xvfb: add randr support (v2)

[Siim Põder]

Hi

This was sent to xorg-devel a few years ago. It still applies and still appears
to work. I resending this because it affects me. Comments or application to the
tree would be greatly appreciated :)

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.

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

---
Second version, modified according to Keith suggestion.
Tested by adding second mode and switching - worked correctly.

diff --git a/hw/vfb/InitOutput.c b/hw/vfb/InitOutput.c
index 97eccfd..bfca068 100644
--- a/hw/vfb/InitOutput.c
+++ b/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
@@ -785,6 +786,125 @@ vfbCloseScreen(ScreenPtr 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)
 {
     vfbScreenInfoPtr pvfb = &vfbScreens[pScreen->myNum];
@@ -860,6 +980,9 @@ vfbScreenInit(ScreenPtr pScreen, int argc, char **argv)
     if (!ret)
         return FALSE;
 
+    if (!vfbRandRInit(pScreen))
+       return FALSE;
+
     pScreen->InstallColormap = vfbInstallColormap;
     pScreen->UninstallColormap = vfbUninstallColormap;
     pScreen->ListInstalledColormaps = vfbListInstalledColormaps;