randr: Support "non-desktop" property

Tracks changes to the non-desktop property so that when non-zero,
outputs will always appear to be disconnected.

Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Adam Jackson <ajax@nwnk.net>

randr/randrstr.h

@@ -153,6 +153,7 @@ struct _rrOutput {
     int numUserModes;
     RRModePtr *userModes;
     Bool changed;
+    Bool nonDesktop;
     RRPropertyPtr properties;
     Bool pendingProperties;
     void *devPrivate;
@@ -551,6 +552,8 @@ extern _X_EXPORT Bool RRScreenInit(ScreenPtr pScreen);
 
 extern _X_EXPORT RROutputPtr RRFirstOutput(ScreenPtr pScreen);
 
+extern _X_EXPORT Bool RROutputSetNonDesktop(RROutputPtr output, Bool non_desktop);
+
 extern _X_EXPORT CARD16
  RRVerticalRefresh(xRRModeInfo * mode);
 

randr/rroutput.c

@@ -22,6 +22,7 @@
  */
 
 #include "randrstr.h"
+#include <X11/Xatom.h>
 
 RESTYPE RROutputType;
 
@@ -65,6 +66,7 @@ RROutputCreate(ScreenPtr pScreen,
     RROutputPtr output;
     RROutputPtr *outputs;
     rrScrPrivPtr pScrPriv;
+    Atom nonDesktopAtom;
 
     if (!RRInit())
         return NULL;
@@ -111,6 +113,13 @@ RROutputCreate(ScreenPtr pScreen,
 
     pScrPriv->outputs[pScrPriv->numOutputs++] = output;
 
+    nonDesktopAtom = MakeAtom(RR_PROPERTY_NON_DESKTOP, strlen(RR_PROPERTY_NON_DESKTOP), TRUE);
+    if (nonDesktopAtom != BAD_RESOURCE) {
+        static const INT32 values[2] = { 0, 1 };
+        (void) RRConfigureOutputProperty(output, nonDesktopAtom, FALSE, FALSE, FALSE,
+                                            2, values);
+    }
+    RROutputSetNonDesktop(output, FALSE);
     RRResourcesChanged(pScreen);
 
     return output;
@@ -311,6 +320,20 @@ RROutputSetPhysicalSize(RROutputPtr output, int mmWidth, int mmHeight)
     return TRUE;
 }
 
+Bool
+RROutputSetNonDesktop(RROutputPtr output, Bool nonDesktop)
+{
+    const char *nonDesktopStr = RR_PROPERTY_NON_DESKTOP;
+    Atom nonDesktopProp = MakeAtom(nonDesktopStr, strlen(nonDesktopStr), TRUE);
+    uint32_t value = nonDesktop ? 1 : 0;
+
+    if (nonDesktopProp == None || nonDesktopProp == BAD_RESOURCE)
+        return FALSE;
+
+    return RRChangeOutputProperty(output, nonDesktopProp, XA_INTEGER, 32,
+                                  PropModeReplace, 1, &value, TRUE, FALSE) == Success;
+}
+
 void
 RRDeliverOutputEvent(ClientPtr client, WindowPtr pWin, RROutputPtr output)
 {
@@ -330,7 +353,7 @@ RRDeliverOutputEvent(ClientPtr client, WindowPtr pWin, RROutputPtr output)
         .crtc = crtc ? crtc->id : None,
         .mode = mode ? mode->mode.id : None,
         .rotation = crtc ? crtc->rotation : RR_Rotate_0,
-        .connection = output->connection,
+        .connection = output->nonDesktop ? RR_Disconnected : output->connection,
         .subpixelOrder = output->subpixelOrder
     };
     WriteEventsToClient(client, 1, (xEvent *) &oe);
@@ -442,6 +465,7 @@ ProcRRGetOutputInfo(ClientPtr client)
         .crtc = output->crtc ? output->crtc->id : None,
         .mmWidth = output->mmWidth,
         .mmHeight = output->mmHeight,
+        .connection = output->nonDesktop ? RR_Disconnected : output->connection,
         .connection = output->connection,
         .subpixelOrder = output->subpixelOrder,
         .nCrtcs = output->numCrtcs,

randr/rrproperty.c

@@ -23,6 +23,7 @@
 #include "randrstr.h"
 #include "propertyst.h"
 #include "swaprep.h"
+#include <X11/Xatom.h>
 
 static int
 DeliverPropertyEvent(WindowPtr pWin, void *value)
@@ -132,6 +133,29 @@ RRDeleteOutputProperty(RROutputPtr output, Atom property)
         }
 }
 
+static void
+RRNoticePropertyChange(RROutputPtr output, Atom property, RRPropertyValuePtr value)
+{
+    const char *non_desktop_str = RR_PROPERTY_NON_DESKTOP;
+    Atom non_desktop_prop = MakeAtom(non_desktop_str, strlen(non_desktop_str), FALSE);
+
+    if (property == non_desktop_prop) {
+        if (value->type == XA_INTEGER && value->format == 32 && value->size >= 1) {
+            uint32_t     nonDesktopData;
+            Bool        nonDesktop;
+
+            memcpy(&nonDesktopData, value->data, sizeof (nonDesktopData));
+            nonDesktop = nonDesktopData != 0;
+
+            if (nonDesktop != output->nonDesktop) {
+                output->nonDesktop = nonDesktop;
+                RROutputChanged(output, 0);
+                RRTellChanged(output->pScreen);
+            }
+        }
+    }
+}
+
 int
 RRChangeOutputProperty(RROutputPtr output, Atom property, Atom type,
                        int format, int mode, unsigned long len,
@@ -235,6 +259,9 @@ RRChangeOutputProperty(RROutputPtr output, Atom property, Atom type,
     if (pending && prop->is_pending)
         output->pendingProperties = TRUE;
 
+    if (!(pending && prop->is_pending))
+        RRNoticePropertyChange(output, prop->propertyName, prop_value);
+
     if (sendevent) {
         xRROutputPropertyNotifyEvent event = {
             .type = RREventBase + RRNotify,