diff options
| -rw-r--r-- | tinywl/Makefile | 3 | ||||
| -rw-r--r-- | tinywl/README.md | 14 | ||||
| -rw-r--r-- | tinywl/tinywl.c | 260 |
3 files changed, 277 insertions, 0 deletions
diff --git a/tinywl/Makefile b/tinywl/Makefile index 3ecd4670..4d988fa2 100644 --- a/tinywl/Makefile +++ b/tinywl/Makefile @@ -1,5 +1,8 @@ WAYLAND_PROTOCOLS=/usr/share/wayland-protocols +# wayland-scanner is a tool which generates C headers and rigging for Wayland +# protocols, which are specified in XML. wlroots requires you to rig these up +# to your build system yourself and provide them in the include path. xdg-shell-protocol.h: wayland-scanner server-header \ $(WAYLAND_PROTOCOLS)/stable/xdg-shell/xdg-shell.xml $@ diff --git a/tinywl/README.md b/tinywl/README.md index 4be9852c..caacc412 100644 --- a/tinywl/README.md +++ b/tinywl/README.md @@ -31,3 +31,17 @@ keybindings. TinyWL supports the following keybindings: - `Alt+Escape`: Terminate the compositor - `Alt+F1`: Cycle between windows + +## Limitations + +Notable omissions from TinyWL: + +- HiDPI support +- Any kind of configuration, e.g. output layout +- Any protocol other than xdg-shell (e.g. layer-shell, for + panels/taskbars/etc; or Xwayland, for proxied X11 windows) +- Optional protocols, e.g. screen capture, primary selection, virtual + keyboard, etc. Most of these are plug-and-play with wlroots, but they're + omitted for brevity. +- Damage tracking, which tracks which parts of the screen are changing and + minimizes redraws accordingly. diff --git a/tinywl/tinywl.c b/tinywl/tinywl.c index d370b04d..069f6451 100644 --- a/tinywl/tinywl.c +++ b/tinywl/tinywl.c @@ -24,6 +24,7 @@ #include <wlr/util/log.h> #include <xkbcommon/xkbcommon.h> +/* For brevity's sake, struct members are annotated where they are used. */ enum tinywl_cursor_mode { TINYWL_CURSOR_PASSTHROUGH, TINYWL_CURSOR_MOVE, @@ -97,6 +98,7 @@ struct tinywl_pointer { }; static void focus_view(struct tinywl_view *view, struct wlr_surface *surface) { + /* Note: this function only deals with keyboard focus. */ if (view == NULL) { return; } @@ -104,31 +106,60 @@ static void focus_view(struct tinywl_view *view, struct wlr_surface *surface) { struct wlr_seat *seat = server->seat; struct wlr_surface *prev_surface = seat->keyboard_state.focused_surface; if (prev_surface == surface) { + /* Don't re-focus an already focused surface. */ return; } if (prev_surface) { + /* + * Deactivate the previously focused surface. This lets the client know + * it no longer has focus and the client will repaint accordingly, e.g. + * stop displaying a caret. + */ struct wlr_xdg_surface *previous = wlr_xdg_surface_from_wlr_surface( seat->keyboard_state.focused_surface); wlr_xdg_toplevel_set_activated(previous, false); } struct wlr_keyboard *keyboard = wlr_seat_get_keyboard(seat); + /* Move the view to the front */ wl_list_remove(&view->link); wl_list_insert(&server->views, &view->link); + /* Activate the new surface */ wlr_xdg_toplevel_set_activated(view->xdg_surface, true); + /* + * Tell the seat to have the keyboard enter this surface. wlroots will keep + * track of this and automatically send key events to the appropriate + * clients without additional work on your part. + */ wlr_seat_keyboard_notify_enter(seat, view->xdg_surface->surface, keyboard->keycodes, keyboard->num_keycodes, &keyboard->modifiers); } static void keyboard_handle_modifiers( struct wl_listener *listener, void *data) { + /* This event is raised when a modifier key, such as shift or alt, is + * pressed. We simply communicate this to the client. */ struct tinywl_keyboard *keyboard = wl_container_of(listener, keyboard, modifiers); + /* + * A seat can only have one keyboard, but this is a limitation of the + * Wayland protocol - not wlroots. We assign all connected keyboards to the + * same seat. You can swap out the underlying wlr_keyboard like this and + * wlr_seat handles this transparently. + */ wlr_seat_set_keyboard(keyboard->server->seat, keyboard->device); + /* Send modifiers to the client. */ wlr_seat_keyboard_notify_modifiers(keyboard->server->seat, &keyboard->device->keyboard->modifiers); } static bool handle_keybinding(struct tinywl_server *server, xkb_keysym_t sym) { + /* + * Here we handle compositor keybindings. This is when the compositor is + * processing keys, rather than passing them on to the client for its own + * processing. + * + * This function assumes Alt is held down. + */ switch (sym) { case XKB_KEY_Escape: wl_display_terminate(server->wl_display); @@ -155,13 +186,16 @@ static bool handle_keybinding(struct tinywl_server *server, xkb_keysym_t sym) { static void keyboard_handle_key( struct wl_listener *listener, void *data) { + /* This event is raised when a key is pressed or released. */ struct tinywl_keyboard *keyboard = wl_container_of(listener, keyboard, key); struct tinywl_server *server = keyboard->server; struct wlr_event_keyboard_key *event = data; struct wlr_seat *seat = server->seat; + /* Translate libinput keycode -> xkbcommon */ uint32_t keycode = event->keycode + 8; + /* Get a list of keysyms based on the keymap for this keyboard */ const xkb_keysym_t *syms; int nsyms = xkb_state_key_get_syms( keyboard->device->keyboard->xkb_state, keycode, &syms); @@ -169,12 +203,15 @@ static void keyboard_handle_key( bool handled = false; uint32_t modifiers = wlr_keyboard_get_modifiers(keyboard->device->keyboard); if ((modifiers & WLR_MODIFIER_ALT) && event->state == WLR_KEY_PRESSED) { + /* If alt is held down and this button was _pressed_, we attempt to + * process it as a compositor keybinding. */ for (int i = 0; i < nsyms; i++) { handled = handle_keybinding(server, syms[i]); } } if (!handled) { + /* Otherwise, we pass it along to the client. */ wlr_seat_set_keyboard(seat, keyboard->device); wlr_seat_keyboard_notify_key(seat, event->time_msec, event->keycode, event->state); @@ -188,6 +225,8 @@ static void server_new_keyboard(struct tinywl_server *server, keyboard->server = server; keyboard->device = device; + /* We need to prepare an XKB keymap and assign it to the keyboard. This + * assumes the defaults (e.g. layout = "us"). */ struct xkb_rule_names rules = { 0 }; struct xkb_context *context = xkb_context_new(XKB_CONTEXT_NO_FLAGS); struct xkb_keymap *keymap = xkb_map_new_from_names(context, &rules, @@ -198,6 +237,7 @@ static void server_new_keyboard(struct tinywl_server *server, xkb_context_unref(context); wlr_keyboard_set_repeat_info(device->keyboard, 25, 600); + /* Here we set up listeners for keyboard events. */ keyboard->modifiers.notify = keyboard_handle_modifiers; wl_signal_add(&device->keyboard->events.modifiers, &keyboard->modifiers); keyboard->key.notify = keyboard_handle_key; @@ -205,15 +245,22 @@ static void server_new_keyboard(struct tinywl_server *server, wlr_seat_set_keyboard(server->seat, device); + /* And add the keyboard to our list of keyboards */ wl_list_insert(&server->keyboards, &keyboard->link); } static void server_new_pointer(struct tinywl_server *server, struct wlr_input_device *device) { + /* We don't do anything special with pointers. All of our pointer handling + * is proxied through wlr_cursor. On another compositor, you might take this + * opportunity to do libinput configuration on the device to set + * acceleration, etc. */ wlr_cursor_attach_input_device(server->cursor, device); } static void server_new_input(struct wl_listener *listener, void *data) { + /* This event is raised by the backend when a new input device becomes + * available. */ struct tinywl_server *server = wl_container_of(listener, server, new_input); struct wlr_input_device *device = data; @@ -225,6 +272,9 @@ static void server_new_input(struct wl_listener *listener, void *data) { server_new_pointer(server, device); break; } + /* We need to let the wlr_seat know what our capabilities are, which is + * communiciated to the client. In TinyWL we always have a cursor, even if + * there are no pointer devices, so we always include that capability. */ uint32_t caps = WL_SEAT_CAPABILITY_POINTER; if (!wl_list_empty(&server->keyboards)) { caps |= WL_SEAT_CAPABILITY_KEYBOARD; @@ -235,10 +285,17 @@ static void server_new_input(struct wl_listener *listener, void *data) { static void seat_request_cursor(struct wl_listener *listener, void *data) { struct tinywl_server *server = wl_container_of( listener, server, request_cursor); + /* This event is rasied by the seat when a client provides a cursor image */ struct wlr_seat_pointer_request_set_cursor_event *event = data; struct wlr_seat_client *focused_client = server->seat->pointer_state.focused_client; + /* This can be sent by any client, so we check to make sure this one is + * actually has pointer focus first. */ if (focused_client == event->seat_client) { + /* Once we've vetted the client, we can tell the cursor to use the + * provided surface as the cursor image. It will set the hardware cursor + * on the output that it's currently on and continue to do so as the + * cursor moves between outputs. */ wlr_cursor_set_surface(server->cursor, event->surface, event->hotspot_x, event->hotspot_y); } @@ -247,6 +304,13 @@ static void seat_request_cursor(struct wl_listener *listener, void *data) { static bool view_at(struct tinywl_view *view, double lx, double ly, struct wlr_surface **surface, double *sx, double *sy) { + /* + * XDG toplevels may have nested surfaces, such as popup windows for context + * menus or tooltips. This function tests if any of those are underneath the + * coordinates lx and ly (in output Layout Coordinates). If so, it sets the + * surface pointer to that wlr_surface and the sx and sy coordinates to the + * coordinates relative to that surface's top-left corner. + */ double view_sx = lx - view->x; double view_sy = ly - view->y; @@ -270,6 +334,8 @@ static bool view_at(struct tinywl_view *view, static struct tinywl_view *desktop_view_at( struct tinywl_server *server, double lx, double ly, struct wlr_surface **surface, double *sx, double *sy) { + /* This iterates over all of our surfaces and attempts to find one under the + * cursor. This relies on server->views being ordered from top-to-bottom. */ struct tinywl_view *view; wl_list_for_each(view, &server->views, link) { if (view_at(view, lx, ly, surface, sx, sy)) { @@ -280,11 +346,22 @@ static struct tinywl_view *desktop_view_at( } static void process_cursor_move(struct tinywl_server *server, uint32_t time) { + /* Move the grabbed view to the new position. */ server->grabbed_view->x = server->cursor->x - server->grab_x; server->grabbed_view->y = server->cursor->y - server->grab_y; } static void process_cursor_resize(struct tinywl_server *server, uint32_t time) { + /* + * Resizing the grabbed view can be a little bit complicated, because we + * could be resizing from any corner or edge. This not only resizes the view + * on one or two axes, but can also move the view if you resize from the top + * or left edges (or top-left corner). + * + * Note that I took some shortcuts here. In a more fleshed-out compositor, + * you'd wait for the client to prepare a buffer at the new size, then + * commit any movement that was prepared. + */ struct tinywl_view *view = server->grabbed_view; double dx = server->cursor->x - server->grab_x; double dy = server->cursor->y - server->grab_y; @@ -316,6 +393,7 @@ static void process_cursor_resize(struct tinywl_server *server, uint32_t time) { } static void process_cursor_motion(struct tinywl_server *server, uint32_t time) { + /* If the mode is non-passthrough, delegate to those functions. */ if (server->cursor_mode == TINYWL_CURSOR_MOVE) { process_cursor_move(server, time); return; @@ -324,30 +402,53 @@ static void process_cursor_motion(struct tinywl_server *server, uint32_t time) { return; } + /* Otherwise, find the view under the pointer and send the event along. */ double sx, sy; struct wlr_seat *seat = server->seat; struct wlr_surface *surface = NULL; struct tinywl_view *view = desktop_view_at(server, server->cursor->x, server->cursor->y, &surface, &sx, &sy); if (!view) { + /* If there's no view under the cursor, set the cursor image to a + * default. This is what makes the cursor image appear when you move it + * around the screen, not over any views. */ wlr_xcursor_manager_set_cursor_image( server->cursor_mgr, "left_ptr", server->cursor); } if (surface) { bool focus_changed = seat->pointer_state.focused_surface != surface; + /* + * "Enter" the surface if necessary. This lets the client know that the + * cursor has entered one of its surfaces. + * + * Note that this gives the surface "pointer focus", which is distinct + * from keyboard focus. You get pointer focus by moving the pointer over + * a window. + */ wlr_seat_pointer_notify_enter(seat, surface, sx, sy); if (!focus_changed) { + /* The enter event contains coordinates, so we only need to notify + * on motion if the focus did not change. */ wlr_seat_pointer_notify_motion(seat, time, sx, sy); } } else { + /* Clear pointer focus so future button events and such are not sent to + * the last client to have the cursor over it. */ wlr_seat_pointer_clear_focus(seat); } } static void server_cursor_motion(struct wl_listener *listener, void *data) { + /* This event is forwarded by the cursor when a pointer emits a _relative_ + * pointer motion event (i.e. a delta) */ struct tinywl_server *server = wl_container_of(listener, server, cursor_motion); struct wlr_event_pointer_motion *event = data; + /* The cursor doesn't move unless we tell it to. The cursor automatically + * handles constraining the motion to the output layout, as well as any + * special configuration applied for the specific input device which + * generated the event. You can pass NULL for the device if you want to move + * the cursor around without any input. */ wlr_cursor_move(server->cursor, event->device, event->delta_x, event->delta_y); process_cursor_motion(server, event->time_msec); @@ -355,6 +456,12 @@ static void server_cursor_motion(struct wl_listener *listener, void *data) { static void server_cursor_motion_absolute( struct wl_listener *listener, void *data) { + /* This event is forwarded by the cursor when a pointer emits an _absolute_ + * motion event, from 0..1 on each axis. This happens, for example, when + * wlroots is running under a Wayland window rather than KMS+DRM, and you + * move the mouse over the window. You could enter the window from any edge, + * so we have to warp the mouse there. There is also some hardware which + * emits these events. */ struct tinywl_server *server = wl_container_of(listener, server, cursor_motion_absolute); struct wlr_event_pointer_motion_absolute *event = data; @@ -363,9 +470,12 @@ static void server_cursor_motion_absolute( } static void server_cursor_button(struct wl_listener *listener, void *data) { + /* This event is forwarded by the cursor when a pointer emits a button + * event. */ struct tinywl_server *server = wl_container_of(listener, server, cursor_button); struct wlr_event_pointer_button *event = data; + /* Notify the client with pointer focus that a button press has occured */ wlr_seat_pointer_notify_button(server->seat, event->time_msec, event->button, event->state); double sx, sy; @@ -374,21 +484,28 @@ static void server_cursor_button(struct wl_listener *listener, void *data) { struct tinywl_view *view = desktop_view_at(server, server->cursor->x, server->cursor->y, &surface, &sx, &sy); if (event->state == WLR_BUTTON_RELEASED) { + /* If you released any buttons, we exit interactive move/resize mode. */ server->cursor_mode = TINYWL_CURSOR_PASSTHROUGH; } else { + /* Focus that client if the button was _pressed_ */ focus_view(view, surface); } } static void server_cursor_axis(struct wl_listener *listener, void *data) { + /* This event is forwarded by the cursor when a pointer emits an axis event, + * for example when you move the scroll wheel. */ struct tinywl_server *server = wl_container_of(listener, server, cursor_axis); struct wlr_event_pointer_axis *event = data; + /* Notify the client with pointer focus of the axis event. */ wlr_seat_pointer_notify_axis(server->seat, event->time_msec, event->orientation, event->delta, event->delta_discrete, event->source); } +/* Used to move all of the data necessary to render a surface from the top-level + * frame handler to the per-surface render function. */ struct render_data { struct wlr_output *output; struct wlr_renderer *renderer; @@ -398,20 +515,32 @@ struct render_data { static void render_surface(struct wlr_surface *surface, int sx, int sy, void *data) { + /* This function is called for every surface that needs to be rendered. */ struct render_data *rdata = data; struct tinywl_view *view = rdata->view; struct wlr_output *output = rdata->output; + /* We first obtain a wlr_texture, which is a GPU resource. wlroots + * automatically handles negotiating these with the client. The underlying + * resource could be an opaque handle passed from the client, or the client + * could have sent a pixel buffer which we copied to the GPU, or a few other + * means. You don't have to worry about this, wlroots takes care of it. */ struct wlr_texture *texture = wlr_surface_get_texture(surface); if (texture == NULL) { return; } + /* The view has a position in layout coordinates. If you have two displays, + * one next to the other, both 1080p, a view on the rightmost display might + * have layout coordinates of 2000,100. We need to translate that to + * output-local coordinates, or (2000 - 1920). */ double ox = 0, oy = 0; wlr_output_layout_output_coords( view->server->output_layout, output, &ox, &oy); ox += view->x + sx, oy += view->y + sy; + /* We also have to apply the scale factor for HiDPI outputs. This is only + * part of the puzzle, TinyWL does not fully support HiDPI. */ struct wlr_box box = { .x = ox * output->scale, .y = oy * output->scale, @@ -419,18 +548,35 @@ static void render_surface(struct wlr_surface *surface, .height = surface->current.height * output->scale, }; + /* + * Those familiar with OpenGL are also familiar with the role of matricies + * in graphics programming. We need to prepare a matrix to render the view + * with. wlr_matrix_project_box is a helper which takes a box with a desired + * x, y coodrinates, width and height, and an output geometry, then + * prepares an orthographic projection and multiplies the necessary + * transforms to produce a model-view-projection matrix. + * + * Naturally you can do this any way you like, for example to make a 3D + * compositor. + */ float matrix[9]; enum wl_output_transform transform = wlr_output_transform_invert(surface->current.transform); wlr_matrix_project_box(matrix, &box, transform, 0, output->transform_matrix); + /* This takes our matrix, the texture, and an alpha, and performs the actual + * rendering on the GPU. */ wlr_render_texture_with_matrix(rdata->renderer, texture, matrix, 1); + /* This lets the client know that we've displayed that frame and it can + * prepare another one now if it likes. */ wlr_surface_send_frame_done(surface, rdata->when); } static void output_frame(struct wl_listener *listener, void *data) { + /* This function is called every time an output is ready to display a frame, + * generally at the output's refresh rate (e.g. 60Hz). */ struct tinywl_output *output = wl_container_of(listener, output, frame); struct wlr_renderer *renderer = output->server->renderer; @@ -438,19 +584,25 @@ static void output_frame(struct wl_listener *listener, void *data) { struct timespec now; clock_gettime(CLOCK_MONOTONIC, &now); + /* wlr_output_make_current makes the OpenGL context current. */ if (!wlr_output_make_current(output->wlr_output, NULL)) { return; } + /* The "effective" resolution can change if you rotate your outputs. */ int width, height; wlr_output_effective_resolution(output->wlr_output, &width, &height); + /* Begin the renderer (calls glViewport and some other GL sanity checks) */ wlr_renderer_begin(renderer, width, height); float color[4] = {0.3, 0.3, 0.3, 1.0}; wlr_renderer_clear(renderer, color); + /* Each subsequent window we render is rendered on top of the last. Because + * our view list is ordered front-to-back, we iterate over it backwards. */ struct tinywl_view *view; wl_list_for_each_reverse(view, &output->server->views, link) { if (!view->mapped) { + /* An unmapped view should not be rendered. */ continue; } struct render_data rdata = { @@ -459,50 +611,73 @@ static void output_frame(struct wl_listener *listener, void *data) { .renderer = renderer, .when = &now, }; + /* This calls our render_surface function for each surface among the + * xdg_surface's toplevel and popups. */ wlr_xdg_surface_for_each_surface(view->xdg_surface, render_surface, &rdata); } + /* Conclude rendering and swap the buffers, showing the final frame + * on-screen. */ wlr_renderer_end(renderer); wlr_output_swap_buffers(output->wlr_output, NULL, NULL); } static void server_new_output(struct wl_listener *listener, void *data) { + /* This event is rasied by the backend when a new output (aka a display or + * monitor) becomes available. */ struct tinywl_server *server = wl_container_of(listener, server, new_output); struct wlr_output *wlr_output = data; + /* Some backends don't have modes. DRM+KMS does, and we need to set a mode + * before we can use the output. The mode is a tuple of (width, height, + * refresh rate), and each monitor supports only a specific set of modes. We + * just pick the first, a more sophisticated compositor would let the user + * configure it or pick the mode the display advertises as preferred. */ if (!wl_list_empty(&wlr_output->modes)) { struct wlr_output_mode *mode = wl_container_of(wlr_output->modes.prev, mode, link); wlr_output_set_mode(wlr_output, mode); } + /* Allocates and configures our state for this output */ struct tinywl_output *output = calloc(1, sizeof(struct tinywl_output)); output->wlr_output = wlr_output; output->server = server; + /* Sets up a listener for the frame notify event. */ output->frame.notify = output_frame; wl_signal_add(&wlr_output->events.frame, &output->frame); wl_list_insert(&server->outputs, &output->link); + /* Adds this to the output layout. The add_auto function arranges outputs + * from left-to-right in the order they appear. A more sophisticated + * compositor would let the user configure the arrangement of outputs in the + * layout. */ wlr_output_layout_add_auto(server->output_layout, wlr_output); + /* Creating the global adds a wl_output global to the display, which Wayland + * clients can see to find out information about the output (such as + * DPI, scale factor, manufacturer, etc). */ wlr_output_create_global(wlr_output); } static void xdg_surface_map(struct wl_listener *listener, void *data) { + /* Called when the surface is mapped, or ready to display on-screen. */ struct tinywl_view *view = wl_container_of(listener, view, map); view->mapped = true; focus_view(view, view->xdg_surface->surface); } static void xdg_surface_unmap(struct wl_listener *listener, void *data) { + /* Called when the surface is unmapped, and should no longer be shown. */ struct tinywl_view *view = wl_container_of(listener, view, unmap); view->mapped = false; } static void xdg_surface_destroy(struct wl_listener *listener, void *data) { + /* Called when the surface is destroyed and should never be shown again. */ struct tinywl_view *view = wl_container_of(listener, view, destroy); wl_list_remove(&view->link); free(view); @@ -510,10 +685,14 @@ static void xdg_surface_destroy(struct wl_listener *listener, void *data) { static void begin_interactive(struct tinywl_view *view, enum tinywl_cursor_mode mode, uint32_t edges) { + /* This function sets up an interactive move or resize operation, where the + * compositor stops propegating pointer events to clients and instead + * consumes them itself, to move or resize windows. */ struct tinywl_server *server = view->server; struct wlr_surface *focused_surface = server->seat->pointer_state.focused_surface; if (view->xdg_surface->surface != focused_surface) { + /* Deny move/resize requests from unfocused clients. */ return; } server->grabbed_view = view; @@ -534,18 +713,30 @@ static void begin_interactive(struct tinywl_view *view, static void xdg_toplevel_request_move( struct wl_listener *listener, void *data) { + /* This event is raised when a client would like to begin an interactive + * move, typically because the user clicked on their client-side + * decorations. Note that a more sophisticated compositor should check the + * provied serial against a list of button press serials sent to this + * client, to prevent the client from requesting this whenver they want. */ struct tinywl_view *view = wl_container_of(listener, view, request_move); begin_interactive(view, TINYWL_CURSOR_MOVE, 0); } static void xdg_toplevel_request_resize( struct wl_listener *listener, void *data) { + /* This event is raised when a client would like to begin an interactive + * resize, typically because the user clicked on their client-side + * decorations. Note that a more sophisticated compositor should check the + * provied serial against a list of button press serials sent to this + * client, to prevent the client from requesting this whenver they want. */ struct wlr_xdg_toplevel_resize_event *event = data; struct tinywl_view *view = wl_container_of(listener, view, request_resize); begin_interactive(view, TINYWL_CURSOR_RESIZE, event->edges); } static void server_new_xdg_surface(struct wl_listener *listener, void *data) { + /* This event is raised when wlr_xdg_shell receives a new xdg surface from a + * client, either a toplevel (application window) or popup. */ struct tinywl_server *server = wl_container_of(listener, server, new_xdg_surface); struct wlr_xdg_surface *xdg_surface = data; @@ -553,11 +744,13 @@ static void server_new_xdg_surface(struct wl_listener *listener, void *data) { return; } + /* Allocate a tinywl_view for this surface */ struct tinywl_view *view = calloc(1, sizeof(struct tinywl_view)); view->server = server; view->xdg_surface = xdg_surface; + /* Listen to the various events it can emit */ view->map.notify = xdg_surface_map; wl_signal_add(&xdg_surface->events.map, &view->map); view->unmap.notify = xdg_surface_unmap; @@ -565,12 +758,14 @@ static void server_new_xdg_surface(struct wl_listener *listener, void *data) { view->destroy.notify = xdg_surface_destroy; wl_signal_add(&xdg_surface->events.destroy, &view->destroy); + /* cotd */ struct wlr_xdg_toplevel *toplevel = xdg_surface->toplevel; view->request_move.notify = xdg_toplevel_request_move; wl_signal_add(&toplevel->events.request_move, &view->request_move); view->request_resize.notify = xdg_toplevel_request_resize; wl_signal_add(&toplevel->events.request_resize, &view->request_resize); + /* Add it to the list of views. */ wl_list_insert(&server->views, &view->link); } @@ -595,34 +790,83 @@ int main(int argc, char *argv[]) { } struct tinywl_server server; + /* The Wayland display is managed by libwayland. It handles accepting + * clients from the Unix socket, manging Wayland globals, and so on. */ server.wl_display = wl_display_create(); + /* The backend is a wlroots feature which abstracts the underlying input and + * output hardware. The autocreate option will choose the most suitable + * backend based on the current environment, such as opening an X11 window + * if an X11 server is running. The NULL argument here optionally allows you + * to pass in a custom renderer if wlr_renderer doesn't meet your needs. The + * backend uses the renderer, for example, to fall back to software cursors + * if the backend does not support hardware cursors (some older GPUs + * don't). */ server.backend = wlr_backend_autocreate(server.wl_display, NULL); + /* If we don't provide a renderer, autocreate makes a GLES2 renderer for us. + * The renderer is responsible for defining the various pixel formats it + * supports for shared memory, this configures that for clients. */ server.renderer = wlr_backend_get_renderer(server.backend); wlr_renderer_init_wl_display(server.renderer, server.wl_display); + /* This creates some hands-off wlroots interfaces. The compositor is + * necessary for clients to allocate surfaces, dmabuf allows them to use + * opaque GPU handles for buffers to avoid copying pixels on the CPU, and + * the data device manager handles the clipboard. Each of these wlroots + * interfaces has room for you to dig your fingers in and play with their + * behavior if you want. */ wlr_compositor_create(server.wl_display, server.renderer); wlr_linux_dmabuf_v1_create(server.wl_display, server.renderer); wlr_data_device_manager_create(server.wl_display); + /* Creates an output layout, which a wlroots utility for working with an + * arrangement of screens in a physical layout. */ server.output_layout = wlr_output_layout_create(); + /* Configure a listener to be notified when new outputs are available on the + * backend. */ wl_list_init(&server.outputs); server.new_output.notify = server_new_output; wl_signal_add(&server.backend->events.new_output, &server.new_output); + /* Set up our list of views and the xdg-shell. The xdg-shell is a Wayland + * protocol which is used for application windows. For more detail on + * shells, refer to my article: + * + * https://drewdevault.com/2018/07/29/Wayland-shells.html + */ wl_list_init(&server.views); server.xdg_shell = wlr_xdg_shell_create(server.wl_display); server.new_xdg_surface.notify = server_new_xdg_surface; wl_signal_add(&server.xdg_shell->events.new_surface, &server.new_xdg_surface); + /* + * Creates a cursor, which is a wlroots utility for tracking the cursor + * image shown on screen. + */ server.cursor = wlr_cursor_create(); wlr_cursor_attach_output_layout(server.cursor, server.output_layout); + /* Creates an xcursor manager, another wlroots utility which loads up + * Xcursor themes to source cursor images from and makes sure that cursor + * images are available at all scale factors on the screen (necessary for + * HiDPI support). We add a cursor theme at scale factor 1 to begin with. */ server.cursor_mgr = wlr_xcursor_manager_create(NULL, 24); wlr_xcursor_manager_load(server.cursor_mgr, 1); + /* + * wlr_cursor *only* displays an image on screen. It does not move around + * when the pointer moves. However, we can attach input devices to it, and + * it will generate aggregate events for all of them. In these events, we + * can choose how we want to process them, forwarding them to clients and + * moving the cursor around. More detail on this process is described in my + * input handling blog post: + * + * https://drewdevault.com/2018/07/17/Input-handling-in-wlroots.html + * + * And more comments are sprinkled throughout the notify functions above. + */ server.cursor_motion.notify = server_cursor_motion; wl_signal_add(&server.cursor->events.motion, &server.cursor_motion); server.cursor_motion_absolute.notify = server_cursor_motion_absolute; @@ -633,6 +877,12 @@ int main(int argc, char *argv[]) { server.cursor_axis.notify = server_cursor_axis; wl_signal_add(&server.cursor->events.axis, &server.cursor_axis); + /* + * Configures a seat, which is a single "seat" at which a user sits and + * operates the computer. This conceptually includes up to one keyboard, + * pointer, touch, and drawing tablet device. We also rig up a listener to + * let us know when new input devices are available on the backend. + */ wl_list_init(&server.keyboards); server.new_input.notify = server_new_input; wl_signal_add(&server.backend->events.new_input, &server.new_input); @@ -641,28 +891,38 @@ int main(int argc, char *argv[]) { wl_signal_add(&server.seat->events.request_set_cursor, &server.request_cursor); + /* Add a Unix socket to the Wayland display. */ const char *socket = wl_display_add_socket_auto(server.wl_display); if (!socket) { wlr_backend_destroy(server.backend); return 1; } + /* Start the backend. This will enumerate outputs and inputs, become the DRM + * master, etc */ if (!wlr_backend_start(server.backend)) { wlr_backend_destroy(server.backend); wl_display_destroy(server.wl_display); return 1; } + /* Set the WAYLAND_DISPLAY environment variable to our socket and run the + * startup command if requested. */ setenv("WAYLAND_DISPLAY", socket, true); if (startup_cmd) { if (fork() == 0) { execl("/bin/sh", "/bin/sh", "-c", startup_cmd, (void *)NULL); } } + /* Run the Wayland event loop. This does not return until you exit the + * compositor. Starting the backend rigged up all of the necessary event + * loop configuration to listen to libinput events, DRM events, generate + * frame events at the refresh rate, and so on. */ wlr_log(WLR_INFO, "Running Wayland compositor on WAYLAND_DISPLAY=%s", socket); wl_display_run(server.wl_display); + /* Once wl_display_run returns, we shut down the server. */ wl_display_destroy_clients(server.wl_display); wl_display_destroy(server.wl_display); return 0; |