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         escape.drawable = data->icon_window;
 152     else
 153         escape.drawable = X11DRV_get_whole_window( top );
 154
 155     escape.code = X11DRV_SET_DRAWABLE;
 156     escape.mode = IncludeInferiors;
 157     ExtEscape( dce->hdc, X11DRV_ESCAPE, sizeof(escape), (LPSTR)&escape, 0, NULL );
 158
 159     /* map region to DC coordinates */
 160     OffsetRgn( vis_rgn,
 161                -(escape.drawable_rect.left + escape.dc_rect.left),
 162                -(escape.drawable_rect.top + escape.dc_rect.top) );
 163     SelectVisRgn16( HDC_16(dce->hdc), HRGN_16(vis_rgn) );
 164     DeleteObject( vis_rgn );
 165 }
 166
 167
 168 /***********************************************************************
 169  *              release_dce
 170  */
 171 static void release_dce( struct dce *dce )
 172 {
 173     struct x11drv_escape_set_drawable escape;
 174
 175     if (!dce->hwnd) return;  /* already released */
 176
 177     if (dce->clip_rgn) DeleteObject( dce->clip_rgn );
 178     dce->clip_rgn = 0;
 179     dce->hwnd     = 0;
 180     dce->flags   &= DCX_CACHE;
 181
 182     escape.code = X11DRV_SET_DRAWABLE;
 183     escape.drawable = root_window;
 184     escape.mode = IncludeInferiors;
 185     escape.drawable_rect = virtual_screen_rect;
 186     SetRect( &escape.dc_rect, 0, 0, virtual_screen_rect.right - virtual_screen_rect.left,
 187              virtual_screen_rect.bottom - virtual_screen_rect.top );
 188     ExtEscape( dce->hdc, X11DRV_ESCAPE, sizeof(escape), (LPSTR)&escape, 0, NULL );
 189 }
 190
 191
 192 /***********************************************************************
 193  *   delete_clip_rgn
 194  */
 195 static void delete_clip_rgn( struct dce *dce )
 196 {
 197     if (!dce->clip_rgn) return;  /* nothing to do */
 198
 199     dce->flags &= ~(DCX_EXCLUDERGN | DCX_INTERSECTRGN);
 200     DeleteObject( dce->clip_rgn );
 201     dce->clip_rgn = 0;
 202
 203     /* make it dirty so that the vis rgn gets recomputed next time */
 204     SetHookFlags16( HDC_16(dce->hdc), DCHF_INVALIDATEVISRGN );
 205 }
 206
 207
 208 /***********************************************************************
 209  *           alloc_cache_dce
 210  *
 211  * Allocate a new cache DCE.
 212  */
 213 static struct dce *alloc_cache_dce(void)
 214 {
 215     struct x11drv_escape_set_dce escape;
 216     struct dce *dce;
 217
 218     if (!(dce = HeapAlloc( GetProcessHeap(), 0, sizeof(*dce) ))) return NULL;
 219     if (!(dce->hdc = CreateDCW( displayW, NULL, NULL, NULL )))
 220     {
 221         HeapFree( GetProcessHeap(), 0, dce );
 222         return 0;
 223     }
 224     SaveDC( dce->hdc );
 225
 226     /* store DCE handle in DC hook data field */
 227     SetDCHook( dce->hdc, dc_hook, (DWORD_PTR)dce );
 228
 229     dce->hwnd      = 0;
 230     dce->clip_rgn  = 0;
 231     dce->flags     = DCX_CACHE;
 232     dce->class_ptr = NULL;
 233     dce->count     = 1;
 234
 235     EnterCriticalSection( &dce_section );
 236     list_add_head( &dce_list, &dce->entry );
 237     LeaveCriticalSection( &dce_section );
 238
 239     escape.code = X11DRV_SET_DCE;
 240     escape.dce  = dce;
 241     ExtEscape( dce->hdc, X11DRV_ESCAPE, sizeof(escape), (LPCSTR)&escape, 0, NULL );
 242
 243     return dce;
 244 }
 245
 246
 247 /***********************************************************************
 248  *           alloc_window_dce
 249  *
 250  * Allocate a DCE for a newly created window if necessary.
 251  */
 252 void alloc_window_dce( struct x11drv_win_data *data )
 253 {
 254     struct x11drv_escape_set_dce escape;
 255     struct dce *dce;
 256     void *class_ptr = NULL;
 257     LONG style = GetClassLongW( data->hwnd, GCL_STYLE );
 258
 259     if (!(style & (CS_CLASSDC|CS_OWNDC))) return;  /* nothing to do */
 260
 261     if (!(style & CS_OWNDC))  /* class dc */
 262     {
 263         /* hack: get the class pointer from the window structure */
 264         WND *win = WIN_GetPtr( data->hwnd );
 265         class_ptr = win->class;
 266         WIN_ReleasePtr( win );
 267
 268         EnterCriticalSection( &dce_section );
 269         LIST_FOR_EACH_ENTRY( dce, &dce_list, struct dce, entry )
 270         {
 271             if (dce->class_ptr == class_ptr)
 272             {
 273                 dce->count++;
 274                 data->dce = dce;
 275                 LeaveCriticalSection( &dce_section );
 276                 return;
 277             }
 278         }
 279         LeaveCriticalSection( &dce_section );
 280     }
 281
 282     /* now allocate a new one */
 283
 284     if (!(dce = HeapAlloc( GetProcessHeap(), 0, sizeof(*dce) ))) return;
 285     if (!(dce->hdc = CreateDCW( displayW, NULL, NULL, NULL )))
 286     {
 287         HeapFree( GetProcessHeap(), 0, dce );
 288         return;
 289     }
 290
 291     /* store DCE handle in DC hook data field */
 292
 293     SetDCHook( dce->hdc, dc_hook, (DWORD_PTR)dce );
 294
 295     dce->hwnd      = data->hwnd;
 296     dce->clip_rgn  = 0;
 297     dce->flags     = 0;
 298     dce->class_ptr = class_ptr;
 299     dce->count     = 1;
 300
 301     if (style & CS_OWNDC)
 302     {
 303         LONG win_style = GetWindowLongW( data->hwnd, GWL_STYLE );
 304         if (win_style & WS_CLIPCHILDREN) dce->flags |= DCX_CLIPCHILDREN;
 305         if (win_style & WS_CLIPSIBLINGS) dce->flags |= DCX_CLIPSIBLINGS;
 306     }
 307     SetHookFlags16( HDC_16(dce->hdc), DCHF_INVALIDATEVISRGN );
 308
 309     EnterCriticalSection( &dce_section );
 310     list_add_tail( &dce_list, &dce->entry );
 311     LeaveCriticalSection( &dce_section );
 312     data->dce = dce;
 313
 314     escape.code = X11DRV_SET_DCE;
 315     escape.dce  = dce;
 316     ExtEscape( dce->hdc, X11DRV_ESCAPE, sizeof(escape), (LPCSTR)&escape, 0, NULL );
 317 }
 318
 319
 320 /***********************************************************************
 321  *           free_window_dce
 322  *
 323  * Free a class or window DCE.
 324  */
 325 void free_window_dce( struct x11drv_win_data *data )
 326 {
 327     struct dce *dce = data->dce;
 328
 329     if (dce)
 330     {
 331         EnterCriticalSection( &dce_section );
 332         if (!--dce->count)
 333         {
 334             list_remove( &dce->entry );
 335             SetDCHook(dce->hdc, NULL, 0L);
 336             DeleteDC( dce->hdc );
 337             if (dce->clip_rgn) DeleteObject( dce->clip_rgn );
 338             HeapFree( GetProcessHeap(), 0, dce );
 339         }
 340         else if (dce->hwnd == data->hwnd)
 341         {
 342             release_dce( dce );
 343         }
 344         LeaveCriticalSection( &dce_section );
 345         data->dce = NULL;
 346     }
 347
 348     /* now check for cache DCEs */
 349
 350     EnterCriticalSection( &dce_section );
 351     LIST_FOR_EACH_ENTRY( dce, &dce_list, struct dce, entry )
 352     {
 353         if (dce->hwnd != data->hwnd) continue;
 354         if (!(dce->flags & DCX_CACHE)) continue;
 355
 356         if (dce->count) WARN( "GetDC() without ReleaseDC() for window %p\n", data->hwnd );
 357         release_dce( dce );
 358         dce->count = 0;
 359     }
 360     LeaveCriticalSection( &dce_section );
 361 }
 362
 363
 364 /***********************************************************************
 365  *   invalidate_dce
 366  *
 367  * It is called from SetWindowPos() - we have to
 368  * mark as dirty all busy DCEs for windows that have pWnd->parent as
 369  * an ancestor and whose client rect intersects with specified update
 370  * rectangle. In addition, pWnd->parent DCEs may need to be updated if
 371  * DCX_CLIPCHILDREN flag is set.
 372  */
 373 void invalidate_dce( HWND hwnd, const RECT *rect )
 374 {
 375     HWND hwndScope = GetAncestor( hwnd, GA_PARENT );
 376
 377     if( hwndScope )
 378     {
 379         struct dce *dce;
 380
 381         TRACE("scope hwnd = %p %s\n", hwndScope, wine_dbgstr_rect(rect) );
 382         if (TRACE_ON(dc)) dump_cache();
 383
 384         /* walk all DCEs and fixup non-empty entries */
 385
 386         LIST_FOR_EACH_ENTRY( dce, &dce_list, struct dce, entry )
 387         {
 388             if (!dce->hwnd) continue;
 389             if ((dce->hwnd == hwndScope) && !(dce->flags & DCX_CLIPCHILDREN))
 390                 continue;  /* child window positions don't bother us */
 391
 392             /* check if DCE window is within the z-order scope */
 393
 394             if (hwndScope == dce->hwnd || hwndScope == GetDesktopWindow() || IsChild( hwndScope, dce->hwnd ))
 395             {
 396                 if (hwnd != dce->hwnd)
 397                 {
 398                     /* check if the window rectangle intersects this DCE window */
 399                     RECT tmp;
 400                     GetWindowRect( dce->hwnd, &tmp );
 401                     MapWindowPoints( 0, hwndScope, (POINT *)&tmp, 2 );
 402                     if (!IntersectRect( &tmp, &tmp, rect )) continue;
 403
 404                 }
 405                 if (!dce->count)
 406                 {
 407                     /* Don't bother with visible regions of unused DCEs */
 408
 409                     TRACE("\tpurged %p dce [%p]\n", dce, dce->hwnd);
 410                     release_dce( dce );
 411                 }
 412                 else
 413                 {
 414                     /* Set dirty bits in the hDC and DCE structs */
 415
 416                     TRACE("\tfixed up %p dce [%p]\n", dce, dce->hwnd);
 417                     SetHookFlags16( HDC_16(dce->hdc), DCHF_INVALIDATEVISRGN );
 418                 }
 419             }
 420         } /* dce list */
 421     }
 422 }
 423
 424
 425 /***********************************************************************
 426  *              X11DRV_GetDCEx   (X11DRV.@)
 427  *
 428  * Unimplemented flags: DCX_LOCKWINDOWUPDATE
 429  */
 430 HDC X11DRV_GetDCEx( HWND hwnd, HRGN hrgnClip, DWORD flags )
 431 {
 432     static const DWORD clip_flags = DCX_PARENTCLIP | DCX_CLIPSIBLINGS | DCX_CLIPCHILDREN | DCX_WINDOW;
 433
 434     struct x11drv_win_data *data = X11DRV_get_win_data( hwnd );
 435     struct dce *dce;
 436     BOOL bUpdateVisRgn = TRUE;
 437     HWND parent;
 438     LONG window_style = GetWindowLongW( hwnd, GWL_STYLE );
 439
 440     TRACE("hwnd %p, hrgnClip %p, flags %08x\n", hwnd, hrgnClip, flags);
 441
 442     /* fixup flags */
 443
 444     if (flags & (DCX_WINDOW | DCX_PARENTCLIP)) flags |= DCX_CACHE;
 445
 446     if (flags & DCX_USESTYLE)
 447     {
 448         flags &= ~(DCX_CLIPCHILDREN | DCX_CLIPSIBLINGS | DCX_PARENTCLIP);
 449
 450         if (window_style & WS_CLIPSIBLINGS) flags |= DCX_CLIPSIBLINGS;
 451
 452         if (!(flags & DCX_WINDOW))
 453         {
 454             if (GetClassLongW( hwnd, GCL_STYLE ) & CS_PARENTDC) flags |= DCX_PARENTCLIP;
 455
 456             if (window_style & WS_CLIPCHILDREN && !(window_style & WS_MINIMIZE))
 457                 flags |= DCX_CLIPCHILDREN;
 458             if (!data || !data->dce) flags |= DCX_CACHE;
 459         }
 460     }
 461
 462     if (flags & DCX_WINDOW) flags &= ~DCX_CLIPCHILDREN;
 463
 464     parent = GetAncestor( hwnd, GA_PARENT );
 465     if (!parent || (parent == GetDesktopWindow()))
 466         flags = (flags & ~DCX_PARENTCLIP) | DCX_CLIPSIBLINGS;
 467
 468     /* it seems parent clip is ignored when clipping siblings or children */
 469     if (flags & (DCX_CLIPSIBLINGS | DCX_CLIPCHILDREN)) flags &= ~DCX_PARENTCLIP;
 470
 471     if( flags & DCX_PARENTCLIP )
 472     {
 473         LONG parent_style = GetWindowLongW( parent, GWL_STYLE );
 474         if( (window_style & WS_VISIBLE) && (parent_style & WS_VISIBLE) )
 475         {
 476             flags &= ~DCX_CLIPCHILDREN;
 477             if (parent_style & WS_CLIPSIBLINGS) flags |= DCX_CLIPSIBLINGS;
 478         }
 479     }
 480
 481     /* find a suitable DCE */
 482
 483     if (flags & DCX_CACHE)
 484     {
 485         struct dce *dceEmpty = NULL, *dceUnused = NULL;
 486
 487         /* Strategy: First, we attempt to find a non-empty but unused DCE with
 488          * compatible flags. Next, we look for an empty entry. If the cache is
 489          * full we have to purge one of the unused entries.
 490          */
 491         EnterCriticalSection( &dce_section );
 492         LIST_FOR_EACH_ENTRY( dce, &dce_list, struct dce, entry )
 493         {
 494             if ((dce->flags & DCX_CACHE) && !dce->count)
 495             {
 496                 dceUnused = dce;
 497
 498                 if (!dce->hwnd) dceEmpty = dce;
 499                 else if ((dce->hwnd == hwnd) && !((dce->flags ^ flags) & clip_flags))
 500                 {
 501                     TRACE("\tfound valid %p dce [%p], flags %08x\n",
 502                           dce, hwnd, dce->flags );
 503                     bUpdateVisRgn = FALSE;
 504                     break;
 505                 }
 506             }
 507         }
 508
 509         if (&dce->entry == &dce_list)  /* nothing found */
 510             dce = dceEmpty ? dceEmpty : dceUnused;
 511
 512         if (dce) dce->count = 1;
 513
 514         LeaveCriticalSection( &dce_section );
 515
 516         /* if there's no dce empty or unused, allocate a new one */
 517         if (!dce) dce = alloc_cache_dce();
 518         if (!dce) return 0;
 519     }
 520     else
 521     {
 522         flags |= DCX_NORESETATTRS;
 523         dce = data->dce;
 524         if (dce->hwnd == hwnd)
 525         {
 526             TRACE("\tskipping hVisRgn update\n");
 527             bUpdateVisRgn = FALSE; /* updated automatically, via DCHook() */
 528         }
 529         else
 530         {
 531             /* we should free dce->clip_rgn here, but Windows apparently doesn't */
 532             dce->flags &= ~(DCX_EXCLUDERGN | DCX_INTERSECTRGN);
 533             dce->clip_rgn = 0;
 534         }
 535     }
 536
 537     if (flags & (DCX_INTERSECTRGN | DCX_EXCLUDERGN))
 538     {
 539         /* if the extra clip region has changed, get rid of the old one */
 540         if (dce->clip_rgn != hrgnClip || ((flags ^ dce->flags) & (DCX_INTERSECTRGN | DCX_EXCLUDERGN)))
 541             delete_clip_rgn( dce );
 542         dce->clip_rgn = hrgnClip;
 543         if (!dce->clip_rgn) dce->clip_rgn = CreateRectRgn( 0, 0, 0, 0 );
 544         dce->flags |= flags & (DCX_INTERSECTRGN | DCX_EXCLUDERGN);
 545         bUpdateVisRgn = TRUE;
 546     }
 547
 548     dce->hwnd = hwnd;
 549     dce->flags = (dce->flags & ~clip_flags) | (flags & clip_flags);
 550
 551     if (SetHookFlags16( HDC_16(dce->hdc), DCHF_VALIDATEVISRGN ))
 552         bUpdateVisRgn = TRUE;  /* DC was dirty */
 553
 554     if (bUpdateVisRgn) update_visible_region( dce );
 555
 556     if (!(flags & DCX_NORESETATTRS))
 557     {
 558         RestoreDC( dce->hdc, 1 );  /* initial save level is always 1 */
 559         SaveDC( dce->hdc );  /* save the state again for next time */
 560     }
 561
 562     TRACE("(%p,%p,0x%x): returning %p\n", hwnd, hrgnClip, flags, dce->hdc);
 563     return dce->hdc;
 564 }
 565
 566
 567 /***********************************************************************
 568  *              X11DRV_ReleaseDC  (X11DRV.@)
 569  */
 570 INT X11DRV_ReleaseDC( HWND hwnd, HDC hdc, BOOL end_paint )
 571 {
 572     enum x11drv_escape_codes escape = X11DRV_GET_DCE;
 573     struct dce *dce;
 574     BOOL ret = FALSE;
 575
 576     TRACE("%p %p\n", hwnd, hdc );
 577
 578     EnterCriticalSection( &dce_section );
 579     if (!ExtEscape( hdc, X11DRV_ESCAPE, sizeof(escape), (LPCSTR)&escape,
 580                     sizeof(dce), (LPSTR)&dce )) dce = NULL;
 581     if (dce && dce->count)
 582     {
 583         if (end_paint || (dce->flags & DCX_CACHE)) delete_clip_rgn( dce );
 584         if (dce->flags & DCX_CACHE) dce->count = 0;
 585         ret = TRUE;
 586     }
 587     LeaveCriticalSection( &dce_section );
 588     return ret;
 589 }
 590
 591 /***********************************************************************
 592  *              dc_hook
 593  *
 594  * See "Undoc. Windows" for hints (DC, SetDCHook, SetHookFlags)..
 595  */
 596 static BOOL CALLBACK dc_hook( HDC hDC, WORD code, DWORD_PTR data, LPARAM lParam )
 597 {
 598     BOOL retv = TRUE;
 599     struct dce *dce = (struct dce *)data;
 600
 601     TRACE("hDC = %p, %u\n", hDC, code);
 602
 603     if (!dce) return 0;
 604     assert( dce->hdc == hDC );
 605
 606     switch( code )
 607     {
 608     case DCHC_INVALIDVISRGN:
 609         /* GDI code calls this when it detects that the
 610          * DC is dirty (usually after SetHookFlags()). This
 611          * means that we have to recompute the visible region.
 612          */
 613         if (dce->count) update_visible_region( dce );
 614         else /* non-fatal but shouldn't happen */
 615             WARN("DC is not in use!\n");
 616         break;
 617     case DCHC_DELETEDC:
 618         /*
 619          * Windows will not let you delete a DC that is busy
 620          * (between GetDC and ReleaseDC)
 621          */
 622         if (dce->count)
 623         {
 624             WARN("Application trying to delete a busy DC %p\n", dce->hdc);
 625             retv = FALSE;
 626         }
 627         else
 628         {
 629             EnterCriticalSection( &dce_section );
 630             list_remove( &dce->entry );
 631             LeaveCriticalSection( &dce_section );
 632             if (dce->clip_rgn) DeleteObject( dce->clip_rgn );
 633             HeapFree( GetProcessHeap(), 0, dce );
 634         }
 635         break;
 636     }
 637     return retv;
 638 }
 639
 640
 641 /**********************************************************************
 642  *              WindowFromDC   (X11DRV.@)
 643  */
 644 HWND X11DRV_WindowFromDC( HDC hdc )
 645 {
 646     enum x11drv_escape_codes escape = X11DRV_GET_DCE;
 647     struct dce *dce;
 648     HWND hwnd = 0;
 649
 650     EnterCriticalSection( &dce_section );
 651     if (!ExtEscape( hdc, X11DRV_ESCAPE, sizeof(escape), (LPCSTR)&escape,
 652                     sizeof(dce), (LPSTR)&dce )) dce = NULL;
 653     if (dce) hwnd = dce->hwnd;
 654     LeaveCriticalSection( &dce_section );
 655     return hwnd;
 656 }