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 "wownt32.h"
  43 #include "wine/winbase16.h"
  44 #include "wine/winuser16.h"
  45
  46 WINE_DEFAULT_DEBUG_CHANNEL(dc);
  47
  48 static DCE *firstDCE;
  49 static HDC16 defaultDCstate;
  50
  51 static void DCE_DeleteClipRgn( DCE* );
  52 static INT DCE_ReleaseDC( DCE* );
  53
  54
  55 /***********************************************************************
  56  *           DCE_DumpCache
  57  */
  58 static void DCE_DumpCache(void)
  59 {
  60     DCE *dce;
  61
  62     USER_Lock();
  63     dce = firstDCE;
  64
  65     DPRINTF("DCE:\n");
  66     while( dce )
  67     {
  68         DPRINTF("\t[0x%08x] hWnd %p, dcx %08x, %s %s\n",
  69              (unsigned)dce, dce->hwndCurrent, (unsigned)dce->DCXflags,
  70              (dce->DCXflags & DCX_CACHE) ? "Cache" : "Owned",
  71              (dce->DCXflags & DCX_DCEBUSY) ? "InUse" : "" );
  72         dce = dce->next;
  73     }
  74
  75     USER_Unlock();
  76 }
  77
  78 /***********************************************************************
  79  *           DCE_AllocDCE
  80  *
  81  * Allocate a new DCE.
  82  */
  83 DCE *DCE_AllocDCE( HWND hWnd, DCE_TYPE type )
  84 {
  85     DCE * dce;
  86
  87     if (!(dce = HeapAlloc( GetProcessHeap(), 0, sizeof(DCE) ))) return NULL;
  88     if (!(dce->hDC = CreateDCA( "DISPLAY", NULL, NULL, NULL )))
  89     {
  90         HeapFree( GetProcessHeap(), 0, dce );
  91         return 0;
  92     }
  93     if (!defaultDCstate) defaultDCstate = GetDCState16( HDC_16(dce->hDC) );
  94
  95     /* store DCE handle in DC hook data field */
  96
  97     SetDCHook( dce->hDC, DCHook16, (DWORD)dce );
  98
  99     dce->hwndCurrent = WIN_GetFullHandle( hWnd );
 100     dce->hClipRgn    = 0;
 101
 102     if( type != DCE_CACHE_DC ) /* owned or class DC */
 103     {
 104         dce->DCXflags = DCX_DCEBUSY;
 105         if( hWnd )
 106         {
 107             LONG style = GetWindowLongW( hWnd, GWL_STYLE );
 108             if (style & WS_CLIPCHILDREN) dce->DCXflags |= DCX_CLIPCHILDREN;
 109             if (style & WS_CLIPSIBLINGS) dce->DCXflags |= DCX_CLIPSIBLINGS;
 110         }
 111         SetHookFlags16( HDC_16(dce->hDC), DCHF_INVALIDATEVISRGN );
 112     }
 113     else dce->DCXflags = DCX_CACHE | DCX_DCEEMPTY;
 114
 115     USER_Lock();
 116     dce->next = firstDCE;
 117     firstDCE = dce;
 118     USER_Unlock();
 119     return dce;
 120 }
 121
 122
 123 /***********************************************************************
 124  *           DCE_FreeDCE
 125  */
 126 DCE* DCE_FreeDCE( DCE *dce )
 127 {
 128     DCE **ppDCE, *ret;
 129
 130     if (!dce) return NULL;
 131
 132     USER_Lock();
 133
 134     ppDCE = &firstDCE;
 135
 136     while (*ppDCE && (*ppDCE != dce)) ppDCE = &(*ppDCE)->next;
 137     if (*ppDCE == dce) *ppDCE = dce->next;
 138     ret = *ppDCE;
 139     USER_Unlock();
 140
 141     SetDCHook(dce->hDC, NULL, 0L);
 142
 143     DeleteDC( dce->hDC );
 144     if( dce->hClipRgn && !(dce->DCXflags & DCX_KEEPCLIPRGN) )
 145         DeleteObject(dce->hClipRgn);
 146     HeapFree( GetProcessHeap(), 0, dce );
 147
 148     return ret;
 149 }
 150
 151 /***********************************************************************
 152  *           DCE_FreeWindowDCE
 153  *
 154  * Remove owned DCE and reset unreleased cache DCEs.
 155  */
 156 void DCE_FreeWindowDCE( HWND hwnd )
 157 {
 158     DCE *pDCE;
 159     WND *pWnd = WIN_GetPtr( hwnd );
 160
 161     pDCE = firstDCE;
 162     while( pDCE )
 163     {
 164         if( pDCE->hwndCurrent == hwnd )
 165         {
 166             if( pDCE == pWnd->dce ) /* owned or Class DCE*/
 167             {
 168                 if (pWnd->clsStyle & CS_OWNDC)  /* owned DCE*/
 169                 {
 170                     pDCE = DCE_FreeDCE( pDCE );
 171                     pWnd->dce = NULL;
 172                     continue;
 173                 }
 174                 else if( pDCE->DCXflags & (DCX_INTERSECTRGN | DCX_EXCLUDERGN) ) /* Class DCE*/
 175                 {
 176                     if (USER_Driver.pReleaseDC)
 177                         USER_Driver.pReleaseDC( pDCE->hwndCurrent, pDCE->hDC );
 178                     DCE_DeleteClipRgn( pDCE );
 179                     pDCE->hwndCurrent = 0;
 180                 }
 181             }
 182             else
 183             {
 184                 if( pDCE->DCXflags & DCX_DCEBUSY ) /* shared cache DCE */
 185                 {
 186                     /* FIXME: AFAICS we are doing the right thing here so
 187                      * this should be a WARN. But this is best left as an ERR
 188                      * because the 'application error' is likely to come from
 189                      * another part of Wine (i.e. it's our fault after all).
 190                      * We should change this to WARN when Wine is more stable
 191                      * (for 1.0?).
 192                      */
 193                     ERR("[%p] GetDC() without ReleaseDC()!\n",hwnd);
 194                     DCE_ReleaseDC( pDCE );
 195                 }
 196
 197                 if (pDCE->hwndCurrent && USER_Driver.pReleaseDC)
 198                     USER_Driver.pReleaseDC( pDCE->hwndCurrent, pDCE->hDC );
 199                 pDCE->DCXflags &= DCX_CACHE;
 200                 pDCE->DCXflags |= DCX_DCEEMPTY;
 201                 pDCE->hwndCurrent = 0;
 202             }
 203         }
 204         pDCE = pDCE->next;
 205     }
 206     WIN_ReleasePtr( pWnd );
 207 }
 208
 209
 210 /***********************************************************************
 211  *   DCE_DeleteClipRgn
 212  */
 213 static void DCE_DeleteClipRgn( DCE* dce )
 214 {
 215     dce->DCXflags &= ~(DCX_EXCLUDERGN | DCX_INTERSECTRGN | DCX_WINDOWPAINT);
 216
 217     if( dce->DCXflags & DCX_KEEPCLIPRGN )
 218         dce->DCXflags &= ~DCX_KEEPCLIPRGN;
 219     else
 220         if( dce->hClipRgn > (HRGN)1 )
 221             DeleteObject( dce->hClipRgn );
 222
 223     dce->hClipRgn = 0;
 224
 225     /* make it dirty so that the vis rgn gets recomputed next time */
 226     dce->DCXflags |= DCX_DCEDIRTY;
 227     SetHookFlags16( HDC_16(dce->hDC), DCHF_INVALIDATEVISRGN );
 228 }
 229
 230
 231 /***********************************************************************
 232  *   DCE_ReleaseDC
 233  */
 234 static INT DCE_ReleaseDC( DCE* dce )
 235 {
 236     if ((dce->DCXflags & (DCX_DCEEMPTY | DCX_DCEBUSY)) != DCX_DCEBUSY) return 0;
 237
 238     /* restore previous visible region */
 239
 240     if ((dce->DCXflags & (DCX_INTERSECTRGN | DCX_EXCLUDERGN)) &&
 241         (dce->DCXflags & (DCX_CACHE | DCX_WINDOWPAINT)) )
 242         DCE_DeleteClipRgn( dce );
 243
 244     if (dce->DCXflags & DCX_CACHE)
 245     {
 246         /* make the DC clean so that SetDCState doesn't try to update the vis rgn */
 247         SetHookFlags16( HDC_16(dce->hDC), DCHF_VALIDATEVISRGN );
 248         SetDCState16( HDC_16(dce->hDC), defaultDCstate );
 249         dce->DCXflags &= ~DCX_DCEBUSY;
 250         if (dce->DCXflags & DCX_DCEDIRTY)
 251         {
 252             /* don't keep around invalidated entries
 253              * because SetDCState() disables hVisRgn updates
 254              * by removing dirty bit. */
 255             if (dce->hwndCurrent && USER_Driver.pReleaseDC)
 256                 USER_Driver.pReleaseDC( dce->hwndCurrent, dce->hDC );
 257             dce->hwndCurrent = 0;
 258             dce->DCXflags &= DCX_CACHE;
 259             dce->DCXflags |= DCX_DCEEMPTY;
 260         }
 261     }
 262     return 1;
 263 }
 264
 265
 266 /***********************************************************************
 267  *   DCE_InvalidateDCE
 268  *
 269  * It is called from SetWindowPos() and EVENT_MapNotify - we have to
 270  * mark as dirty all busy DCEs for windows that have pWnd->parent as
 271  * an ancestor and whose client rect intersects with specified update
 272  * rectangle. In addition, pWnd->parent DCEs may need to be updated if
 273  * DCX_CLIPCHILDREN flag is set.  */
 274 BOOL DCE_InvalidateDCE(HWND hwnd, const RECT* pRectUpdate)
 275 {
 276     HWND hwndScope = GetAncestor( hwnd, GA_PARENT );
 277     BOOL bRet = FALSE;
 278
 279     if( hwndScope )
 280     {
 281         DCE *dce;
 282
 283         TRACE("scope hwnd = %p, (%ld,%ld - %ld,%ld)\n",
 284               hwndScope, pRectUpdate->left,pRectUpdate->top,
 285               pRectUpdate->right,pRectUpdate->bottom);
 286         if(TRACE_ON(dc))
 287           DCE_DumpCache();
 288
 289         /* walk all DCEs and fixup non-empty entries */
 290
 291         for (dce = firstDCE; (dce); dce = dce->next)
 292         {
 293             if (dce->DCXflags & DCX_DCEEMPTY) continue;
 294             if ((dce->hwndCurrent == hwndScope) && !(dce->DCXflags & DCX_CLIPCHILDREN))
 295                 continue;  /* child window positions don't bother us */
 296
 297             /* check if DCE window is within the z-order scope */
 298
 299             if (hwndScope == dce->hwndCurrent || IsChild( hwndScope, dce->hwndCurrent ))
 300             {
 301                 if (hwnd != dce->hwndCurrent)
 302                 {
 303                     /* check if the window rectangle intersects this DCE window */
 304                     RECT rect;
 305                     GetWindowRect( dce->hwndCurrent, &rect );
 306                     MapWindowPoints( 0, hwndScope, (POINT *)&rect, 2 );
 307                     if (!IntersectRect( &rect, &rect, pRectUpdate )) continue;
 308
 309                 }
 310                 if( !(dce->DCXflags & DCX_DCEBUSY) )
 311                 {
 312                     /* Don't bother with visible regions of unused DCEs */
 313
 314                     TRACE("\tpurged %p dce [%p]\n", dce, dce->hwndCurrent);
 315                     if (dce->hwndCurrent && USER_Driver.pReleaseDC)
 316                         USER_Driver.pReleaseDC( dce->hwndCurrent, dce->hDC );
 317                     dce->hwndCurrent = 0;
 318                     dce->DCXflags &= DCX_CACHE;
 319                     dce->DCXflags |= DCX_DCEEMPTY;
 320                 }
 321                 else
 322                 {
 323                     /* Set dirty bits in the hDC and DCE structs */
 324
 325                     TRACE("\tfixed up %p dce [%p]\n", dce, dce->hwndCurrent);
 326                     dce->DCXflags |= DCX_DCEDIRTY;
 327                     SetHookFlags16( HDC_16(dce->hDC), DCHF_INVALIDATEVISRGN );
 328                     bRet = TRUE;
 329                 }
 330             }
 331         } /* dce list */
 332     }
 333     return bRet;
 334 }
 335
 336
 337 /***********************************************************************
 338  *           DCE_ExcludeRgn
 339  *
 340  *  Translate given region from the wnd client to the DC coordinates
 341  *  and add it to the clipping region.
 342  */
 343 INT DCE_ExcludeRgn( HDC hDC, HWND hwnd, HRGN hRgn )
 344 {
 345   POINT  pt = {0, 0};
 346   DCE     *dce = firstDCE;
 347
 348   while (dce && (dce->hDC != hDC)) dce = dce->next;
 349   if (!dce) return ERROR;
 350
 351   MapWindowPoints( hwnd, dce->hwndCurrent, &pt, 1);
 352   if( dce->DCXflags & DCX_WINDOW )
 353   {
 354       WND *wnd = WIN_FindWndPtr(dce->hwndCurrent);
 355       pt.x += wnd->rectClient.left - wnd->rectWindow.left;
 356       pt.y += wnd->rectClient.top - wnd->rectWindow.top;
 357       WIN_ReleaseWndPtr(wnd);
 358   }
 359   OffsetRgn(hRgn, pt.x, pt.y);
 360
 361   return ExtSelectClipRgn( hDC, hRgn, RGN_DIFF );
 362 }
 363
 364
 365 /***********************************************************************
 366  *              GetDCEx (USER32.@)
 367  *
 368  * Unimplemented flags: DCX_LOCKWINDOWUPDATE
 369  *
 370  * FIXME: Full support for hrgnClip == 1 (alias for entire window).
 371  */
 372 HDC WINAPI GetDCEx( HWND hwnd, HRGN hrgnClip, DWORD flags )
 373 {
 374     HDC         hdc = 0;
 375     DCE *       dce;
 376     WND *       wndPtr;
 377     DWORD       dcxFlags = 0;
 378     BOOL        bUpdateVisRgn = TRUE;
 379     BOOL        bUpdateClipOrigin = FALSE;
 380     HWND parent, full;
 381
 382     TRACE("hwnd %p, hrgnClip %p, flags %08lx\n", hwnd, hrgnClip, flags);
 383
 384     if (!hwnd) hwnd = GetDesktopWindow();
 385     if (!(full = WIN_IsCurrentProcess( hwnd )))
 386     {
 387         FIXME( "not supported yet on other process window %p\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 %p dce [%p], flags %08lx\n",
 464                           dce, hwnd, 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_16(hdc), DCHF_INVALIDATEVISRGN ); /* force update */
 514
 515     if (!USER_Driver.pGetDC( hwnd, hdc, hrgnClip, flags )) hdc = 0;
 516
 517     TRACE("(%p,%p,0x%lx): returning %p\n", hwnd, hrgnClip, flags, hdc);
 518 END:
 519     WIN_ReleasePtr(wndPtr);
 520     return hdc;
 521 }
 522
 523
 524 /***********************************************************************
 525  *              GetDC (USER32.@)
 526  *
 527  * Get a device context.
 528  *
 529  * RETURNS
 530  *      Success: Handle to the device context
 531  *      Failure: NULL.
 532  */
 533 HDC WINAPI GetDC(
 534              HWND hwnd /* [in] handle of window - may be NULL */
 535 ) {
 536     if (!hwnd)
 537         return GetDCEx( 0, 0, DCX_CACHE | DCX_WINDOW );
 538     return GetDCEx( hwnd, 0, DCX_USESTYLE );
 539 }
 540
 541
 542 /***********************************************************************
 543  *              GetWindowDC (USER32.@)
 544  */
 545 HDC WINAPI GetWindowDC( HWND hwnd )
 546 {
 547     return GetDCEx( hwnd, 0, DCX_USESTYLE | DCX_WINDOW );
 548 }
 549
 550
 551 /***********************************************************************
 552  *              ReleaseDC (USER32.@)
 553  *
 554  * Release a device context.
 555  *
 556  * RETURNS
 557  *      Success: Non-zero. Resources used by hdc are released.
 558  *      Failure: 0.
 559  */
 560 INT WINAPI ReleaseDC(
 561              HWND hwnd, /* [in] Handle of window - ignored */
 562              HDC hdc   /* [in] Handle of device context */
 563 ) {
 564     DCE * dce;
 565     INT nRet = 0;
 566
 567     USER_Lock();
 568     dce = firstDCE;
 569
 570     TRACE("%p %p\n", hwnd, hdc );
 571
 572     while (dce && (dce->hDC != hdc)) dce = dce->next;
 573
 574     if ( dce )
 575         if ( dce->DCXflags & DCX_DCEBUSY )
 576             nRet = DCE_ReleaseDC( dce );
 577
 578     USER_Unlock();
 579
 580     return nRet;
 581 }
 582
 583 /***********************************************************************
 584  *              DCHook (USER.362)
 585  *
 586  * See "Undoc. Windows" for hints (DC, SetDCHook, SetHookFlags)..
 587  */
 588 BOOL16 WINAPI DCHook16( HDC16 hDC, WORD code, DWORD data, LPARAM lParam )
 589 {
 590     BOOL retv = TRUE;
 591     DCE *dce = (DCE *)data;
 592
 593     TRACE("hDC = %04x, %i\n", hDC, code);
 594
 595     if (!dce) return 0;
 596     assert( HDC_16(dce->hDC) == hDC );
 597
 598     /* Grab the windows lock before doing anything else  */
 599     USER_Lock();
 600
 601     switch( code )
 602     {
 603       case DCHC_INVALIDVISRGN:
 604            /* GDI code calls this when it detects that the
 605             * DC is dirty (usually after SetHookFlags()). This
 606             * means that we have to recompute the visible region.
 607             */
 608            if( dce->DCXflags & DCX_DCEBUSY )
 609            {
 610                /* Dirty bit has been cleared by caller, set it again so that
 611                 * pGetDC recomputes the visible region. */
 612                SetHookFlags16( hDC, DCHF_INVALIDATEVISRGN );
 613                USER_Driver.pGetDC( dce->hwndCurrent, dce->hDC, dce->hClipRgn, dce->DCXflags );
 614            }
 615            else /* non-fatal but shouldn't happen */
 616              WARN("DC is not in use!\n");
 617            break;
 618
 619       case DCHC_DELETEDC:
 620            /*
 621             * Windows will not let you delete a DC that is busy
 622             * (between GetDC and ReleaseDC)
 623             */
 624
 625            if ( dce->DCXflags & DCX_DCEBUSY )
 626            {
 627                WARN("Application trying to delete a busy DC\n");
 628                retv = FALSE;
 629            }
 630            else DCE_FreeDCE( dce );
 631            break;
 632
 633       default:
 634            FIXME("unknown code\n");
 635     }
 636
 637   USER_Unlock();  /* Release the wnd lock */
 638   return retv;
 639 }
 640
 641
 642 /**********************************************************************
 643  *              WindowFromDC (USER32.@)
 644  */
 645 HWND WINAPI WindowFromDC( HDC hDC )
 646 {
 647     DCE *dce;
 648     HWND hwnd;
 649
 650     USER_Lock();
 651     dce = firstDCE;
 652
 653     while (dce && (dce->hDC != hDC)) dce = dce->next;
 654
 655     hwnd = dce ? dce->hwndCurrent : 0;
 656     USER_Unlock();
 657
 658     return hwnd;
 659 }
 660
 661
 662 /***********************************************************************
 663  *              LockWindowUpdate (USER32.@)
 664  */
 665 BOOL WINAPI LockWindowUpdate( HWND hwnd )
 666 {
 667     static HWND lockedWnd;
 668
 669     FIXME("(%p), partial stub!\n",hwnd);
 670
 671     USER_Lock();
 672     if (lockedWnd)
 673     {
 674         if (!hwnd)
 675         {
 676             /* Unlock lockedWnd */
 677             /* FIXME: Do something */
 678         }
 679         else
 680         {
 681             /* Attempted to lock a second window */
 682             /* Return FALSE and do nothing */
 683             USER_Unlock();
 684             return FALSE;
 685         }
 686     }
 687     lockedWnd = hwnd;
 688     USER_Unlock();
 689     return TRUE;
 690 }