swaylock: implement a proper render loop

3 files changed, 105 insertions, 57 deletions

diff --git a/swaylock/main.c b/swaylock/main.c
index f89f2849..591df7b4 100644
--- a/swaylock/main.c
+++ b/swaylock/main.c
@@ -131,14 +131,58 @@ static const struct zwlr_layer_surface_v1_listener layer_surface_listener = {
         .closed = layer_surface_closed,
 };
 
-static void handle_wl_output_geometry(void *data, struct wl_output *output, int32_t x,
-                int32_t y, int32_t width_mm, int32_t height_mm, int32_t subpixel,
-                const char *make, const char *model, int32_t transform) {
+static const struct wl_callback_listener surface_frame_listener;
+
+static void surface_frame_handle_done(void *data, struct wl_callback *callback,
+                uint32_t time) {
+        struct swaylock_surface *surface = data;
+
+        wl_callback_destroy(callback);
+        surface->frame_pending = false;
+
+        if (surface->dirty) {
+                // Schedule a frame in case the surface is damaged again
+                struct wl_callback *callback = wl_surface_frame(surface->surface);
+                wl_callback_add_listener(callback, &surface_frame_listener, surface);
+                surface->frame_pending = true;
+
+                render_frame(surface);
+                surface->dirty = false;
+        }
+}
+
+static const struct wl_callback_listener surface_frame_listener = {
+        .done = surface_frame_handle_done,
+};
+
+void damage_surface(struct swaylock_surface *surface) {
+        surface->dirty = true;
+        if (surface->frame_pending) {
+                return;
+        }
+
+        struct wl_callback *callback = wl_surface_frame(surface->surface);
+        wl_callback_add_listener(callback, &surface_frame_listener, surface);
+        surface->frame_pending = true;
+        wl_surface_commit(surface->surface);
+}
+
+void damage_state(struct swaylock_state *state) {
+        struct swaylock_surface *surface;
+        wl_list_for_each(surface, &state->surfaces, link) {
+                damage_surface(surface);
+        }
+}
+
+static void handle_wl_output_geometry(void *data, struct wl_output *output,
+                int32_t x, int32_t y, int32_t width_mm, int32_t height_mm,
+                int32_t subpixel, const char *make, const char *model,
+                int32_t transform) {
         // Who cares
 }
 
-static void handle_wl_output_mode(void *data, struct wl_output *output, uint32_t flags,
-                int32_t width, int32_t height, int32_t refresh) {
+static void handle_wl_output_mode(void *data, struct wl_output *output,
+                uint32_t flags, int32_t width, int32_t height, int32_t refresh) {
         // Who cares
 }
 
@@ -151,7 +195,7 @@ static void handle_wl_output_scale(void *data, struct wl_output *output,
         struct swaylock_surface *surface = data;
         surface->scale = factor;
         if (surface->state->run_display) {
-                render_frames(surface->state);
+                damage_surface(surface);
         }
 }
 
diff --git a/swaylock/password.c b/swaylock/password.c
index 1ad5cd81..6d493309 100644
--- a/swaylock/password.c
+++ b/swaylock/password.c
@@ -93,58 +93,58 @@ static void append_ch(struct swaylock_password *pw, uint32_t codepoint) {
 void swaylock_handle_key(struct swaylock_state *state,
                 xkb_keysym_t keysym, uint32_t codepoint) {
         switch (keysym) {
-                case XKB_KEY_KP_Enter: /* fallthrough */
-                case XKB_KEY_Return:
-                        state->auth_state = AUTH_STATE_VALIDATING;
-                        render_frames(state);
-                        wl_display_roundtrip(state->display);
-                        if (attempt_password(&state->password)) {
-                                state->run_display = false;
-                                break;
-                        }
-                        state->auth_state = AUTH_STATE_INVALID;
-                        render_frames(state);
+        case XKB_KEY_KP_Enter: /* fallthrough */
+        case XKB_KEY_Return:
+                state->auth_state = AUTH_STATE_VALIDATING;
+                damage_state(state);
+                wl_display_roundtrip(state->display);
+                if (attempt_password(&state->password)) {
+                        state->run_display = false;
                         break;
-                case XKB_KEY_Delete:
-                case XKB_KEY_BackSpace:
-                        if (backspace(&state->password)) {
-                                state->auth_state = AUTH_STATE_BACKSPACE;
-                        } else {
-                                state->auth_state = AUTH_STATE_CLEAR;
-                        }
-                        render_frames(state);
-                        break;
-                case XKB_KEY_Escape: 
-                        clear_password_buffer(&state->password);
+                }
+                state->auth_state = AUTH_STATE_INVALID;
+                damage_state(state);
+                break;
+        case XKB_KEY_Delete:
+        case XKB_KEY_BackSpace:
+                if (backspace(&state->password)) {
+                        state->auth_state = AUTH_STATE_BACKSPACE;
+                } else {
                         state->auth_state = AUTH_STATE_CLEAR;
-                        render_frames(state);
-                        break;
-                case XKB_KEY_Caps_Lock:
-                        /* The state is getting active after this
-                         * so we need to manually toggle it */
-                        state->xkb.caps_lock = !state->xkb.caps_lock;
-                        state->auth_state = AUTH_STATE_INPUT_NOP;
-                        render_frames(state);
-                        break;
-                case XKB_KEY_Shift_L:
-                case XKB_KEY_Shift_R:
-                case XKB_KEY_Control_L:
-                case XKB_KEY_Control_R:
-                case XKB_KEY_Meta_L:
-                case XKB_KEY_Meta_R:
-                case XKB_KEY_Alt_L:
-                case XKB_KEY_Alt_R:
-                case XKB_KEY_Super_L:
-                case XKB_KEY_Super_R:
-                        state->auth_state = AUTH_STATE_INPUT_NOP;
-                        render_frames(state);
-                        break;
-                default:
-                        if (codepoint) {
-                                append_ch(&state->password, codepoint);
-                                state->auth_state = AUTH_STATE_INPUT;
-                                render_frames(state);
-                        }
-                        break;
+                }
+                damage_state(state);
+                break;
+        case XKB_KEY_Escape:
+                clear_password_buffer(&state->password);
+                state->auth_state = AUTH_STATE_CLEAR;
+                damage_state(state);
+                break;
+        case XKB_KEY_Caps_Lock:
+                /* The state is getting active after this
+                 * so we need to manually toggle it */
+                state->xkb.caps_lock = !state->xkb.caps_lock;
+                state->auth_state = AUTH_STATE_INPUT_NOP;
+                damage_state(state);
+                break;
+        case XKB_KEY_Shift_L:
+        case XKB_KEY_Shift_R:
+        case XKB_KEY_Control_L:
+        case XKB_KEY_Control_R:
+        case XKB_KEY_Meta_L:
+        case XKB_KEY_Meta_R:
+        case XKB_KEY_Alt_L:
+        case XKB_KEY_Alt_R:
+        case XKB_KEY_Super_L:
+        case XKB_KEY_Super_R:
+                state->auth_state = AUTH_STATE_INPUT_NOP;
+                damage_state(state);
+                break;
+        default:
+                if (codepoint) {
+                        append_ch(&state->password, codepoint);
+                        state->auth_state = AUTH_STATE_INPUT;
+                        damage_state(state);
+                }
+                break;
         }
 }
diff --git a/swaylock/render.c b/swaylock/render.c
index 05236dea..2032ddcf 100644
--- a/swaylock/render.c
+++ b/swaylock/render.c
@@ -23,6 +23,10 @@ void render_frame(struct swaylock_surface *surface) {
 
         surface->current_buffer = get_next_buffer(state->shm,
                         surface->buffers, buffer_width, buffer_height);
+        if (surface->current_buffer == NULL) {
+                return;
+        }
+
         cairo_t *cairo = surface->current_buffer->cairo;
         cairo_identity_matrix(cairo);