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   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 (flags & (DCX_WINDOW | DCX_PARENTCLIP)) 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             if (!wndPtr->dce) flags |= DCX_CACHE;
 429         }
 430     }
 431
 432     if (flags & DCX_WINDOW) flags &= ~DCX_CLIPCHILDREN;
 433
 434     if (!wndPtr->parent || (wndPtr->parent->hwndSelf == GetDesktopWindow()))
 435         flags = (flags & ~DCX_PARENTCLIP) | DCX_CLIPSIBLINGS;
 436
 437     /* it seems parent clip is ignored when clipping siblings or children */
 438     if (flags & (DCX_CLIPSIBLINGS | DCX_CLIPCHILDREN)) flags &= ~DCX_PARENTCLIP;
 439
 440     if( flags & DCX_PARENTCLIP )
 441     {
 442         if( (wndPtr->dwStyle & WS_VISIBLE) && (wndPtr->parent->dwStyle & WS_VISIBLE) )
 443         {
 444             flags &= ~DCX_CLIPCHILDREN;
 445             if( wndPtr->parent->dwStyle & WS_CLIPSIBLINGS )
 446                 flags |= DCX_CLIPSIBLINGS;
 447         }
 448     }
 449
 450     /* find a suitable DCE */
 451
 452     dcxFlags = flags & (DCX_PARENTCLIP | DCX_CLIPSIBLINGS | DCX_CLIPCHILDREN |
 453                         DCX_CACHE | DCX_WINDOW);
 454
 455     if (flags & DCX_CACHE)
 456     {
 457         DCE*    dceEmpty;
 458         DCE*    dceUnused;
 459
 460         dceEmpty = dceUnused = NULL;
 461
 462         /* Strategy: First, we attempt to find a non-empty but unused DCE with
 463          * compatible flags. Next, we look for an empty entry. If the cache is
 464          * full we have to purge one of the unused entries.
 465          */
 466
 467         for (dce = firstDCE; (dce); dce = dce->next)
 468         {
 469             if ((dce->DCXflags & (DCX_CACHE | DCX_DCEBUSY)) == DCX_CACHE )
 470             {
 471                 dceUnused = dce;
 472
 473                 if (dce->DCXflags & DCX_DCEEMPTY)
 474                     dceEmpty = dce;
 475                 else
 476                 if ((dce->hwndCurrent == hwnd) &&
 477                    ((dce->DCXflags & (DCX_CLIPSIBLINGS | DCX_CLIPCHILDREN |
 478                                       DCX_CACHE | DCX_WINDOW | DCX_PARENTCLIP)) == dcxFlags))
 479                 {
 480                     TRACE("\tfound valid %08x dce [%04x], flags %08x\n",
 481                                         (unsigned)dce, hwnd, (unsigned)dcxFlags );
 482                     bUpdateVisRgn = FALSE;
 483                     bUpdateClipOrigin = TRUE;
 484                     break;
 485                 }
 486             }
 487         }
 488
 489         if (!dce) dce = (dceEmpty) ? dceEmpty : dceUnused;
 490
 491         /* if there's no dce empty or unused, allocate a new one */
 492         if (!dce)
 493         {
 494             dce = DCE_AllocDCE( 0, DCE_CACHE_DC );
 495         }
 496     }
 497     else
 498     {
 499         dce = wndPtr->dce;
 500         if (dce && dce->hwndCurrent == hwnd)
 501         {
 502             TRACE("\tskipping hVisRgn update\n");
 503             bUpdateVisRgn = FALSE; /* updated automatically, via DCHook() */
 504         }
 505     }
 506     if (!dce)
 507     {
 508         hdc = 0;
 509         goto END;
 510     }
 511
 512     if (!(flags & (DCX_INTERSECTRGN | DCX_EXCLUDERGN))) hrgnClip = 0;
 513
 514     if (((flags ^ dce->DCXflags) & (DCX_INTERSECTRGN | DCX_EXCLUDERGN)) &&
 515         (dce->hClipRgn != hrgnClip))
 516     {
 517         /* if the extra clip region has changed, get rid of the old one */
 518         DCE_DeleteClipRgn( dce );
 519     }
 520
 521     dce->hwndCurrent = hwnd;
 522     dce->hClipRgn = hrgnClip;
 523     dce->DCXflags = flags & (DCX_PARENTCLIP | DCX_CLIPSIBLINGS | DCX_CLIPCHILDREN |
 524                              DCX_CACHE | DCX_WINDOW | DCX_WINDOWPAINT |
 525                              DCX_KEEPCLIPRGN | DCX_INTERSECTRGN | DCX_EXCLUDERGN);
 526     dce->DCXflags |= DCX_DCEBUSY;
 527     dce->DCXflags &= ~DCX_DCEDIRTY;
 528     hdc = dce->hDC;
 529
 530     if (bUpdateVisRgn) SetHookFlags16( hdc, DCHF_INVALIDATEVISRGN ); /* force update */
 531
 532     if (!USER_Driver.pGetDC( hwnd, hdc, hrgnClip, flags )) hdc = 0;
 533
 534     TRACE("(%04x,%04x,0x%lx): returning %04x\n", hwnd, hrgnClip, flags, hdc);
 535 END:
 536     WIN_ReleaseWndPtr(wndPtr);
 537     return hdc;
 538 }
 539
 540
 541 /***********************************************************************
 542  *              GetDC (USER.66)
 543  */
 544 HDC16 WINAPI GetDC16( HWND16 hwnd )
 545 {
 546     return (HDC16)GetDC( hwnd );
 547 }
 548
 549
 550 /***********************************************************************
 551  *              GetDC (USER32.@)
 552  * RETURNS
 553  *      :Handle to DC
 554  *      NULL: Failure
 555  */
 556 HDC WINAPI GetDC(
 557              HWND hwnd /* [in] handle of window */
 558 ) {
 559     if (!hwnd)
 560         return GetDCEx( 0, 0, DCX_CACHE | DCX_WINDOW );
 561     return GetDCEx( hwnd, 0, DCX_USESTYLE );
 562 }
 563
 564
 565 /***********************************************************************
 566  *              GetWindowDC (USER.67)
 567  */
 568 HDC16 WINAPI GetWindowDC16( HWND16 hwnd )
 569 {
 570     return GetDCEx16( hwnd, 0, DCX_USESTYLE | DCX_WINDOW );
 571 }
 572
 573
 574 /***********************************************************************
 575  *              GetWindowDC (USER32.@)
 576  */
 577 HDC WINAPI GetWindowDC( HWND hwnd )
 578 {
 579     return GetDCEx( hwnd, 0, DCX_USESTYLE | DCX_WINDOW );
 580 }
 581
 582
 583 /***********************************************************************
 584  *              ReleaseDC (USER.68)
 585  */
 586 INT16 WINAPI ReleaseDC16( HWND16 hwnd, HDC16 hdc )
 587 {
 588     return (INT16)ReleaseDC( hwnd, hdc );
 589 }
 590
 591
 592 /***********************************************************************
 593  *              ReleaseDC (USER32.@)
 594  *
 595  * RETURNS
 596  *      1: Success
 597  *      0: Failure
 598  */
 599 INT WINAPI ReleaseDC(
 600              HWND hwnd /* [in] Handle of window - ignored */,
 601              HDC hdc   /* [in] Handle of device context */
 602 ) {
 603     DCE * dce;
 604     INT nRet = 0;
 605
 606     WIN_LockWnds();
 607     dce = firstDCE;
 608
 609     TRACE("%04x %04x\n", hwnd, hdc );
 610
 611     while (dce && (dce->hDC != hdc)) dce = dce->next;
 612
 613     if ( dce )
 614         if ( dce->DCXflags & DCX_DCEBUSY )
 615             nRet = DCE_ReleaseDC( dce );
 616
 617     WIN_UnlockWnds();
 618
 619     return nRet;
 620 }
 621
 622 /***********************************************************************
 623  *              DCHook (USER.362)
 624  *
 625  * See "Undoc. Windows" for hints (DC, SetDCHook, SetHookFlags)..
 626  */
 627 BOOL16 WINAPI DCHook16( HDC16 hDC, WORD code, DWORD data, LPARAM lParam )
 628 {
 629     BOOL retv = TRUE;
 630     DCE *dce = (DCE *)data;
 631
 632     TRACE("hDC = %04x, %i\n", hDC, code);
 633
 634     if (!dce) return 0;
 635     assert(dce->hDC == hDC);
 636
 637     /* Grab the windows lock before doing anything else  */
 638     WIN_LockWnds();
 639
 640     switch( code )
 641     {
 642       case DCHC_INVALIDVISRGN:
 643            /* GDI code calls this when it detects that the
 644             * DC is dirty (usually after SetHookFlags()). This
 645             * means that we have to recompute the visible region.
 646             */
 647            if( dce->DCXflags & DCX_DCEBUSY )
 648            {
 649                /* Dirty bit has been cleared by caller, set it again so that
 650                 * pGetDC recomputes the visible region. */
 651                SetHookFlags16( dce->hDC, DCHF_INVALIDATEVISRGN );
 652                USER_Driver.pGetDC( dce->hwndCurrent, dce->hDC, dce->hClipRgn, dce->DCXflags );
 653            }
 654            else /* non-fatal but shouldn't happen */
 655              WARN("DC is not in use!\n");
 656            break;
 657
 658       case DCHC_DELETEDC:
 659            /*
 660             * Windows will not let you delete a DC that is busy
 661             * (between GetDC and ReleaseDC)
 662             */
 663
 664            if ( dce->DCXflags & DCX_DCEBUSY )
 665            {
 666                WARN("Application trying to delete a busy DC\n");
 667                retv = FALSE;
 668            }
 669            break;
 670
 671       default:
 672            FIXME("unknown code\n");
 673     }
 674
 675   WIN_UnlockWnds();  /* Release the wnd lock */
 676   return retv;
 677 }
 678
 679
 680 /**********************************************************************
 681  *              WindowFromDC (USER.117)
 682  */
 683 HWND16 WINAPI WindowFromDC16( HDC16 hDC )
 684 {
 685     return (HWND16)WindowFromDC( hDC );
 686 }
 687
 688
 689 /**********************************************************************
 690  *              WindowFromDC (USER32.@)
 691  */
 692 HWND WINAPI WindowFromDC( HDC hDC )
 693 {
 694     DCE *dce;
 695     HWND hwnd;
 696
 697     WIN_LockWnds();
 698     dce = firstDCE;
 699
 700     while (dce && (dce->hDC != hDC)) dce = dce->next;
 701
 702     hwnd = dce ? dce->hwndCurrent : 0;
 703     WIN_UnlockWnds();
 704
 705     return hwnd;
 706 }
 707
 708
 709 /***********************************************************************
 710  *              LockWindowUpdate (USER.294)
 711  */
 712 BOOL16 WINAPI LockWindowUpdate16( HWND16 hwnd )
 713 {
 714     return LockWindowUpdate( hwnd );
 715 }
 716
 717 /***********************************************************************
 718  *              LockWindowUpdate (USER32.@)
 719  */
 720 BOOL WINAPI LockWindowUpdate( HWND hwnd )
 721 {
 722     FIXME("(%x), stub!\n",hwnd);
 723     return TRUE;
 724 }