rom/graphics/graphics_driver.c

   1 /*
   2     Copyright © 1995-2015, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Driver for using gfxhidd for gfx output
   6     Lang: english
   7 */
   8
   9 #include <aros/debug.h>
  10
  11 #include <proto/exec.h>
  12 #include <proto/graphics.h>
  13 #include <proto/arossupport.h>
  14 #include <proto/utility.h>
  15 #include <proto/oop.h>
  16
  17 #include <exec/memory.h>
  18 #include <exec/semaphores.h>
  19 #include <clib/macros.h>
  20
  21 #include <graphics/rastport.h>
  22 #include <graphics/gfxbase.h>
  23 #include <graphics/text.h>
  24 #include <graphics/view.h>
  25 #include <graphics/layers.h>
  26 #include <graphics/clip.h>
  27 #include <graphics/gfxmacros.h>
  28 #include <graphics/regions.h>
  29 #include <graphics/scale.h>
  30
  31 #include <oop/oop.h>
  32 #include <utility/tagitem.h>
  33 #include <aros/asmcall.h>
  34
  35 #include <intuition/intuition.h>
  36
  37 #include <hidd/compositor.h>
  38 #include <hidd/graphics.h>
  39
  40 #include <cybergraphx/cybergraphics.h>
  41
  42 #include <stdio.h>
  43 #include <string.h>
  44
  45 #include "graphics_intern.h"
  46 #include "compositor_driver.h"
  47 #include "fakegfxhidd.h"
  48 #include "intregions.h"
  49 #include "dispinfo.h"
  50 #include "gfxfuncsupport.h"
  51 #include "fontsupport.h"
  52
  53 #define DEBUG_INIT(x)
  54 #define DEBUG_LOADVIEW(x)
  55
  56 /* Define this if you wish to enforce using software mouse sprite
  57    even for drivers that support hardware one. Useful for debugging
  58    and testing
  59 #define FORCE_SOFTWARE_SPRITE */
  60
  61 struct ETextFont
  62 {
  63     struct TextFont     etf_Font;
  64 };
  65
  66 /* *********************** RastPort extra data handling *********************** */
  67
  68 struct gfx_driverdata *AllocDriverData(struct RastPort *rp, BOOL alloc, struct GfxBase *GfxBase)
  69 {
  70     struct gfx_driverdata *dd = ObtainDriverData(rp);
  71
  72     if (alloc && !dd)
  73     {
  74         dd = AllocVec(sizeof(struct gfx_driverdata), MEMF_CLEAR);
  75         if (dd)
  76         {
  77             rp->RP_Extra    = dd;
  78             dd->dd_RastPort = rp;
  79         }
  80     }
  81
  82     return dd;
  83 }
  84
  85 /* *********************** Display driver handling *********************** */
  86
  87 int driver_init(struct GfxBase * GfxBase)
  88 {
  89
  90     EnterFunc(bug("driver_init()\n"));
  91
  92     /* Our underlying RTG subsystem core must be already up and running */
  93     if (!OpenLibrary("graphics.hidd", 0))
  94         return FALSE;
  95
  96     /* Initialize the semaphores */
  97     InitSemaphore(&(PrivGBase(GfxBase)->blit_sema));
  98
  99     /* Init the needed attrbases */
 100
 101     __IHidd_BitMap      = OOP_ObtainAttrBase(IID_Hidd_BitMap);
 102     __IHidd_GC          = OOP_ObtainAttrBase(IID_Hidd_GC);
 103     __IHidd_Sync        = OOP_ObtainAttrBase(IID_Hidd_Sync);
 104     __IHidd_PixFmt      = OOP_ObtainAttrBase(IID_Hidd_PixFmt);
 105     __IHidd_PlanarBM    = OOP_ObtainAttrBase(IID_Hidd_PlanarBM);
 106     __IHidd_Gfx         = OOP_ObtainAttrBase(IID_Hidd_Gfx);
 107     __IHidd_FakeGfxHidd = OOP_ObtainAttrBase(IID_Hidd_FakeGfxHidd);
 108
 109     if (__IHidd_BitMap   &&
 110         __IHidd_GC       &&
 111         __IHidd_Sync     &&
 112         __IHidd_PixFmt   &&
 113         __IHidd_PlanarBM &&
 114         __IHidd_Gfx      &&
 115         __IHidd_FakeGfxHidd)
 116     {
 117         CDD(GfxBase)->gcClass = OOP_FindClass(CLID_Hidd_GC);
 118         if (!CDD(GfxBase)->gcClass)
 119             return FALSE;
 120
 121         /* Init display mode database */
 122         InitSemaphore(&CDD(GfxBase)->displaydb_sem);
 123         CDD(GfxBase)->invalid_id = INVALID_ID;
 124         CDD(GfxBase)->last_id = AROS_RTG_MONITOR_ID;
 125
 126         /* Init memory driver */
 127         CDD(GfxBase)->memorygfx = OOP_NewObject(NULL, CLID_Hidd_Gfx, NULL);
 128         DEBUG_INIT(bug("[driver_init] Memory driver object 0x%p\n", CDD(GfxBase)->memorygfx));
 129
 130         if (CDD(GfxBase)->memorygfx)
 131         {
 132             struct TagItem bm_create_tags[] =
 133             {
 134                 { aHidd_BitMap_GfxHidd , (IPTR)CDD(GfxBase)->memorygfx },
 135                 { aHidd_PlanarBM_BitMap, 0                             },
 136                 { TAG_DONE             , 0                             }
 137             };
 138
 139             CDD(GfxBase)->planarbm_cache = create_object_cache(NULL, CLID_Hidd_PlanarBM, bm_create_tags, GfxBase);
 140             DEBUG_INIT(bug("[driver_init] Planar bitmap cache 0x%p\n", CDD(GfxBase)->planarbm_cache));
 141
 142             if (CDD(GfxBase)->planarbm_cache)
 143             {
 144                 CDD(GfxBase)->gc_cache = create_object_cache(NULL, CLID_Hidd_GC, NULL, GfxBase);
 145                 DEBUG_INIT(bug("[driver_init] GC cache 0x%p\n", CDD(GfxBase)->planarbm_cache));
 146
 147                 if (CDD(GfxBase)->gc_cache)
 148                     ReturnInt("driver_init", int, TRUE);
 149
 150                 delete_object_cache(CDD(GfxBase)->planarbm_cache, GfxBase);
 151             }
 152             OOP_DisposeObject(CDD(GfxBase)->memorygfx);
 153         }
 154     }
 155
 156     ReturnInt("driver_init", int, FALSE);
 157 }
 158
 159 /* Called after DOS is up & running */
 160 static OOP_Object *create_framebuffer(struct monitor_driverdata *mdd, struct GfxBase *GfxBase)
 161 {
 162     struct TagItem fbtags[] = {
 163         { aHidd_BitMap_FrameBuffer,     TRUE    },
 164         { aHidd_BitMap_ModeID,          0       },
 165         { TAG_DONE, 0 }
 166     };
 167
 168     HIDDT_ModeID hiddmode;
 169     OOP_Object *fb = NULL;
 170
 171     /* Get the highest available resolution at the best possible depth */
 172     hiddmode = get_best_resolution_and_depth(mdd, GfxBase);
 173     if (vHidd_ModeID_Invalid == hiddmode) {
 174         D(bug("!!! create_framebuffer(): COULD NOT GET HIDD MODEID !!!\n"));
 175     } else {
 176         /* Create the framebuffer object */
 177         fbtags[1].ti_Data = hiddmode;
 178         fb = HIDD_Gfx_CreateObject(mdd->gfxhidd, PrivGBase(GfxBase)->basebm, fbtags);
 179     }
 180
 181     return fb;
 182 }
 183
 184 /*
 185  * Set up graphics display driver.
 186  * Creates necessary OS structures around it.
 187  *
 188  * gfxhidd - newly created driver object
 189  * result  - master driver structure
 190  */
 191
 192 struct monitor_driverdata *driver_Setup(OOP_Object *gfxhidd, struct GfxBase *GfxBase)
 193 {
 194     ULONG cnt = 0;
 195     IPTR hwcursor = 0;
 196     IPTR fbtype = vHidd_FrameBuffer_Direct; /* We default to direct for historical reasons */
 197     UWORD compose = 0;
 198     BOOL can_compose = FALSE;
 199     BOOL ok = TRUE;
 200     ULONG i;
 201     HIDDT_ModeID *modes, *m;
 202     struct monitor_driverdata *mdd;
 203     struct HIDD_ModeProperties props = {0};
 204
 205     D(bug("[driver_Setup] gfxhidd=0x%p (%s)\n", gfxhidd, OOP_OCLASS(gfxhidd)->ClassNode.ln_Name));
 206
 207     modes = HIDD_Gfx_QueryModeIDs(gfxhidd, NULL);
 208     if (!modes)
 209         return NULL;
 210
 211     /* Count number of display modes */
 212     for (m = modes; *m != vHidd_ModeID_Invalid; m ++)
 213         cnt++;
 214
 215     mdd = AllocVec(sizeof(struct monitor_driverdata) + cnt * sizeof(struct DisplayInfoHandle), MEMF_PUBLIC|MEMF_CLEAR);
 216     D(bug("[driver_Setup] Allocated driverdata at 0x%p\n", mdd));
 217     if (!mdd)
 218     {
 219         HIDD_Gfx_ReleaseModeIDs(gfxhidd, modes);
 220         return NULL;
 221     }
 222
 223     mdd->gfxhidd_orig = gfxhidd;
 224
 225     /*
 226      * 1. Fill in ModeID database in the driverdata.
 227      * 2. Check if at least one mode supports composition.
 228      * 3. Check if the driver has at least one non-palettized mode.
 229      * (2) and (3) are needed to determine if we need/can use software screen
 230      * composition with this driver.
 231      */
 232     for (i = 0; i <= cnt; i++)
 233     {
 234         mdd->modes[i].id  = modes[i];
 235         mdd->modes[i].drv = mdd;
 236
 237         /* Watch out! The last record in the array is terminator (vHidd_ModeID_Invalid) */
 238         if ((i < cnt) && (!compose))
 239         {
 240             HIDD_Gfx_ModeProperties(gfxhidd, modes[i], &props, sizeof(props));
 241             compose |= props.CompositionFlags;
 242
 243             if (!can_compose)
 244             {
 245                 OOP_Object *sync, *pf;
 246                 IPTR colmod;
 247
 248                 HIDD_Gfx_GetMode(gfxhidd, modes[i], &sync, &pf);
 249                 OOP_GetAttr(pf, aHidd_PixFmt_ColorModel, &colmod);
 250
 251                 if (colmod == vHidd_ColorModel_TrueColor)
 252                 {
 253                     /*
 254                      * At the moment software compositor supports only truecolor screens.
 255                      * There also definitions for DirectColor, gray, etc, but there is
 256                      * no such hardware supported by now.
 257                      */
 258                     can_compose = TRUE;
 259                 }
 260             }
 261         }
 262     }
 263
 264     HIDD_Gfx_ReleaseModeIDs(gfxhidd, modes);
 265
 266     /* Query properties of our driver */
 267 #ifndef FORCE_SOFTWARE_SPRITE
 268     OOP_GetAttr(gfxhidd, aHidd_Gfx_HWSpriteTypes, &hwcursor);
 269 #endif
 270     OOP_GetAttr(gfxhidd, aHidd_Gfx_FrameBufferType, &fbtype);
 271
 272     if (hwcursor)
 273     {
 274         mdd->gfxhidd = gfxhidd;
 275     }
 276     else
 277     {
 278         D(bug("[driver_Setup] Hardware mouse cursor is not supported, using fakegfx.hidd\n"));
 279
 280         mdd->gfxhidd = init_fakegfxhidd(gfxhidd, GfxBase);
 281         if (mdd->gfxhidd)
 282             mdd->flags |= DF_UseFakeGfx;
 283         else
 284             ok = FALSE;
 285     }
 286
 287     if (ok)
 288     {
 289         D(bug("[driver_Setup] Ok, framebuffer type %ld\n", fbtype));
 290
 291         /*
 292          * Instantiate framebuffer if needed.
 293          * Note that we perform this operation on fakegfx.hidd if it was plugged in.
 294          * This enables software mouse sprite on a framebuffer.
 295          */
 296         switch (fbtype)
 297         {
 298         case vHidd_FrameBuffer_Direct:
 299             mdd->flags |= DF_DirectFB;
 300
 301         case vHidd_FrameBuffer_Mirrored:
 302             mdd->framebuffer = create_framebuffer(mdd, GfxBase);
 303             break;
 304         }
 305
 306         if ((fbtype == vHidd_FrameBuffer_None) || mdd->framebuffer)
 307         {
 308             D(bug("[driver_Setup] FRAMEBUFFER OK: %p\n", mdd->framebuffer));
 309
 310             if ((!compose) && can_compose)
 311             {
 312                 D(bug("[driver_Setup] Software screen composition required\n"));
 313
 314                 mdd->flags |= DF_SoftCompose;
 315                 compositor_Setup(mdd, GfxBase);
 316             }
 317
 318             return mdd;
 319         }
 320
 321         if (mdd->framebuffer)
 322             OOP_DisposeObject(mdd->framebuffer);
 323     } /* if (fake gfx stuff ok) */
 324
 325     if (mdd->flags & DF_UseFakeGfx)
 326         OOP_DisposeObject(mdd->gfxhidd);
 327
 328     FreeVec(mdd);
 329
 330     return NULL;
 331 }
 332
 333 /*
 334  * Completely remove a driver from the OS.
 335  *
 336  * mdd - Driver structure to remove.
 337  *
 338  * Note that removing a driver is very unsafe operation. You must be
 339  * sure that no bitmaps of this driver exist at the moment. Perhaps
 340  * something should be done with it.
 341  *
 342  */
 343
 344 void driver_Expunge(struct monitor_driverdata *mdd, struct GfxBase *GfxBase)
 345 {
 346     /* Notify Intuition */
 347     if (CDD(GfxBase)->DriverNotify)
 348         CDD(GfxBase)->DriverNotify(mdd->userdata, FALSE, CDD(GfxBase)->notify_data);
 349
 350     /* Dispose associated stuff */
 351     OOP_DisposeObject(mdd->compositor);
 352     OOP_DisposeObject(mdd->framebuffer);
 353
 354     if (mdd->flags & DF_UseFakeGfx)
 355         OOP_DisposeObject(mdd->gfxhidd);
 356
 357     /* Dispose driver object. This will take care about syncs etc */
 358     OOP_DisposeObject(mdd->gfxhidd_orig );
 359
 360     FreeVec(mdd);
 361 }
 362
 363 #if 0 /* Unused? */
 364
 365 static ULONG getbitmappixel(struct BitMap *bm
 366         , LONG x
 367         , LONG y
 368         , UBYTE depth
 369         , UBYTE plane_mask)
 370 {
 371     UBYTE i;
 372     ULONG idx;
 373
 374     ULONG mask;
 375     ULONG pen = 0;
 376
 377     idx = COORD_TO_BYTEIDX(x, y, bm->BytesPerRow);
 378     mask = XCOORD_TO_MASK( x );
 379
 380     for (i = depth - 1; depth; i -- , depth -- )
 381     {
 382         pen <<= 1; /* stegerg: moved to here, was inside if!? */
 383
 384         if ((1L << i) & plane_mask)
 385         {
 386             UBYTE *plane = bm->Planes[i];
 387
 388             if (plane == (PLANEPTR)-1)
 389             {
 390                 pen |= 1;
 391             }
 392             else if (plane != NULL)
 393             {
 394                 if ((plane[idx] & mask) != 0)
 395                     pen |= 1;
 396             }
 397         }
 398
 399     }
 400     return pen;
 401 }
 402
 403 #endif
 404
 405 /* This is called for every ViewPorts chain during MrgCop() */
 406 ULONG driver_PrepareViewPorts(struct HIDD_ViewPortData *vpd, struct View *v, struct monitor_driverdata *mdd, struct GfxBase *GfxBase)
 407 {
 408     /* Do not bother the driver if there's nothing to prepare. Can be changed if needed. */
 409     return vpd ? HIDD_Gfx_PrepareViewPorts(mdd->gfxhidd, vpd, v) : MCOP_OK;
 410 }
 411
 412 /*
 413  * This is called for every ViewPorts chain during LoadView()
 414  * LoadView() actually has no rights for errors because error condition
 415  * in it will screw up the display, likely with no chance to recover.
 416  * Because of this we always return zero here.
 417  */
 418 ULONG driver_LoadViewPorts(struct HIDD_ViewPortData *vpd, struct View *v, struct monitor_driverdata *mdd, struct GfxBase *GfxBase)
 419 {
 420     struct BitMap *bitmap;
 421     OOP_Object *bm, *fb;
 422     BOOL compositing = FALSE;
 423
 424     DEBUG_LOADVIEW(bug("[driver_LoadViewPorts] Showing ViewPortData 0x%p, BitMap object 0x%p\n", vpd, vpd ? vpd->Bitmap : NULL));
 425     mdd->display = vpd;
 426
 427     /* First try the new method */
 428     if (HIDD_Gfx_ShowViewPorts(mdd->gfxhidd, vpd))
 429     {
 430         DEBUG_LOADVIEW(bug("[driver_LoadViewPorts] ShowViewPorts() worked\n"));
 431         return 0;
 432     }
 433
 434     /*
 435      * ShowViewPorts not supported.
 436      * Perhaps we can use software screen compositor. But for proper operation
 437      * we need to figure out our frontmost bitmap.
 438      */
 439     if (vpd)
 440     {
 441         bitmap = vpd->vpe->ViewPort->RasInfo->BitMap;
 442         bm     = vpd->Bitmap;
 443     }
 444     else
 445     {
 446         bitmap = NULL;
 447         bm     = NULL;
 448     }
 449     DEBUG_LOADVIEW(bug("[driver_LoadViewPorts] Old bitmap 0x%p, New bitmap 0x%p, object 0x%p\n", mdd->frontbm, bitmap, bm));
 450
 451     if (mdd->compositor)
 452     {
 453         /*
 454          * Compositor present. Give ViewPorts chain to it.
 455          * For improved visual appearance it will call Show itself and return its result.
 456          * The compositor is expected to handle all possible failures internally. If some
 457          * internal error happens, it must fail back to single HIDD_Gfx_Show().
 458          */
 459         fb = compositor_LoadViewPorts(mdd->compositor, vpd, &compositing, GfxBase);
 460         DEBUG_LOADVIEW(bug("[driver_LoadViewPorts] Compositor returned 0x%p, active: %d\n", fb, compositing));
 461     }
 462     else
 463     {
 464         /*
 465          * First check if the bitmap is already displayed. If so, do nothing (because
 466          * displaying the same bitmap twice may cause some problems)
 467          */
 468         if (mdd->frontbm == bitmap)
 469             return 0;
 470
 471         fb = HIDD_Gfx_Show(mdd->gfxhidd, bm, fHidd_Gfx_Show_CopyBack);
 472         DEBUG_LOADVIEW(bug("[driver_LoadViewPorts] Show() returned 0x%p\n", fb));
 473     }
 474
 475     /* Summary of possible responses (when no error happened):
 476        NoFrameBuffer = FALSE: bm = NULL  -> fb != NULL and bm != fb
 477        NoFrameBuffer = FALSE: bm != NULL -> fb != NULL and bm != fb
 478        NoFrameBuffer = TRUE : bm = NULL  -> fb == NULL and bm == fb
 479        NoFrameBuffer = TRUE : bm != NULL -> fb != NULL and bm == fb
 480     */
 481     if (fb)
 482     {
 483         /* The screen is not empty, 'fb' is on display now. */
 484         IPTR width, height;
 485
 486         /* Uninstall the framebuffer from old frontmost BitMap (if present) */
 487         UninstallFB(mdd, GfxBase);
 488
 489         /*
 490          * We need to always remember our new frontmost bitmap, even if we do not work
 491          * with a framebuffer. This is needed for the check against showing the same
 492          * bitmap twice.
 493          */
 494         mdd->frontbm = bitmap;
 495
 496         /*
 497          * Install the framebuffer into new bitmap. Only if software composition is inactive.
 498          * If it is active, our BitMap is mirrored, not replaced.
 499          */
 500         if (!compositing)
 501             InstallFB(mdd, GfxBase);
 502
 503         /* Tell the driver to refresh the screen */
 504         OOP_GetAttr(fb, aHidd_BitMap_Width, &width);
 505         OOP_GetAttr(fb, aHidd_BitMap_Height, &height);
 506         DEBUG_LOADVIEW(bug("[driver_LoadViewPorts] Updating display, new size: %d x %d\n", width, height));
 507
 508         HIDD_BM_UpdateRect(fb, 0, 0, width, height);
 509     }
 510     else
 511     {
 512         /*
 513          * Screen is empty, simply reset the current bitmap.
 514          * Only framebuffer-less driver can return NULL. So we don't need
 515          * to call UninstallFB() here.
 516          */
 517         mdd->frontbm = NULL;
 518     }
 519
 520     return 0;
 521 }
 522
 523 /*
 524  * In-Place framebuffer install/uninstall routines.
 525  *
 526  * The idea behind: we gave some bitmap to display, the driver *HAS COPIED* it
 527  * into the framebuffer. After this we must use a framebuffer bitmap instead of
 528  * original one for all rendering operations.
 529  * When another bitmap is displayed, the framebuffer contents will be put back
 530  * into the original bitmap, and we will swap it back.
 531  *
 532  * This swap actually happens only of DF_DirectFB is set for the driver.
 533  *
 534  * FIXME: THIS IS NOT THREADSAFE
 535  * To make this threadsafe we have to lock all gfx access in all the rendering
 536  * calls.
 537  */
 538 void InstallFB(struct monitor_driverdata *mdd, struct GfxBase *GfxBase)
 539 {
 540     if ((mdd->flags & DF_DirectFB) && mdd->frontbm)
 541     {
 542         struct BitMap *bitmap = mdd->frontbm;
 543         OOP_Object *pf;
 544
 545         /* Backup original data */
 546         mdd->bm_bak     = HIDD_BM_OBJ(bitmap);
 547         mdd->colmod_bak = HIDD_BM_COLMOD(bitmap);
 548         mdd->colmap_bak = HIDD_BM_COLMAP(bitmap);
 549
 550         /* Insert the framebuffer in its place */
 551         OOP_GetAttr(mdd->framebuffer, aHidd_BitMap_PixFmt, (IPTR *)&pf);
 552
 553         HIDD_BM_OBJ(bitmap)    = mdd->framebuffer;
 554         HIDD_BM_COLMOD(bitmap) = OOP_GET(pf, aHidd_PixFmt_ColorModel);
 555         HIDD_BM_COLMAP(bitmap) = (OOP_Object *)OOP_GET(mdd->framebuffer, aHidd_BitMap_ColorMap);
 556
 557         DEBUG_LOADVIEW(bug("[driver_LoadViewPorts] Installed framebuffer: BitMap 0x%p, object 0x%p\n", mdd->frontbm, mdd->bm_bak));
 558     }
 559 }
 560
 561 void UninstallFB(struct monitor_driverdata *mdd, struct GfxBase *GfxBase)
 562 {
 563     if (mdd->bm_bak)
 564     {
 565         /* Put back the old values into the old bitmap */
 566         struct BitMap *oldbm = mdd->frontbm;
 567
 568         DEBUG_LOADVIEW(bug("[driver_LoadViewPorts] Uninstalling framebuffer: BitMap 0x%p, object 0x%p\n", mdd->frontbm, mdd->bm_bak));
 569
 570         HIDD_BM_OBJ(oldbm)    = mdd->bm_bak;
 571         HIDD_BM_COLMOD(oldbm) = mdd->colmod_bak;
 572         HIDD_BM_COLMAP(oldbm) = mdd->colmap_bak;
 573
 574         /* No framebuffer installed */
 575         mdd->bm_bak = NULL;
 576     }
 577 }
 578
 579 /* Find the first visible ViewPortData for the specified monitor in the View */
 580 struct HIDD_ViewPortData *driver_FindViewPorts(struct View *view, struct monitor_driverdata *mdd, struct GfxBase *GfxBase)
 581 {
 582     struct ViewPort *vp;
 583
 584     for (vp = view->ViewPort; vp; vp = vp->Next)
 585     {
 586         if (!(vp->Modes & VP_HIDE))
 587         {
 588             struct ViewPortExtra *vpe = (struct ViewPortExtra *)GfxLookUp(vp);
 589
 590             if (VPE_DRIVER(vpe) == mdd)
 591                 return VPE_DATA(vpe);
 592         }
 593     }
 594     return NULL;
 595 }
 596
 597 /*
 598  * Iterate through HIDD_ViewPortData chains in the view and call
 599  * the specified function for every chain and every driver.
 600  * The function will be called at least once for every driver.
 601  * If there is no ViewPorts for the driver, the function will be
 602  * called with ViewPortData = NULL.
 603  */
 604 ULONG DoViewFunction(struct View *view, VIEW_FUNC fn, struct GfxBase *GfxBase)
 605 {
 606     struct monitor_driverdata *mdd;
 607     ULONG rc = 0;
 608
 609     ObtainSemaphoreShared(&CDD(GfxBase)->displaydb_sem);
 610
 611     for (mdd = CDD(GfxBase)->monitors; mdd; mdd = mdd->next)
 612     {
 613         struct HIDD_ViewPortData *vpd = NULL;
 614
 615         /*
 616          * Find the first visible ViewPort for this display. It
 617          * will be a start of bitmaps chain to process.
 618          */
 619         if (view)
 620             vpd = driver_FindViewPorts(view, mdd, GfxBase);
 621
 622         rc = fn(vpd, view, mdd, GfxBase);
 623
 624         /* Interrupt immediately if the callback returned error */
 625         if (rc)
 626             break;
 627     }
 628
 629     ReleaseSemaphore(&CDD(GfxBase)->displaydb_sem);
 630
 631     return rc;
 632 }