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                     if (USER_Driver.pReleaseDC)
 176                         USER_Driver.pReleaseDC( pDCE->hwndCurrent, pDCE->hDC );
 177                     DCE_DeleteClipRgn( pDCE );
 178                     pDCE->hwndCurrent = 0;
 179                 }
 180             }
 181             else
 182             {
 183                 if( pDCE->DCXflags & DCX_DCEBUSY ) /* shared cache DCE */
 184                 {
 185                     /* FIXME: AFAICS we are doing the right thing here so
 186                      * this should be a WARN. But this is best left as an ERR
 187                      * because the 'application error' is likely to come from
 188                      * another part of Wine (i.e. it's our fault after all).
 189                      * We should change this to WARN when Wine is more stable
 190                      * (for 1.0?).
 191                      */
 192                     ERR("[%08x] GetDC() without ReleaseDC()!\n",hwnd);
 193                     DCE_ReleaseDC( pDCE );
 194                 }
 195
 196                 if (pDCE->hwndCurrent && USER_Driver.pReleaseDC)
 197                     USER_Driver.pReleaseDC( pDCE->hwndCurrent, pDCE->hDC );
 198                 pDCE->DCXflags &= DCX_CACHE;
 199                 pDCE->DCXflags |= DCX_DCEEMPTY;
 200                 pDCE->hwndCurrent = 0;
 201             }
 202         }
 203         pDCE = pDCE->next;
 204     }
 205     WIN_ReleasePtr( pWnd );
 206 }
 207
 208
 209 /***********************************************************************
 210  *   DCE_DeleteClipRgn
 211  */
 212 static void DCE_DeleteClipRgn( DCE* dce )
 213 {
 214     dce->DCXflags &= ~(DCX_EXCLUDERGN | DCX_INTERSECTRGN | DCX_WINDOWPAINT);
 215
 216     if( dce->DCXflags & DCX_KEEPCLIPRGN )
 217         dce->DCXflags &= ~DCX_KEEPCLIPRGN;
 218     else
 219         if( dce->hClipRgn > 1 )
 220             DeleteObject( dce->hClipRgn );
 221
 222     dce->hClipRgn = 0;
 223
 224     /* make it dirty so that the vis rgn gets recomputed next time */
 225     dce->DCXflags |= DCX_DCEDIRTY;
 226     SetHookFlags16( dce->hDC, DCHF_INVALIDATEVISRGN );
 227 }
 228
 229
 230 /***********************************************************************
 231  *   DCE_ReleaseDC
 232  */
 233 static INT DCE_ReleaseDC( DCE* dce )
 234 {
 235     if ((dce->DCXflags & (DCX_DCEEMPTY | DCX_DCEBUSY)) != DCX_DCEBUSY) return 0;
 236
 237     /* restore previous visible region */
 238
 239     if ((dce->DCXflags & (DCX_INTERSECTRGN | DCX_EXCLUDERGN)) &&
 240         (dce->DCXflags & (DCX_CACHE | DCX_WINDOWPAINT)) )
 241         DCE_DeleteClipRgn( dce );
 242
 243     if (dce->DCXflags & DCX_CACHE)
 244     {
 245         /* make the DC clean so that SetDCState doesn't try to update the vis rgn */
 246         SetHookFlags16( dce->hDC, DCHF_VALIDATEVISRGN );
 247         SetDCState16( dce->hDC, defaultDCstate );
 248         dce->DCXflags &= ~DCX_DCEBUSY;
 249         if (dce->DCXflags & DCX_DCEDIRTY)
 250         {
 251             /* don't keep around invalidated entries
 252              * because SetDCState() disables hVisRgn updates
 253              * by removing dirty bit. */
 254             if (dce->hwndCurrent && USER_Driver.pReleaseDC)
 255                 USER_Driver.pReleaseDC( dce->hwndCurrent, dce->hDC );
 256             dce->hwndCurrent = 0;
 257             dce->DCXflags &= DCX_CACHE;
 258             dce->DCXflags |= DCX_DCEEMPTY;
 259         }
 260     }
 261     return 1;
 262 }
 263
 264
 265 /***********************************************************************
 266  *   DCE_InvalidateDCE
 267  *
 268  * It is called from SetWindowPos() and EVENT_MapNotify - we have to
 269  * mark as dirty all busy DCEs for windows that have pWnd->parent as
 270  * an ancestor and whose client rect intersects with specified update
 271  * rectangle. In addition, pWnd->parent DCEs may need to be updated if
 272  * DCX_CLIPCHILDREN flag is set.  */
 273 BOOL DCE_InvalidateDCE(HWND hwnd, const RECT* pRectUpdate)
 274 {
 275     HWND hwndScope = GetAncestor( hwnd, GA_PARENT );
 276     BOOL bRet = FALSE;
 277
 278     if( hwndScope )
 279     {
 280         DCE *dce;
 281
 282         TRACE("scope hwnd = %04x, (%i,%i - %i,%i)\n",
 283                      hwndScope, pRectUpdate->left,pRectUpdate->top,
 284                      pRectUpdate->right,pRectUpdate->bottom);
 285         if(TRACE_ON(dc))
 286           DCE_DumpCache();
 287
 288         /* walk all DCEs and fixup non-empty entries */
 289
 290         for (dce = firstDCE; (dce); dce = dce->next)
 291         {
 292             if (dce->DCXflags & DCX_DCEEMPTY) continue;
 293             if ((dce->hwndCurrent == hwndScope) && !(dce->DCXflags & DCX_CLIPCHILDREN))
 294                 continue;  /* child window positions don't bother us */
 295
 296             /* check if DCE window is within the z-order scope */
 297
 298             if (hwndScope == dce->hwndCurrent || IsChild( hwndScope, dce->hwndCurrent ))
 299             {
 300                 if (hwnd != dce->hwndCurrent)
 301                 {
 302                     /* check if the window rectangle intersects this DCE window */
 303                     RECT rect;
 304                     GetWindowRect( dce->hwndCurrent, &rect );
 305                     MapWindowPoints( 0, hwndScope, (POINT *)&rect, 2 );
 306                     if (!IntersectRect( &rect, &rect, pRectUpdate )) continue;
 307
 308                 }
 309                 if( !(dce->DCXflags & DCX_DCEBUSY) )
 310                 {
 311                     /* Don't bother with visible regions of unused DCEs */
 312
 313                     TRACE("\tpurged %p dce [%04x]\n", dce, dce->hwndCurrent);
 314                     if (dce->hwndCurrent && USER_Driver.pReleaseDC)
 315                         USER_Driver.pReleaseDC( dce->hwndCurrent, dce->hDC );
 316                     dce->hwndCurrent = 0;
 317                     dce->DCXflags &= DCX_CACHE;
 318                     dce->DCXflags |= DCX_DCEEMPTY;
 319                 }
 320                 else
 321                 {
 322                     /* Set dirty bits in the hDC and DCE structs */
 323
 324                     TRACE("\tfixed up %p dce [%04x]\n", dce, dce->hwndCurrent);
 325                     dce->DCXflags |= DCX_DCEDIRTY;
 326                     SetHookFlags16(dce->hDC, DCHF_INVALIDATEVISRGN);
 327                     bRet = TRUE;
 328                 }
 329             }
 330         } /* dce list */
 331     }
 332     return bRet;
 333 }
 334
 335
 336 /***********************************************************************
 337  *           DCE_ExcludeRgn
 338  *
 339  *  Translate given region from the wnd client to the DC coordinates
 340  *  and add it to the clipping region.
 341  */
 342 INT DCE_ExcludeRgn( HDC hDC, HWND hwnd, HRGN hRgn )
 343 {
 344   POINT  pt = {0, 0};
 345   DCE     *dce = firstDCE;
 346
 347   while (dce && (dce->hDC != hDC)) dce = dce->next;
 348   if (!dce) return ERROR;
 349
 350   MapWindowPoints( hwnd, dce->hwndCurrent, &pt, 1);
 351   if( dce->DCXflags & DCX_WINDOW )
 352   {
 353       WND *wnd = WIN_FindWndPtr(dce->hwndCurrent);
 354       pt.x += wnd->rectClient.left - wnd->rectWindow.left;
 355       pt.y += wnd->rectClient.top - wnd->rectWindow.top;
 356       WIN_ReleaseWndPtr(wnd);
 357   }
 358   OffsetRgn(hRgn, pt.x, pt.y);
 359
 360   return ExtSelectClipRgn( hDC, hRgn, RGN_DIFF );
 361 }
 362
 363
 364 /***********************************************************************
 365  *              GetDCEx (USER32.@)
 366  *
 367  * Unimplemented flags: DCX_LOCKWINDOWUPDATE
 368  *
 369  * FIXME: Full support for hrgnClip == 1 (alias for entire window).
 370  */
 371 HDC WINAPI GetDCEx( HWND hwnd, HRGN hrgnClip, DWORD flags )
 372 {
 373     HDC         hdc = 0;
 374     DCE *       dce;
 375     WND *       wndPtr;
 376     DWORD       dcxFlags = 0;
 377     BOOL        bUpdateVisRgn = TRUE;
 378     BOOL        bUpdateClipOrigin = FALSE;
 379     HWND parent, full;
 380
 381     TRACE("hwnd %04x, hrgnClip %04x, flags %08x\n",
 382           hwnd, hrgnClip, (unsigned)flags);
 383
 384     if (!hwnd) hwnd = GetDesktopWindow();
 385     if (!(full = WIN_IsCurrentProcess( hwnd )))
 386     {
 387         FIXME( "not supported yet on other process window %x\n", hwnd );
 388         return 0;
 389     }
 390     hwnd = full;
 391     if (!(wndPtr = WIN_GetPtr( hwnd ))) return 0;
 392
 393     /* fixup flags */
 394
 395     if (flags & (DCX_WINDOW | DCX_PARENTCLIP)) flags |= DCX_CACHE;
 396
 397     if (flags & DCX_USESTYLE)
 398     {
 399         flags &= ~( DCX_CLIPCHILDREN | DCX_CLIPSIBLINGS | DCX_PARENTCLIP);
 400
 401         if( wndPtr->dwStyle & WS_CLIPSIBLINGS )
 402             flags |= DCX_CLIPSIBLINGS;
 403
 404         if ( !(flags & DCX_WINDOW) )
 405         {
 406             if (wndPtr->clsStyle & CS_PARENTDC) flags |= DCX_PARENTCLIP;
 407
 408             if (wndPtr->dwStyle & WS_CLIPCHILDREN &&
 409                      !(wndPtr->dwStyle & WS_MINIMIZE) ) flags |= DCX_CLIPCHILDREN;
 410             if (!wndPtr->dce) flags |= DCX_CACHE;
 411         }
 412     }
 413
 414     if (flags & DCX_WINDOW) flags &= ~DCX_CLIPCHILDREN;
 415
 416     parent = GetAncestor( hwnd, GA_PARENT );
 417     if (!parent || (parent == GetDesktopWindow()))
 418         flags = (flags & ~DCX_PARENTCLIP) | DCX_CLIPSIBLINGS;
 419
 420     /* it seems parent clip is ignored when clipping siblings or children */
 421     if (flags & (DCX_CLIPSIBLINGS | DCX_CLIPCHILDREN)) flags &= ~DCX_PARENTCLIP;
 422
 423     if( flags & DCX_PARENTCLIP )
 424     {
 425         LONG parent_style = GetWindowLongW( parent, GWL_STYLE );
 426         if( (wndPtr->dwStyle & WS_VISIBLE) && (parent_style & WS_VISIBLE) )
 427         {
 428             flags &= ~DCX_CLIPCHILDREN;
 429             if (parent_style & WS_CLIPSIBLINGS) flags |= DCX_CLIPSIBLINGS;
 430         }
 431     }
 432
 433     /* find a suitable DCE */
 434
 435     dcxFlags = flags & (DCX_PARENTCLIP | DCX_CLIPSIBLINGS | DCX_CLIPCHILDREN |
 436                         DCX_CACHE | DCX_WINDOW);
 437
 438     if (flags & DCX_CACHE)
 439     {
 440         DCE*    dceEmpty;
 441         DCE*    dceUnused;
 442
 443         dceEmpty = dceUnused = NULL;
 444
 445         /* Strategy: First, we attempt to find a non-empty but unused DCE with
 446          * compatible flags. Next, we look for an empty entry. If the cache is
 447          * full we have to purge one of the unused entries.
 448          */
 449
 450         for (dce = firstDCE; (dce); dce = dce->next)
 451         {
 452             if ((dce->DCXflags & (DCX_CACHE | DCX_DCEBUSY)) == DCX_CACHE )
 453             {
 454                 dceUnused = dce;
 455
 456                 if (dce->DCXflags & DCX_DCEEMPTY)
 457                     dceEmpty = dce;
 458                 else
 459                 if ((dce->hwndCurrent == hwnd) &&
 460                    ((dce->DCXflags & (DCX_CLIPSIBLINGS | DCX_CLIPCHILDREN |
 461                                       DCX_CACHE | DCX_WINDOW | DCX_PARENTCLIP)) == dcxFlags))
 462                 {
 463                     TRACE("\tfound valid %08x dce [%04x], flags %08x\n",
 464                                         (unsigned)dce, hwnd, (unsigned)dcxFlags );
 465                     bUpdateVisRgn = FALSE;
 466                     bUpdateClipOrigin = TRUE;
 467                     break;
 468                 }
 469             }
 470         }
 471
 472         if (!dce) dce = (dceEmpty) ? dceEmpty : dceUnused;
 473
 474         /* if there's no dce empty or unused, allocate a new one */
 475         if (!dce)
 476         {
 477             dce = DCE_AllocDCE( 0, DCE_CACHE_DC );
 478         }
 479     }
 480     else
 481     {
 482         dce = wndPtr->dce;
 483         if (dce && dce->hwndCurrent == hwnd)
 484         {
 485             TRACE("\tskipping hVisRgn update\n");
 486             bUpdateVisRgn = FALSE; /* updated automatically, via DCHook() */
 487         }
 488     }
 489     if (!dce)
 490     {
 491         hdc = 0;
 492         goto END;
 493     }
 494
 495     if (!(flags & (DCX_INTERSECTRGN | DCX_EXCLUDERGN))) hrgnClip = 0;
 496
 497     if (((flags ^ dce->DCXflags) & (DCX_INTERSECTRGN | DCX_EXCLUDERGN)) &&
 498         (dce->hClipRgn != hrgnClip))
 499     {
 500         /* if the extra clip region has changed, get rid of the old one */
 501         DCE_DeleteClipRgn( dce );
 502     }
 503
 504     dce->hwndCurrent = hwnd;
 505     dce->hClipRgn = hrgnClip;
 506     dce->DCXflags = flags & (DCX_PARENTCLIP | DCX_CLIPSIBLINGS | DCX_CLIPCHILDREN |
 507                              DCX_CACHE | DCX_WINDOW | DCX_WINDOWPAINT |
 508                              DCX_KEEPCLIPRGN | DCX_INTERSECTRGN | DCX_EXCLUDERGN);
 509     dce->DCXflags |= DCX_DCEBUSY;
 510     dce->DCXflags &= ~DCX_DCEDIRTY;
 511     hdc = dce->hDC;
 512
 513     if (bUpdateVisRgn) SetHookFlags16( hdc, DCHF_INVALIDATEVISRGN ); /* force update */
 514
 515     if (!USER_Driver.pGetDC( hwnd, hdc, hrgnClip, flags )) hdc = 0;
 516
 517     TRACE("(%04x,%04x,0x%lx): returning %04x\n", hwnd, hrgnClip, flags, hdc);
 518 END:
 519     WIN_ReleasePtr(wndPtr);
 520     return hdc;
 521 }
 522
 523
 524 /***********************************************************************
 525  *              GetDC (USER32.@)
 526  * RETURNS
 527  *      :Handle to DC
 528  *      NULL: Failure
 529  */
 530 HDC WINAPI GetDC(
 531              HWND hwnd /* [in] handle of window */
 532 ) {
 533     if (!hwnd)
 534         return GetDCEx( 0, 0, DCX_CACHE | DCX_WINDOW );
 535     return GetDCEx( hwnd, 0, DCX_USESTYLE );
 536 }
 537
 538
 539 /***********************************************************************
 540  *              GetWindowDC (USER32.@)
 541  */
 542 HDC WINAPI GetWindowDC( HWND hwnd )
 543 {
 544     return GetDCEx( hwnd, 0, DCX_USESTYLE | DCX_WINDOW );
 545 }
 546
 547
 548 /***********************************************************************
 549  *              ReleaseDC (USER32.@)
 550  *
 551  * RETURNS
 552  *      1: Success
 553  *      0: Failure
 554  */
 555 INT WINAPI ReleaseDC(
 556              HWND hwnd /* [in] Handle of window - ignored */,
 557              HDC hdc   /* [in] Handle of device context */
 558 ) {
 559     DCE * dce;
 560     INT nRet = 0;
 561
 562     USER_Lock();
 563     dce = firstDCE;
 564
 565     TRACE("%04x %04x\n", hwnd, hdc );
 566
 567     while (dce && (dce->hDC != hdc)) dce = dce->next;
 568
 569     if ( dce )
 570         if ( dce->DCXflags & DCX_DCEBUSY )
 571             nRet = DCE_ReleaseDC( dce );
 572
 573     USER_Unlock();
 574
 575     return nRet;
 576 }
 577
 578 /***********************************************************************
 579  *              DCHook (USER.362)
 580  *
 581  * See "Undoc. Windows" for hints (DC, SetDCHook, SetHookFlags)..
 582  */
 583 BOOL16 WINAPI DCHook16( HDC16 hDC, WORD code, DWORD data, LPARAM lParam )
 584 {
 585     BOOL retv = TRUE;
 586     DCE *dce = (DCE *)data;
 587
 588     TRACE("hDC = %04x, %i\n", hDC, code);
 589
 590     if (!dce) return 0;
 591     assert(dce->hDC == hDC);
 592
 593     /* Grab the windows lock before doing anything else  */
 594     USER_Lock();
 595
 596     switch( code )
 597     {
 598       case DCHC_INVALIDVISRGN:
 599            /* GDI code calls this when it detects that the
 600             * DC is dirty (usually after SetHookFlags()). This
 601             * means that we have to recompute the visible region.
 602             */
 603            if( dce->DCXflags & DCX_DCEBUSY )
 604            {
 605                /* Dirty bit has been cleared by caller, set it again so that
 606                 * pGetDC recomputes the visible region. */
 607                SetHookFlags16( dce->hDC, DCHF_INVALIDATEVISRGN );
 608                USER_Driver.pGetDC( dce->hwndCurrent, dce->hDC, dce->hClipRgn, dce->DCXflags );
 609            }
 610            else /* non-fatal but shouldn't happen */
 611              WARN("DC is not in use!\n");
 612            break;
 613
 614       case DCHC_DELETEDC:
 615            /*
 616             * Windows will not let you delete a DC that is busy
 617             * (between GetDC and ReleaseDC)
 618             */
 619
 620            if ( dce->DCXflags & DCX_DCEBUSY )
 621            {
 622                WARN("Application trying to delete a busy DC\n");
 623                retv = FALSE;
 624            }
 625            else DCE_FreeDCE( dce );
 626            break;
 627
 628       default:
 629            FIXME("unknown code\n");
 630     }
 631
 632   USER_Unlock();  /* Release the wnd lock */
 633   return retv;
 634 }
 635
 636
 637 /**********************************************************************
 638  *              WindowFromDC (USER32.@)
 639  */
 640 HWND WINAPI WindowFromDC( HDC hDC )
 641 {
 642     DCE *dce;
 643     HWND hwnd;
 644
 645     USER_Lock();
 646     dce = firstDCE;
 647
 648     while (dce && (dce->hDC != hDC)) dce = dce->next;
 649
 650     hwnd = dce ? dce->hwndCurrent : 0;
 651     USER_Unlock();
 652
 653     return hwnd;
 654 }
 655
 656
 657 /***********************************************************************
 658  *              LockWindowUpdate (USER32.@)
 659  */
 660 BOOL WINAPI LockWindowUpdate( HWND hwnd )
 661 {
 662     static HWND lockedWnd;
 663
 664     FIXME("(%x), partial stub!\n",hwnd);
 665
 666     USER_Lock();
 667     if (lockedWnd)
 668     {
 669         if (!hwnd)
 670         {
 671             /* Unlock lockedWnd */
 672             /* FIXME: Do something */
 673         }
 674         else
 675         {
 676             /* Attempted to lock a second window */
 677             /* Return FALSE and do nothing */
 678             USER_Unlock();
 679             return FALSE;
 680         }
 681     }
 682     lockedWnd = hwnd;
 683     USER_Unlock();
 684     return TRUE;
 685 }