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.

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() {
-  Display *display = getXDisplay();
-  XRRScreenConfiguration *conf = XRRGetScreenInfo(display, RootWindow(display, 0));
-  Rotation original_rotation;
-  return XRRConfigCurrentConfiguration(conf, &original_rotation);
-}
+// Inspired by https://fossies.org/linux/xwayland/hw/xwayland/xwayland-cvt.c
+XRRModeInfo XCreateScreenModeInfo(int hdisplay, int vdisplay, short vrefresh) {
+  XRRModeInfo modeinfo;
+  memset(&modeinfo, 0, sizeof modeinfo);
 
-short XGetScreenRate() {
-  Display *display = getXDisplay();
-  XRRScreenConfiguration *conf = XRRGetScreenInfo(display, RootWindow(display, 0));
-  return XRRConfigCurrentRate(conf);
+#ifdef _LIBCVT_H_
+  struct libxcvt_mode_info *mode_info;
+
+  // 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 {
-		if size.Width == width && size.Height == height {
-			for _, fps := range size.Rates {
-				if rate == fps {
-					C.XSetScreenConfiguration(C.int(index), C.short(fps))
-					return nil
-				}
-			}
-		}
+	// round width and height to 8
+	width = width - (width % 8)
+	height = height - (height % 8)
+
+	// convert variables to C types
+	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())
-	rate := int16(C.XGetScreenRate())
+	c_width, c_height, c_rate := C.int(0), C.int(0), C.short(0)
+	C.XGetScreenConfiguration(&c_width, &c_height, &c_rate)
 
-	if conf, ok := ScreenConfigurations[index]; ok {
-		return &types.ScreenSize{
-			Width:  conf.Width,
-			Height: conf.Height,
-			Rate:   rate,
-		}
+	return types.ScreenSize{
+		Width:  int(c_width),
+		Height: int(c_height),
+		Rate:   int16(c_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)
-
-	// filter out all irrelevant rates
-	if rate > 60 || (rate > 30 && rate%10 != 0) {
-		return
-	}
-
-	ScreenConfigurations[int(index)].Rates[int(rate_index)] = rate
+	ScreenConfigurations[int(index)].Rates[int(rate_index)] = int16(rateC)
 }

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);
-int XGetScreenSize();
-short XGetScreenRate();
+void XCreateScreenMode(int width, int height, short rate);
+XRRModeInfo XCreateScreenModeInfo(int hdisplay, int vdisplay, short vrefresh);
 
 void XSetKeyboardModifier(int mod, int on);
 char XGetKeyboardModifiers();