dix: Remove the magic WhenMapped backing store hack

Automatic compositing exists, if that's what you want then use it.

Signed-off-by: Adam Jackson <ajax@redhat.com>

dix/window.c

@@ -468,9 +468,6 @@ WalkTree(ScreenPtr pScreen, VisitWindowProcPtr func, void *data)
     return (TraverseTree(pScreen->root, func, data));
 }
 
-/* hack for forcing backing store on all windows */
-int defaultBackingStore = NotUseful;
-
 /* hack to force no backing store */
 Bool disableBackingStore = FALSE;
 Bool enableBackingStore = FALSE;
@@ -502,7 +499,6 @@ SetWindowToDefaults(WindowPtr pWin)
     pWin->eventMask = 0;
     pWin->deliverableEvents = 0;
     pWin->dontPropagate = 0;
-    pWin->forcedBS = FALSE;
     pWin->redirectDraw = RedirectDrawNone;
     pWin->forcedBG = FALSE;
     pWin->unhittable = FALSE;
@@ -693,8 +689,7 @@ InitRootWindow(WindowPtr pWin)
         backFlag |= CWBackPixel;
     }
 
-    pWin->backingStore = defaultBackingStore;
+    pWin->backingStore = NotUseful;
-    pWin->forcedBS = (defaultBackingStore != NotUseful);
     /* We SHOULD check for an error value here XXX */
     (*pScreen->ChangeWindowAttributes) (pWin, backFlag);
 
@@ -943,13 +938,6 @@ CreateWindow(Window wid, WindowPtr pParent, int x, int y, unsigned w,
         DeleteWindow(pWin, None);
         return NullWindow;
     }
-    if (!(vmask & CWBackingStore) && (defaultBackingStore != NotUseful)) {
-        XID value = defaultBackingStore;
-
-        (void) ChangeWindowAttributes(pWin, CWBackingStore, &value,
-                                      wClient(pWin));
-        pWin->forcedBS = TRUE;
-    }
 
     if (SubSend(pParent)) {
         xEvent event = {
@@ -1341,7 +1329,6 @@ ChangeWindowAttributes(WindowPtr pWin, Mask vmask, XID *vlist, ClientPtr client)
                 goto PatchUp;
             }
             pWin->backingStore = val;
-            pWin->forcedBS = FALSE;
             break;
         case CWBackingPlanes:
             if (pWin->optional || ((CARD32) *pVlist != (CARD32) ~0L)) {
@@ -1610,10 +1597,7 @@ GetWindowAttributes(WindowPtr pWin, ClientPtr client,
     wa->type = X_Reply;
     wa->bitGravity = pWin->bitGravity;
     wa->winGravity = pWin->winGravity;
-    if (pWin->forcedBS && pWin->backingStore != Always)
+    wa->backingStore = pWin->backingStore;
-        wa->backingStore = NotUseful;
-    else
-        wa->backingStore = pWin->backingStore;
     wa->length = bytes_to_int32(sizeof(xGetWindowAttributesReply) -
                                 sizeof(xGenericReply));
     wa->sequenceNumber = client->sequence;

include/opaque.h

@@ -53,7 +53,6 @@ extern _X_EXPORT const char *display;
 extern _X_EXPORT int displayfd;
 extern _X_EXPORT Bool explicit_display;
 
-extern _X_EXPORT int defaultBackingStore;
 extern _X_EXPORT Bool disableBackingStore;
 extern _X_EXPORT Bool enableBackingStore;
 extern _X_EXPORT Bool enableIndirectGLX;

include/windowstr.h

@@ -159,7 +159,6 @@ typedef struct _Window {
     unsigned realized:1;        /* ancestors are all mapped */
     unsigned viewable:1;        /* realized && InputOutput */
     unsigned dontPropagate:3;   /* index into DontPropagateMasks */
-    unsigned forcedBS:1;        /* system-supplied backingStore */
     unsigned redirectDraw:2;    /* COMPOSITE rendering redirect */
     unsigned forcedBG:1;        /* must have an opaque background */
     unsigned unhittable:1;      /* doesn't hit-test, for rootless */

man/Xserver.man

@@ -289,17 +289,6 @@ sets video-off screen-saver preference.
 .B \-v
 sets video-on screen-saver preference.
 .TP 8
-.B \-wm
-forces the default backing-store of all windows to be WhenMapped.  This
-is a backdoor way of getting backing-store to apply to all windows.
-Although all mapped windows will have backing store, the backing store
-attribute value reported by the server for a window will be the last
-value established by a client.  If it has never been set by a client,
-the server will report the default value, NotUseful.  This behavior is
-required by the X protocol, which allows the server to exceed the
-client's backing store expectations but does not provide a way to tell
-the client that it is doing so.
-.TP 8
 .B \-wr
 sets the default root window to solid white instead of the standard root weave
 pattern.

os/utils.c

@@ -566,7 +566,6 @@ UseMsg(void)
     ErrorF("ttyxx                  server started from init on /dev/ttyxx\n");
     ErrorF("v                      video blanking for screen-saver\n");
     ErrorF("-v                     screen-saver without video blanking\n");
-    ErrorF("-wm                    WhenMapped default backing-store\n");
     ErrorF("-wr                    create root window with white background\n");
     ErrorF("-maxbigreqsize         set maximal bigrequest size \n");
 #ifdef PANORAMIX
@@ -943,8 +942,6 @@ ProcessCommandLine(int argc, char *argv[])
             defaultScreenSaverBlanking = PreferBlanking;
         else if (strcmp(argv[i], "-v") == 0)
             defaultScreenSaverBlanking = DontPreferBlanking;
-        else if (strcmp(argv[i], "-wm") == 0)
-            defaultBackingStore = WhenMapped;
         else if (strcmp(argv[i], "-wr") == 0)
             whiteRoot = TRUE;
         else if (strcmp(argv[i], "-background") == 0) {