Custom sizes with XRandR (#25)

* xserver dummy with RandR.

* update.

* remove screen configurations from xorg.

* screen size cannot be nil anymore.

* use predefined screen configurations.

* use screen configurations.

* fix error.

* remove comment.

Dockerfile

@@ -1,3 +1,33 @@
+#
+# Stage 0: Build xserver-xorg-video-dummy 0.3.8-2 with RandR support.
+#
+FROM debian:bullseye-slim as xserver-xorg-video-dummy
+
+WORKDIR /usr/local/src
+
+ENV DEBIAN_FRONTEND=noninteractive
+RUN set -eux; \
+    cp /etc/apt/sources.list /etc/apt/sources.list~; \
+    sed -Ei 's/^deb /deb-src /' /etc/apt/sources.list; \
+    cat /etc/apt/sources.list~ >> /etc/apt/sources.list; \
+    apt-get update; \
+	apt-get install -y dpkg-dev git; \
+    apt-get build-dep -y xserver-xorg-video-dummy; \
+    git clone --depth 1 --branch xserver-xorg-video-dummy-1_0.3.8-2 https://salsa.debian.org/xorg-team/driver/xserver-xorg-video-dummy; \
+    #
+    # clean up
+    apt-get clean -y; \
+    rm -rf /var/lib/apt/lists/* /var/cache/apt/*
+
+COPY runtime/xdummy-randr.patch /tmp/xdummy-randr.patch
+
+RUN set -eux; \
+    cd xserver-xorg-video-dummy; \
+    patch -p1 < /tmp/xdummy-randr.patch; \
+	bash ./autogen.sh; \
+	make; \
+    make install;
+
 #
 # Stage 1: Build.
 #
@@ -12,6 +42,10 @@ RUN set -eux; \
     apt-get install -y --no-install-recommends \
         libx11-dev libxrandr-dev libxtst-dev libgtk-3-dev \
         libgstreamer1.0-dev libgstreamer-plugins-base1.0-dev; \
+    # install libxcvt-dev (not available in debian:bullseye)
+    wget http://ftp.de.debian.org/debian/pool/main/libx/libxcvt/libxcvt-dev_0.1.2-1_amd64.deb; \
+    wget http://ftp.de.debian.org/debian/pool/main/libx/libxcvt/libxcvt0_0.1.2-1_amd64.deb; \
+    apt-get install  --no-install-recommends ./libxcvt0_0.1.2-1_amd64.deb ./libxcvt-dev_0.1.2-1_amd64.deb; \
     #
     # clean up
     apt-get clean -y; \
@@ -57,6 +91,10 @@ RUN set -eux; \
         gstreamer1.0-plugins-base gstreamer1.0-plugins-good \
         gstreamer1.0-plugins-bad gstreamer1.0-plugins-ugly \
         gstreamer1.0-pulseaudio; \
+    # install libxcvt0 (not available in debian:bullseye)
+    wget http://ftp.de.debian.org/debian/pool/main/libx/libxcvt/libxcvt0_0.1.2-1_amd64.deb; \
+    apt-get install  --no-install-recommends ./libxcvt0_0.1.2-1_amd64.deb; \
+    rm ./libxcvt0_0.1.2-1_amd64.deb; \
     #
     # create a non-root user
     groupadd --gid $USER_GID $USERNAME; \
@@ -95,6 +133,9 @@ RUN set -eux; \
     apt-get clean -y; \
     rm -rf /var/lib/apt/lists/* /var/cache/apt/*
 
+# replace version
+COPY --from=xserver-xorg-video-dummy /usr/local/lib/xorg/modules/drivers/dummy_drv.so /usr/lib/xorg/modules/drivers/dummy_drv.so
+
 #
 # copy runtime configs
 COPY --chown=neko:neko runtime/.Xresources /home/$USERNAME/.Xresources

Dockerfile.nvidia

@@ -1,6 +1,36 @@
 ARG UBUNTU_RELEASE=20.04
 ARG CUDA_VERSION=11.2.2
 
+#
+# Stage 0: Build xserver-xorg-video-dummy 0.3.8-2 with RandR support.
+#
+FROM debian:bullseye-slim as xserver-xorg-video-dummy
+
+WORKDIR /usr/local/src
+
+ENV DEBIAN_FRONTEND=noninteractive
+RUN set -eux; \
+    cp /etc/apt/sources.list /etc/apt/sources.list~; \
+    sed -Ei 's/^deb /deb-src /' /etc/apt/sources.list; \
+    cat /etc/apt/sources.list~ >> /etc/apt/sources.list; \
+    apt-get update; \
+	apt-get install -y dpkg-dev git; \
+    apt-get build-dep -y xserver-xorg-video-dummy; \
+    git clone --depth 1 --branch xserver-xorg-video-dummy-1_0.3.8-2 https://salsa.debian.org/xorg-team/driver/xserver-xorg-video-dummy; \
+    #
+    # clean up
+    apt-get clean -y; \
+    rm -rf /var/lib/apt/lists/* /var/cache/apt/*
+
+COPY runtime/xdummy-randr.patch /tmp/xdummy-randr.patch
+
+RUN set -eux; \
+    cd xserver-xorg-video-dummy; \
+    patch -p1 < /tmp/xdummy-randr.patch; \
+	bash ./autogen.sh; \
+	make; \
+    make install;
+
 #
 # Stage 1: Build.
 #
@@ -15,6 +45,10 @@ RUN set -eux; \
     apt-get install -y --no-install-recommends \
         libx11-dev libxrandr-dev libxtst-dev libgtk-3-dev \
         libgstreamer1.0-dev libgstreamer-plugins-base1.0-dev; \
+    # install libxcvt-dev (not available in debian:bullseye)
+    wget http://ftp.de.debian.org/debian/pool/main/libx/libxcvt/libxcvt-dev_0.1.2-1_amd64.deb; \
+    wget http://ftp.de.debian.org/debian/pool/main/libx/libxcvt/libxcvt0_0.1.2-1_amd64.deb; \
+    apt-get install  --no-install-recommends ./libxcvt0_0.1.2-1_amd64.deb ./libxcvt-dev_0.1.2-1_amd64.deb; \
     #
     # clean up
     apt-get clean -y; \
@@ -73,6 +107,10 @@ RUN set -eux; \
         gstreamer1.0-plugins-base gstreamer1.0-plugins-good \
         gstreamer1.0-plugins-bad gstreamer1.0-plugins-ugly \
         gstreamer1.0-pulseaudio; \
+    # install libxcvt0 (not available in debian:bullseye)
+    wget http://ftp.de.debian.org/debian/pool/main/libx/libxcvt/libxcvt0_0.1.2-1_amd64.deb; \
+    apt-get install  --no-install-recommends ./libxcvt0_0.1.2-1_amd64.deb; \
+    rm ./libxcvt0_0.1.2-1_amd64.deb; \
     #
     # create a non-root user
     groupadd --gid $USER_GID $USERNAME; \
@@ -111,6 +149,9 @@ RUN set -eux; \
     apt-get clean -y; \
     rm -rf /var/lib/apt/lists/* /var/cache/apt/*
 
+# replace version
+COPY --from=xserver-xorg-video-dummy /usr/local/lib/xorg/modules/drivers/dummy_drv.so /usr/lib/xorg/modules/drivers/dummy_drv.so
+
 #
 # Install and configure Vulkan manually
 RUN if [ "${UBUNTU_RELEASE}" = "18.04" ]; then apt-get update && apt-get install --no-install-recommends -y vulkan-utils; else apt-get update && apt-get install --no-install-recommends -y vulkan-tools; fi && \

internal/api/room/screen.go

@@ -20,12 +20,11 @@ type ScreenConfigurationPayload struct {
 func (h *RoomHandler) screenConfiguration(w http.ResponseWriter, r *http.Request) error {
 	size := h.desktop.GetScreenSize()
 
-	if size == nil {
+	return utils.HttpSuccess(w, ScreenConfigurationPayload{
-		return utils.HttpInternalServerError().WithInternalMsg("unable to get screen configuration")
+		Width:  size.Width,
-	}
+		Height: size.Height,
-
+		Rate:   size.Rate,
-	payload := ScreenConfigurationPayload(*size)
+	})
-	return utils.HttpSuccess(w, payload)
 }
 
 func (h *RoomHandler) screenConfigurationChange(w http.ResponseWriter, r *http.Request) error {
@@ -34,29 +33,36 @@ func (h *RoomHandler) screenConfigurationChange(w http.ResponseWriter, r *http.R
 		return err
 	}
 
-	size := types.ScreenSize(*data)
+	size, err := h.desktop.SetScreenSize(types.ScreenSize{
-	if err := h.desktop.SetScreenSize(size); err != nil {
+		Width:  data.Width,
+		Height: data.Height,
+		Rate:   data.Rate,
+	})
+
+	if err != nil {
 		return utils.HttpUnprocessableEntity("cannot set screen size").WithInternalErr(err)
 	}
 
-	payload := message.ScreenSize(*data)
+	h.sessions.Broadcast(event.SCREEN_UPDATED, message.ScreenSize{
-	h.sessions.Broadcast(event.SCREEN_UPDATED, payload)
+		Width:  size.Width,
+		Height: size.Height,
+		Rate:   size.Rate,
+	})
 
 	return utils.HttpSuccess(w, data)
 }
 
+// TODO: remove.
 func (h *RoomHandler) screenConfigurationsList(w http.ResponseWriter, r *http.Request) error {
-	list := []ScreenConfigurationPayload{}
+	configurations := h.desktop.ScreenConfigurations()
 
-	ScreenConfigurations := h.desktop.ScreenConfigurations()
+	list := make([]ScreenConfigurationPayload, 0, len(configurations))
-	for _, size := range ScreenConfigurations {
+	for _, conf := range configurations {
-		for _, fps := range size.Rates {
+		list = append(list, ScreenConfigurationPayload{
-			list = append(list, ScreenConfigurationPayload{
+			Width:  conf.Width,
-				Width:  size.Width,
+			Height: conf.Height,
-				Height: size.Height,
+			Rate:   conf.Rate,
-				Rate:   fps,
+		})
-			})
-		}
 	}
 
 	return utils.HttpSuccess(w, list)

internal/capture/manager.go

@@ -44,7 +44,7 @@ func New(desktop types.DesktopManager, config *config.Capture) *CaptureManagerCt
 			}
 
 			screen := desktop.GetScreenSize()
-			pipeline, err := pipelineConf.GetPipeline(*screen)
+			pipeline, err := pipelineConf.GetPipeline(screen)
 			if err != nil {
 				return "", err
 			}

internal/desktop/manager.go

@@ -40,9 +40,9 @@ func (manager *DesktopManagerCtx) Start() {
 
 	xorg.GetScreenConfigurations()
 
-	err := xorg.ChangeScreenSize(manager.config.ScreenWidth, manager.config.ScreenHeight, manager.config.ScreenRate)
+	width, height, rate, err := xorg.ChangeScreenSize(manager.config.ScreenWidth, manager.config.ScreenHeight, manager.config.ScreenRate)
 	manager.logger.Err(err).
-		Str("screen_size", fmt.Sprintf("%dx%d@%d", manager.config.ScreenWidth, manager.config.ScreenHeight, manager.config.ScreenRate)).
+		Str("screen_size", fmt.Sprintf("%dx%d@%d", width, height, rate)).
 		Msgf("setting initial screen size")
 
 	go xevent.EventLoop(manager.config.Display)

internal/desktop/xorg.go

@@ -66,11 +66,26 @@ func (manager *DesktopManagerCtx) ResetKeys() {
 	xorg.ResetKeys()
 }
 
-func (manager *DesktopManagerCtx) ScreenConfigurations() map[int]types.ScreenConfiguration {
+func (manager *DesktopManagerCtx) ScreenConfigurations() []types.ScreenSize {
-	return xorg.ScreenConfigurations
+	var configs []types.ScreenSize
+	for _, size := range xorg.ScreenConfigurations {
+		for _, fps := range size.Rates {
+			// filter out all irrelevant rates
+			if fps > 60 || (fps > 30 && fps%10 != 0) {
+				continue
+			}
+
+			configs = append(configs, types.ScreenSize{
+				Width:  size.Width,
+				Height: size.Height,
+				Rate:   fps,
+			})
+		}
+	}
+	return configs
 }
 
-func (manager *DesktopManagerCtx) SetScreenSize(size types.ScreenSize) error {
+func (manager *DesktopManagerCtx) SetScreenSize(size types.ScreenSize) (types.ScreenSize, error) {
 	mu.Lock()
 	manager.emmiter.Emit("before_screen_size_change")
 
@@ -79,10 +94,15 @@ func (manager *DesktopManagerCtx) SetScreenSize(size types.ScreenSize) error {
 		mu.Unlock()
 	}()
 
-	return xorg.ChangeScreenSize(size.Width, size.Height, size.Rate)
+	w, h, r, err := xorg.ChangeScreenSize(size.Width, size.Height, size.Rate)
+	return types.ScreenSize{
+		Width:  w,
+		Height: h,
+		Rate:   r,
+	}, err
 }
 
-func (manager *DesktopManagerCtx) GetScreenSize() *types.ScreenSize {
+func (manager *DesktopManagerCtx) GetScreenSize() types.ScreenSize {
 	return xorg.GetScreenSize()
 }
 

internal/websocket/handler/screen.go

@@ -13,11 +13,20 @@ func (h *MessageHandlerCtx) screenSet(session types.Session, payload *message.Sc
 		return errors.New("is not the admin")
 	}
 
-	data := types.ScreenSize(*payload)
+	size, err := h.desktop.SetScreenSize(types.ScreenSize{
-	if err := h.desktop.SetScreenSize(data); err != nil {
+		Width:  payload.Width,
+		Height: payload.Height,
+		Rate:   payload.Rate,
+	})
+
+	if err != nil {
 		return err
 	}
 
-	h.sessions.Broadcast(event.SCREEN_UPDATED, payload)
+	h.sessions.Broadcast(event.SCREEN_UPDATED, message.ScreenSize{
+		Width:  size.Width,
+		Height: size.Height,
+		Rate:   size.Rate,
+	})
 	return nil
 }

internal/websocket/handler/system.go

@@ -1,8 +1,6 @@
 package handler
 
 import (
-	"errors"
-
 	"github.com/rs/zerolog"
 	"github.com/rs/zerolog/log"
 
@@ -25,8 +23,10 @@ func (h *MessageHandlerCtx) systemInit(session types.Session) error {
 	}
 
 	size := h.desktop.GetScreenSize()
-	if size == nil {
+	screenSize := message.ScreenSize{
-		return errors.New("could not get screen size")
+		Width:  size.Width,
+		Height: size.Height,
+		Rate:   size.Rate,
 	}
 
 	sessions := map[string]message.SessionData{}
@@ -44,7 +44,7 @@ func (h *MessageHandlerCtx) systemInit(session types.Session) error {
 		message.SystemInit{
 			SessionId:         session.ID(),
 			ControlHost:       controlHost,
-			ScreenSize:        message.ScreenSize(*size),
+			ScreenSize:        screenSize,
 			Sessions:          sessions,
 			Settings:          h.sessions.Settings(),
 			ScreencastEnabled: h.capture.Screencast().Enabled(),
@@ -57,22 +57,22 @@ func (h *MessageHandlerCtx) systemInit(session types.Session) error {
 }
 
 func (h *MessageHandlerCtx) systemAdmin(session types.Session) error {
-	screenSizesList := []message.ScreenSize{}
+	configurations := h.desktop.ScreenConfigurations()
-	for _, size := range h.desktop.ScreenConfigurations() {
+
-		for _, rate := range size.Rates {
+	list := make([]message.ScreenSize, 0, len(configurations))
-			screenSizesList = append(screenSizesList, message.ScreenSize{
+	for _, conf := range configurations {
-				Width:  size.Width,
+		list = append(list, message.ScreenSize{
-				Height: size.Height,
+			Width:  conf.Width,
-				Rate:   rate,
+			Height: conf.Height,
-			})
+			Rate:   conf.Rate,
-		}
+		})
 	}
 
 	broadcast := h.capture.Broadcast()
 	session.Send(
 		event.SYSTEM_ADMIN,
 		message.SystemAdmin{
-			ScreenSizesList: screenSizesList,
+			ScreenSizesList: list, // TODO: remove
 			BroadcastStatus: message.BroadcastStatus{
 				IsActive: broadcast.Started(),
 				URL:      broadcast.Url(),

pkg/types/capture.go

@@ -188,16 +188,13 @@ func (config *VideoConfig) GetPipeline(screen ScreenSize) (string, error) {
 	}[:], " "), nil
 }
 
-func (config *VideoConfig) GetBitrateFn(getScreen func() *ScreenSize) func() (int, error) {
+func (config *VideoConfig) GetBitrateFn(getScreen func() ScreenSize) func() (int, error) {
 	return func() (int, error) {
 		if config.Bitrate > 0 {
 			return config.Bitrate, nil
 		}
 
 		screen := getScreen()
-		if screen == nil {
-			return 0, fmt.Errorf("screen is nil")
-		}
 
 		values := map[string]any{
 			"width":  screen.Width,

pkg/types/desktop.go

@@ -19,12 +19,6 @@ type ScreenSize struct {
 	Rate   int16
 }
 
-type ScreenConfiguration struct {
-	Width  int
-	Height int
-	Rates  map[int]int16
-}
-
 type KeyboardModifiers struct {
 	NumLock  *bool
 	CapsLock *bool
@@ -57,9 +51,9 @@ type DesktopManager interface {
 	ButtonPress(code uint32) error
 	KeyPress(codes ...uint32) error
 	ResetKeys()
-	ScreenConfigurations() map[int]ScreenConfiguration
+	ScreenConfigurations() []ScreenSize
-	SetScreenSize(ScreenSize) error
+	SetScreenSize(ScreenSize) (ScreenSize, error)
-	GetScreenSize() *ScreenSize
+	GetScreenSize() ScreenSize
 	SetKeyboardMap(KeyboardMap) error
 	GetKeyboardMap() (*KeyboardMap, error)
 	SetKeyboardModifiers(mod KeyboardModifiers)

pkg/xorg/xorg.c

@@ -229,6 +229,82 @@ void XKey(KeySym keysym, int down) {
   XSync(display, 0);
 }
 
+Status XSetScreenConfiguration(int width, int height, short *rate) {
+  Display *display = getXDisplay();
+  Window root = RootWindow(display, 0);
+  XRRScreenConfiguration *conf = XRRGetScreenInfo(display, root);
+
+  XRRScreenSize *xrrs;
+  int num_sizes;
+  xrrs = XRRConfigSizes(conf, &num_sizes);
+
+  int size_index = -1;
+  for (int i = 0; i < num_sizes; i++) {
+    if (xrrs[i].width == width && xrrs[i].height == height) {
+      size_index = i;
+      break;
+    }
+  }
+
+  // if we cannot find the size
+  if (size_index == -1) {
+    return RRSetConfigFailed;
+  }
+
+  short current_rate = 0;
+  if (rate != NULL) {
+    short *rates;
+    int num_rates;
+    rates = XRRConfigRates(conf, size_index, &num_rates);
+
+    // try to find the nearest rate
+    short nearest_rate = 0;
+    float diff = 0;
+    for (int i = 0; i < num_rates; i++) {
+      if (nearest_rate == 0 || abs(rates[i] - *rate) < diff) {
+        nearest_rate = rates[i];
+        diff = abs(rates[i] - *rate);
+      }
+    }
+
+    if (nearest_rate != 0 && diff < 10) {
+      current_rate = nearest_rate;
+    }
+
+    *rate = current_rate;
+  }
+
+  Status status;
+  status = XRRSetScreenConfigAndRate(display, conf, root, size_index, RR_Rotate_0, current_rate, CurrentTime);
+
+  XRRFreeScreenConfigInfo(conf);
+  return status;
+}
+
+void XGetScreenConfiguration(int *width, int *height, short *rate) {
+  Display *display = getXDisplay();
+  Window root = RootWindow(display, 0);
+  XRRScreenConfiguration *conf = XRRGetScreenInfo(display, root);
+
+  Rotation current_rotation;
+  SizeID current_size_id = XRRConfigCurrentConfiguration(conf, &current_rotation);
+
+  XRRScreenSize *xrrs;
+  int num_sizes;
+  xrrs = XRRConfigSizes(conf, &num_sizes);
+
+  // if we cannot find the size
+  if (current_size_id >= num_sizes) {
+    return;
+  }
+
+  *width = xrrs[current_size_id].width;
+  *height = xrrs[current_size_id].height;
+  *rate = XRRConfigCurrentRate(conf);
+
+  XRRFreeScreenConfigInfo(conf);
+}
+
 void XGetScreenConfigurations() {
   Display *display = getXDisplay();
   Window root = RootWindow(display, 0);
@@ -248,23 +324,71 @@ void XGetScreenConfigurations() {
   }
 }
 
-void XSetScreenConfiguration(int index, short rate) {
+// Inspired by https://github.com/raboof/xrandr/blob/master/xrandr.c
+void XCreateScreenMode(int width, int height, short rate) {
   Display *display = getXDisplay();
   Window root = RootWindow(display, 0);
-  XRRSetScreenConfigAndRate(display, XRRGetScreenInfo(display, root), root, index, RR_Rotate_0, rate, CurrentTime);
+
+  char name[128];
+  XRRModeInfo mode;
+  mode = XCreateScreenModeInfo(width, height, rate);
+
+  snprintf(name, sizeof name, "%dx%d_%d", width, height, rate);
+  mode.nameLength = strlen(name);
+  mode.name = name;
+
+  // create new mode
+  XRRCreateMode(display, root, &mode);
+  XSync(display, 0);
+
+  // find newly created mode in resources
+  RRMode mode_id;
+	XRRScreenResources *resources = XRRGetScreenResources(display, root);
+  for (int i = 0; i < resources->nmode; ++i) {
+    if (strcmp(resources->modes[i].name, mode.name) == 0) {
+      mode_id = resources->modes[i].id;
+      break;
+    }
+  }
+
+  // add new mode to all outputs
+  for (int i = 0; i < resources->noutput; ++i) {
+    XRRAddOutputMode(display, resources->outputs[i], mode_id);
+  }
+
+  XRRFreeScreenResources(resources);
 }
 
-int XGetScreenSize() {
+// Inspired by https://fossies.org/linux/xwayland/hw/xwayland/xwayland-cvt.c
-  Display *display = getXDisplay();
+XRRModeInfo XCreateScreenModeInfo(int hdisplay, int vdisplay, short vrefresh) {
-  XRRScreenConfiguration *conf = XRRGetScreenInfo(display, RootWindow(display, 0));
+  XRRModeInfo modeinfo;
-  Rotation original_rotation;
+  memset(&modeinfo, 0, sizeof modeinfo);
-  return XRRConfigCurrentConfiguration(conf, &original_rotation);
-}
 
-short XGetScreenRate() {
+#ifdef _LIBCVT_H_
-  Display *display = getXDisplay();
+  struct libxcvt_mode_info *mode_info;
-  XRRScreenConfiguration *conf = XRRGetScreenInfo(display, RootWindow(display, 0));
+
-  return XRRConfigCurrentRate(conf);
+  // get screen mode from libxcvt, if available
+  mode_info = libxcvt_gen_mode_info(hdisplay, vdisplay, vrefresh, false, false);
+
+  modeinfo.width      = mode_info->hdisplay;
+  modeinfo.height     = mode_info->vdisplay;
+  modeinfo.dotClock   = mode_info->dot_clock * 1000;
+  modeinfo.hSyncStart = mode_info->hsync_start;
+  modeinfo.hSyncEnd   = mode_info->hsync_end;
+  modeinfo.hTotal     = mode_info->htotal;
+  modeinfo.vSyncStart = mode_info->vsync_start;
+  modeinfo.vSyncEnd   = mode_info->vsync_end;
+  modeinfo.vTotal     = mode_info->vtotal;
+  modeinfo.modeFlags  = mode_info->mode_flags;
+
+  free(mode_info);
+#else
+  // fallback to a simple mode without refresh rate
+  modeinfo.width = hdisplay;
+  modeinfo.height = vdisplay;
+#endif
+
+  return modeinfo;
 }
 
 void XSetKeyboardModifier(int mod, int on) {

pkg/xorg/xorg.go

@@ -1,7 +1,7 @@
 package xorg
 
 /*
-#cgo LDFLAGS: -lX11 -lXrandr -lXtst -lXfixes
+#cgo LDFLAGS: -lX11 -lXrandr -lXtst -lXfixes -lxcvt
 
 #include "xorg.h"
 */
@@ -27,7 +27,13 @@ const (
 	KbdModNumLock  KbdMod = 16
 )
 
-var ScreenConfigurations = make(map[int]types.ScreenConfiguration)
+type ScreenConfiguration struct {
+	Width  int
+	Height int
+	Rates  map[int]int16
+}
+
+var ScreenConfigurations = make(map[int]ScreenConfiguration)
 
 var debounce_button = make(map[uint32]time.Time)
 var debounce_key = make(map[uint32]time.Time)
@@ -178,40 +184,46 @@ func CheckKeys(duration time.Duration) {
 	}
 }
 
-func ChangeScreenSize(width int, height int, rate int16) error {
+// set screen configuration, create new one if not exists
+func ChangeScreenSize(width int, height int, rate int16) (int, int, int16, error) {
 	mu.Lock()
 	defer mu.Unlock()
 
-	for index, size := range ScreenConfigurations {
+	// round width and height to 8
-		if size.Width == width && size.Height == height {
+	width = width - (width % 8)
-			for _, fps := range size.Rates {
+	height = height - (height % 8)
-				if rate == fps {
+
-					C.XSetScreenConfiguration(C.int(index), C.short(fps))
+	// convert variables to C types
-					return nil
+	c_width, c_height, c_rate := C.int(width), C.int(height), C.short(rate)
-				}
+
-			}
+	// if screen configuration already exists, just set it
-		}
+	if status := C.XSetScreenConfiguration(c_width, c_height, &c_rate); status == C.RRSetConfigSuccess {
+		return width, height, int16(c_rate), nil
 	}
 
-	return fmt.Errorf("unknown screen configuration %dx%d@%d", width, height, rate)
+	// create new screen configuration
+	C.XCreateScreenMode(c_width, c_height, c_rate)
+
+	// screen configuration should exist now, set it
+	if status := C.XSetScreenConfiguration(c_width, c_height, &c_rate); status == C.RRSetConfigSuccess {
+		return width, height, int16(c_rate), nil
+	}
+
+	return 0, 0, 0, fmt.Errorf("unknown screen configuration %dx%d@%d", width, height, rate)
 }
 
-func GetScreenSize() *types.ScreenSize {
+func GetScreenSize() types.ScreenSize {
 	mu.Lock()
 	defer mu.Unlock()
 
-	index := int(C.XGetScreenSize())
+	c_width, c_height, c_rate := C.int(0), C.int(0), C.short(0)
-	rate := int16(C.XGetScreenRate())
+	C.XGetScreenConfiguration(&c_width, &c_height, &c_rate)
 
-	if conf, ok := ScreenConfigurations[index]; ok {
+	return types.ScreenSize{
-		return &types.ScreenSize{
+		Width:  int(c_width),
-			Width:  conf.Width,
+		Height: int(c_height),
-			Height: conf.Height,
+		Rate:   int16(c_rate),
-			Rate:   rate,
-		}
 	}
-
-	return nil
 }
 
 func SetKeyboardModifier(mod KbdMod, active bool) {
@@ -300,7 +312,7 @@ func GetScreenshotImage() *image.RGBA {
 
 //export goCreateScreenSize
 func goCreateScreenSize(index C.int, width C.int, height C.int, mwidth C.int, mheight C.int) {
-	ScreenConfigurations[int(index)] = types.ScreenConfiguration{
+	ScreenConfigurations[int(index)] = ScreenConfiguration{
 		Width:  int(width),
 		Height: int(height),
 		Rates:  make(map[int]int16),
@@ -309,12 +321,5 @@ func goCreateScreenSize(index C.int, width C.int, height C.int, mwidth C.int, mh
 
 //export goSetScreenRates
 func goSetScreenRates(index C.int, rate_index C.int, rateC C.short) {
-	rate := int16(rateC)
+	ScreenConfigurations[int(index)].Rates[int(rate_index)] = int16(rateC)
-
-	// filter out all irrelevant rates
-	if rate > 60 || (rate > 30 && rate%10 != 0) {
-		return
-	}
-
-	ScreenConfigurations[int(index)].Rates[int(rate_index)] = rate
 }

pkg/xorg/xorg.h

@@ -7,6 +7,11 @@
 #include <X11/extensions/XTest.h>
 #include <X11/extensions/Xfixes.h>
 #include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+// for computing xrandr modelines at runtime
+#include <libxcvt/libxcvt.h>
 
 extern void goCreateScreenSize(int index, int width, int height, int mwidth, int mheight);
 extern void goSetScreenRates(int index, int rate_index, short rate);
@@ -31,10 +36,11 @@ static KeyCode XKeyEntryGet(KeySym keysym);
 static KeyCode XkbKeysymToKeycode(Display *dpy, KeySym keysym);
 void XKey(KeySym keysym, int down);
 
+Status XSetScreenConfiguration(int width, int height, short *rate);
+void XGetScreenConfiguration(int *width, int *height, short *rate);
 void XGetScreenConfigurations();
-void XSetScreenConfiguration(int index, short rate);
+void XCreateScreenMode(int width, int height, short rate);
-int XGetScreenSize();
+XRRModeInfo XCreateScreenModeInfo(int hdisplay, int vdisplay, short vrefresh);
-short XGetScreenRate();
 
 void XSetKeyboardModifier(int mod, int on);
 char XGetKeyboardModifiers();

runtime/xdummy-randr.patch

@@ -0,0 +1,316 @@
+diff --git a/src/dummy.h b/src/dummy.h
+index c3fdd6e..9c74f56 100644
+--- a/src/dummy.h
++++ b/src/dummy.h
+@@ -13,6 +13,8 @@
+ 
+ #include "compat-api.h"
+ 
++#define DUMMY_MAX_SCREENS 4
++
+ /* Supported chipsets */
+ typedef enum {
+     DUMMY_CHIP
+@@ -72,6 +74,12 @@ typedef struct dummyRec
+     pointer* FBBase;
+     Bool        (*CreateWindow)() ;     /* wrapped CreateWindow */
+     Bool prop;
++    /* XRANDR support begin */
++    int num_screens;
++    struct _xf86Crtc *paCrtcs[DUMMY_MAX_SCREENS];
++    struct _xf86Output *paOutputs[DUMMY_MAX_SCREENS];
++    int connected_outputs;
++    /* XRANDR support end */
+ } DUMMYRec, *DUMMYPtr;
+ 
+ /* The privates of the DUMMY driver */
+diff --git a/src/dummy_driver.c b/src/dummy_driver.c
+index 2656602..069e330 100644
+--- a/src/dummy_driver.c
++++ b/src/dummy_driver.c
+@@ -34,6 +34,8 @@
+ #include <X11/extensions/Xv.h>
+ #endif
+ 
++#include "xf86Crtc.h"
++
+ /*
+  * Driver data structures.
+  */
+@@ -141,6 +143,219 @@ static XF86ModuleVersionInfo dummyVersRec =
+ 	{0,0,0,0}
+ };
+ 
++
++/************************
++ * XRANDR support begin *
++ ************************/
++
++static Bool dummy_config_resize(ScrnInfoPtr pScrn, int cw, int ch);
++static Bool DUMMYAdjustScreenPixmap(ScrnInfoPtr pScrn, int width, int height);
++
++static const xf86CrtcConfigFuncsRec DUMMYCrtcConfigFuncs = {
++    .resize = dummy_config_resize
++};
++
++
++static void
++dummy_crtc_dpms(xf86CrtcPtr crtc, int mode)
++{
++}
++
++static Bool
++dummy_crtc_lock (xf86CrtcPtr crtc)
++{
++    return FALSE;
++}
++
++static Bool
++dummy_crtc_mode_fixup (xf86CrtcPtr crtc, DisplayModePtr mode,
++                              DisplayModePtr adjusted_mode)
++{
++    return TRUE;
++}
++
++static void
++dummy_crtc_stub (xf86CrtcPtr crtc)
++{
++}
++
++static void
++dummy_crtc_gamma_set (xf86CrtcPtr crtc, CARD16 *red,
++                             CARD16 *green, CARD16 *blue, int size)
++{
++}
++
++static void *
++dummy_crtc_shadow_allocate (xf86CrtcPtr crtc, int width, int height)
++{
++    return NULL;
++}
++
++static void
++dummy_crtc_mode_set (xf86CrtcPtr crtc, DisplayModePtr mode,
++                            DisplayModePtr adjusted_mode, int x, int y)
++{
++}
++
++static const xf86CrtcFuncsRec DUMMYCrtcFuncs = {
++    .dpms = dummy_crtc_dpms,
++    .save = NULL, /* These two are never called by the server. */
++    .restore = NULL,
++    .lock = dummy_crtc_lock,
++    .unlock = NULL, /* This will not be invoked if lock returns FALSE. */
++    .mode_fixup = dummy_crtc_mode_fixup,
++    .prepare = dummy_crtc_stub,
++    .mode_set = dummy_crtc_mode_set,
++    .commit = dummy_crtc_stub,
++    .gamma_set = dummy_crtc_gamma_set,
++    .shadow_allocate = dummy_crtc_shadow_allocate,
++    .shadow_create = NULL, /* These two should not be invoked if allocate
++                              returns NULL. */
++    .shadow_destroy = NULL,
++    .set_cursor_colors = NULL,
++    .set_cursor_position = NULL,
++    .show_cursor = NULL,
++    .hide_cursor = NULL,
++    .load_cursor_argb = NULL,
++    .destroy = dummy_crtc_stub
++};
++
++static void
++dummy_output_stub (xf86OutputPtr output)
++{
++}
++
++static void
++dummy_output_dpms (xf86OutputPtr output, int mode)
++{
++}
++
++static int
++dummy_output_mode_valid (xf86OutputPtr output, DisplayModePtr mode)
++{
++    return MODE_OK;
++}
++
++static Bool
++dummy_output_mode_fixup (xf86OutputPtr output, DisplayModePtr mode,
++        DisplayModePtr adjusted_mode)
++{
++    return TRUE;
++}
++
++static void
++dummy_output_mode_set (xf86OutputPtr output, DisplayModePtr mode,
++        DisplayModePtr adjusted_mode)
++{
++    DUMMYPtr dPtr = DUMMYPTR(output->scrn);
++    int index = (int64_t)output->driver_private;
++
++    /* set to connected at first mode set */
++    dPtr->connected_outputs |= 1 << index;
++}
++
++/* The first virtual monitor is always connected. Others only after setting its
++ * mode */
++static xf86OutputStatus
++dummy_output_detect (xf86OutputPtr output)
++{
++    DUMMYPtr dPtr = DUMMYPTR(output->scrn);
++    int index = (int64_t)output->driver_private;
++
++    if (dPtr->connected_outputs & (1 << index))
++        return XF86OutputStatusConnected;
++    else
++        return XF86OutputStatusDisconnected;
++}
++
++static DisplayModePtr
++dummy_output_get_modes (xf86OutputPtr output)
++{
++    DisplayModePtr pModes = NULL, pMode, pModeSrc;
++
++    /* copy modes from config */
++    for (pModeSrc = output->scrn->modes; pModeSrc; pModeSrc = pModeSrc->next)
++    {
++            pMode = xnfcalloc(1, sizeof(DisplayModeRec));
++            memcpy(pMode, pModeSrc, sizeof(DisplayModeRec));
++            pMode->next = NULL;
++            pMode->prev = NULL;
++            pMode->name = strdup(pModeSrc->name);
++            pModes = xf86ModesAdd(pModes, pMode);
++            if (pModeSrc->next == output->scrn->modes)
++                break;
++    }
++    return pModes;
++}
++
++
++static const xf86OutputFuncsRec DUMMYOutputFuncs = {
++    .create_resources = dummy_output_stub,
++    .dpms = dummy_output_dpms,
++    .save = NULL, /* These two are never called by the server. */
++    .restore = NULL,
++    .mode_valid = dummy_output_mode_valid,
++    .mode_fixup = dummy_output_mode_fixup,
++    .prepare = dummy_output_stub,
++    .commit = dummy_output_stub,
++    .mode_set = dummy_output_mode_set,
++    .detect = dummy_output_detect,
++    .get_modes = dummy_output_get_modes,
++#ifdef RANDR_12_INTERFACE
++    .set_property = NULL,
++#endif
++    .destroy = dummy_output_stub
++};
++
++static Bool
++dummy_config_resize(ScrnInfoPtr pScrn, int cw, int ch)
++{
++    if (!pScrn->vtSema) {
++        xf86DrvMsg(pScrn->scrnIndex, X_ERROR,
++                "We do not own the active VT, exiting.\n");
++        return TRUE;
++    }
++    return DUMMYAdjustScreenPixmap(pScrn, cw, ch);
++}
++
++Bool DUMMYAdjustScreenPixmap(ScrnInfoPtr pScrn, int width, int height)
++{
++    ScreenPtr pScreen = pScrn->pScreen;
++    PixmapPtr pPixmap = pScreen->GetScreenPixmap(pScreen);
++    DUMMYPtr dPtr = DUMMYPTR(pScrn);
++    uint64_t cbLine = (width * xf86GetBppFromDepth(pScrn, pScrn->depth) / 8 + 3) & ~3;
++    int displayWidth = cbLine * 8 / xf86GetBppFromDepth(pScrn, pScrn->depth);
++
++    if (   width == pScrn->virtualX
++            && height == pScrn->virtualY
++            && displayWidth == pScrn->displayWidth)
++        return TRUE;
++    if (!pPixmap) {
++        xf86DrvMsg(pScrn->scrnIndex, X_ERROR,
++                "Failed to get the screen pixmap.\n");
++        return FALSE;
++    }
++    if (cbLine > UINT32_MAX || cbLine * height >= pScrn->videoRam * 1024)
++    {
++        xf86DrvMsg(pScrn->scrnIndex, X_ERROR,
++                "Unable to set up a virtual screen size of %dx%d with %d Kb of video memory available.  Please increase the video memory size.\n",
++                width, height, pScrn->videoRam);
++        return FALSE;
++    }
++    pScreen->ModifyPixmapHeader(pPixmap, width, height,
++            pScrn->depth, xf86GetBppFromDepth(pScrn, pScrn->depth), cbLine,
++            pPixmap->devPrivate.ptr);
++    pScrn->virtualX = width;
++    pScrn->virtualY = height;
++    pScrn->displayWidth = displayWidth;
++
++    return TRUE;
++}
++
++/**********************
++ * XRANDR support end *
++ **********************/
++
+ /*
+  * This is the module init data.
+  * Its name has to be the driver name followed by ModuleData
+@@ -568,6 +783,56 @@ DUMMYScreenInit(SCREEN_INIT_ARGS_DECL)
+ 
+     xf86SetBlackWhitePixels(pScreen);
+ 
++    /* initialize XRANDR */
++    xf86CrtcConfigInit(pScrn, &DUMMYCrtcConfigFuncs);
++    /* FIXME */
++    dPtr->num_screens = DUMMY_MAX_SCREENS;
++
++    for (int i=0; i < dPtr->num_screens; i++) {
++        char szOutput[256];
++
++        dPtr->paCrtcs[i] = xf86CrtcCreate(pScrn, &DUMMYCrtcFuncs);
++        dPtr->paCrtcs[i]->driver_private = (void *)(uintptr_t)i;
++
++        /* Set up our virtual outputs. */
++        snprintf(szOutput, sizeof(szOutput), "DUMMY%u", i);
++        dPtr->paOutputs[i] = xf86OutputCreate(pScrn, &DUMMYOutputFuncs,
++                szOutput);
++
++
++        xf86OutputUseScreenMonitor(dPtr->paOutputs[i], FALSE);
++        dPtr->paOutputs[i]->possible_crtcs = 1 << i;
++        dPtr->paOutputs[i]->possible_clones = 0;
++        dPtr->paOutputs[i]->driver_private = (void *)(uintptr_t)i;
++        xf86DrvMsg(pScrn->scrnIndex, X_INFO, "Created crtc (%p) and output %s (%p)\n",
++                (void *)dPtr->paCrtcs[i], szOutput,
++                (void *)dPtr->paOutputs[i]);
++
++    }
++
++    /* bitmask */
++    dPtr->connected_outputs = 1;
++
++    xf86CrtcSetSizeRange(pScrn, 64, 64, DUMMY_MAX_WIDTH, DUMMY_MAX_HEIGHT);
++
++
++    /* Now create our initial CRTC/output configuration. */
++    if (!xf86InitialConfiguration(pScrn, TRUE)) {
++        xf86DrvMsg(pScrn->scrnIndex, X_ERROR, "Initial CRTC configuration failed!\n");
++        return (FALSE);
++    }
++
++    /* Initialise randr 1.2 mode-setting functions and set first mode.
++     * Note that the mode won't be usable until the server has resized the
++     * framebuffer to something reasonable. */
++    if (!xf86CrtcScreenInit(pScreen)) {
++        return FALSE;
++    }
++    if (!xf86SetDesiredModes(pScrn)) {
++        return FALSE;
++    }
++    /* XRANDR initialization end */
++
+ #ifdef USE_DGA
+     DUMMYDGAInit(pScreen);
+ #endif