windows/dce.c

   1 /*
   2  * USER DCE functions
   3  *
   4  * Copyright 1993 Alexandre Julliard
   5  *           1996,1997 Alex Korobka
   6  *
   7  *
   8  * Note: Visible regions of CS_OWNDC/CS_CLASSDC window DCs
   9  * have to be updated dynamically.
  10  *
  11  * Internal DCX flags:
  12  *
  13  * DCX_DCEEMPTY    - dce is uninitialized
  14  * DCX_DCEBUSY     - dce is in use
  15  * DCX_DCEDIRTY    - ReleaseDC() should wipe instead of caching
  16  * DCX_KEEPCLIPRGN - ReleaseDC() should not delete the clipping region
  17  * DCX_WINDOWPAINT - BeginPaint() is in effect
  18  */
  19
  20 #include <assert.h>
  21 #include "dce.h"
  22 #include "win.h"
  23 #include "gdi.h"
  24 #include "region.h"
  25 #include "user.h"
  26 #include "debugtools.h"
  27 #include "windef.h"
  28 #include "wingdi.h"
  29 #include "wine/winbase16.h"
  30 #include "wine/winuser16.h"
  31
  32 DEFAULT_DEBUG_CHANNEL(dc);
  33
  34 static DCE *firstDCE;
  35 static HDC defaultDCstate;
  36
  37 static void DCE_DeleteClipRgn( DCE* );
  38 static INT DCE_ReleaseDC( DCE* );
  39
  40
  41 /***********************************************************************
  42  *           DCE_DumpCache
  43  */
  44 static void DCE_DumpCache(void)
  45 {
  46     DCE *dce;
  47
  48     WIN_LockWnds();
  49     dce = firstDCE;
  50
  51     DPRINTF("DCE:\n");
  52     while( dce )
  53     {
  54         DPRINTF("\t[0x%08x] hWnd 0x%04x, dcx %08x, %s %s\n",
  55              (unsigned)dce, dce->hwndCurrent, (unsigned)dce->DCXflags,
  56              (dce->DCXflags & DCX_CACHE) ? "Cache" : "Owned",
  57              (dce->DCXflags & DCX_DCEBUSY) ? "InUse" : "" );
  58         dce = dce->next;
  59     }
  60
  61     WIN_UnlockWnds();
  62 }
  63
  64 /***********************************************************************
  65  *           DCE_AllocDCE
  66  *
  67  * Allocate a new DCE.
  68  */
  69 DCE *DCE_AllocDCE( HWND hWnd, DCE_TYPE type )
  70 {
  71     FARPROC16 hookProc;
  72     DCE * dce;
  73     WND* wnd;
  74
  75     if (!(dce = HeapAlloc( GetProcessHeap(), 0, sizeof(DCE) ))) return NULL;
  76     if (!(dce->hDC = CreateDCA( "DISPLAY", NULL, NULL, NULL )))
  77     {
  78         HeapFree( GetProcessHeap(), 0, dce );
  79         return 0;
  80     }
  81     if (!defaultDCstate) defaultDCstate = GetDCState16( dce->hDC );
  82
  83     wnd = WIN_FindWndPtr(hWnd);
  84
  85     /* store DCE handle in DC hook data field */
  86
  87     hookProc = GetProcAddress16( GetModuleHandle16("USER"), (LPCSTR)362 );
  88     SetDCHook( dce->hDC, hookProc, (DWORD)dce );
  89
  90     dce->hwndCurrent = hWnd;
  91     dce->hClipRgn    = 0;
  92     dce->next        = firstDCE;
  93     firstDCE = dce;
  94
  95     if( type != DCE_CACHE_DC ) /* owned or class DC */
  96     {
  97         dce->DCXflags = DCX_DCEBUSY;
  98         if( hWnd )
  99         {
 100             if( wnd->dwStyle & WS_CLIPCHILDREN ) dce->DCXflags |= DCX_CLIPCHILDREN;
 101             if( wnd->dwStyle & WS_CLIPSIBLINGS ) dce->DCXflags |= DCX_CLIPSIBLINGS;
 102         }
 103         SetHookFlags16(dce->hDC,DCHF_INVALIDATEVISRGN);
 104     }
 105     else dce->DCXflags = DCX_CACHE | DCX_DCEEMPTY;
 106
 107     WIN_ReleaseWndPtr(wnd);
 108
 109     return dce;
 110 }
 111
 112
 113 /***********************************************************************
 114  *           DCE_FreeDCE
 115  */
 116 DCE* DCE_FreeDCE( DCE *dce )
 117 {
 118     DCE **ppDCE;
 119
 120     if (!dce) return NULL;
 121
 122     WIN_LockWnds();
 123
 124     ppDCE = &firstDCE;
 125
 126     while (*ppDCE && (*ppDCE != dce)) ppDCE = &(*ppDCE)->next;
 127     if (*ppDCE == dce) *ppDCE = dce->next;
 128
 129     SetDCHook(dce->hDC, NULL, 0L);
 130
 131     DeleteDC( dce->hDC );
 132     if( dce->hClipRgn && !(dce->DCXflags & DCX_KEEPCLIPRGN) )
 133         DeleteObject(dce->hClipRgn);
 134     HeapFree( GetProcessHeap(), 0, dce );
 135
 136     WIN_UnlockWnds();
 137
 138     return *ppDCE;
 139 }
 140
 141 /***********************************************************************
 142  *           DCE_FreeWindowDCE
 143  *
 144  * Remove owned DCE and reset unreleased cache DCEs.
 145  */
 146 void DCE_FreeWindowDCE( WND* pWnd )
 147 {
 148     DCE *pDCE;
 149
 150     WIN_LockWnds();
 151     pDCE = firstDCE;
 152
 153     while( pDCE )
 154     {
 155         if( pDCE->hwndCurrent == pWnd->hwndSelf )
 156         {
 157             if( pDCE == pWnd->dce ) /* owned or Class DCE*/
 158             {
 159                 if (pWnd->clsStyle & CS_OWNDC)  /* owned DCE*/
 160                 {
 161                     pDCE = DCE_FreeDCE( pDCE );
 162                     pWnd->dce = NULL;
 163                     continue;
 164                 }
 165                 else if( pDCE->DCXflags & (DCX_INTERSECTRGN | DCX_EXCLUDERGN) ) /* Class DCE*/
 166                 {
 167                     DCE_DeleteClipRgn( pDCE );
 168                     pDCE->hwndCurrent = 0;
 169                 }
 170             }
 171             else
 172             {
 173                 if( pDCE->DCXflags & DCX_DCEBUSY ) /* shared cache DCE */
 174                 {
 175                     /* FIXME: AFAICS we are doing the right thing here so
 176                      * this should be a WARN. But this is best left as an ERR
 177                      * because the 'application error' is likely to come from
 178                      * another part of Wine (i.e. it's our fault after all).
 179                      * We should change this to WARN when Wine is more stable
 180                      * (for 1.0?).
 181                      */
 182                     ERR("[%04x] GetDC() without ReleaseDC()!\n",
 183                         pWnd->hwndSelf);
 184                     DCE_ReleaseDC( pDCE );
 185                 }
 186
 187                 pDCE->DCXflags &= DCX_CACHE;
 188                 pDCE->DCXflags |= DCX_DCEEMPTY;
 189                 pDCE->hwndCurrent = 0;
 190             }
 191         }
 192         pDCE = pDCE->next;
 193     }
 194
 195     WIN_UnlockWnds();
 196 }
 197
 198
 199 /***********************************************************************
 200  *   DCE_DeleteClipRgn
 201  */
 202 static void DCE_DeleteClipRgn( DCE* dce )
 203 {
 204     dce->DCXflags &= ~(DCX_EXCLUDERGN | DCX_INTERSECTRGN | DCX_WINDOWPAINT);
 205
 206     if( dce->DCXflags & DCX_KEEPCLIPRGN )
 207         dce->DCXflags &= ~DCX_KEEPCLIPRGN;
 208     else
 209         if( dce->hClipRgn > 1 )
 210             DeleteObject( dce->hClipRgn );
 211
 212     dce->hClipRgn = 0;
 213
 214     /* make it dirty so that the vis rgn gets recomputed next time */
 215     dce->DCXflags |= DCX_DCEDIRTY;
 216     SetHookFlags16( dce->hDC, DCHF_INVALIDATEVISRGN );
 217 }
 218
 219
 220 /***********************************************************************
 221  *   DCE_ReleaseDC
 222  */
 223 static INT DCE_ReleaseDC( DCE* dce )
 224 {
 225     if ((dce->DCXflags & (DCX_DCEEMPTY | DCX_DCEBUSY)) != DCX_DCEBUSY) return 0;
 226
 227     /* restore previous visible region */
 228
 229     if ((dce->DCXflags & (DCX_INTERSECTRGN | DCX_EXCLUDERGN)) &&
 230         (dce->DCXflags & (DCX_CACHE | DCX_WINDOWPAINT)) )
 231         DCE_DeleteClipRgn( dce );
 232
 233     if (dce->DCXflags & DCX_CACHE)
 234     {
 235         SetDCState16( dce->hDC, defaultDCstate );
 236         dce->DCXflags &= ~DCX_DCEBUSY;
 237         if (dce->DCXflags & DCX_DCEDIRTY)
 238         {
 239             /* don't keep around invalidated entries
 240              * because SetDCState() disables hVisRgn updates
 241              * by removing dirty bit. */
 242
 243             dce->hwndCurrent = 0;
 244             dce->DCXflags &= DCX_CACHE;
 245             dce->DCXflags |= DCX_DCEEMPTY;
 246         }
 247     }
 248     return 1;
 249 }
 250
 251
 252 /***********************************************************************
 253  *   DCE_InvalidateDCE
 254  *
 255  * It is called from SetWindowPos() and EVENT_MapNotify - we have to
 256  * mark as dirty all busy DCEs for windows that have pWnd->parent as
 257  * an ancestor and whose client rect intersects with specified update
 258  * rectangle. In addition, pWnd->parent DCEs may need to be updated if
 259  * DCX_CLIPCHILDREN flag is set.  */
 260 BOOL DCE_InvalidateDCE(WND* pWnd, const RECT* pRectUpdate)
 261 {
 262     WND* wndScope = WIN_LockWndPtr(pWnd->parent);
 263     BOOL bRet = FALSE;
 264
 265     if( wndScope )
 266     {
 267         DCE *dce;
 268
 269         TRACE("scope hwnd = %04x, (%i,%i - %i,%i)\n",
 270                      wndScope->hwndSelf, pRectUpdate->left,pRectUpdate->top,
 271                      pRectUpdate->right,pRectUpdate->bottom);
 272         if(TRACE_ON(dc))
 273           DCE_DumpCache();
 274
 275         /* walk all DCEs and fixup non-empty entries */
 276
 277         for (dce = firstDCE; (dce); dce = dce->next)
 278         {
 279             if( !(dce->DCXflags & DCX_DCEEMPTY) )
 280             {
 281                 WND* wndCurrent = WIN_FindWndPtr(dce->hwndCurrent);
 282
 283                 if( wndCurrent )
 284                 {
 285                     WND* wnd = NULL;
 286                     INT xoffset = 0, yoffset = 0;
 287
 288                     if( (wndCurrent == wndScope) && !(dce->DCXflags & DCX_CLIPCHILDREN) )
 289                     {
 290                         /* child window positions don't bother us */
 291                         WIN_ReleaseWndPtr(wndCurrent);
 292                         continue;
 293                     }
 294
 295                     /* check if DCE window is within the z-order scope */
 296
 297                     for( wnd = WIN_LockWndPtr(wndCurrent); wnd; WIN_UpdateWndPtr(&wnd,wnd->parent))
 298                     {
 299                         if( wnd == wndScope )
 300                         {
 301                             RECT wndRect;
 302
 303                             wndRect = wndCurrent->rectWindow;
 304
 305                             OffsetRect( &wndRect, xoffset - wndCurrent->rectClient.left,
 306                                                     yoffset - wndCurrent->rectClient.top);
 307
 308                             if (pWnd == wndCurrent ||
 309                                 IntersectRect( &wndRect, &wndRect, pRectUpdate ))
 310                             {
 311                                 if( !(dce->DCXflags & DCX_DCEBUSY) )
 312                                 {
 313                                     /* Don't bother with visible regions of unused DCEs */
 314
 315                                     TRACE("\tpurged %08x dce [%04x]\n",
 316                                                 (unsigned)dce, wndCurrent->hwndSelf);
 317
 318                                     dce->hwndCurrent = 0;
 319                                     dce->DCXflags &= DCX_CACHE;
 320                                     dce->DCXflags |= DCX_DCEEMPTY;
 321                                 }
 322                                 else
 323                                 {
 324                                     /* Set dirty bits in the hDC and DCE structs */
 325
 326                                     TRACE("\tfixed up %08x dce [%04x]\n",
 327                                                 (unsigned)dce, wndCurrent->hwndSelf);
 328
 329                                     dce->DCXflags |= DCX_DCEDIRTY;
 330                                     SetHookFlags16(dce->hDC, DCHF_INVALIDATEVISRGN);
 331                                     bRet = TRUE;
 332                                 }
 333                             }
 334                             WIN_ReleaseWndPtr(wnd);
 335                             break;
 336                         }
 337                         xoffset += wnd->rectClient.left;
 338                         yoffset += wnd->rectClient.top;
 339                     }
 340                 }
 341                 WIN_ReleaseWndPtr(wndCurrent);
 342             }
 343         } /* dce list */
 344         WIN_ReleaseWndPtr(wndScope);
 345     }
 346     return bRet;
 347 }
 348
 349
 350 /***********************************************************************
 351  *           DCE_ExcludeRgn
 352  *
 353  *  Translate given region from the wnd client to the DC coordinates
 354  *  and add it to the clipping region.
 355  */
 356 INT DCE_ExcludeRgn( HDC hDC, WND* wnd, HRGN hRgn )
 357 {
 358   POINT  pt = {0, 0};
 359   DCE     *dce = firstDCE;
 360
 361   while (dce && (dce->hDC != hDC)) dce = dce->next;
 362   if( dce )
 363   {
 364       MapWindowPoints( wnd->hwndSelf, dce->hwndCurrent, &pt, 1);
 365       if( dce->DCXflags & DCX_WINDOW )
 366       {
 367           wnd = WIN_FindWndPtr(dce->hwndCurrent);
 368           pt.x += wnd->rectClient.left - wnd->rectWindow.left;
 369           pt.y += wnd->rectClient.top - wnd->rectWindow.top;
 370           WIN_ReleaseWndPtr(wnd);
 371       }
 372   }
 373   else return ERROR;
 374   OffsetRgn(hRgn, pt.x, pt.y);
 375
 376   return ExtSelectClipRgn( hDC, hRgn, RGN_DIFF );
 377 }
 378
 379
 380 /***********************************************************************
 381  *              GetDCEx (USER.359)
 382  */
 383 HDC16 WINAPI GetDCEx16( HWND16 hwnd, HRGN16 hrgnClip, DWORD flags )
 384 {
 385     return (HDC16)GetDCEx( hwnd, hrgnClip, flags );
 386 }
 387
 388
 389 /***********************************************************************
 390  *              GetDCEx (USER32.@)
 391  *
 392  * Unimplemented flags: DCX_LOCKWINDOWUPDATE
 393  *
 394  * FIXME: Full support for hrgnClip == 1 (alias for entire window).
 395  */
 396 HDC WINAPI GetDCEx( HWND hwnd, HRGN hrgnClip, DWORD flags )
 397 {
 398     HDC         hdc = 0;
 399     DCE *       dce;
 400     WND *       wndPtr;
 401     DWORD       dcxFlags = 0;
 402     BOOL        bUpdateVisRgn = TRUE;
 403     BOOL        bUpdateClipOrigin = FALSE;
 404
 405     TRACE("hwnd %04x, hrgnClip %04x, flags %08x\n",
 406           hwnd, hrgnClip, (unsigned)flags);
 407
 408     if (!hwnd) hwnd = GetDesktopWindow();
 409     if (!(wndPtr = WIN_FindWndPtr( hwnd ))) return 0;
 410
 411     /* fixup flags */
 412
 413     if (!wndPtr->dce) flags |= DCX_CACHE;
 414
 415     if (flags & DCX_USESTYLE)
 416     {
 417         flags &= ~( DCX_CLIPCHILDREN | DCX_CLIPSIBLINGS | DCX_PARENTCLIP);
 418
 419         if( wndPtr->dwStyle & WS_CLIPSIBLINGS )
 420             flags |= DCX_CLIPSIBLINGS;
 421
 422         if ( !(flags & DCX_WINDOW) )
 423         {
 424             if (wndPtr->clsStyle & CS_PARENTDC) flags |= DCX_PARENTCLIP;
 425
 426             if (wndPtr->dwStyle & WS_CLIPCHILDREN &&
 427                      !(wndPtr->dwStyle & WS_MINIMIZE) ) flags |= DCX_CLIPCHILDREN;
 428         }
 429         else flags |= DCX_CACHE;
 430     }
 431
 432     if (flags & DCX_WINDOW)
 433         flags = (flags & ~DCX_CLIPCHILDREN) | DCX_CACHE;
 434
 435     if (!wndPtr->parent || (wndPtr->parent->hwndSelf == GetDesktopWindow()))
 436         flags = (flags & ~DCX_PARENTCLIP) | DCX_CLIPSIBLINGS;
 437     else if( flags & DCX_PARENTCLIP )
 438     {
 439         flags |= DCX_CACHE;
 440         if( !(flags & (DCX_CLIPSIBLINGS | DCX_CLIPCHILDREN)) )
 441             if( (wndPtr->dwStyle & WS_VISIBLE) && (wndPtr->parent->dwStyle & WS_VISIBLE) )
 442             {
 443                 flags &= ~DCX_CLIPCHILDREN;
 444                 if( wndPtr->parent->dwStyle & WS_CLIPSIBLINGS )
 445                     flags |= DCX_CLIPSIBLINGS;
 446             }
 447     }
 448
 449     /* find a suitable DCE */
 450
 451     dcxFlags = flags & (DCX_PARENTCLIP | DCX_CLIPSIBLINGS | DCX_CLIPCHILDREN |
 452                         DCX_CACHE | DCX_WINDOW);
 453
 454     if (flags & DCX_CACHE)
 455     {
 456         DCE*    dceEmpty;
 457         DCE*    dceUnused;
 458
 459         dceEmpty = dceUnused = NULL;
 460
 461         /* Strategy: First, we attempt to find a non-empty but unused DCE with
 462          * compatible flags. Next, we look for an empty entry. If the cache is
 463          * full we have to purge one of the unused entries.
 464          */
 465
 466         for (dce = firstDCE; (dce); dce = dce->next)
 467         {
 468             if ((dce->DCXflags & (DCX_CACHE | DCX_DCEBUSY)) == DCX_CACHE )
 469             {
 470                 dceUnused = dce;
 471
 472                 if (dce->DCXflags & DCX_DCEEMPTY)
 473                     dceEmpty = dce;
 474                 else
 475                 if ((dce->hwndCurrent == hwnd) &&
 476                    ((dce->DCXflags & (DCX_CLIPSIBLINGS | DCX_CLIPCHILDREN |
 477                                       DCX_CACHE | DCX_WINDOW | DCX_PARENTCLIP)) == dcxFlags))
 478                 {
 479                     TRACE("\tfound valid %08x dce [%04x], flags %08x\n",
 480                                         (unsigned)dce, hwnd, (unsigned)dcxFlags );
 481                     bUpdateVisRgn = FALSE;
 482                     bUpdateClipOrigin = TRUE;
 483                     break;
 484                 }
 485             }
 486         }
 487
 488         if (!dce) dce = (dceEmpty) ? dceEmpty : dceUnused;
 489
 490         /* if there's no dce empty or unused, allocate a new one */
 491         if (!dce)
 492         {
 493             dce = DCE_AllocDCE( 0, DCE_CACHE_DC );
 494         }
 495     }
 496     else
 497     {
 498         dce = wndPtr->dce;
 499         if( dce->hwndCurrent == hwnd )
 500         {
 501             TRACE("\tskipping hVisRgn update\n");
 502             bUpdateVisRgn = FALSE; /* updated automatically, via DCHook() */
 503         }
 504     }
 505     if (!dce)
 506     {
 507         hdc = 0;
 508         goto END;
 509     }
 510
 511     if (!(flags & (DCX_INTERSECTRGN | DCX_EXCLUDERGN))) hrgnClip = 0;
 512
 513     if (((flags ^ dce->DCXflags) & (DCX_INTERSECTRGN | DCX_EXCLUDERGN)) &&
 514         (dce->hClipRgn != hrgnClip))
 515     {
 516         /* if the extra clip region has changed, get rid of the old one */
 517         DCE_DeleteClipRgn( dce );
 518     }
 519
 520     dce->hwndCurrent = hwnd;
 521     dce->hClipRgn = hrgnClip;
 522     dce->DCXflags = flags & (DCX_PARENTCLIP | DCX_CLIPSIBLINGS | DCX_CLIPCHILDREN |
 523                              DCX_CACHE | DCX_WINDOW | DCX_WINDOWPAINT |
 524                              DCX_KEEPCLIPRGN | DCX_INTERSECTRGN | DCX_EXCLUDERGN);
 525     dce->DCXflags |= DCX_DCEBUSY;
 526     dce->DCXflags &= ~DCX_DCEDIRTY;
 527     hdc = dce->hDC;
 528
 529     if (bUpdateVisRgn) SetHookFlags16( hdc, DCHF_INVALIDATEVISRGN ); /* force update */
 530
 531     if (!USER_Driver.pGetDC( hwnd, hdc, hrgnClip, flags )) hdc = 0;
 532
 533     TRACE("(%04x,%04x,0x%lx): returning %04x\n", hwnd, hrgnClip, flags, hdc);
 534 END:
 535     WIN_ReleaseWndPtr(wndPtr);
 536     return hdc;
 537 }
 538
 539
 540 /***********************************************************************
 541  *              GetDC (USER.66)
 542  */
 543 HDC16 WINAPI GetDC16( HWND16 hwnd )
 544 {
 545     return (HDC16)GetDC( hwnd );
 546 }
 547
 548
 549 /***********************************************************************
 550  *              GetDC (USER32.@)
 551  * RETURNS
 552  *      :Handle to DC
 553  *      NULL: Failure
 554  */
 555 HDC WINAPI GetDC(
 556              HWND hwnd /* [in] handle of window */
 557 ) {
 558     if (!hwnd)
 559         return GetDCEx( 0, 0, DCX_CACHE | DCX_WINDOW );
 560     return GetDCEx( hwnd, 0, DCX_USESTYLE );
 561 }
 562
 563
 564 /***********************************************************************
 565  *              GetWindowDC (USER.67)
 566  */
 567 HDC16 WINAPI GetWindowDC16( HWND16 hwnd )
 568 {
 569     return GetDCEx16( hwnd, 0, DCX_USESTYLE | DCX_WINDOW );
 570 }
 571
 572
 573 /***********************************************************************
 574  *              GetWindowDC (USER32.@)
 575  */
 576 HDC WINAPI GetWindowDC( HWND hwnd )
 577 {
 578     return GetDCEx( hwnd, 0, DCX_USESTYLE | DCX_WINDOW );
 579 }
 580
 581
 582 /***********************************************************************
 583  *              ReleaseDC (USER.68)
 584  */
 585 INT16 WINAPI ReleaseDC16( HWND16 hwnd, HDC16 hdc )
 586 {
 587     return (INT16)ReleaseDC( hwnd, hdc );
 588 }
 589
 590
 591 /***********************************************************************
 592  *              ReleaseDC (USER32.@)
 593  *
 594  * RETURNS
 595  *      1: Success
 596  *      0: Failure
 597  */
 598 INT WINAPI ReleaseDC(
 599              HWND hwnd /* [in] Handle of window - ignored */,
 600              HDC hdc   /* [in] Handle of device context */
 601 ) {
 602     DCE * dce;
 603     INT nRet = 0;
 604
 605     WIN_LockWnds();
 606     dce = firstDCE;
 607
 608     TRACE("%04x %04x\n", hwnd, hdc );
 609
 610     while (dce && (dce->hDC != hdc)) dce = dce->next;
 611
 612     if ( dce )
 613         if ( dce->DCXflags & DCX_DCEBUSY )
 614             nRet = DCE_ReleaseDC( dce );
 615
 616     WIN_UnlockWnds();
 617
 618     return nRet;
 619 }
 620
 621 /***********************************************************************
 622  *              DCHook (USER.362)
 623  *
 624  * See "Undoc. Windows" for hints (DC, SetDCHook, SetHookFlags)..
 625  */
 626 BOOL16 WINAPI DCHook16( HDC16 hDC, WORD code, DWORD data, LPARAM lParam )
 627 {
 628     BOOL retv = TRUE;
 629     DCE *dce = (DCE *)data;
 630
 631     TRACE("hDC = %04x, %i\n", hDC, code);
 632
 633     if (!dce) return 0;
 634     assert(dce->hDC == hDC);
 635
 636     /* Grab the windows lock before doing anything else  */
 637     WIN_LockWnds();
 638
 639     switch( code )
 640     {
 641       case DCHC_INVALIDVISRGN:
 642            /* GDI code calls this when it detects that the
 643             * DC is dirty (usually after SetHookFlags()). This
 644             * means that we have to recompute the visible region.
 645             */
 646            if( dce->DCXflags & DCX_DCEBUSY )
 647            {
 648                /* Dirty bit has been cleared by caller, set it again so that
 649                 * pGetDC recomputes the visible region. */
 650                SetHookFlags16( dce->hDC, DCHF_INVALIDATEVISRGN );
 651                USER_Driver.pGetDC( dce->hwndCurrent, dce->hDC, dce->hClipRgn, dce->DCXflags );
 652            }
 653            else /* non-fatal but shouldn't happen */
 654              WARN("DC is not in use!\n");
 655            break;
 656
 657       case DCHC_DELETEDC:
 658            /*
 659             * Windows will not let you delete a DC that is busy
 660             * (between GetDC and ReleaseDC)
 661             */
 662
 663            if ( dce->DCXflags & DCX_DCEBUSY )
 664            {
 665                WARN("Application trying to delete a busy DC\n");
 666                retv = FALSE;
 667            }
 668            break;
 669
 670       default:
 671            FIXME("unknown code\n");
 672     }
 673
 674   WIN_UnlockWnds();  /* Release the wnd lock */
 675   return retv;
 676 }
 677
 678
 679 /**********************************************************************
 680  *              WindowFromDC (USER.117)
 681  */
 682 HWND16 WINAPI WindowFromDC16( HDC16 hDC )
 683 {
 684     return (HWND16)WindowFromDC( hDC );
 685 }
 686
 687
 688 /**********************************************************************
 689  *              WindowFromDC (USER32.@)
 690  */
 691 HWND WINAPI WindowFromDC( HDC hDC )
 692 {
 693     DCE *dce;
 694     HWND hwnd;
 695
 696     WIN_LockWnds();
 697     dce = firstDCE;
 698
 699     while (dce && (dce->hDC != hDC)) dce = dce->next;
 700
 701     hwnd = dce ? dce->hwndCurrent : 0;
 702     WIN_UnlockWnds();
 703
 704     return hwnd;
 705 }
 706
 707
 708 /***********************************************************************
 709  *              LockWindowUpdate (USER.294)
 710  */
 711 BOOL16 WINAPI LockWindowUpdate16( HWND16 hwnd )
 712 {
 713     return LockWindowUpdate( hwnd );
 714 }
 715
 716 /***********************************************************************
 717  *              LockWindowUpdate (USER32.@)
 718  */
 719 BOOL WINAPI LockWindowUpdate( HWND hwnd )
 720 {
 721     FIXME("(%x), stub!\n",hwnd);
 722     return TRUE;
 723 }