vfb: add randr support (v2)

The motivation for getting this is chrome remote desktop that runs under
Xvfb and wants to use RANDR to adjust screen size according to the
remote desktop client screen size. Apparently there are other use cases
as well, the bug mentions gnome-settings-daemon testing.

[ajax: massaged commit message]

Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=26391
Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Lambros Lambrou <lambroslambrou@google.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Michal Srb <msrb@suse.com>
Signed-off-by: Siim Põder <siim@p6drad-teel.net>

hw/vfb/InitOutput.c

@@ -66,6 +66,7 @@ from The Open Group.
 #include "dix.h"
 #include "miline.h"
 #include "glx_extinit.h"
+#include "randrstr.h"
 
 #define VFB_DEFAULT_WIDTH      1280
 #define VFB_DEFAULT_HEIGHT     1024
@@ -738,6 +739,125 @@ vfbCloseScreen(ScreenPtr pScreen)
     return pScreen->CloseScreen(pScreen);
 }
 
+static Bool
+vfbRROutputValidateMode(ScreenPtr           pScreen,
+                        RROutputPtr         output,
+                        RRModePtr           mode)
+{
+    rrScrPriv(pScreen);
+
+    if (pScrPriv->minWidth <= mode->mode.width &&
+        pScrPriv->maxWidth >= mode->mode.width &&
+        pScrPriv->minHeight <= mode->mode.height &&
+        pScrPriv->maxHeight >= mode->mode.height)
+        return TRUE;
+    else
+        return FALSE;
+}
+
+static Bool
+vfbRRScreenSetSize(ScreenPtr  pScreen,
+                   CARD16     width,
+                   CARD16     height,
+                   CARD32     mmWidth,
+                   CARD32     mmHeight)
+{
+    // Prevent screen updates while we change things around
+    SetRootClip(pScreen, FALSE);
+
+    pScreen->width = width;
+    pScreen->height = height;
+    pScreen->mmWidth = mmWidth;
+    pScreen->mmHeight = mmHeight;
+
+    // Restore the ability to update screen, now with new dimensions
+    SetRootClip(pScreen, TRUE);
+
+    RRScreenSizeNotify (pScreen);
+    RRTellChanged(pScreen);
+
+    return TRUE;
+}
+
+static Bool
+vfbRRCrtcSet(ScreenPtr pScreen,
+             RRCrtcPtr crtc,
+             RRModePtr mode,
+             int       x,
+             int       y,
+             Rotation  rotation,
+             int       numOutput,
+             RROutputPtr *outputs)
+{
+  return RRCrtcNotify(crtc, mode, x, y, rotation, NULL, numOutput, outputs);
+}
+
+static Bool
+vfbRRGetInfo(ScreenPtr pScreen, Rotation *rotations)
+{
+    return TRUE;
+}
+
+static Bool
+vfbRandRInit(ScreenPtr pScreen)
+{
+    rrScrPrivPtr pScrPriv;
+#if RANDR_12_INTERFACE
+    RRModePtr  mode;
+    RRCrtcPtr  crtc;
+    RROutputPtr        output;
+    xRRModeInfo modeInfo;
+    char       name[64];
+#endif
+
+    if (!RRScreenInit (pScreen))
+       return FALSE;
+    pScrPriv = rrGetScrPriv(pScreen);
+    pScrPriv->rrGetInfo = vfbRRGetInfo;
+#if RANDR_12_INTERFACE
+    pScrPriv->rrCrtcSet = vfbRRCrtcSet;
+    pScrPriv->rrScreenSetSize = vfbRRScreenSetSize;
+    pScrPriv->rrOutputSetProperty = NULL;
+#if RANDR_13_INTERFACE
+    pScrPriv->rrOutputGetProperty = NULL;
+#endif
+    pScrPriv->rrOutputValidateMode = vfbRROutputValidateMode;
+    pScrPriv->rrModeDestroy = NULL;
+
+    RRScreenSetSizeRange (pScreen,
+                         1, 1,
+                         pScreen->width, pScreen->height);
+
+    sprintf (name, "%dx%d", pScreen->width, pScreen->height);
+    memset (&modeInfo, '\0', sizeof (modeInfo));
+    modeInfo.width = pScreen->width;
+    modeInfo.height = pScreen->height;
+    modeInfo.nameLength = strlen (name);
+
+    mode = RRModeGet (&modeInfo, name);
+    if (!mode)
+       return FALSE;
+
+    crtc = RRCrtcCreate (pScreen, NULL);
+    if (!crtc)
+       return FALSE;
+
+    output = RROutputCreate (pScreen, "screen", 6, NULL);
+    if (!output)
+       return FALSE;
+    if (!RROutputSetClones (output, NULL, 0))
+       return FALSE;
+    if (!RROutputSetModes (output, &mode, 1, 0))
+       return FALSE;
+    if (!RROutputSetCrtcs (output, &crtc, 1))
+       return FALSE;
+    if (!RROutputSetConnection (output, RR_Connected))
+       return FALSE;
+    RRCrtcNotify (crtc, mode, 0, 0, RR_Rotate_0, NULL, 1, &output);
+#endif
+    return TRUE;
+}
+
 static Bool
 vfbScreenInit(ScreenPtr pScreen, int argc, char **argv)
 {
@@ -811,6 +931,9 @@ vfbScreenInit(ScreenPtr pScreen, int argc, char **argv)
     if (!ret)
         return FALSE;
 
+    if (!vfbRandRInit(pScreen))
+       return FALSE;
+
     pScreen->InstallColormap = vfbInstallColormap;
 
     pScreen->SaveScreen = vfbSaveScreen;