dlls/winex11.drv/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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  20  */
  21
  22 #include "config.h"
  23
  24 #include <assert.h>
  25 #include "ntstatus.h"
  26 #define WIN32_NO_STATUS
  27 #include "win.h"
  28 #include "windef.h"
  29 #include "wingdi.h"
  30 #include "wownt32.h"
  31 #include "x11drv.h"
  32 #include "wine/winbase16.h"
  33 #include "wine/wingdi16.h"
  34 #include "wine/server.h"
  35 #include "wine/list.h"
  36 #include "wine/debug.h"
  37
  38 WINE_DEFAULT_DEBUG_CHANNEL(dc);
  39
  40 struct dce
  41 {
  42     struct list entry;         /* entry in global DCE list */
  43     HDC         hdc;
  44     HWND        hwnd;
  45     HRGN        clip_rgn;
  46     DWORD       flags;
  47     void       *class_ptr;     /* ptr to identify window class for class DCEs */
  48     ULONG       count;         /* usage count; 0 or 1 for cache DCEs, always 1 for window DCEs,
  49                                   always >= 1 for class DCEs */
  50 };
  51
  52 static struct list dce_list = LIST_INIT(dce_list);
  53
  54 static BOOL CALLBACK dc_hook( HDC hDC, WORD code, DWORD_PTR data, LPARAM lParam );
  55
  56 static CRITICAL_SECTION dce_section;
  57 static CRITICAL_SECTION_DEBUG critsect_debug =
  58 {
  59     0, 0, &dce_section,
  60     { &critsect_debug.ProcessLocksList, &critsect_debug.ProcessLocksList },
  61       0, 0, { (DWORD_PTR)(__FILE__ ": dce_section") }
  62 };
  63 static CRITICAL_SECTION dce_section = { &critsect_debug, -1, 0, 0, 0, 0 };
  64
  65 static const WCHAR displayW[] = { 'D','I','S','P','L','A','Y',0 };
  66
  67
  68 /***********************************************************************
  69  *           dump_cache
  70  */
  71 static void dump_cache(void)
  72 {
  73     struct dce *dce;
  74
  75     EnterCriticalSection( &dce_section );
  76
  77     LIST_FOR_EACH_ENTRY( dce, &dce_list, struct dce, entry )
  78     {
  79         TRACE("%p: hwnd %p dcx %08x %s %s\n",
  80               dce, dce->hwnd, dce->flags,
  81               (dce->flags & DCX_CACHE) ? "Cache" : "Owned",
  82               dce->count ? "InUse" : "" );
  83     }
  84
  85     LeaveCriticalSection( &dce_section );
  86 }
  87
  88
  89 /***********************************************************************
  90  *              update_visible_region
  91  *
  92  * Set the visible region and X11 drawable for the DC associated to
  93  * a given window.
  94  */
  95 static void update_visible_region( struct dce *dce )
  96 {
  97     NTSTATUS status;
  98     HRGN vis_rgn = 0;
  99     HWND top = 0;
 100     struct x11drv_escape_set_drawable escape;
 101     struct x11drv_win_data *data;
 102     DWORD flags = dce->flags;
 103     size_t size = 256;
 104
 105     /* don't clip siblings if using parent clip region */
 106     if (flags & DCX_PARENTCLIP) flags &= ~DCX_CLIPSIBLINGS;
 107
 108     /* fetch the visible region from the server */
 109     do
 110     {
 111         RGNDATA *data = HeapAlloc( GetProcessHeap(), 0, sizeof(*data) + size - 1 );
 112         if (!data) return;
 113
 114         SERVER_START_REQ( get_visible_region )
 115         {
 116             req->window  = dce->hwnd;
 117             req->flags   = flags;
 118             wine_server_set_reply( req, data->Buffer, size );
 119             if (!(status = wine_server_call( req )))
 120             {
 121                 size_t reply_size = wine_server_reply_size( reply );
 122                 data->rdh.dwSize   = sizeof(data->rdh);
 123                 data->rdh.iType    = RDH_RECTANGLES;
 124                 data->rdh.nCount   = reply_size / sizeof(RECT);
 125                 data->rdh.nRgnSize = reply_size;
 126                 vis_rgn = ExtCreateRegion( NULL, size, data );
 127
 128                 top = reply->top_win;
 129                 escape.dc_rect.left = reply->win_rect.left - reply->top_rect.left;
 130                 escape.dc_rect.top = reply->win_rect.top - reply->top_rect.top;
 131                 escape.dc_rect.right = reply->win_rect.right - reply->top_rect.left;
 132                 escape.dc_rect.bottom = reply->win_rect.bottom - reply->top_rect.top;
 133                 escape.drawable_rect.left = reply->top_rect.left;
 134                 escape.drawable_rect.top = reply->top_rect.top;
 135                 escape.drawable_rect.right = reply->top_rect.right;
 136                 escape.drawable_rect.bottom = reply->top_rect.bottom;
 137             }
 138             else size = reply->total_size;
 139         }
 140         SERVER_END_REQ;
 141         HeapFree( GetProcessHeap(), 0, data );
 142     } while (status == STATUS_BUFFER_OVERFLOW);
 143
 144     if (status || !vis_rgn) return;
 145
 146     if (dce->clip_rgn) CombineRgn( vis_rgn, vis_rgn, dce->clip_rgn,
 147                                    (flags & DCX_INTERSECTRGN) ? RGN_AND : RGN_DIFF );
 148
 149     if (top == dce->hwnd && ((data = X11DRV_get_win_data( dce->hwnd )) != NULL) &&
 150          IsIconic( dce->hwnd ) && data->icon_window)
 151     {
 152         escape.drawable = data->icon_window;
 153         escape.fbconfig_id = 0;
 154         escape.gl_drawable = 0;
 155         escape.pixmap = 0;
 156     }
 157     else
 158     {
 159         escape.drawable = X11DRV_get_whole_window( top );
 160         escape.fbconfig_id = X11DRV_get_fbconfig_id( dce->hwnd );
 161         escape.gl_drawable = X11DRV_get_gl_drawable( dce->hwnd );
 162         escape.pixmap = X11DRV_get_gl_pixmap( dce->hwnd );
 163     }
 164
 165     escape.code = X11DRV_SET_DRAWABLE;
 166     escape.mode = IncludeInferiors;
 167     ExtEscape( dce->hdc, X11DRV_ESCAPE, sizeof(escape), (LPSTR)&escape, 0, NULL );
 168
 169     /* map region to DC coordinates */
 170     OffsetRgn( vis_rgn,
 171                -(escape.drawable_rect.left + escape.dc_rect.left),
 172                -(escape.drawable_rect.top + escape.dc_rect.top) );
 173     SelectVisRgn16( HDC_16(dce->hdc), HRGN_16(vis_rgn) );
 174     DeleteObject( vis_rgn );
 175 }
 176
 177
 178 /***********************************************************************
 179  *              release_dce
 180  */
 181 static void release_dce( struct dce *dce )
 182 {
 183     struct x11drv_escape_set_drawable escape;
 184
 185     if (!dce->hwnd) return;  /* already released */
 186
 187     if (dce->clip_rgn) DeleteObject( dce->clip_rgn );
 188     dce->clip_rgn = 0;
 189     dce->hwnd     = 0;
 190     dce->flags   &= DCX_CACHE;
 191
 192     escape.code = X11DRV_SET_DRAWABLE;
 193     escape.drawable = root_window;
 194     escape.mode = IncludeInferiors;
 195     escape.drawable_rect = virtual_screen_rect;
 196     SetRect( &escape.dc_rect, 0, 0, virtual_screen_rect.right - virtual_screen_rect.left,
 197              virtual_screen_rect.bottom - virtual_screen_rect.top );
 198     escape.fbconfig_id = 0;
 199     escape.gl_drawable = 0;
 200     escape.pixmap = 0;
 201     ExtEscape( dce->hdc, X11DRV_ESCAPE, sizeof(escape), (LPSTR)&escape, 0, NULL );
 202 }
 203
 204
 205 /***********************************************************************
 206  *   delete_clip_rgn
 207  */
 208 static void delete_clip_rgn( struct dce *dce )
 209 {
 210     if (!dce->clip_rgn) return;  /* nothing to do */
 211
 212     dce->flags &= ~(DCX_EXCLUDERGN | DCX_INTERSECTRGN);
 213     DeleteObject( dce->clip_rgn );
 214     dce->clip_rgn = 0;
 215
 216     /* make it dirty so that the vis rgn gets recomputed next time */
 217     SetHookFlags16( HDC_16(dce->hdc), DCHF_INVALIDATEVISRGN );
 218 }
 219
 220
 221 /***********************************************************************
 222  *           alloc_cache_dce
 223  *
 224  * Allocate a new cache DCE.
 225  */
 226 static struct dce *alloc_cache_dce(void)
 227 {
 228     struct x11drv_escape_set_dce escape;
 229     struct dce *dce;
 230
 231     if (!(dce = HeapAlloc( GetProcessHeap(), 0, sizeof(*dce) ))) return NULL;
 232     if (!(dce->hdc = CreateDCW( displayW, NULL, NULL, NULL )))
 233     {
 234         HeapFree( GetProcessHeap(), 0, dce );
 235         return 0;
 236     }
 237     SaveDC( dce->hdc );
 238
 239     /* store DCE handle in DC hook data field */
 240     SetDCHook( dce->hdc, dc_hook, (DWORD_PTR)dce );
 241
 242     dce->hwnd      = 0;
 243     dce->clip_rgn  = 0;
 244     dce->flags     = DCX_CACHE;
 245     dce->class_ptr = NULL;
 246     dce->count     = 1;
 247
 248     EnterCriticalSection( &dce_section );
 249     list_add_head( &dce_list, &dce->entry );
 250     LeaveCriticalSection( &dce_section );
 251
 252     escape.code = X11DRV_SET_DCE;
 253     escape.dce  = dce;
 254     ExtEscape( dce->hdc, X11DRV_ESCAPE, sizeof(escape), (LPCSTR)&escape, 0, NULL );
 255
 256     return dce;
 257 }
 258
 259
 260 /***********************************************************************
 261  *           alloc_window_dce
 262  *
 263  * Allocate a DCE for a newly created window if necessary.
 264  */
 265 void alloc_window_dce( struct x11drv_win_data *data )
 266 {
 267     struct x11drv_escape_set_dce escape;
 268     struct dce *dce;
 269     void *class_ptr = NULL;
 270     LONG style = GetClassLongW( data->hwnd, GCL_STYLE );
 271
 272     if (!(style & (CS_CLASSDC|CS_OWNDC))) return;  /* nothing to do */
 273
 274     if (!(style & CS_OWNDC))  /* class dc */
 275     {
 276         /* hack: get the class pointer from the window structure */
 277         WND *win = WIN_GetPtr( data->hwnd );
 278         class_ptr = win->class;
 279         WIN_ReleasePtr( win );
 280
 281         EnterCriticalSection( &dce_section );
 282         LIST_FOR_EACH_ENTRY( dce, &dce_list, struct dce, entry )
 283         {
 284             if (dce->class_ptr == class_ptr)
 285             {
 286                 dce->count++;
 287                 data->dce = dce;
 288                 LeaveCriticalSection( &dce_section );
 289                 return;
 290             }
 291         }
 292         LeaveCriticalSection( &dce_section );
 293     }
 294
 295     /* now allocate a new one */
 296
 297     if (!(dce = HeapAlloc( GetProcessHeap(), 0, sizeof(*dce) ))) return;
 298     if (!(dce->hdc = CreateDCW( displayW, NULL, NULL, NULL )))
 299     {
 300         HeapFree( GetProcessHeap(), 0, dce );
 301         return;
 302     }
 303
 304     /* store DCE handle in DC hook data field */
 305
 306     SetDCHook( dce->hdc, dc_hook, (DWORD_PTR)dce );
 307
 308     dce->hwnd      = data->hwnd;
 309     dce->clip_rgn  = 0;
 310     dce->flags     = 0;
 311     dce->class_ptr = class_ptr;
 312     dce->count     = 1;
 313
 314     if (style & CS_OWNDC)
 315     {
 316         LONG win_style = GetWindowLongW( data->hwnd, GWL_STYLE );
 317         if (win_style & WS_CLIPCHILDREN) dce->flags |= DCX_CLIPCHILDREN;
 318         if (win_style & WS_CLIPSIBLINGS) dce->flags |= DCX_CLIPSIBLINGS;
 319     }
 320     SetHookFlags16( HDC_16(dce->hdc), DCHF_INVALIDATEVISRGN );
 321
 322     EnterCriticalSection( &dce_section );
 323     list_add_tail( &dce_list, &dce->entry );
 324     LeaveCriticalSection( &dce_section );
 325     data->dce = dce;
 326
 327     escape.code = X11DRV_SET_DCE;
 328     escape.dce  = dce;
 329     ExtEscape( dce->hdc, X11DRV_ESCAPE, sizeof(escape), (LPCSTR)&escape, 0, NULL );
 330 }
 331
 332
 333 /***********************************************************************
 334  *           free_window_dce
 335  *
 336  * Free a class or window DCE.
 337  */
 338 void free_window_dce( struct x11drv_win_data *data )
 339 {
 340     struct dce *dce = data->dce;
 341
 342     if (dce)
 343     {
 344         EnterCriticalSection( &dce_section );
 345         if (!--dce->count)
 346         {
 347             list_remove( &dce->entry );
 348             SetDCHook(dce->hdc, NULL, 0L);
 349             DeleteDC( dce->hdc );
 350             if (dce->clip_rgn) DeleteObject( dce->clip_rgn );
 351             HeapFree( GetProcessHeap(), 0, dce );
 352         }
 353         else if (dce->hwnd == data->hwnd)
 354         {
 355             release_dce( dce );
 356         }
 357         LeaveCriticalSection( &dce_section );
 358         data->dce = NULL;
 359     }
 360
 361     /* now check for cache DCEs */
 362
 363     EnterCriticalSection( &dce_section );
 364     LIST_FOR_EACH_ENTRY( dce, &dce_list, struct dce, entry )
 365     {
 366         if (dce->hwnd != data->hwnd) continue;
 367         if (!(dce->flags & DCX_CACHE)) continue;
 368
 369         if (dce->count) WARN( "GetDC() without ReleaseDC() for window %p\n", data->hwnd );
 370         release_dce( dce );
 371         dce->count = 0;
 372     }
 373     LeaveCriticalSection( &dce_section );
 374 }
 375
 376
 377 /***********************************************************************
 378  *   invalidate_dce
 379  *
 380  * It is called from SetWindowPos() - we have to
 381  * mark as dirty all busy DCEs for windows that have pWnd->parent as
 382  * an ancestor and whose client rect intersects with specified update
 383  * rectangle. In addition, pWnd->parent DCEs may need to be updated if
 384  * DCX_CLIPCHILDREN flag is set.
 385  */
 386 void invalidate_dce( HWND hwnd, const RECT *rect )
 387 {
 388     HWND hwndScope = GetAncestor( hwnd, GA_PARENT );
 389
 390     if( hwndScope )
 391     {
 392         struct dce *dce;
 393
 394         TRACE("scope hwnd = %p %s\n", hwndScope, wine_dbgstr_rect(rect) );
 395         if (TRACE_ON(dc)) dump_cache();
 396
 397         /* walk all DCEs and fixup non-empty entries */
 398
 399         LIST_FOR_EACH_ENTRY( dce, &dce_list, struct dce, entry )
 400         {
 401             if (!dce->hwnd) continue;
 402             if ((dce->hwnd == hwndScope) && !(dce->flags & DCX_CLIPCHILDREN))
 403                 continue;  /* child window positions don't bother us */
 404
 405             /* check if DCE window is within the z-order scope */
 406
 407             if (hwndScope == dce->hwnd || hwndScope == GetDesktopWindow() || IsChild( hwndScope, dce->hwnd ))
 408             {
 409                 if (hwnd != dce->hwnd)
 410                 {
 411                     /* check if the window rectangle intersects this DCE window */
 412                     RECT tmp;
 413                     GetWindowRect( dce->hwnd, &tmp );
 414                     MapWindowPoints( 0, hwndScope, (POINT *)&tmp, 2 );
 415                     if (!IntersectRect( &tmp, &tmp, rect )) continue;
 416
 417                 }
 418                 if (!dce->count)
 419                 {
 420                     /* Don't bother with visible regions of unused DCEs */
 421
 422                     TRACE("\tpurged %p dce [%p]\n", dce, dce->hwnd);
 423                     release_dce( dce );
 424                 }
 425                 else
 426                 {
 427                     /* Set dirty bits in the hDC and DCE structs */
 428
 429                     TRACE("\tfixed up %p dce [%p]\n", dce, dce->hwnd);
 430                     SetHookFlags16( HDC_16(dce->hdc), DCHF_INVALIDATEVISRGN );
 431                 }
 432             }
 433         } /* dce list */
 434     }
 435 }
 436
 437
 438 /***********************************************************************
 439  *              X11DRV_GetDCEx   (X11DRV.@)
 440  *
 441  * Unimplemented flags: DCX_LOCKWINDOWUPDATE
 442  */
 443 HDC X11DRV_GetDCEx( HWND hwnd, HRGN hrgnClip, DWORD flags )
 444 {
 445     static const DWORD clip_flags = DCX_PARENTCLIP | DCX_CLIPSIBLINGS | DCX_CLIPCHILDREN | DCX_WINDOW;
 446
 447     struct x11drv_win_data *data = X11DRV_get_win_data( hwnd );
 448     struct dce *dce;
 449     BOOL bUpdateVisRgn = TRUE;
 450     HWND parent;
 451     LONG window_style = GetWindowLongW( hwnd, GWL_STYLE );
 452
 453     TRACE("hwnd %p, hrgnClip %p, flags %08x\n", hwnd, hrgnClip, flags);
 454
 455     /* fixup flags */
 456
 457     if (flags & (DCX_WINDOW | DCX_PARENTCLIP)) flags |= DCX_CACHE;
 458
 459     if (flags & DCX_USESTYLE)
 460     {
 461         flags &= ~(DCX_CLIPCHILDREN | DCX_CLIPSIBLINGS | DCX_PARENTCLIP);
 462
 463         if (window_style & WS_CLIPSIBLINGS) flags |= DCX_CLIPSIBLINGS;
 464
 465         if (!(flags & DCX_WINDOW))
 466         {
 467             if (GetClassLongW( hwnd, GCL_STYLE ) & CS_PARENTDC) flags |= DCX_PARENTCLIP;
 468
 469             if (window_style & WS_CLIPCHILDREN && !(window_style & WS_MINIMIZE))
 470                 flags |= DCX_CLIPCHILDREN;
 471             if (!data || !data->dce) flags |= DCX_CACHE;
 472         }
 473     }
 474
 475     if (flags & DCX_WINDOW) flags &= ~DCX_CLIPCHILDREN;
 476
 477     parent = GetAncestor( hwnd, GA_PARENT );
 478     if (!parent || (parent == GetDesktopWindow()))
 479         flags = (flags & ~DCX_PARENTCLIP) | DCX_CLIPSIBLINGS;
 480
 481     /* it seems parent clip is ignored when clipping siblings or children */
 482     if (flags & (DCX_CLIPSIBLINGS | DCX_CLIPCHILDREN)) flags &= ~DCX_PARENTCLIP;
 483
 484     if( flags & DCX_PARENTCLIP )
 485     {
 486         LONG parent_style = GetWindowLongW( parent, GWL_STYLE );
 487         if( (window_style & WS_VISIBLE) && (parent_style & WS_VISIBLE) )
 488         {
 489             flags &= ~DCX_CLIPCHILDREN;
 490             if (parent_style & WS_CLIPSIBLINGS) flags |= DCX_CLIPSIBLINGS;
 491         }
 492     }
 493
 494     /* find a suitable DCE */
 495
 496     if (flags & DCX_CACHE)
 497     {
 498         struct dce *dceEmpty = NULL, *dceUnused = NULL;
 499
 500         /* Strategy: First, we attempt to find a non-empty but unused DCE with
 501          * compatible flags. Next, we look for an empty entry. If the cache is
 502          * full we have to purge one of the unused entries.
 503          */
 504         EnterCriticalSection( &dce_section );
 505         LIST_FOR_EACH_ENTRY( dce, &dce_list, struct dce, entry )
 506         {
 507             if ((dce->flags & DCX_CACHE) && !dce->count)
 508             {
 509                 dceUnused = dce;
 510
 511                 if (!dce->hwnd) dceEmpty = dce;
 512                 else if ((dce->hwnd == hwnd) && !((dce->flags ^ flags) & clip_flags))
 513                 {
 514                     TRACE("\tfound valid %p dce [%p], flags %08x\n",
 515                           dce, hwnd, dce->flags );
 516                     bUpdateVisRgn = FALSE;
 517                     break;
 518                 }
 519             }
 520         }
 521
 522         if (&dce->entry == &dce_list)  /* nothing found */
 523             dce = dceEmpty ? dceEmpty : dceUnused;
 524
 525         if (dce) dce->count = 1;
 526
 527         LeaveCriticalSection( &dce_section );
 528
 529         /* if there's no dce empty or unused, allocate a new one */
 530         if (!dce) dce = alloc_cache_dce();
 531         if (!dce) return 0;
 532     }
 533     else
 534     {
 535         flags |= DCX_NORESETATTRS;
 536         dce = data->dce;
 537         if (dce->hwnd == hwnd)
 538         {
 539             TRACE("\tskipping hVisRgn update\n");
 540             bUpdateVisRgn = FALSE; /* updated automatically, via DCHook() */
 541         }
 542         else
 543         {
 544             /* we should free dce->clip_rgn here, but Windows apparently doesn't */
 545             dce->flags &= ~(DCX_EXCLUDERGN | DCX_INTERSECTRGN);
 546             dce->clip_rgn = 0;
 547         }
 548     }
 549
 550     if (flags & (DCX_INTERSECTRGN | DCX_EXCLUDERGN))
 551     {
 552         /* if the extra clip region has changed, get rid of the old one */
 553         if (dce->clip_rgn != hrgnClip || ((flags ^ dce->flags) & (DCX_INTERSECTRGN | DCX_EXCLUDERGN)))
 554             delete_clip_rgn( dce );
 555         dce->clip_rgn = hrgnClip;
 556         if (!dce->clip_rgn) dce->clip_rgn = CreateRectRgn( 0, 0, 0, 0 );
 557         dce->flags |= flags & (DCX_INTERSECTRGN | DCX_EXCLUDERGN);
 558         bUpdateVisRgn = TRUE;
 559     }
 560
 561     dce->hwnd = hwnd;
 562     dce->flags = (dce->flags & ~clip_flags) | (flags & clip_flags);
 563
 564     if (SetHookFlags16( HDC_16(dce->hdc), DCHF_VALIDATEVISRGN ))
 565         bUpdateVisRgn = TRUE;  /* DC was dirty */
 566
 567     if (bUpdateVisRgn) update_visible_region( dce );
 568
 569     if (!(flags & DCX_NORESETATTRS))
 570     {
 571         RestoreDC( dce->hdc, 1 );  /* initial save level is always 1 */
 572         SaveDC( dce->hdc );  /* save the state again for next time */
 573     }
 574
 575     TRACE("(%p,%p,0x%x): returning %p\n", hwnd, hrgnClip, flags, dce->hdc);
 576     return dce->hdc;
 577 }
 578
 579
 580 /***********************************************************************
 581  *              X11DRV_ReleaseDC  (X11DRV.@)
 582  */
 583 INT X11DRV_ReleaseDC( HWND hwnd, HDC hdc, BOOL end_paint )
 584 {
 585     enum x11drv_escape_codes escape = X11DRV_GET_DCE;
 586     struct dce *dce;
 587     BOOL ret = FALSE;
 588
 589     TRACE("%p %p\n", hwnd, hdc );
 590
 591     EnterCriticalSection( &dce_section );
 592     if (!ExtEscape( hdc, X11DRV_ESCAPE, sizeof(escape), (LPCSTR)&escape,
 593                     sizeof(dce), (LPSTR)&dce )) dce = NULL;
 594     if (dce && dce->count)
 595     {
 596         if (end_paint || (dce->flags & DCX_CACHE)) delete_clip_rgn( dce );
 597         if (dce->flags & DCX_CACHE) dce->count = 0;
 598         ret = TRUE;
 599     }
 600     LeaveCriticalSection( &dce_section );
 601     return ret;
 602 }
 603
 604 /***********************************************************************
 605  *              dc_hook
 606  *
 607  * See "Undoc. Windows" for hints (DC, SetDCHook, SetHookFlags)..
 608  */
 609 static BOOL CALLBACK dc_hook( HDC hDC, WORD code, DWORD_PTR data, LPARAM lParam )
 610 {
 611     BOOL retv = TRUE;
 612     struct dce *dce = (struct dce *)data;
 613
 614     TRACE("hDC = %p, %u\n", hDC, code);
 615
 616     if (!dce) return 0;
 617     assert( dce->hdc == hDC );
 618
 619     switch( code )
 620     {
 621     case DCHC_INVALIDVISRGN:
 622         /* GDI code calls this when it detects that the
 623          * DC is dirty (usually after SetHookFlags()). This
 624          * means that we have to recompute the visible region.
 625          */
 626         if (dce->count) update_visible_region( dce );
 627         else /* non-fatal but shouldn't happen */
 628             WARN("DC is not in use!\n");
 629         break;
 630     case DCHC_DELETEDC:
 631         /*
 632          * Windows will not let you delete a DC that is busy
 633          * (between GetDC and ReleaseDC)
 634          */
 635         if (dce->count)
 636         {
 637             WARN("Application trying to delete a busy DC %p\n", dce->hdc);
 638             retv = FALSE;
 639         }
 640         else
 641         {
 642             EnterCriticalSection( &dce_section );
 643             list_remove( &dce->entry );
 644             LeaveCriticalSection( &dce_section );
 645             if (dce->clip_rgn) DeleteObject( dce->clip_rgn );
 646             HeapFree( GetProcessHeap(), 0, dce );
 647         }
 648         break;
 649     }
 650     return retv;
 651 }
 652
 653
 654 /**********************************************************************
 655  *              WindowFromDC   (X11DRV.@)
 656  */
 657 HWND X11DRV_WindowFromDC( HDC hdc )
 658 {
 659     enum x11drv_escape_codes escape = X11DRV_GET_DCE;
 660     struct dce *dce;
 661     HWND hwnd = 0;
 662
 663     EnterCriticalSection( &dce_section );
 664     if (!ExtEscape( hdc, X11DRV_ESCAPE, sizeof(escape), (LPCSTR)&escape,
 665                     sizeof(dce), (LPSTR)&dce )) dce = NULL;
 666     if (dce) hwnd = dce->hwnd;
 667     LeaveCriticalSection( &dce_section );
 668     return hwnd;
 669 }