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     static const WCHAR szDisplayW[] = { 'D','I','S','P','L','A','Y','\0' };
  85     DCE * dce;
  86
  87     TRACE("(%p,%d)\n", hWnd, type);
  88
  89     if (!(dce = HeapAlloc( GetProcessHeap(), 0, sizeof(DCE) ))) return NULL;
  90     if (!(dce->hDC = CreateDCW( szDisplayW, NULL, NULL, NULL )))
  91     {
  92         HeapFree( GetProcessHeap(), 0, dce );
  93         return 0;
  94     }
  95     if (!defaultDCstate) defaultDCstate = GetDCState16( HDC_16(dce->hDC) );
  96
  97     /* store DCE handle in DC hook data field */
  98
  99     SetDCHook( dce->hDC, DCHook16, (DWORD)dce );
 100
 101     dce->hwndCurrent = WIN_GetFullHandle( hWnd );
 102     dce->hClipRgn    = 0;
 103
 104     if( type != DCE_CACHE_DC ) /* owned or class DC */
 105     {
 106         dce->DCXflags = DCX_DCEBUSY;
 107         if( hWnd )
 108         {
 109             LONG style = GetWindowLongW( hWnd, GWL_STYLE );
 110             if (style & WS_CLIPCHILDREN) dce->DCXflags |= DCX_CLIPCHILDREN;
 111             if (style & WS_CLIPSIBLINGS) dce->DCXflags |= DCX_CLIPSIBLINGS;
 112         }
 113         SetHookFlags16( HDC_16(dce->hDC), DCHF_INVALIDATEVISRGN );
 114     }
 115     else dce->DCXflags = DCX_CACHE | DCX_DCEEMPTY;
 116
 117     USER_Lock();
 118     dce->next = firstDCE;
 119     firstDCE = dce;
 120     USER_Unlock();
 121     return dce;
 122 }
 123
 124
 125 /***********************************************************************
 126  *           DCE_FreeDCE
 127  */
 128 DCE* DCE_FreeDCE( DCE *dce )
 129 {
 130     DCE **ppDCE, *ret;
 131
 132     if (!dce) return NULL;
 133
 134     USER_Lock();
 135
 136     ppDCE = &firstDCE;
 137
 138     while (*ppDCE && (*ppDCE != dce)) ppDCE = &(*ppDCE)->next;
 139     if (*ppDCE == dce) *ppDCE = dce->next;
 140     ret = *ppDCE;
 141     USER_Unlock();
 142
 143     SetDCHook(dce->hDC, NULL, 0L);
 144
 145     DeleteDC( dce->hDC );
 146     if( dce->hClipRgn && !(dce->DCXflags & DCX_KEEPCLIPRGN) )
 147         DeleteObject(dce->hClipRgn);
 148     HeapFree( GetProcessHeap(), 0, dce );
 149
 150     return ret;
 151 }
 152
 153 /***********************************************************************
 154  *           DCE_FreeWindowDCE
 155  *
 156  * Remove owned DCE and reset unreleased cache DCEs.
 157  */
 158 void DCE_FreeWindowDCE( HWND hwnd )
 159 {
 160     DCE *pDCE;
 161     WND *pWnd = WIN_GetPtr( hwnd );
 162
 163     pDCE = firstDCE;
 164     while( pDCE )
 165     {
 166         if( pDCE->hwndCurrent == hwnd )
 167         {
 168             if( pDCE == pWnd->dce ) /* owned or Class DCE*/
 169             {
 170                 if (pWnd->clsStyle & CS_OWNDC)  /* owned DCE*/
 171                 {
 172                     pDCE = DCE_FreeDCE( pDCE );
 173                     pWnd->dce = NULL;
 174                     continue;
 175                 }
 176                 else if( pDCE->DCXflags & (DCX_INTERSECTRGN | DCX_EXCLUDERGN) ) /* Class DCE*/
 177                 {
 178                     if (USER_Driver.pReleaseDC)
 179                         USER_Driver.pReleaseDC( pDCE->hwndCurrent, pDCE->hDC );
 180                     DCE_DeleteClipRgn( pDCE );
 181                     pDCE->hwndCurrent = 0;
 182                 }
 183             }
 184             else
 185             {
 186                 if( pDCE->DCXflags & DCX_DCEBUSY ) /* shared cache DCE */
 187                 {
 188                     /* FIXME: AFAICS we are doing the right thing here so
 189                      * this should be a WARN. But this is best left as an ERR
 190                      * because the 'application error' is likely to come from
 191                      * another part of Wine (i.e. it's our fault after all).
 192                      * We should change this to WARN when Wine is more stable
 193                      * (for 1.0?).
 194                      */
 195                     ERR("[%p] GetDC() without ReleaseDC()!\n",hwnd);
 196                     DCE_ReleaseDC( pDCE );
 197                 }
 198
 199                 if (pDCE->hwndCurrent && USER_Driver.pReleaseDC)
 200                     USER_Driver.pReleaseDC( pDCE->hwndCurrent, pDCE->hDC );
 201                 pDCE->DCXflags &= DCX_CACHE;
 202                 pDCE->DCXflags |= DCX_DCEEMPTY;
 203                 pDCE->hwndCurrent = 0;
 204             }
 205         }
 206         pDCE = pDCE->next;
 207     }
 208     WIN_ReleasePtr( pWnd );
 209 }
 210
 211
 212 /***********************************************************************
 213  *   DCE_DeleteClipRgn
 214  */
 215 static void DCE_DeleteClipRgn( DCE* dce )
 216 {
 217     dce->DCXflags &= ~(DCX_EXCLUDERGN | DCX_INTERSECTRGN | DCX_WINDOWPAINT);
 218
 219     if( dce->DCXflags & DCX_KEEPCLIPRGN )
 220         dce->DCXflags &= ~DCX_KEEPCLIPRGN;
 221     else
 222         if( dce->hClipRgn > (HRGN)1 )
 223             DeleteObject( dce->hClipRgn );
 224
 225     dce->hClipRgn = 0;
 226
 227     /* make it dirty so that the vis rgn gets recomputed next time */
 228     dce->DCXflags |= DCX_DCEDIRTY;
 229     SetHookFlags16( HDC_16(dce->hDC), DCHF_INVALIDATEVISRGN );
 230 }
 231
 232
 233 /***********************************************************************
 234  *   DCE_ReleaseDC
 235  */
 236 static INT DCE_ReleaseDC( DCE* dce )
 237 {
 238     if ((dce->DCXflags & (DCX_DCEEMPTY | DCX_DCEBUSY)) != DCX_DCEBUSY) return 0;
 239
 240     /* restore previous visible region */
 241
 242     if ((dce->DCXflags & (DCX_INTERSECTRGN | DCX_EXCLUDERGN)) &&
 243         (dce->DCXflags & (DCX_CACHE | DCX_WINDOWPAINT)) )
 244         DCE_DeleteClipRgn( dce );
 245
 246     if (dce->DCXflags & DCX_CACHE)
 247     {
 248         /* make the DC clean so that SetDCState doesn't try to update the vis rgn */
 249         SetHookFlags16( HDC_16(dce->hDC), DCHF_VALIDATEVISRGN );
 250         SetDCState16( HDC_16(dce->hDC), defaultDCstate );
 251         dce->DCXflags &= ~DCX_DCEBUSY;
 252         if (dce->DCXflags & DCX_DCEDIRTY)
 253         {
 254             /* don't keep around invalidated entries
 255              * because SetDCState() disables hVisRgn updates
 256              * by removing dirty bit. */
 257             if (dce->hwndCurrent && USER_Driver.pReleaseDC)
 258                 USER_Driver.pReleaseDC( dce->hwndCurrent, dce->hDC );
 259             dce->hwndCurrent = 0;
 260             dce->DCXflags &= DCX_CACHE;
 261             dce->DCXflags |= DCX_DCEEMPTY;
 262         }
 263     }
 264     return 1;
 265 }
 266
 267
 268 /***********************************************************************
 269  *   DCE_InvalidateDCE
 270  *
 271  * It is called from SetWindowPos() and EVENT_MapNotify - we have to
 272  * mark as dirty all busy DCEs for windows that have pWnd->parent as
 273  * an ancestor and whose client rect intersects with specified update
 274  * rectangle. In addition, pWnd->parent DCEs may need to be updated if
 275  * DCX_CLIPCHILDREN flag is set.  */
 276 BOOL DCE_InvalidateDCE(HWND hwnd, const RECT* pRectUpdate)
 277 {
 278     HWND hwndScope = GetAncestor( hwnd, GA_PARENT );
 279     BOOL bRet = FALSE;
 280
 281     if( hwndScope )
 282     {
 283         DCE *dce;
 284
 285         TRACE("scope hwnd = %p, (%ld,%ld - %ld,%ld)\n",
 286               hwndScope, pRectUpdate->left,pRectUpdate->top,
 287               pRectUpdate->right,pRectUpdate->bottom);
 288         if(TRACE_ON(dc))
 289           DCE_DumpCache();
 290
 291         /* walk all DCEs and fixup non-empty entries */
 292
 293         for (dce = firstDCE; (dce); dce = dce->next)
 294         {
 295             if (dce->DCXflags & DCX_DCEEMPTY) continue;
 296             if ((dce->hwndCurrent == hwndScope) && !(dce->DCXflags & DCX_CLIPCHILDREN))
 297                 continue;  /* child window positions don't bother us */
 298
 299             /* check if DCE window is within the z-order scope */
 300
 301             if (hwndScope == dce->hwndCurrent || IsChild( hwndScope, dce->hwndCurrent ))
 302             {
 303                 if (hwnd != dce->hwndCurrent)
 304                 {
 305                     /* check if the window rectangle intersects this DCE window */
 306                     RECT rect;
 307                     GetWindowRect( dce->hwndCurrent, &rect );
 308                     MapWindowPoints( 0, hwndScope, (POINT *)&rect, 2 );
 309                     if (!IntersectRect( &rect, &rect, pRectUpdate )) continue;
 310
 311                 }
 312                 if( !(dce->DCXflags & DCX_DCEBUSY) )
 313                 {
 314                     /* Don't bother with visible regions of unused DCEs */
 315
 316                     TRACE("\tpurged %p dce [%p]\n", dce, dce->hwndCurrent);
 317                     if (dce->hwndCurrent && USER_Driver.pReleaseDC)
 318                         USER_Driver.pReleaseDC( dce->hwndCurrent, dce->hDC );
 319                     dce->hwndCurrent = 0;
 320                     dce->DCXflags &= DCX_CACHE;
 321                     dce->DCXflags |= DCX_DCEEMPTY;
 322                 }
 323                 else
 324                 {
 325                     /* Set dirty bits in the hDC and DCE structs */
 326
 327                     TRACE("\tfixed up %p dce [%p]\n", dce, dce->hwndCurrent);
 328                     dce->DCXflags |= DCX_DCEDIRTY;
 329                     SetHookFlags16( HDC_16(dce->hDC), DCHF_INVALIDATEVISRGN );
 330                     bRet = TRUE;
 331                 }
 332             }
 333         } /* dce list */
 334     }
 335     return bRet;
 336 }
 337
 338
 339 /***********************************************************************
 340  *           DCE_ExcludeRgn
 341  *
 342  *  Translate given region from the wnd client to the DC coordinates
 343  *  and add it to the clipping region.
 344  */
 345 INT DCE_ExcludeRgn( HDC hDC, HWND hwnd, HRGN hRgn )
 346 {
 347   POINT  pt = {0, 0};
 348   DCE     *dce = firstDCE;
 349
 350   while (dce && (dce->hDC != hDC)) dce = dce->next;
 351   if (!dce) return ERROR;
 352
 353   MapWindowPoints( hwnd, dce->hwndCurrent, &pt, 1);
 354   if( dce->DCXflags & DCX_WINDOW )
 355   {
 356       WND *wnd = WIN_FindWndPtr(dce->hwndCurrent);
 357       pt.x += wnd->rectClient.left - wnd->rectWindow.left;
 358       pt.y += wnd->rectClient.top - wnd->rectWindow.top;
 359       WIN_ReleaseWndPtr(wnd);
 360   }
 361   OffsetRgn(hRgn, pt.x, pt.y);
 362
 363   return ExtSelectClipRgn( hDC, hRgn, RGN_DIFF );
 364 }
 365
 366
 367 /***********************************************************************
 368  *              GetDCEx (USER32.@)
 369  *
 370  * Unimplemented flags: DCX_LOCKWINDOWUPDATE
 371  *
 372  * FIXME: Full support for hrgnClip == 1 (alias for entire window).
 373  */
 374 HDC WINAPI GetDCEx( HWND hwnd, HRGN hrgnClip, DWORD flags )
 375 {
 376     HDC         hdc = 0;
 377     DCE *       dce;
 378     WND *       wndPtr;
 379     DWORD       dcxFlags = 0;
 380     BOOL        bUpdateVisRgn = TRUE;
 381     BOOL        bUpdateClipOrigin = FALSE;
 382     HWND parent, full;
 383
 384     TRACE("hwnd %p, hrgnClip %p, flags %08lx\n", hwnd, hrgnClip, flags);
 385
 386     if (flags & (DCX_LOCKWINDOWUPDATE)) {
 387        FIXME("not yet supported - see source\n");
 388        /* See the comment in LockWindowUpdate for more explanation. This flag is not implemented
 389         * by that patch, but we need LockWindowUpdate implemented correctly before this can be done.
 390         */
 391     }
 392
 393     if (!hwnd) hwnd = GetDesktopWindow();
 394     if (!(full = WIN_IsCurrentProcess( hwnd )))
 395     {
 396         FIXME( "not supported yet on other process window %p\n", hwnd );
 397         return 0;
 398     }
 399     hwnd = full;
 400     if (!(wndPtr = WIN_GetPtr( hwnd ))) return 0;
 401
 402     /* fixup flags */
 403
 404     if (flags & (DCX_WINDOW | DCX_PARENTCLIP)) flags |= DCX_CACHE;
 405
 406     if (flags & DCX_USESTYLE)
 407     {
 408         flags &= ~( DCX_CLIPCHILDREN | DCX_CLIPSIBLINGS | DCX_PARENTCLIP);
 409
 410         if( wndPtr->dwStyle & WS_CLIPSIBLINGS )
 411             flags |= DCX_CLIPSIBLINGS;
 412
 413         if ( !(flags & DCX_WINDOW) )
 414         {
 415             if (wndPtr->clsStyle & CS_PARENTDC) flags |= DCX_PARENTCLIP;
 416
 417             if (wndPtr->dwStyle & WS_CLIPCHILDREN &&
 418                      !(wndPtr->dwStyle & WS_MINIMIZE) ) flags |= DCX_CLIPCHILDREN;
 419             if (!wndPtr->dce) flags |= DCX_CACHE;
 420         }
 421     }
 422
 423     if (flags & DCX_WINDOW) flags &= ~DCX_CLIPCHILDREN;
 424
 425     parent = GetAncestor( hwnd, GA_PARENT );
 426     if (!parent || (parent == GetDesktopWindow()))
 427         flags = (flags & ~DCX_PARENTCLIP) | DCX_CLIPSIBLINGS;
 428
 429     /* it seems parent clip is ignored when clipping siblings or children */
 430     if (flags & (DCX_CLIPSIBLINGS | DCX_CLIPCHILDREN)) flags &= ~DCX_PARENTCLIP;
 431
 432     if( flags & DCX_PARENTCLIP )
 433     {
 434         LONG parent_style = GetWindowLongW( parent, GWL_STYLE );
 435         if( (wndPtr->dwStyle & WS_VISIBLE) && (parent_style & WS_VISIBLE) )
 436         {
 437             flags &= ~DCX_CLIPCHILDREN;
 438             if (parent_style & WS_CLIPSIBLINGS) flags |= DCX_CLIPSIBLINGS;
 439         }
 440     }
 441
 442     /* find a suitable DCE */
 443
 444     dcxFlags = flags & (DCX_PARENTCLIP | DCX_CLIPSIBLINGS | DCX_CLIPCHILDREN |
 445                         DCX_CACHE | DCX_WINDOW);
 446
 447     if (flags & DCX_CACHE)
 448     {
 449         DCE*    dceEmpty;
 450         DCE*    dceUnused;
 451
 452         dceEmpty = dceUnused = NULL;
 453
 454         /* Strategy: First, we attempt to find a non-empty but unused DCE with
 455          * compatible flags. Next, we look for an empty entry. If the cache is
 456          * full we have to purge one of the unused entries.
 457          */
 458
 459         for (dce = firstDCE; (dce); dce = dce->next)
 460         {
 461             if ((dce->DCXflags & (DCX_CACHE | DCX_DCEBUSY)) == DCX_CACHE )
 462             {
 463                 dceUnused = dce;
 464
 465                 if (dce->DCXflags & DCX_DCEEMPTY)
 466                     dceEmpty = dce;
 467                 else
 468                 if ((dce->hwndCurrent == hwnd) &&
 469                    ((dce->DCXflags & (DCX_CLIPSIBLINGS | DCX_CLIPCHILDREN |
 470                                       DCX_CACHE | DCX_WINDOW | DCX_PARENTCLIP)) == dcxFlags))
 471                 {
 472                     TRACE("\tfound valid %p dce [%p], flags %08lx\n",
 473                           dce, hwnd, dcxFlags );
 474                     bUpdateVisRgn = FALSE;
 475                     bUpdateClipOrigin = TRUE;
 476                     break;
 477                 }
 478             }
 479         }
 480
 481         if (!dce) dce = (dceEmpty) ? dceEmpty : dceUnused;
 482
 483         /* if there's no dce empty or unused, allocate a new one */
 484         if (!dce)
 485         {
 486             dce = DCE_AllocDCE( 0, DCE_CACHE_DC );
 487         }
 488     }
 489     else
 490     {
 491         dce = wndPtr->dce;
 492         if (dce && dce->hwndCurrent == hwnd)
 493         {
 494             TRACE("\tskipping hVisRgn update\n");
 495             bUpdateVisRgn = FALSE; /* updated automatically, via DCHook() */
 496         }
 497     }
 498     if (!dce)
 499     {
 500         hdc = 0;
 501         goto END;
 502     }
 503
 504     if (!(flags & (DCX_INTERSECTRGN | DCX_EXCLUDERGN))) hrgnClip = 0;
 505
 506     if (((flags ^ dce->DCXflags) & (DCX_INTERSECTRGN | DCX_EXCLUDERGN)) &&
 507         (dce->hClipRgn != hrgnClip))
 508     {
 509         /* if the extra clip region has changed, get rid of the old one */
 510         DCE_DeleteClipRgn( dce );
 511     }
 512
 513     dce->hwndCurrent = hwnd;
 514     dce->hClipRgn = hrgnClip;
 515     dce->DCXflags = flags & (DCX_PARENTCLIP | DCX_CLIPSIBLINGS | DCX_CLIPCHILDREN |
 516                              DCX_CACHE | DCX_WINDOW | DCX_WINDOWPAINT |
 517                              DCX_KEEPCLIPRGN | DCX_INTERSECTRGN | DCX_EXCLUDERGN);
 518     dce->DCXflags |= DCX_DCEBUSY;
 519     dce->DCXflags &= ~DCX_DCEDIRTY;
 520     hdc = dce->hDC;
 521
 522     if (bUpdateVisRgn) SetHookFlags16( HDC_16(hdc), DCHF_INVALIDATEVISRGN ); /* force update */
 523
 524     if (!USER_Driver.pGetDC( hwnd, hdc, hrgnClip, flags )) hdc = 0;
 525
 526     TRACE("(%p,%p,0x%lx): returning %p\n", hwnd, hrgnClip, flags, hdc);
 527 END:
 528     WIN_ReleasePtr(wndPtr);
 529     return hdc;
 530 }
 531
 532
 533 /***********************************************************************
 534  *              GetDC (USER32.@)
 535  *
 536  * Get a device context.
 537  *
 538  * RETURNS
 539  *      Success: Handle to the device context
 540  *      Failure: NULL.
 541  */
 542 HDC WINAPI GetDC(
 543              HWND hwnd /* [in] handle of window - may be NULL */
 544 ) {
 545     if (!hwnd)
 546         return GetDCEx( 0, 0, DCX_CACHE | DCX_WINDOW );
 547     return GetDCEx( hwnd, 0, DCX_USESTYLE );
 548 }
 549
 550
 551 /***********************************************************************
 552  *              GetWindowDC (USER32.@)
 553  */
 554 HDC WINAPI GetWindowDC( HWND hwnd )
 555 {
 556     return GetDCEx( hwnd, 0, DCX_USESTYLE | DCX_WINDOW );
 557 }
 558
 559
 560 /***********************************************************************
 561  *              ReleaseDC (USER32.@)
 562  *
 563  * Release a device context.
 564  *
 565  * RETURNS
 566  *      Success: Non-zero. Resources used by hdc are released.
 567  *      Failure: 0.
 568  */
 569 INT WINAPI ReleaseDC(
 570              HWND hwnd, /* [in] Handle of window - ignored */
 571              HDC hdc   /* [in] Handle of device context */
 572 ) {
 573     DCE * dce;
 574     INT nRet = 0;
 575
 576     USER_Lock();
 577     dce = firstDCE;
 578
 579     TRACE("%p %p\n", hwnd, hdc );
 580
 581     while (dce && (dce->hDC != hdc)) dce = dce->next;
 582
 583     if ( dce )
 584         if ( dce->DCXflags & DCX_DCEBUSY )
 585             nRet = DCE_ReleaseDC( dce );
 586
 587     USER_Unlock();
 588
 589     return nRet;
 590 }
 591
 592 /***********************************************************************
 593  *              DCHook (USER.362)
 594  *
 595  * See "Undoc. Windows" for hints (DC, SetDCHook, SetHookFlags)..
 596  */
 597 BOOL16 WINAPI DCHook16( HDC16 hDC, WORD code, DWORD data, LPARAM lParam )
 598 {
 599     BOOL retv = TRUE;
 600     DCE *dce = (DCE *)data;
 601
 602     TRACE("hDC = %04x, %i\n", hDC, code);
 603
 604     if (!dce) return 0;
 605     assert( HDC_16(dce->hDC) == hDC );
 606
 607     /* Grab the windows lock before doing anything else  */
 608     USER_Lock();
 609
 610     switch( code )
 611     {
 612       case DCHC_INVALIDVISRGN:
 613            /* GDI code calls this when it detects that the
 614             * DC is dirty (usually after SetHookFlags()). This
 615             * means that we have to recompute the visible region.
 616             */
 617            if( dce->DCXflags & DCX_DCEBUSY )
 618            {
 619                /* Dirty bit has been cleared by caller, set it again so that
 620                 * pGetDC recomputes the visible region. */
 621                SetHookFlags16( hDC, DCHF_INVALIDATEVISRGN );
 622                USER_Driver.pGetDC( dce->hwndCurrent, dce->hDC, dce->hClipRgn, dce->DCXflags );
 623            }
 624            else /* non-fatal but shouldn't happen */
 625              WARN("DC is not in use!\n");
 626            break;
 627
 628       case DCHC_DELETEDC:
 629            /*
 630             * Windows will not let you delete a DC that is busy
 631             * (between GetDC and ReleaseDC)
 632             */
 633
 634            if ( dce->DCXflags & DCX_DCEBUSY )
 635            {
 636                WARN("Application trying to delete a busy DC\n");
 637                retv = FALSE;
 638            }
 639            else DCE_FreeDCE( dce );
 640            break;
 641
 642       default:
 643            FIXME("unknown code\n");
 644     }
 645
 646   USER_Unlock();  /* Release the wnd lock */
 647   return retv;
 648 }
 649
 650
 651 /**********************************************************************
 652  *              WindowFromDC (USER32.@)
 653  */
 654 HWND WINAPI WindowFromDC( HDC hDC )
 655 {
 656     DCE *dce;
 657     HWND hwnd;
 658
 659     USER_Lock();
 660     dce = firstDCE;
 661
 662     while (dce && (dce->hDC != hDC)) dce = dce->next;
 663
 664     hwnd = dce ? dce->hwndCurrent : 0;
 665     USER_Unlock();
 666
 667     return hwnd;
 668 }
 669
 670
 671 /***********************************************************************
 672  *              LockWindowUpdate (USER32.@)
 673  */
 674 BOOL WINAPI LockWindowUpdate( HWND hwnd )
 675 {
 676     static HWND lockedWnd;
 677
 678     /* This function is fully implemented by the following patch:
 679      *
 680      * http://www.winehq.org/hypermail/wine-patches/2004/01/0142.html
 681      *
 682      * but in order to work properly, it needs the ability to invalidate
 683      * DCEs in other processes when the lock window is changed, which
 684      * isn't possible yet.
 685      * -mike
 686      */
 687
 688     FIXME("(%p), partial stub!\n",hwnd);
 689
 690     USER_Lock();
 691     if (lockedWnd)
 692     {
 693         if (!hwnd)
 694         {
 695             /* Unlock lockedWnd */
 696             /* FIXME: Do something */
 697         }
 698         else
 699         {
 700             /* Attempted to lock a second window */
 701             /* Return FALSE and do nothing */
 702             USER_Unlock();
 703             return FALSE;
 704         }
 705     }
 706     lockedWnd = hwnd;
 707     USER_Unlock();
 708     return TRUE;
 709 }