Implemented XCB backend

CMakeLists.txt

@@ -68,9 +68,11 @@ if(NOT MSVC)
 endif()
 
 # Dependencies
+set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_SOURCE_DIR}/cmake")
 find_package(OpenGL QUIET)
 find_package(ZLIB QUIET)
 find_package(X11 QUIET)
+find_package(XCB QUIET)
 
 if (NOT OPENGL_FOUND)
     message(WARNING "OpenGL not found. Corresponding backend will be disabled")
@@ -209,4 +211,10 @@ if (TARGET_LINUX)
     else()
         message(FATAL_ERROR "X11 could not be located")
     endif()
+    if (XCB_FOUND)
+        include_directories(${XCB_INCLUDE_DIRS})
+        target_link_libraries(nucleus ${XCB_LIBRARIES})
+    else()
+        message(FATAL_ERROR "XCB could not be located")
+    endif()
 endif()

cmake/FindXCB.cmake

@@ -0,0 +1,51 @@
+# - FindXCB
+#
+# Copyright (C) 2015 Valve Corporation
+
+find_package(PkgConfig)
+
+if(NOT XCB_FIND_COMPONENTS)
+    set(XCB_FIND_COMPONENTS xcb)
+endif()
+
+include(FindPackageHandleStandardArgs)
+set(XCB_FOUND true)
+set(XCB_INCLUDE_DIRS "")
+set(XCB_LIBRARIES "")
+foreach(comp ${XCB_FIND_COMPONENTS})
+    # component name
+    string(TOUPPER ${comp} compname)
+    string(REPLACE "-" "_" compname ${compname})
+    # header name
+    string(REPLACE "xcb-" "" headername xcb/${comp}.h)
+    # library name
+    set(libname ${comp})
+
+    pkg_check_modules(PC_${comp} QUIET ${comp})
+
+    find_path(${compname}_INCLUDE_DIR NAMES ${headername}
+        HINTS
+        ${PC_${comp}_INCLUDEDIR}
+        ${PC_${comp}_INCLUDE_DIRS}
+        )
+
+    find_library(${compname}_LIBRARY NAMES ${libname}
+        HINTS
+        ${PC_${comp}_LIBDIR}
+        ${PC_${comp}_LIBRARY_DIRS}
+        )
+
+    find_package_handle_standard_args(${comp}
+        FOUND_VAR ${comp}_FOUND
+        REQUIRED_VARS ${compname}_INCLUDE_DIR ${compname}_LIBRARY)
+    mark_as_advanced(${compname}_INCLUDE_DIR ${compname}_LIBRARY)
+
+    list(APPEND XCB_INCLUDE_DIRS ${${compname}_INCLUDE_DIR})
+    list(APPEND XCB_LIBRARIES ${${compname}_LIBRARY})
+
+    if(NOT ${comp}_FOUND)
+        set(XCB_FOUND false)
+    endif()
+endforeach()
+
+list(REMOVE_DUPLICATES XCB_INCLUDE_DIRS)

wrappers/linux/main.cpp

@@ -27,7 +27,7 @@ int main(int argc, char **argv) {
     // Using UI
     if (!config.console) {
         // Choose Window manager
-        WindowBackend backend = WINDOW_BACKEND_XLIB;
+        WindowBackend backend = WINDOW_BACKEND_XCB;
         for (int i = 1; i < argc; i++) {
             if (strcmp(argv[i], "--wayland") == 0) {
                 backend = WINDOW_BACKEND_WAYLAND;

wrappers/linux/window-xcb.cpp

@@ -8,8 +8,96 @@
 // Nucleus
 #include "nucleus/nucleus.h"
 
+#include <xcb/xcb.h>
+
+#include <cstdio>
 #include <cstring>
 #include <thread>
 
 void createWindowXcb(int argc, char **argv) {
+    // XCB connection
+    int scr;
+    xcb_connection_t* connection = xcb_connect(NULL, &scr);
+    if (connection == NULL) {
+        printf("Cannot open a XCB connection.\nExiting...\n");
+        exit(1);
+    }
+
+    const xcb_setup_t *setup = xcb_get_setup(connection);
+    xcb_screen_iterator_t iter = xcb_setup_roots_iterator(setup);
+    while (scr-- > 0) {
+        xcb_screen_next(&iter);
+    }
+    xcb_screen_t* screen = iter.data;
+
+    // XCB window properties
+    const char* title = "Nucleus";
+    unsigned int width = 960;
+    unsigned int height = 544;
+    uint32_t value_mask = XCB_CW_BACK_PIXEL | XCB_CW_EVENT_MASK;
+    uint32_t value_list[32];
+    value_list[0] = screen->black_pixel;
+    value_list[1] = XCB_EVENT_MASK_KEY_RELEASE | XCB_EVENT_MASK_EXPOSURE |
+                    XCB_EVENT_MASK_STRUCTURE_NOTIFY;
+
+    xcb_window_t window = xcb_generate_id(connection);
+    xcb_create_window(connection, XCB_COPY_FROM_PARENT, window, screen->root, 0, 0,
+        width, height, 0, XCB_WINDOW_CLASS_INPUT_OUTPUT, screen->root_visual, value_mask, value_list);
+    xcb_change_property(connection, XCB_PROP_MODE_REPLACE, window,
+        XCB_ATOM_WM_NAME, XCB_ATOM_STRING, 8, strlen(title), title);
+
+    // Notification when window is destroyed
+    xcb_intern_atom_cookie_t cookie1 = xcb_intern_atom(connection, 1, 12, "WM_PROTOCOLS");
+    xcb_intern_atom_reply_t* reply = xcb_intern_atom_reply(connection, cookie1, 0);
+    xcb_intern_atom_cookie_t cookie2 = xcb_intern_atom(connection, 0, 16, "WM_DELETE_WINDOW");
+    xcb_intern_atom_reply_t* atom_wm_delete_window = xcb_intern_atom_reply(connection, cookie2, 0);
+    xcb_change_property(connection, XCB_PROP_MODE_REPLACE, window,
+        (*reply).atom, 4, 32, 1, &(*atom_wm_delete_window).atom);
+    free(reply);
+
+    const uint32_t coords[] = {100, 100};
+    xcb_map_window(connection, window);
+    xcb_configure_window(connection, window, XCB_CONFIG_WINDOW_X | XCB_CONFIG_WINDOW_Y, coords);
+    xcb_flush(connection);
+
+    // Events
+    bool quit = false;
+    while (!quit) {
+        xcb_generic_event_t* event;
+        event = xcb_poll_for_event(connection);
+        if (!event) {
+            continue;
+        }
+
+        uint8_t code = event->response_type & 0x7f;
+        switch (code) {
+        case XCB_EXPOSE:
+            // TODO: Resize window
+            break;
+        case XCB_CLIENT_MESSAGE: {
+            const auto& msg = *(const xcb_client_message_event_t*)event;
+            if (msg.data.data32[0] == atom_wm_delete_window->atom) {
+                quit = true;
+            }
+            break;
+        }
+        case XCB_KEY_RELEASE: {
+            const auto& key = *(const xcb_key_release_event_t*)event;
+            // TODO: Handle event
+            break;
+        }
+        case XCB_CONFIGURE_NOTIFY: {
+            const auto& cfg = *(const xcb_configure_notify_event_t*)event;
+            // TODO: Handle event
+            break;
+        }
+        default:
+            break;
+        }
+
+        free(event);
+    }
+
+    xcb_destroy_window(connection, window);
+    xcb_disconnect(connection);
 }

wrappers/linux/window-xlib.cpp

@@ -29,7 +29,7 @@ void createWindowXlib(int argc, char **argv) {
     hint.flags = PSize;
 
     Window window = XCreateSimpleWindow(display, DefaultRootWindow(display),
-                                        hint.x, hint.y, hint.width, hint.height, 5, foreground, background);
+        hint.x, hint.y, hint.width, hint.height, 5, foreground, background);
 
     const char appName[] = "Nucleus";
     XSetStandardProperties(display, window, appName, appName, None, argv, argc, &hint);

wrappers/linux/window-xlib.h

@@ -5,6 +5,5 @@
 
 #pragma once
 
-
 // Creates a window with Xlib and initializes Nucleus
 void createWindowXlib(int argc, char** argv);