backend/x11: Revert usage of present extension

This reverts commit 3317134adf.
This reverts commit a3c3b928a3.

There are some serious issues when running this on a real X server, as
opposed to running this on Xwayland, where this was tested.

More investigation needs to be done into why these issues happen and if
our usage of the present extension is correct.

backend/x11/backend.c

@@ -12,7 +12,6 @@
 #include <X11/Xlib-xcb.h>
 #include <wayland-server-core.h>
 #include <xcb/xcb.h>
-#include <xcb/present.h>
 #include <xcb/xfixes.h>
 #include <xcb/xinput.h>
 
@@ -51,6 +50,16 @@ static void handle_x11_event(struct wlr_x11_backend *x11,
 		}
 		break;
 	}
+	case XCB_CONFIGURE_NOTIFY: {
+		xcb_configure_notify_event_t *ev =
+			(xcb_configure_notify_event_t *)event;
+		struct wlr_x11_output *output =
+			get_x11_output_from_window_id(x11, ev->window);
+		if (output != NULL) {
+			handle_x11_configure_notify(output, ev);
+		}
+		break;
+	}
 	case XCB_CLIENT_MESSAGE: {
 		xcb_client_message_event_t *ev = (xcb_client_message_event_t *)event;
 		if (ev->data.data32[0] == x11->atoms.wm_delete_window) {
@@ -64,10 +73,7 @@ static void handle_x11_event(struct wlr_x11_backend *x11,
 	}
 	case XCB_GE_GENERIC: {
 		xcb_ge_generic_event_t *ev = (xcb_ge_generic_event_t *)event;
-		if (ev->extension == x11->present_opcode) {
+		if (ev->extension == x11->xinput_opcode) {
-			handle_x11_present_event(x11,
-				(xcb_present_generic_event_t *)ev);
-		} else if (ev->extension == x11->xinput_opcode) {
 			handle_x11_xinput_event(x11, ev);
 		}
 	}
@@ -218,29 +224,6 @@ struct wlr_backend *wlr_x11_backend_create(struct wl_display *display,
 
 	const xcb_query_extension_reply_t *ext;
 
-	/* Present extension */
-
-	ext = xcb_get_extension_data(x11->xcb, &xcb_present_id);
-	if (!ext || !ext->present) {
-		wlr_log(WLR_ERROR, "X11 does not support Present extension");
-		goto error_display;
-	}
-	x11->present_opcode = ext->major_opcode;
-
-	xcb_present_query_version_cookie_t present_cookie =
-		xcb_present_query_version(x11->xcb, 1, 0);
-	xcb_present_query_version_reply_t *present_reply =
-		xcb_present_query_version_reply(x11->xcb, present_cookie, NULL);
-
-	if (!present_reply) {
-		wlr_log(WLR_ERROR, "X11 does not support required Present version");
-		free(present_reply);
-		goto error_display;
-	}
-	free(present_reply);
-
-	/* Xfixes extension */
-
 	ext = xcb_get_extension_data(x11->xcb, &xcb_xfixes_id);
 	if (!ext || !ext->present) {
 		wlr_log(WLR_ERROR, "X11 does not support Xfixes extension");
@@ -259,8 +242,6 @@ struct wlr_backend *wlr_x11_backend_create(struct wl_display *display,
 	}
 	free(fixes_reply);
 
-	/* Xinput extension */
-
 	ext = xcb_get_extension_data(x11->xcb, &xcb_input_id);
 	if (!ext || !ext->present) {
 		wlr_log(WLR_ERROR, "X11 does not support Xinput extension");

backend/x11/meson.build

@@ -2,9 +2,8 @@ x11_libs = []
 x11_required = [
 	'x11-xcb',
 	'xcb',
-	'xcb-present',
-	'xcb-xfixes',
 	'xcb-xinput',
+	'xcb-xfixes',
 ]
 
 foreach lib : x11_required

backend/x11/output.c

@@ -5,7 +5,6 @@
 #include <string.h>
 
 #include <xcb/xcb.h>
-#include <xcb/present.h>
 #include <xcb/xinput.h>
 
 #include <wlr/interfaces/wlr_output.h>
@@ -16,6 +15,13 @@
 #include "backend/x11.h"
 #include "util/signal.h"
 
+static int signal_frame(void *data) {
+	struct wlr_x11_output *output = data;
+	wlr_output_send_frame(&output->wlr_output);
+	wl_event_source_timer_update(output->frame_timer, output->frame_delay);
+	return 0;
+}
+
 static void parse_xcb_setup(struct wlr_output *output,
 		xcb_connection_t *xcb) {
 	const xcb_setup_t *xcb_setup = xcb_get_setup(xcb);
@@ -34,11 +40,26 @@ static struct wlr_x11_output *get_x11_output_from_output(
 	return (struct wlr_x11_output *)wlr_output;
 }
 
+static void output_set_refresh(struct wlr_output *wlr_output, int32_t refresh) {
+	struct wlr_x11_output *output = get_x11_output_from_output(wlr_output);
+
+	if (refresh <= 0) {
+		refresh = X11_DEFAULT_REFRESH;
+	}
+
+	wlr_output_update_custom_mode(&output->wlr_output, wlr_output->width,
+		wlr_output->height, refresh);
+
+	output->frame_delay = 1000000 / refresh;
+}
+
 static bool output_set_custom_mode(struct wlr_output *wlr_output,
 		int32_t width, int32_t height, int32_t refresh) {
 	struct wlr_x11_output *output = get_x11_output_from_output(wlr_output);
 	struct wlr_x11_backend *x11 = output->x11;
 
+	output_set_refresh(&output->wlr_output, refresh);
+
 	const uint32_t values[] = { width, height };
 	xcb_void_cookie_t cookie = xcb_configure_window_checked(
 		x11->xcb, output->win,
@@ -63,6 +84,7 @@ static void output_destroy(struct wlr_output *wlr_output) {
 	wlr_input_device_destroy(&output->touch_dev);
 
 	wl_list_remove(&output->link);
+	wl_event_source_remove(output->frame_timer);
 	wlr_egl_destroy_surface(&x11->egl, output->surf);
 	xcb_destroy_window(x11->xcb, output->win);
 	xcb_flush(x11->xcb);
@@ -118,15 +140,19 @@ struct wlr_output *wlr_x11_output_create(struct wlr_backend *backend) {
 	struct wlr_output *wlr_output = &output->wlr_output;
 	wlr_output_init(wlr_output, &x11->backend, &output_impl, x11->wl_display);
 
-	wlr_output_update_custom_mode(&output->wlr_output, 1024, 768, 0);
+	wlr_output->width = 1024;
-	wlr_output_update_enabled(wlr_output, true);
+	wlr_output->height = 768;
+
+	output_set_refresh(&output->wlr_output, 0);
 
 	snprintf(wlr_output->name, sizeof(wlr_output->name), "X11-%zd",
 		++x11->last_output_num);
 	parse_xcb_setup(wlr_output, x11->xcb);
 
 	uint32_t mask = XCB_CW_EVENT_MASK;
-	uint32_t values[] = { XCB_EVENT_MASK_EXPOSURE };
+	uint32_t values[] = {
+		XCB_EVENT_MASK_EXPOSURE | XCB_EVENT_MASK_STRUCTURE_NOTIFY
+	};
 	output->win = xcb_generate_id(x11->xcb);
 	xcb_create_window(x11->xcb, XCB_COPY_FROM_PARENT, output->win,
 		x11->screen->root, 0, 0, wlr_output->width, wlr_output->height, 1,
@@ -150,11 +176,6 @@ struct wlr_output *wlr_x11_output_create(struct wlr_backend *backend) {
 	};
 	xcb_input_xi_select_events(x11->xcb, output->win, 1, &xinput_mask.head);
 
-	output->present_context = xcb_generate_id(x11->xcb);
-	xcb_present_select_input(x11->xcb, output->present_context, output->win,
-		XCB_PRESENT_EVENT_MASK_CONFIGURE_NOTIFY |
-		XCB_PRESENT_EVENT_MASK_COMPLETE_NOTIFY);
-
 	output->surf = wlr_egl_create_surface(&x11->egl, &output->win);
 	if (!output->surf) {
 		wlr_log(WLR_ERROR, "Failed to create EGL surface");
@@ -168,8 +189,17 @@ struct wlr_output *wlr_x11_output_create(struct wlr_backend *backend) {
 
 	wlr_x11_output_set_title(wlr_output, NULL);
 
+	xcb_map_window(x11->xcb, output->win);
+	xcb_flush(x11->xcb);
+
+	struct wl_event_loop *ev = wl_display_get_event_loop(x11->wl_display);
+	output->frame_timer = wl_event_loop_add_timer(ev, signal_frame, output);
+
 	wl_list_insert(&x11->outputs, &output->link);
 
+	wl_event_source_timer_update(output->frame_timer, output->frame_delay);
+	wlr_output_update_enabled(wlr_output, true);
+
 	wlr_input_device_init(&output->pointer_dev, WLR_INPUT_DEVICE_POINTER,
 		&input_device_impl, "X11 pointer", 0, 0);
 	wlr_pointer_init(&output->pointer, &pointer_impl);
@@ -187,60 +217,22 @@ struct wlr_output *wlr_x11_output_create(struct wlr_backend *backend) {
 	wlr_signal_emit_safe(&x11->backend.events.new_input, &output->pointer_dev);
 	wlr_signal_emit_safe(&x11->backend.events.new_input, &output->touch_dev);
 
-	// Start the vsync loop
-	xcb_present_notify_msc(x11->xcb, output->win, 0, 0, 1, 0);
-	xcb_map_window(x11->xcb, output->win);
-	xcb_flush(x11->xcb);
-
 	return wlr_output;
 }
 
-void handle_x11_present_event(struct wlr_x11_backend *x11,
+void handle_x11_configure_notify(struct wlr_x11_output *output,
-		xcb_present_generic_event_t *base) {
+		xcb_configure_notify_event_t *ev) {
-	struct wlr_x11_output *output;
+	// ignore events that set an invalid size:
-
+	if (ev->width > 0 && ev->height > 0) {
-	switch (base->evtype) {
+		wlr_output_update_custom_mode(&output->wlr_output, ev->width,
-	case XCB_PRESENT_CONFIGURE_NOTIFY: {
+			ev->height, output->wlr_output.refresh);
-		xcb_present_configure_notify_event_t *ev =
-			(xcb_present_configure_notify_event_t *)base;
-
-		output = get_x11_output_from_window_id(x11, ev->window);
-		if (!output || output->present_context != ev->event) {
-			break;
-		}
-
-		if (ev->width <= 0 || ev->height <= 0) {
-			break;
-		}
-
-		/*
-		 * We don't need to resize anything here ourselves.
-		 * The EGL/OpenGL driver does that automatically.
-		 */
-		wlr_output_update_custom_mode(&output->wlr_output,
-			ev->width, ev->height, 0);
 
 		// Move the pointer to its new location
 		update_x11_pointer_position(output, output->x11->time);
-
+	} else {
-		break;
+		wlr_log(WLR_DEBUG,
-	}
+			"Ignoring X11 configure event for height=%d, width=%d",
-	case XCB_PRESENT_COMPLETE_NOTIFY: {
+			ev->width, ev->height);
-		xcb_present_complete_notify_event_t *ev =
-			(xcb_present_complete_notify_event_t *)base;
-
-		output = get_x11_output_from_window_id(x11, ev->window);
-		if (!output || output->present_context != ev->event) {
-			break;
-		}
-
-		wlr_output_send_frame(&output->wlr_output);
-
-		xcb_present_notify_msc(x11->xcb, output->win, 0, 0, 1, 0);
-		xcb_flush(x11->xcb);
-
-		break;
-	}
 	}
 }
 

include/backend/x11.h

@@ -6,7 +6,6 @@
 #include <X11/Xlib-xcb.h>
 #include <wayland-server-core.h>
 #include <xcb/xcb.h>
-#include <xcb/present.h>
 
 #include <wlr/backend/x11.h>
 #include <wlr/config.h>
@@ -17,6 +16,8 @@
 
 #define XCB_EVENT_RESPONSE_TYPE_MASK 0x7f
 
+#define X11_DEFAULT_REFRESH (60 * 1000) // 60 Hz
+
 struct wlr_x11_backend;
 
 struct wlr_x11_output {
@@ -34,7 +35,8 @@ struct wlr_x11_output {
 	struct wlr_input_device touch_dev;
 	struct wl_list touchpoints; // wlr_x11_touchpoint::link
 
-	xcb_present_event_t present_context;
+	struct wl_event_source *frame_timer;
+	int frame_delay;
 
 	bool cursor_hidden;
 };
@@ -76,7 +78,6 @@ struct wlr_x11_backend {
 	xcb_timestamp_t time;
 
 	uint8_t xinput_opcode;
-	uint8_t present_opcode;
 
 	struct wl_listener display_destroy;
 };
@@ -96,7 +97,7 @@ void handle_x11_xinput_event(struct wlr_x11_backend *x11,
 void update_x11_pointer_position(struct wlr_x11_output *output,
 	xcb_timestamp_t time);
 
-void handle_x11_present_event(struct wlr_x11_backend *x11,
+void handle_x11_configure_notify(struct wlr_x11_output *output,
-		xcb_present_generic_event_t *ev);
+	xcb_configure_notify_event_t *event);
 
 #endif