  50 static void DCE_DeleteClipRgn( DCE* );
  51 static INT DCE_ReleaseDC( DCE* );
  52
  53
  54 /***********************************************************************
  55  *           DCE_DumpCache
  56  */
  57 static void DCE_DumpCache(void)
  58 {
  59     DCE *dce;
  60
  61     USER_Lock();
  62     dce = firstDCE;
  63
  64     DPRINTF("DCE:\n");
  65     while( dce )
  66     {
  67         DPRINTF("\t[0x%08x] hWnd 0x%04x, dcx %08x, %s %s\n",
  68              (unsigned)dce, dce->hwndCurrent, (unsigned)dce->DCXflags,
  69              (dce->DCXflags & DCX_CACHE) ? "Cache" : "Owned",
  70              (dce->DCXflags & DCX_DCEBUSY) ? "InUse" : "" );
  71         dce = dce->next;
  72     }
  73
  74     USER_Unlock();
  75 }
  76
  77 /***********************************************************************
  78  *           DCE_AllocDCE
  79  *
  80  * Allocate a new DCE.
  81  */
  82 DCE *DCE_AllocDCE( HWND hWnd, DCE_TYPE type )
  83 {
  84     DCE * dce;
  85
  86     if (!(dce = HeapAlloc( GetProcessHeap(), 0, sizeof(DCE) ))) return NULL;
  87     if (!(dce->hDC = CreateDCA( "DISPLAY", NULL, NULL, NULL )))
  88     {
  89         HeapFree( GetProcessHeap(), 0, dce );
  90         return 0;
  91     }
  92     if (!defaultDCstate) defaultDCstate = GetDCState16( dce->hDC );
  93
  94     /* store DCE handle in DC hook data field */
  95
  96     SetDCHook( dce->hDC, DCHook16, (DWORD)dce );
  97
  98     dce->hwndCurrent = WIN_GetFullHandle( hWnd );
  99     dce->hClipRgn    = 0;
 100
 101     if( type != DCE_CACHE_DC ) /* owned or class DC */
 102     {
 103         dce->DCXflags = DCX_DCEBUSY;
 104         if( hWnd )
 105         {
 106             LONG style = GetWindowLongW( hWnd, GWL_STYLE );
 107             if (style & WS_CLIPCHILDREN) dce->DCXflags |= DCX_CLIPCHILDREN;
 108             if (style & WS_CLIPSIBLINGS) dce->DCXflags |= DCX_CLIPSIBLINGS;
 109         }
 110         SetHookFlags16(dce->hDC,DCHF_INVALIDATEVISRGN);
 111     }
 112     else dce->DCXflags = DCX_CACHE | DCX_DCEEMPTY;
 113
 114     USER_Lock();
 115     dce->next = firstDCE;
 116     firstDCE = dce;
 117     USER_Unlock();
 118     return dce;
 119 }
 120
 121
 122 /***********************************************************************
 123  *           DCE_FreeDCE
 124  */
 125 DCE* DCE_FreeDCE( DCE *dce )
 126 {
 127     DCE **ppDCE, *ret;
 128
 129     if (!dce) return NULL;
 130
 131     USER_Lock();
 132
 133     ppDCE = &firstDCE;
 134
 135     while (*ppDCE && (*ppDCE != dce)) ppDCE = &(*ppDCE)->next;
 136     if (*ppDCE == dce) *ppDCE = dce->next;
 137     ret = *ppDCE;
 138     USER_Unlock();
 139
 140     SetDCHook(dce->hDC, NULL, 0L);
 141
 142     DeleteDC( dce->hDC );
 143     if( dce->hClipRgn && !(dce->DCXflags & DCX_KEEPCLIPRGN) )
 144         DeleteObject(dce->hClipRgn);
 145     HeapFree( GetProcessHeap(), 0, dce );
 146
 147     return ret;
 148 }
 149
 150 /***********************************************************************
 151  *           DCE_FreeWindowDCE
 152  *
 153  * Remove owned DCE and reset unreleased cache DCEs.
 154  */
 155 void DCE_FreeWindowDCE( HWND hwnd )
 156 {
 157     DCE *pDCE;
 158     WND *pWnd = WIN_GetPtr( hwnd );
 159
 160     pDCE = firstDCE;
 161     while( pDCE )
 162     {
 163         if( pDCE->hwndCurrent == hwnd )
 164         {
 165             if( pDCE == pWnd->dce ) /* owned or Class DCE*/
 166             {
 167                 if (pWnd->clsStyle & CS_OWNDC)  /* owned DCE*/
 168                 {
 169                     pDCE = DCE_FreeDCE( pDCE );
 170                     pWnd->dce = NULL;
 171                     continue;
 172                 }
 173                 else if( pDCE->DCXflags & (DCX_INTERSECTRGN | DCX_EXCLUDERGN) ) /* Class DCE*/
 174                 {
 175                     DCE_DeleteClipRgn( pDCE );
 176                     pDCE->hwndCurrent = 0;
 177                 }
 178             }
 179             else
 180             {
 181                 if( pDCE->DCXflags & DCX_DCEBUSY ) /* shared cache DCE */
 182                 {
 183                     /* FIXME: AFAICS we are doing the right thing here so
 184                      * this should be a WARN. But this is best left as an ERR
 185                      * because the 'application error' is likely to come from
 186                      * another part of Wine (i.e. it's our fault after all).
 187                      * We should change this to WARN when Wine is more stable
 188                      * (for 1.0?).
 189                      */
 190                     ERR("[%08x] GetDC() without ReleaseDC()!\n",hwnd);
 191                     DCE_ReleaseDC( pDCE );
 192                 }
 193
 194                 pDCE->DCXflags &= DCX_CACHE;
 195                 pDCE->DCXflags |= DCX_DCEEMPTY;
 196                 pDCE->hwndCurrent = 0;
 197             }
 198         }
 199         pDCE = pDCE->next;
 200     }
 201     WIN_ReleasePtr( pWnd );
 202 }
 203
 204
 205 /***********************************************************************
 206  *   DCE_DeleteClipRgn
 207  */
 208 static void DCE_DeleteClipRgn( DCE* dce )
 209 {
 210     dce->DCXflags &= ~(DCX_EXCLUDERGN | DCX_INTERSECTRGN | DCX_WINDOWPAINT);
 211
 212     if( dce->DCXflags & DCX_KEEPCLIPRGN )
 213         dce->DCXflags &= ~DCX_KEEPCLIPRGN;
 214     else
 215         if( dce->hClipRgn > 1 )
 216             DeleteObject( dce->hClipRgn );
 217
 218     dce->hClipRgn = 0;
 219
 220     /* make it dirty so that the vis rgn gets recomputed next time */
 221     dce->DCXflags |= DCX_DCEDIRTY;
 222     SetHookFlags16( dce->hDC, DCHF_INVALIDATEVISRGN );
 223 }
 224
 225
 226 /***********************************************************************
 227  *   DCE_ReleaseDC
 228  */
 229 static INT DCE_ReleaseDC( DCE* dce )
 230 {
 231     if ((dce->DCXflags & (DCX_DCEEMPTY | DCX_DCEBUSY)) != DCX_DCEBUSY) return 0;
 232
 233     /* restore previous visible region */
 234
 235     if ((dce->DCXflags & (DCX_INTERSECTRGN | DCX_EXCLUDERGN)) &&
 236         (dce->DCXflags & (DCX_CACHE | DCX_WINDOWPAINT)) )
 237         DCE_DeleteClipRgn( dce );
 238
 239     if (dce->DCXflags & DCX_CACHE)
 240     {
 241         /* make the DC clean so that SetDCState doesn't try to update the vis rgn */
 242         SetHookFlags16( dce->hDC, DCHF_VALIDATEVISRGN );
 243         SetDCState16( dce->hDC, defaultDCstate );
 244         dce->DCXflags &= ~DCX_DCEBUSY;
 245         if (dce->DCXflags & DCX_DCEDIRTY)
 246         {
 247             /* don't keep around invalidated entries
 248              * because SetDCState() disables hVisRgn updates
 249              * by removing dirty bit. */
 250
 251             dce->hwndCurrent = 0;
 252             dce->DCXflags &= DCX_CACHE;
 253             dce->DCXflags |= DCX_DCEEMPTY;
 254         }
 255     }
 256     return 1;
 257 }
 258
 259
 260 /***********************************************************************
 261  *   DCE_InvalidateDCE
 262  *
 263  * It is called from SetWindowPos() and EVENT_MapNotify - we have to
 264  * mark as dirty all busy DCEs for windows that have pWnd->parent as
 265  * an ancestor and whose client rect intersects with specified update
 266  * rectangle. In addition, pWnd->parent DCEs may need to be updated if
 267  * DCX_CLIPCHILDREN flag is set.  */
 268 BOOL DCE_InvalidateDCE(HWND hwnd, const RECT* pRectUpdate)
 269 {
 270     HWND hwndScope = GetAncestor( hwnd, GA_PARENT );
 271     BOOL bRet = FALSE;
 272
 273     if( hwndScope )
 274     {
 275         DCE *dce;
 276
 277         TRACE("scope hwnd = %04x, (%i,%i - %i,%i)\n",
 278                      hwndScope, pRectUpdate->left,pRectUpdate->top,
 279                      pRectUpdate->right,pRectUpdate->bottom);
 280         if(TRACE_ON(dc))
 281           DCE_DumpCache();
 282
 283         /* walk all DCEs and fixup non-empty entries */
 284
 285         for (dce = firstDCE; (dce); dce = dce->next)
 286         {
 287             if (dce->DCXflags & DCX_DCEEMPTY) continue;
 288             if ((dce->hwndCurrent == hwndScope) && !(dce->DCXflags & DCX_CLIPCHILDREN))
 289                 continue;  /* child window positions don't bother us */
 290
 291             /* check if DCE window is within the z-order scope */
 292
 293             if (hwndScope == dce->hwndCurrent || IsChild( hwndScope, dce->hwndCurrent ))
 294             {
 295                 if (hwnd != dce->hwndCurrent)
 296                 {
 297                     /* check if the window rectangle intersects this DCE window */
 298                     RECT rect;
 299                     GetWindowRect( dce->hwndCurrent, &rect );
 300                     MapWindowPoints( 0, hwndScope, (POINT *)&rect, 2 );
 301                     if (!IntersectRect( &rect, &rect, pRectUpdate )) continue;
 302
 303                 }
 304                 if( !(dce->DCXflags & DCX_DCEBUSY) )
 305                 {
 306                     /* Don't bother with visible regions of unused DCEs */
 307
 308                     TRACE("\tpurged %p dce [%04x]\n", dce, dce->hwndCurrent);
 309                     dce->hwndCurrent = 0;
 310                     dce->DCXflags &= DCX_CACHE;
 311                     dce->DCXflags |= DCX_DCEEMPTY;
 312                 }
 313                 else
 314                 {
 315                     /* Set dirty bits in the hDC and DCE structs */
 316
 317                     TRACE("\tfixed up %p dce [%04x]\n", dce, dce->hwndCurrent);
 318                     dce->DCXflags |= DCX_DCEDIRTY;
 319                     SetHookFlags16(dce->hDC, DCHF_INVALIDATEVISRGN);
 320                     bRet = TRUE;
 321                 }
 322             }
 323         } /* dce list */
 324     }
 325     return bRet;
 326 }
 327
 328
 329 /***********************************************************************
 330  *           DCE_ExcludeRgn
 331  *
 332  *  Translate given region from the wnd client to the DC coordinates
 333  *  and add it to the clipping region.
 334  */
 335 INT DCE_ExcludeRgn( HDC hDC, HWND hwnd, HRGN hRgn )
 336 {
 337   POINT  pt = {0, 0};
 338   DCE     *dce = firstDCE;
 339
 340   while (dce && (dce->hDC != hDC)) dce = dce->next;
 341   if (!dce) return ERROR;
 342
 343   MapWindowPoints( hwnd, dce->hwndCurrent, &pt, 1);
 344   if( dce->DCXflags & DCX_WINDOW )
 345   {
 346       WND *wnd = WIN_FindWndPtr(dce->hwndCurrent);
 347       pt.x += wnd->rectClient.left - wnd->rectWindow.left;
 348       pt.y += wnd->rectClient.top - wnd->rectWindow.top;
 349       WIN_ReleaseWndPtr(wnd);
 350   }
 351   OffsetRgn(hRgn, pt.x, pt.y);
 352
 353   return ExtSelectClipRgn( hDC, hRgn, RGN_DIFF );
 354 }
 355
 356
 357 /***********************************************************************
 358  *              GetDCEx (USER32.@)
 359  *
 360  * Unimplemented flags: DCX_LOCKWINDOWUPDATE
 361  *
 362  * FIXME: Full support for hrgnClip == 1 (alias for entire window).
 363  */
 364 HDC WINAPI GetDCEx( HWND hwnd, HRGN hrgnClip, DWORD flags )
 365 {
 366     HDC         hdc = 0;
 367     DCE *       dce;
 368     WND *       wndPtr;
 369     DWORD       dcxFlags = 0;
 370     BOOL        bUpdateVisRgn = TRUE;
 371     BOOL        bUpdateClipOrigin = FALSE;
 372     HWND parent, full;
 373
 374     TRACE("hwnd %04x, hrgnClip %04x, flags %08x\n",
 375           hwnd, hrgnClip, (unsigned)flags);
 376
 377     if (!hwnd) hwnd = GetDesktopWindow();
 378     if (!(full = WIN_IsCurrentProcess( hwnd )))
 379     {
 380         FIXME( "not supported yet on other process window %x\n", hwnd );
 381         return 0;
 382     }
 383     hwnd = full;
 384     if (!(wndPtr = WIN_GetPtr( hwnd ))) return 0;
 385
 386     /* fixup flags */
 387
 388     if (flags & (DCX_WINDOW | DCX_PARENTCLIP)) flags |= DCX_CACHE;
 389
 390     if (flags & DCX_USESTYLE)
 391     {
 392         flags &= ~( DCX_CLIPCHILDREN | DCX_CLIPSIBLINGS | DCX_PARENTCLIP);
 393
 394         if( wndPtr->dwStyle & WS_CLIPSIBLINGS )
 395             flags |= DCX_CLIPSIBLINGS;
 396
 397         if ( !(flags & DCX_WINDOW) )
 398         {
 399             if (wndPtr->clsStyle & CS_PARENTDC) flags |= DCX_PARENTCLIP;
 400
 401             if (wndPtr->dwStyle & WS_CLIPCHILDREN &&
 402                      !(wndPtr->dwStyle & WS_MINIMIZE) ) flags |= DCX_CLIPCHILDREN;
 403             if (!wndPtr->dce) flags |= DCX_CACHE;
 404         }
 405     }
 406
 407     if (flags & DCX_WINDOW) flags &= ~DCX_CLIPCHILDREN;
 408
 409     parent = GetAncestor( hwnd, GA_PARENT );
 410     if (!parent || (parent == GetDesktopWindow()))
 411         flags = (flags & ~DCX_PARENTCLIP) | DCX_CLIPSIBLINGS;
 412
 413     /* it seems parent clip is ignored when clipping siblings or children */
 414     if (flags & (DCX_CLIPSIBLINGS | DCX_CLIPCHILDREN)) flags &= ~DCX_PARENTCLIP;
 415
 416     if( flags & DCX_PARENTCLIP )
 417     {
 418         LONG parent_style = GetWindowLongW( parent, GWL_STYLE );
 419         if( (wndPtr->dwStyle & WS_VISIBLE) && (parent_style & WS_VISIBLE) )
 420         {
 421             flags &= ~DCX_CLIPCHILDREN;
 422             if (parent_style & WS_CLIPSIBLINGS) flags |= DCX_CLIPSIBLINGS;
 423         }
 424     }
 425
 426     /* find a suitable DCE */
 427
 428     dcxFlags = flags & (DCX_PARENTCLIP | DCX_CLIPSIBLINGS | DCX_CLIPCHILDREN |
 429                         DCX_CACHE | DCX_WINDOW);
 430
 431     if (flags & DCX_CACHE)
 432     {
 433         DCE*    dceEmpty;
 434         DCE*    dceUnused;
 435
 436         dceEmpty = dceUnused = NULL;
 437
 438         /* Strategy: First, we attempt to find a non-empty but unused DCE with
 439          * compatible flags. Next, we look for an empty entry. If the cache is
 440          * full we have to purge one of the unused entries.
 441          */
 442
 443         for (dce = firstDCE; (dce); dce = dce->next)
 444         {
 445             if ((dce->DCXflags & (DCX_CACHE | DCX_DCEBUSY)) == DCX_CACHE )
 446             {
 447                 dceUnused = dce;
 448
 449                 if (dce->DCXflags & DCX_DCEEMPTY)
 450                     dceEmpty = dce;
 451                 else
 452                 if ((dce->hwndCurrent == hwnd) &&
 453                    ((dce->DCXflags & (DCX_CLIPSIBLINGS | DCX_CLIPCHILDREN |
 454                                       DCX_CACHE | DCX_WINDOW | DCX_PARENTCLIP)) == dcxFlags))
 455                 {
 456                     TRACE("\tfound valid %08x dce [%04x], flags %08x\n",
 457                                         (unsigned)dce, hwnd, (unsigned)dcxFlags );
 458                     bUpdateVisRgn = FALSE;
 459                     bUpdateClipOrigin = TRUE;
 460                     break;
 461                 }
 462             }
 463         }
 464
 465         if (!dce) dce = (dceEmpty) ? dceEmpty : dceUnused;
 466
 467         /* if there's no dce empty or unused, allocate a new one */
 468         if (!dce)
 469         {
 470             dce = DCE_AllocDCE( 0, DCE_CACHE_DC );
 471         }
 472     }
 473     else
 474     {
 475         dce = wndPtr->dce;
 476         if (dce && dce->hwndCurrent == hwnd)
 477         {
 478             TRACE("\tskipping hVisRgn update\n");
 479             bUpdateVisRgn = FALSE; /* updated automatically, via DCHook() */
 480         }
 481     }
 482     if (!dce)
 483     {
 484         hdc = 0;
 485         goto END;
 486     }
 487
 488     if (!(flags & (DCX_INTERSECTRGN | DCX_EXCLUDERGN))) hrgnClip = 0;
 489
 490     if (((flags ^ dce->DCXflags) & (DCX_INTERSECTRGN | DCX_EXCLUDERGN)) &&
 491         (dce->hClipRgn != hrgnClip))
 492     {
 493         /* if the extra clip region has changed, get rid of the old one */
 494         DCE_DeleteClipRgn( dce );
 495     }
 496
 497     dce->hwndCurrent = hwnd;
 498     dce->hClipRgn = hrgnClip;
 499     dce->DCXflags = flags & (DCX_PARENTCLIP | DCX_CLIPSIBLINGS | DCX_CLIPCHILDREN |
 500                              DCX_CACHE | DCX_WINDOW | DCX_WINDOWPAINT |
 501                              DCX_KEEPCLIPRGN | DCX_INTERSECTRGN | DCX_EXCLUDERGN);
 502     dce->DCXflags |= DCX_DCEBUSY;
 503     dce->DCXflags &= ~DCX_DCEDIRTY;
 504     hdc = dce->hDC;
 505
 506     if (bUpdateVisRgn) SetHookFlags16( hdc, DCHF_INVALIDATEVISRGN ); /* force update */
 507
 508     if (!USER_Driver.pGetDC( hwnd, hdc, hrgnClip, flags )) hdc = 0;
 509
 510     TRACE("(%04x,%04x,0x%lx): returning %04x\n", hwnd, hrgnClip, flags, hdc);
 511 END:
 512     WIN_ReleasePtr(wndPtr);
 513     return hdc;
 514 }
 515
 516
 517 /***********************************************************************
 518  *              GetDC (USER32.@)
 519  * RETURNS
 520  *      :Handle to DC
 521  *      NULL: Failure
 522  */
 523 HDC WINAPI GetDC(
 524              HWND hwnd /* [in] handle of window */
 525 ) {
 526     if (!hwnd)
 527         return GetDCEx( 0, 0, DCX_CACHE | DCX_WINDOW );
 528     return GetDCEx( hwnd, 0, DCX_USESTYLE );
 529 }
 530
 531
 532 /***********************************************************************
 533  *              GetWindowDC (USER32.@)
 534  */
 535 HDC WINAPI GetWindowDC( HWND hwnd )
 536 {
 537     return GetDCEx( hwnd, 0, DCX_USESTYLE | DCX_WINDOW );
 538 }
 539
 540
 541 /***********************************************************************
 542  *              ReleaseDC (USER32.@)
 543  *
 544  * RETURNS
 545  *      1: Success
 546  *      0: Failure
 547  */
 548 INT WINAPI ReleaseDC(
 549              HWND hwnd /* [in] Handle of window - ignored */,
 550              HDC hdc   /* [in] Handle of device context */
 551 ) {
 552     DCE * dce;
 553     INT nRet = 0;
 554
 555     USER_Lock();
 556     dce = firstDCE;
 557
 558     TRACE("%04x %04x\n", hwnd, hdc );
 559
 560     while (dce && (dce->hDC != hdc)) dce = dce->next;
 561
 562     if ( dce )
 563         if ( dce->DCXflags & DCX_DCEBUSY )
 564             nRet = DCE_ReleaseDC( dce );
 565
 566     USER_Unlock();
 567
 568     return nRet;
 569 }
 570
 571 /***********************************************************************
 572  *              DCHook (USER.362)
 573  *
 574  * See "Undoc. Windows" for hints (DC, SetDCHook, SetHookFlags)..
 575  */
 576 BOOL16 WINAPI DCHook16( HDC16 hDC, WORD code, DWORD data, LPARAM lParam )
 577 {
 578     BOOL retv = TRUE;
 579     DCE *dce = (DCE *)data;
 580
 581     TRACE("hDC = %04x, %i\n", hDC, code);
 582
 583     if (!dce) return 0;
 584     assert(dce->hDC == hDC);
 585
 586     /* Grab the windows lock before doing anything else  */
 587     USER_Lock();
 588
 589     switch( code )
 590     {
 591       case DCHC_INVALIDVISRGN:
 592            /* GDI code calls this when it detects that the
 593             * DC is dirty (usually after SetHookFlags()). This
 594             * means that we have to recompute the visible region.
 595             */
 596            if( dce->DCXflags & DCX_DCEBUSY )
 597            {
 598                /* Dirty bit has been cleared by caller, set it again so that
 599                 * pGetDC recomputes the visible region. */
 600                SetHookFlags16( dce->hDC, DCHF_INVALIDATEVISRGN );
 601                USER_Driver.pGetDC( dce->hwndCurrent, dce->hDC, dce->hClipRgn, dce->DCXflags );
 602            }
 603            else /* non-fatal but shouldn't happen */
 604              WARN("DC is not in use!\n");
 605            break;
 606
 607       case DCHC_DELETEDC:
 608            /*
 609             * Windows will not let you delete a DC that is busy
 610             * (between GetDC and ReleaseDC)
 611             */
 612
 613            if ( dce->DCXflags & DCX_DCEBUSY )
 614            {
 615                WARN("Application trying to delete a busy DC\n");
 616                retv = FALSE;
 617            }
 618            else DCE_FreeDCE( dce );
 619            break;
 620
 621       default:
 622            FIXME("unknown code\n");
 623     }
 624
 625   USER_Unlock();  /* Release the wnd lock */
 626   return retv;
 627 }
 628
 629
 630 /**********************************************************************
 631  *              WindowFromDC (USER32.@)
 632  */
 633 HWND WINAPI WindowFromDC( HDC hDC )
 634 {
 635     DCE *dce;
 636     HWND hwnd;
 637
 638     USER_Lock();
 639     dce = firstDCE;
 640
 641     while (dce && (dce->hDC != hDC)) dce = dce->next;
 642
 643     hwnd = dce ? dce->hwndCurrent : 0;
 644     USER_Unlock();
 645
 646     return hwnd;
 647 }
 648
 649
 650 /***********************************************************************
 651  *              LockWindowUpdate (USER32.@)
 652  */
 653 BOOL WINAPI LockWindowUpdate( HWND hwnd )
 654 {
 655     FIXME("(%x), stub!\n",hwnd);
 656     return TRUE;
 657 }