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 "user.h"
  38 #include "wine/debug.h"
  39 #include "windef.h"
  40 #include "wingdi.h"
  41 #include "wownt32.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 HDC16 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 %p, 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( HDC_16(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( HDC_16(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("[%p] 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 > (HRGN)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( HDC_16(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( HDC_16(dce->hDC), DCHF_VALIDATEVISRGN );
 247         SetDCState16( HDC_16(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 = %p, (%ld,%ld - %ld,%ld)\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 [%p]\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 [%p]\n", dce, dce->hwndCurrent);
 325                     dce->DCXflags |= DCX_DCEDIRTY;
 326                     SetHookFlags16( HDC_16(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 %p, hrgnClip %p, flags %08lx\n", hwnd, hrgnClip, flags);
 382
 383     if (!hwnd) hwnd = GetDesktopWindow();
 384     if (!(full = WIN_IsCurrentProcess( hwnd )))
 385     {
 386         FIXME( "not supported yet on other process window %p\n", hwnd );
 387         return 0;
 388     }
 389     hwnd = full;
 390     if (!(wndPtr = WIN_GetPtr( hwnd ))) return 0;
 391
 392     /* fixup flags */
 393
 394     if (flags & (DCX_WINDOW | DCX_PARENTCLIP)) flags |= DCX_CACHE;
 395
 396     if (flags & DCX_USESTYLE)
 397     {
 398         flags &= ~( DCX_CLIPCHILDREN | DCX_CLIPSIBLINGS | DCX_PARENTCLIP);
 399
 400         if( wndPtr->dwStyle & WS_CLIPSIBLINGS )
 401             flags |= DCX_CLIPSIBLINGS;
 402
 403         if ( !(flags & DCX_WINDOW) )
 404         {
 405             if (wndPtr->clsStyle & CS_PARENTDC) flags |= DCX_PARENTCLIP;
 406
 407             if (wndPtr->dwStyle & WS_CLIPCHILDREN &&
 408                      !(wndPtr->dwStyle & WS_MINIMIZE) ) flags |= DCX_CLIPCHILDREN;
 409             if (!wndPtr->dce) flags |= DCX_CACHE;
 410         }
 411     }
 412
 413     if (flags & DCX_WINDOW) flags &= ~DCX_CLIPCHILDREN;
 414
 415     parent = GetAncestor( hwnd, GA_PARENT );
 416     if (!parent || (parent == GetDesktopWindow()))
 417         flags = (flags & ~DCX_PARENTCLIP) | DCX_CLIPSIBLINGS;
 418
 419     /* it seems parent clip is ignored when clipping siblings or children */
 420     if (flags & (DCX_CLIPSIBLINGS | DCX_CLIPCHILDREN)) flags &= ~DCX_PARENTCLIP;
 421
 422     if( flags & DCX_PARENTCLIP )
 423     {
 424         LONG parent_style = GetWindowLongW( parent, GWL_STYLE );
 425         if( (wndPtr->dwStyle & WS_VISIBLE) && (parent_style & WS_VISIBLE) )
 426         {
 427             flags &= ~DCX_CLIPCHILDREN;
 428             if (parent_style & WS_CLIPSIBLINGS) flags |= DCX_CLIPSIBLINGS;
 429         }
 430     }
 431
 432     /* find a suitable DCE */
 433
 434     dcxFlags = flags & (DCX_PARENTCLIP | DCX_CLIPSIBLINGS | DCX_CLIPCHILDREN |
 435                         DCX_CACHE | DCX_WINDOW);
 436
 437     if (flags & DCX_CACHE)
 438     {
 439         DCE*    dceEmpty;
 440         DCE*    dceUnused;
 441
 442         dceEmpty = dceUnused = NULL;
 443
 444         /* Strategy: First, we attempt to find a non-empty but unused DCE with
 445          * compatible flags. Next, we look for an empty entry. If the cache is
 446          * full we have to purge one of the unused entries.
 447          */
 448
 449         for (dce = firstDCE; (dce); dce = dce->next)
 450         {
 451             if ((dce->DCXflags & (DCX_CACHE | DCX_DCEBUSY)) == DCX_CACHE )
 452             {
 453                 dceUnused = dce;
 454
 455                 if (dce->DCXflags & DCX_DCEEMPTY)
 456                     dceEmpty = dce;
 457                 else
 458                 if ((dce->hwndCurrent == hwnd) &&
 459                    ((dce->DCXflags & (DCX_CLIPSIBLINGS | DCX_CLIPCHILDREN |
 460                                       DCX_CACHE | DCX_WINDOW | DCX_PARENTCLIP)) == dcxFlags))
 461                 {
 462                     TRACE("\tfound valid %p dce [%p], flags %08lx\n",
 463                           dce, hwnd, dcxFlags );
 464                     bUpdateVisRgn = FALSE;
 465                     bUpdateClipOrigin = TRUE;
 466                     break;
 467                 }
 468             }
 469         }
 470
 471         if (!dce) dce = (dceEmpty) ? dceEmpty : dceUnused;
 472
 473         /* if there's no dce empty or unused, allocate a new one */
 474         if (!dce)
 475         {
 476             dce = DCE_AllocDCE( 0, DCE_CACHE_DC );
 477         }
 478     }
 479     else
 480     {
 481         dce = wndPtr->dce;
 482         if (dce && dce->hwndCurrent == hwnd)
 483         {
 484             TRACE("\tskipping hVisRgn update\n");
 485             bUpdateVisRgn = FALSE; /* updated automatically, via DCHook() */
 486         }
 487     }
 488     if (!dce)
 489     {
 490         hdc = 0;
 491         goto END;
 492     }
 493
 494     if (!(flags & (DCX_INTERSECTRGN | DCX_EXCLUDERGN))) hrgnClip = 0;
 495
 496     if (((flags ^ dce->DCXflags) & (DCX_INTERSECTRGN | DCX_EXCLUDERGN)) &&
 497         (dce->hClipRgn != hrgnClip))
 498     {
 499         /* if the extra clip region has changed, get rid of the old one */
 500         DCE_DeleteClipRgn( dce );
 501     }
 502
 503     dce->hwndCurrent = hwnd;
 504     dce->hClipRgn = hrgnClip;
 505     dce->DCXflags = flags & (DCX_PARENTCLIP | DCX_CLIPSIBLINGS | DCX_CLIPCHILDREN |
 506                              DCX_CACHE | DCX_WINDOW | DCX_WINDOWPAINT |
 507                              DCX_KEEPCLIPRGN | DCX_INTERSECTRGN | DCX_EXCLUDERGN);
 508     dce->DCXflags |= DCX_DCEBUSY;
 509     dce->DCXflags &= ~DCX_DCEDIRTY;
 510     hdc = dce->hDC;
 511
 512     if (bUpdateVisRgn) SetHookFlags16( HDC_16(hdc), DCHF_INVALIDATEVISRGN ); /* force update */
 513
 514     if (!USER_Driver.pGetDC( hwnd, hdc, hrgnClip, flags )) hdc = 0;
 515
 516     TRACE("(%p,%p,0x%lx): returning %p\n", hwnd, hrgnClip, flags, hdc);
 517 END:
 518     WIN_ReleasePtr(wndPtr);
 519     return hdc;
 520 }
 521
 522
 523 /***********************************************************************
 524  *              GetDC (USER32.@)
 525  *
 526  * Get a device context.
 527  *
 528  * RETURNS
 529  *      Success: Handle to the device context
 530  *      Failure: NULL.
 531  */
 532 HDC WINAPI GetDC(
 533              HWND hwnd /* [in] handle of window - may be NULL */
 534 ) {
 535     if (!hwnd)
 536         return GetDCEx( 0, 0, DCX_CACHE | DCX_WINDOW );
 537     return GetDCEx( hwnd, 0, DCX_USESTYLE );
 538 }
 539
 540
 541 /***********************************************************************
 542  *              GetWindowDC (USER32.@)
 543  */
 544 HDC WINAPI GetWindowDC( HWND hwnd )
 545 {
 546     return GetDCEx( hwnd, 0, DCX_USESTYLE | DCX_WINDOW );
 547 }
 548
 549
 550 /***********************************************************************
 551  *              ReleaseDC (USER32.@)
 552  *
 553  * Release a device context.
 554  *
 555  * RETURNS
 556  *      Success: Non-zero. Resources used by hdc are released.
 557  *      Failure: 0.
 558  */
 559 INT WINAPI ReleaseDC(
 560              HWND hwnd, /* [in] Handle of window - ignored */
 561              HDC hdc   /* [in] Handle of device context */
 562 ) {
 563     DCE * dce;
 564     INT nRet = 0;
 565
 566     USER_Lock();
 567     dce = firstDCE;
 568
 569     TRACE("%p %p\n", hwnd, hdc );
 570
 571     while (dce && (dce->hDC != hdc)) dce = dce->next;
 572
 573     if ( dce )
 574         if ( dce->DCXflags & DCX_DCEBUSY )
 575             nRet = DCE_ReleaseDC( dce );
 576
 577     USER_Unlock();
 578
 579     return nRet;
 580 }
 581
 582 /***********************************************************************
 583  *              DCHook (USER.362)
 584  *
 585  * See "Undoc. Windows" for hints (DC, SetDCHook, SetHookFlags)..
 586  */
 587 BOOL16 WINAPI DCHook16( HDC16 hDC, WORD code, DWORD data, LPARAM lParam )
 588 {
 589     BOOL retv = TRUE;
 590     DCE *dce = (DCE *)data;
 591
 592     TRACE("hDC = %04x, %i\n", hDC, code);
 593
 594     if (!dce) return 0;
 595     assert( HDC_16(dce->hDC) == hDC );
 596
 597     /* Grab the windows lock before doing anything else  */
 598     USER_Lock();
 599
 600     switch( code )
 601     {
 602       case DCHC_INVALIDVISRGN:
 603            /* GDI code calls this when it detects that the
 604             * DC is dirty (usually after SetHookFlags()). This
 605             * means that we have to recompute the visible region.
 606             */
 607            if( dce->DCXflags & DCX_DCEBUSY )
 608            {
 609                /* Dirty bit has been cleared by caller, set it again so that
 610                 * pGetDC recomputes the visible region. */
 611                SetHookFlags16( hDC, DCHF_INVALIDATEVISRGN );
 612                USER_Driver.pGetDC( dce->hwndCurrent, dce->hDC, dce->hClipRgn, dce->DCXflags );
 613            }
 614            else /* non-fatal but shouldn't happen */
 615              WARN("DC is not in use!\n");
 616            break;
 617
 618       case DCHC_DELETEDC:
 619            /*
 620             * Windows will not let you delete a DC that is busy
 621             * (between GetDC and ReleaseDC)
 622             */
 623
 624            if ( dce->DCXflags & DCX_DCEBUSY )
 625            {
 626                WARN("Application trying to delete a busy DC\n");
 627                retv = FALSE;
 628            }
 629            else DCE_FreeDCE( dce );
 630            break;
 631
 632       default:
 633            FIXME("unknown code\n");
 634     }
 635
 636   USER_Unlock();  /* Release the wnd lock */
 637   return retv;
 638 }
 639
 640
 641 /**********************************************************************
 642  *              WindowFromDC (USER32.@)
 643  */
 644 HWND WINAPI WindowFromDC( HDC hDC )
 645 {
 646     DCE *dce;
 647     HWND hwnd;
 648
 649     USER_Lock();
 650     dce = firstDCE;
 651
 652     while (dce && (dce->hDC != hDC)) dce = dce->next;
 653
 654     hwnd = dce ? dce->hwndCurrent : 0;
 655     USER_Unlock();
 656
 657     return hwnd;
 658 }
 659
 660
 661 /***********************************************************************
 662  *              LockWindowUpdate (USER32.@)
 663  */
 664 BOOL WINAPI LockWindowUpdate( HWND hwnd )
 665 {
 666     static HWND lockedWnd;
 667
 668     FIXME("(%p), partial stub!\n",hwnd);
 669
 670     USER_Lock();
 671     if (lockedWnd)
 672     {
 673         if (!hwnd)
 674         {
 675             /* Unlock lockedWnd */
 676             /* FIXME: Do something */
 677         }
 678         else
 679         {
 680             /* Attempted to lock a second window */
 681             /* Return FALSE and do nothing */
 682             USER_Unlock();
 683             return FALSE;
 684         }
 685     }
 686     lockedWnd = hwnd;
 687     USER_Unlock();
 688     return TRUE;
 689 }