dlls/x11drv/dce.c

   1 /*
   2 * USER DCE functions
   3  *
   4  * Copyright 1993, 2005 Alexandre Julliard
   5  * Copyright 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 #include "config.h"
  23
  24 #include <assert.h>
  25 #include "win.h"
  26 #include "windef.h"
  27 #include "wingdi.h"
  28 #include "wownt32.h"
  29 #include "ntstatus.h"
  30 #include "x11drv.h"
  31 #include "wine/winbase16.h"
  32 #include "wine/wingdi16.h"
  33 #include "wine/server.h"
  34 #include "wine/list.h"
  35 #include "wine/debug.h"
  36
  37 WINE_DEFAULT_DEBUG_CHANNEL(dc);
  38
  39 struct dce
  40 {
  41     struct list entry;         /* entry in global DCE list */
  42     HDC         hdc;
  43     HWND        hwnd;
  44     HRGN        clip_rgn;
  45     DWORD       flags;
  46     void       *class_ptr;     /* ptr to identify window class for class DCEs */
  47     ULONG       count;         /* usage count; 0 or 1 for cache DCEs, always 1 for window DCEs,
  48                                   always >= 1 for class DCEs */
  49 };
  50
  51 static struct list dce_list = LIST_INIT(dce_list);
  52
  53 static BOOL16 CALLBACK dc_hook( HDC16 hDC, WORD code, DWORD data, LPARAM lParam );
  54
  55 static CRITICAL_SECTION dce_section;
  56 static CRITICAL_SECTION_DEBUG critsect_debug =
  57 {
  58     0, 0, &dce_section,
  59     { &critsect_debug.ProcessLocksList, &critsect_debug.ProcessLocksList },
  60       0, 0, { (DWORD_PTR)(__FILE__ ": dce_section") }
  61 };
  62 static CRITICAL_SECTION dce_section = { &critsect_debug, -1, 0, 0, 0, 0 };
  63
  64 static const WCHAR displayW[] = { 'D','I','S','P','L','A','Y',0 };
  65
  66
  67 /***********************************************************************
  68  *           dump_cache
  69  */
  70 static void dump_cache(void)
  71 {
  72     struct dce *dce;
  73
  74     EnterCriticalSection( &dce_section );
  75
  76     LIST_FOR_EACH_ENTRY( dce, &dce_list, struct dce, entry )
  77     {
  78         TRACE("%p: hwnd %p dcx %08lx %s %s\n",
  79               dce, dce->hwnd, dce->flags,
  80               (dce->flags & DCX_CACHE) ? "Cache" : "Owned",
  81               dce->count ? "InUse" : "" );
  82     }
  83
  84     LeaveCriticalSection( &dce_section );
  85 }
  86
  87
  88 /***********************************************************************
  89  *              update_visible_region
  90  *
  91  * Set the visible region and X11 drawable for the DC associated to
  92  * a given window.
  93  */
  94 static void update_visible_region( struct dce *dce )
  95 {
  96     NTSTATUS status;
  97     HRGN vis_rgn = 0;
  98     HWND top = 0;
  99     struct x11drv_escape_set_drawable escape;
 100     struct x11drv_win_data *data;
 101     DWORD flags = dce->flags;
 102     size_t size = 256;
 103
 104     /* don't clip siblings if using parent clip region */
 105     if (flags & DCX_PARENTCLIP) flags &= ~DCX_CLIPSIBLINGS;
 106
 107     /* fetch the visible region from the server */
 108     do
 109     {
 110         RGNDATA *data = HeapAlloc( GetProcessHeap(), 0, sizeof(*data) + size - 1 );
 111         if (!data) return;
 112
 113         SERVER_START_REQ( get_visible_region )
 114         {
 115             req->window  = dce->hwnd;
 116             req->flags   = flags;
 117             wine_server_set_reply( req, data->Buffer, size );
 118             if (!(status = wine_server_call( req )))
 119             {
 120                 size_t reply_size = wine_server_reply_size( reply );
 121                 data->rdh.dwSize   = sizeof(data->rdh);
 122                 data->rdh.iType    = RDH_RECTANGLES;
 123                 data->rdh.nCount   = reply_size / sizeof(RECT);
 124                 data->rdh.nRgnSize = reply_size;
 125                 vis_rgn = ExtCreateRegion( NULL, size, data );
 126
 127                 top = reply->top_win;
 128                 escape.org.x = reply->win_org_x - reply->top_org_x;
 129                 escape.org.y = reply->win_org_y - reply->top_org_y;
 130                 escape.drawable_org.x = reply->top_org_x;
 131                 escape.drawable_org.y = reply->top_org_y;
 132             }
 133             else size = reply->total_size;
 134         }
 135         SERVER_END_REQ;
 136         HeapFree( GetProcessHeap(), 0, data );
 137     } while (status == STATUS_BUFFER_OVERFLOW);
 138
 139     if (status || !vis_rgn) return;
 140
 141     if (dce->clip_rgn) CombineRgn( vis_rgn, vis_rgn, dce->clip_rgn,
 142                                    (flags & DCX_INTERSECTRGN) ? RGN_AND : RGN_DIFF );
 143
 144     if (top == dce->hwnd && ((data = X11DRV_get_win_data( dce->hwnd )) != NULL) &&
 145          IsIconic( dce->hwnd ) && data->icon_window)
 146         escape.drawable = data->icon_window;
 147     else
 148         escape.drawable = X11DRV_get_whole_window( top );
 149
 150     escape.code = X11DRV_SET_DRAWABLE;
 151     escape.mode = IncludeInferiors;
 152     ExtEscape( dce->hdc, X11DRV_ESCAPE, sizeof(escape), (LPSTR)&escape, 0, NULL );
 153
 154     /* map region to DC coordinates */
 155     OffsetRgn( vis_rgn,
 156                -(escape.drawable_org.x + escape.org.x),
 157                -(escape.drawable_org.y + escape.org.y) );
 158     SelectVisRgn16( HDC_16(dce->hdc), HRGN_16(vis_rgn) );
 159     DeleteObject( vis_rgn );
 160 }
 161
 162
 163 /***********************************************************************
 164  *              release_dce
 165  */
 166 static void release_dce( struct dce *dce )
 167 {
 168     struct x11drv_escape_set_drawable escape;
 169
 170     if (!dce->hwnd) return;  /* already released */
 171
 172     if (dce->clip_rgn) DeleteObject( dce->clip_rgn );
 173     dce->clip_rgn = 0;
 174     dce->hwnd     = 0;
 175     dce->flags   &= DCX_CACHE;
 176
 177     escape.code = X11DRV_SET_DRAWABLE;
 178     escape.drawable = root_window;
 179     escape.mode = IncludeInferiors;
 180     escape.org.x = escape.org.y = 0;
 181     escape.drawable_org.x = escape.drawable_org.y = 0;
 182     ExtEscape( dce->hdc, X11DRV_ESCAPE, sizeof(escape), (LPSTR)&escape, 0, NULL );
 183 }
 184
 185
 186 /***********************************************************************
 187  *   delete_clip_rgn
 188  */
 189 static void delete_clip_rgn( struct dce *dce )
 190 {
 191     if (!dce->clip_rgn) return;  /* nothing to do */
 192
 193     dce->flags &= ~(DCX_EXCLUDERGN | DCX_INTERSECTRGN);
 194     DeleteObject( dce->clip_rgn );
 195     dce->clip_rgn = 0;
 196
 197     /* make it dirty so that the vis rgn gets recomputed next time */
 198     SetHookFlags16( HDC_16(dce->hdc), DCHF_INVALIDATEVISRGN );
 199 }
 200
 201
 202 /***********************************************************************
 203  *           alloc_cache_dce
 204  *
 205  * Allocate a new cache DCE.
 206  */
 207 static struct dce *alloc_cache_dce(void)
 208 {
 209     struct x11drv_escape_set_dce escape;
 210     struct dce *dce;
 211
 212     if (!(dce = HeapAlloc( GetProcessHeap(), 0, sizeof(*dce) ))) return NULL;
 213     if (!(dce->hdc = CreateDCW( displayW, NULL, NULL, NULL )))
 214     {
 215         HeapFree( GetProcessHeap(), 0, dce );
 216         return 0;
 217     }
 218     SaveDC( dce->hdc );
 219
 220     /* store DCE handle in DC hook data field */
 221     SetDCHook( dce->hdc, dc_hook, (DWORD)dce );
 222
 223     dce->hwnd      = 0;
 224     dce->clip_rgn  = 0;
 225     dce->flags     = DCX_CACHE;
 226     dce->class_ptr = NULL;
 227     dce->count     = 1;
 228
 229     EnterCriticalSection( &dce_section );
 230     list_add_head( &dce_list, &dce->entry );
 231     LeaveCriticalSection( &dce_section );
 232
 233     escape.code = X11DRV_SET_DCE;
 234     escape.dce  = dce;
 235     ExtEscape( dce->hdc, X11DRV_ESCAPE, sizeof(escape), (LPCSTR)&escape, 0, NULL );
 236
 237     return dce;
 238 }
 239
 240
 241 /***********************************************************************
 242  *           alloc_window_dce
 243  *
 244  * Allocate a DCE for a newly created window if necessary.
 245  */
 246 void alloc_window_dce( struct x11drv_win_data *data )
 247 {
 248     struct x11drv_escape_set_dce escape;
 249     struct dce *dce;
 250     void *class_ptr = NULL;
 251     LONG style = GetClassLongW( data->hwnd, GCL_STYLE );
 252
 253     if (!(style & (CS_CLASSDC|CS_OWNDC))) return;  /* nothing to do */
 254
 255     if (!(style & CS_OWNDC))  /* class dc */
 256     {
 257         /* hack: get the class pointer from the window structure */
 258         WND *win = WIN_GetPtr( data->hwnd );
 259         class_ptr = win->class;
 260         WIN_ReleasePtr( win );
 261
 262         EnterCriticalSection( &dce_section );
 263         LIST_FOR_EACH_ENTRY( dce, &dce_list, struct dce, entry )
 264         {
 265             if (dce->class_ptr == class_ptr)
 266             {
 267                 dce->count++;
 268                 data->dce = dce;
 269                 LeaveCriticalSection( &dce_section );
 270                 return;
 271             }
 272         }
 273         LeaveCriticalSection( &dce_section );
 274     }
 275
 276     /* now allocate a new one */
 277
 278     if (!(dce = HeapAlloc( GetProcessHeap(), 0, sizeof(*dce) ))) return;
 279     if (!(dce->hdc = CreateDCW( displayW, NULL, NULL, NULL )))
 280     {
 281         HeapFree( GetProcessHeap(), 0, dce );
 282         return;
 283     }
 284
 285     /* store DCE handle in DC hook data field */
 286
 287     SetDCHook( dce->hdc, dc_hook, (DWORD)dce );
 288
 289     dce->hwnd      = data->hwnd;
 290     dce->clip_rgn  = 0;
 291     dce->flags     = 0;
 292     dce->class_ptr = class_ptr;
 293     dce->count     = 1;
 294
 295     if (style & CS_OWNDC)
 296     {
 297         LONG win_style = GetWindowLongW( data->hwnd, GWL_STYLE );
 298         if (win_style & WS_CLIPCHILDREN) dce->flags |= DCX_CLIPCHILDREN;
 299         if (win_style & WS_CLIPSIBLINGS) dce->flags |= DCX_CLIPSIBLINGS;
 300     }
 301     SetHookFlags16( HDC_16(dce->hdc), DCHF_INVALIDATEVISRGN );
 302
 303     EnterCriticalSection( &dce_section );
 304     list_add_tail( &dce_list, &dce->entry );
 305     LeaveCriticalSection( &dce_section );
 306     data->dce = dce;
 307
 308     escape.code = X11DRV_SET_DCE;
 309     escape.dce  = dce;
 310     ExtEscape( dce->hdc, X11DRV_ESCAPE, sizeof(escape), (LPCSTR)&escape, 0, NULL );
 311 }
 312
 313
 314 /***********************************************************************
 315  *           free_window_dce
 316  *
 317  * Free a class or window DCE.
 318  */
 319 void free_window_dce( struct x11drv_win_data *data )
 320 {
 321     struct dce *dce = data->dce;
 322
 323     if (dce)
 324     {
 325         EnterCriticalSection( &dce_section );
 326         if (!--dce->count)
 327         {
 328             list_remove( &dce->entry );
 329             SetDCHook(dce->hdc, NULL, 0L);
 330             DeleteDC( dce->hdc );
 331             if (dce->clip_rgn) DeleteObject( dce->clip_rgn );
 332             HeapFree( GetProcessHeap(), 0, dce );
 333         }
 334         else if (dce->hwnd == data->hwnd)
 335         {
 336             release_dce( dce );
 337         }
 338         LeaveCriticalSection( &dce_section );
 339         data->dce = NULL;
 340     }
 341
 342     /* now check for cache DCEs */
 343
 344     EnterCriticalSection( &dce_section );
 345     LIST_FOR_EACH_ENTRY( dce, &dce_list, struct dce, entry )
 346     {
 347         if (dce->hwnd != data->hwnd) continue;
 348         if (!(dce->flags & DCX_CACHE)) continue;
 349
 350         if (dce->count) WARN( "GetDC() without ReleaseDC() for window %p\n", data->hwnd );
 351         release_dce( dce );
 352         dce->count = 0;
 353     }
 354     LeaveCriticalSection( &dce_section );
 355 }
 356
 357
 358 /***********************************************************************
 359  *   invalidate_dce
 360  *
 361  * It is called from SetWindowPos() - we have to
 362  * mark as dirty all busy DCEs for windows that have pWnd->parent as
 363  * an ancestor and whose client rect intersects with specified update
 364  * rectangle. In addition, pWnd->parent DCEs may need to be updated if
 365  * DCX_CLIPCHILDREN flag is set.
 366  */
 367 void invalidate_dce( HWND hwnd, const RECT *rect )
 368 {
 369     HWND hwndScope = GetAncestor( hwnd, GA_PARENT );
 370
 371     if( hwndScope )
 372     {
 373         struct dce *dce;
 374
 375         TRACE("scope hwnd = %p %s\n", hwndScope, wine_dbgstr_rect(rect) );
 376         if (TRACE_ON(dc)) dump_cache();
 377
 378         /* walk all DCEs and fixup non-empty entries */
 379
 380         LIST_FOR_EACH_ENTRY( dce, &dce_list, struct dce, entry )
 381         {
 382             if (!dce->hwnd) continue;
 383             if ((dce->hwnd == hwndScope) && !(dce->flags & DCX_CLIPCHILDREN))
 384                 continue;  /* child window positions don't bother us */
 385
 386             /* check if DCE window is within the z-order scope */
 387
 388             if (hwndScope == dce->hwnd || IsChild( hwndScope, dce->hwnd ))
 389             {
 390                 if (hwnd != dce->hwnd)
 391                 {
 392                     /* check if the window rectangle intersects this DCE window */
 393                     RECT tmp;
 394                     GetWindowRect( dce->hwnd, &tmp );
 395                     MapWindowPoints( 0, hwndScope, (POINT *)&tmp, 2 );
 396                     if (!IntersectRect( &tmp, &tmp, rect )) continue;
 397
 398                 }
 399                 if (!dce->count)
 400                 {
 401                     /* Don't bother with visible regions of unused DCEs */
 402
 403                     TRACE("\tpurged %p dce [%p]\n", dce, dce->hwnd);
 404                     release_dce( dce );
 405                 }
 406                 else
 407                 {
 408                     /* Set dirty bits in the hDC and DCE structs */
 409
 410                     TRACE("\tfixed up %p dce [%p]\n", dce, dce->hwnd);
 411                     SetHookFlags16( HDC_16(dce->hdc), DCHF_INVALIDATEVISRGN );
 412                 }
 413             }
 414         } /* dce list */
 415     }
 416 }
 417
 418
 419 /***********************************************************************
 420  *              X11DRV_GetDCEx   (X11DRV.@)
 421  *
 422  * Unimplemented flags: DCX_LOCKWINDOWUPDATE
 423  */
 424 HDC X11DRV_GetDCEx( HWND hwnd, HRGN hrgnClip, DWORD flags )
 425 {
 426     static const DWORD clip_flags = DCX_PARENTCLIP | DCX_CLIPSIBLINGS | DCX_CLIPCHILDREN | DCX_WINDOW;
 427
 428     struct x11drv_win_data *data = X11DRV_get_win_data( hwnd );
 429     struct dce *dce;
 430     BOOL bUpdateVisRgn = TRUE;
 431     HWND parent;
 432     LONG window_style = GetWindowLongW( hwnd, GWL_STYLE );
 433
 434     TRACE("hwnd %p, hrgnClip %p, flags %08lx\n", hwnd, hrgnClip, flags);
 435
 436     /* fixup flags */
 437
 438     if (flags & (DCX_WINDOW | DCX_PARENTCLIP)) flags |= DCX_CACHE;
 439
 440     if (flags & DCX_USESTYLE)
 441     {
 442         flags &= ~(DCX_CLIPCHILDREN | DCX_CLIPSIBLINGS | DCX_PARENTCLIP);
 443
 444         if (window_style & WS_CLIPSIBLINGS) flags |= DCX_CLIPSIBLINGS;
 445
 446         if (!(flags & DCX_WINDOW))
 447         {
 448             if (GetClassLongW( hwnd, GCL_STYLE ) & CS_PARENTDC) flags |= DCX_PARENTCLIP;
 449
 450             if (window_style & WS_CLIPCHILDREN && !(window_style & WS_MINIMIZE))
 451                 flags |= DCX_CLIPCHILDREN;
 452             if (!data || !data->dce) flags |= DCX_CACHE;
 453         }
 454     }
 455
 456     if (flags & DCX_WINDOW) flags &= ~DCX_CLIPCHILDREN;
 457
 458     parent = GetAncestor( hwnd, GA_PARENT );
 459     if (!parent || (parent == GetDesktopWindow()))
 460         flags = (flags & ~DCX_PARENTCLIP) | DCX_CLIPSIBLINGS;
 461
 462     /* it seems parent clip is ignored when clipping siblings or children */
 463     if (flags & (DCX_CLIPSIBLINGS | DCX_CLIPCHILDREN)) flags &= ~DCX_PARENTCLIP;
 464
 465     if( flags & DCX_PARENTCLIP )
 466     {
 467         LONG parent_style = GetWindowLongW( parent, GWL_STYLE );
 468         if( (window_style & WS_VISIBLE) && (parent_style & WS_VISIBLE) )
 469         {
 470             flags &= ~DCX_CLIPCHILDREN;
 471             if (parent_style & WS_CLIPSIBLINGS) flags |= DCX_CLIPSIBLINGS;
 472         }
 473     }
 474
 475     /* find a suitable DCE */
 476
 477     if (flags & DCX_CACHE)
 478     {
 479         struct dce *dceEmpty = NULL, *dceUnused = NULL;
 480
 481         /* Strategy: First, we attempt to find a non-empty but unused DCE with
 482          * compatible flags. Next, we look for an empty entry. If the cache is
 483          * full we have to purge one of the unused entries.
 484          */
 485         EnterCriticalSection( &dce_section );
 486         LIST_FOR_EACH_ENTRY( dce, &dce_list, struct dce, entry )
 487         {
 488             if ((dce->flags & DCX_CACHE) && !dce->count)
 489             {
 490                 dceUnused = dce;
 491
 492                 if (!dce->hwnd) dceEmpty = dce;
 493                 else if ((dce->hwnd == hwnd) && !((dce->flags ^ flags) & clip_flags))
 494                 {
 495                     TRACE("\tfound valid %p dce [%p], flags %08lx\n",
 496                           dce, hwnd, dce->flags );
 497                     bUpdateVisRgn = FALSE;
 498                     break;
 499                 }
 500             }
 501         }
 502
 503         if (&dce->entry == &dce_list)  /* nothing found */
 504             dce = dceEmpty ? dceEmpty : dceUnused;
 505
 506         if (dce) dce->count = 1;
 507
 508         LeaveCriticalSection( &dce_section );
 509
 510         /* if there's no dce empty or unused, allocate a new one */
 511         if (!dce) dce = alloc_cache_dce();
 512         if (!dce) return 0;
 513     }
 514     else
 515     {
 516         flags |= DCX_NORESETATTRS;
 517         dce = data->dce;
 518         if (dce->hwnd == hwnd)
 519         {
 520             TRACE("\tskipping hVisRgn update\n");
 521             bUpdateVisRgn = FALSE; /* updated automatically, via DCHook() */
 522         }
 523         else
 524         {
 525             /* we should free dce->clip_rgn here, but Windows apparently doesn't */
 526             dce->flags &= ~(DCX_EXCLUDERGN | DCX_INTERSECTRGN);
 527             dce->clip_rgn = 0;
 528         }
 529     }
 530
 531     if (flags & (DCX_INTERSECTRGN | DCX_EXCLUDERGN))
 532     {
 533         /* if the extra clip region has changed, get rid of the old one */
 534         if (dce->clip_rgn != hrgnClip || ((flags ^ dce->flags) & (DCX_INTERSECTRGN | DCX_EXCLUDERGN)))
 535             delete_clip_rgn( dce );
 536         dce->clip_rgn = hrgnClip;
 537         if (!dce->clip_rgn) dce->clip_rgn = CreateRectRgn( 0, 0, 0, 0 );
 538         dce->flags |= flags & (DCX_INTERSECTRGN | DCX_EXCLUDERGN);
 539         bUpdateVisRgn = TRUE;
 540     }
 541
 542     dce->hwnd = hwnd;
 543     dce->flags = (dce->flags & ~clip_flags) | (flags & clip_flags);
 544
 545     if (SetHookFlags16( HDC_16(dce->hdc), DCHF_VALIDATEVISRGN ))
 546         bUpdateVisRgn = TRUE;  /* DC was dirty */
 547
 548     if (bUpdateVisRgn) update_visible_region( dce );
 549
 550     if (!(flags & DCX_NORESETATTRS))
 551     {
 552         RestoreDC( dce->hdc, 1 );  /* initial save level is always 1 */
 553         SaveDC( dce->hdc );  /* save the state again for next time */
 554     }
 555
 556     TRACE("(%p,%p,0x%lx): returning %p\n", hwnd, hrgnClip, flags, dce->hdc);
 557     return dce->hdc;
 558 }
 559
 560
 561 /***********************************************************************
 562  *              X11DRV_ReleaseDC  (X11DRV.@)
 563  */
 564 INT X11DRV_ReleaseDC( HWND hwnd, HDC hdc, BOOL end_paint )
 565 {
 566     enum x11drv_escape_codes escape = X11DRV_GET_DCE;
 567     struct dce *dce;
 568     BOOL ret = FALSE;
 569
 570     TRACE("%p %p\n", hwnd, hdc );
 571
 572     EnterCriticalSection( &dce_section );
 573     if (!ExtEscape( hdc, X11DRV_ESCAPE, sizeof(escape), (LPCSTR)&escape,
 574                     sizeof(dce), (LPSTR)&dce )) dce = NULL;
 575     if (dce && dce->count)
 576     {
 577         if (end_paint || (dce->flags & DCX_CACHE)) delete_clip_rgn( dce );
 578         if (dce->flags & DCX_CACHE) dce->count = 0;
 579         ret = TRUE;
 580     }
 581     LeaveCriticalSection( &dce_section );
 582     return ret;
 583 }
 584
 585 /***********************************************************************
 586  *              dc_hook
 587  *
 588  * See "Undoc. Windows" for hints (DC, SetDCHook, SetHookFlags)..
 589  */
 590 static BOOL16 CALLBACK dc_hook( HDC16 hDC, WORD code, DWORD data, LPARAM lParam )
 591 {
 592     BOOL retv = TRUE;
 593     struct dce *dce = (struct dce *)data;
 594
 595     TRACE("hDC = %04x, %i\n", hDC, code);
 596
 597     if (!dce) return 0;
 598     assert( HDC_16(dce->hdc) == hDC );
 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->count) update_visible_region( dce );
 608         else /* non-fatal but shouldn't happen */
 609             WARN("DC is not in use!\n");
 610         break;
 611     case DCHC_DELETEDC:
 612         /*
 613          * Windows will not let you delete a DC that is busy
 614          * (between GetDC and ReleaseDC)
 615          */
 616         if (dce->count)
 617         {
 618             WARN("Application trying to delete a busy DC %p\n", dce->hdc);
 619             retv = FALSE;
 620         }
 621         else
 622         {
 623             EnterCriticalSection( &dce_section );
 624             list_remove( &dce->entry );
 625             LeaveCriticalSection( &dce_section );
 626             if (dce->clip_rgn) DeleteObject( dce->clip_rgn );
 627             HeapFree( GetProcessHeap(), 0, dce );
 628         }
 629         break;
 630     }
 631     return retv;
 632 }
 633
 634
 635 /**********************************************************************
 636  *              WindowFromDC   (X11DRV.@)
 637  */
 638 HWND X11DRV_WindowFromDC( HDC hdc )
 639 {
 640     enum x11drv_escape_codes escape = X11DRV_GET_DCE;
 641     struct dce *dce;
 642     HWND hwnd = 0;
 643
 644     EnterCriticalSection( &dce_section );
 645     if (!ExtEscape( hdc, X11DRV_ESCAPE, sizeof(escape), (LPCSTR)&escape,
 646                     sizeof(dce), (LPSTR)&dce )) dce = NULL;
 647     if (dce) hwnd = dce->hwnd;
 648     LeaveCriticalSection( &dce_section );
 649     return hwnd;
 650 }