8 files changed, 34 insertions, 6 deletions
diff --git a/rootston/desktop.c b/rootston/desktop.c
index 8ac741bb..b42a71a2 100644
--- a/rootston/desktop.c
+++ b/rootston/desktop.c
@@ -23,6 +23,16 @@
 #include "rootston/view.h"
 #include "rootston/xcursor.h"
 
+
+struct roots_view *view_create() {
+	struct roots_view *view = calloc(1, sizeof(struct roots_view));
+	if (!view) {
+		return NULL;
+	}
+	view->alpha = 1.0f;
+	return view;
+}
+
 void view_get_box(const struct roots_view *view, struct wlr_box *box) {
 	box->x = view->x;
 	box->y = view->y;
@@ -269,6 +279,15 @@ void view_rotate(struct roots_view *view, float rotation) {
 	view_damage_whole(view);
 }
 
+void view_cycle_alpha(struct roots_view *view) {
+	view->alpha -= 0.05;
+	/* Don't go completely transparent */
+	if (view->alpha < 0.1) {
+		view->alpha = 1.0;
+	}
+	view_damage_whole(view);
+}
+
 void view_close(struct roots_view *view) {
 	if (view->close) {
 		view->close(view);
diff --git a/rootston/keyboard.c b/rootston/keyboard.c
index 6ec90c31..b5dac51c 100644
--- a/rootston/keyboard.c
+++ b/rootston/keyboard.c
@@ -106,6 +106,11 @@ static void keyboard_binding_execute(struct roots_keyboard *keyboard,
 		}
 	} else if (strcmp(command, "next_window") == 0) {
 		roots_seat_cycle_focus(seat);
+	} else if (strcmp(command, "alpha") == 0) {
+		struct roots_view *focus = roots_seat_get_focus(seat);
+		if (focus != NULL) {
+			view_cycle_alpha(focus);
+		}
 	} else if (strncmp(exec_prefix, command, strlen(exec_prefix)) == 0) {
 		const char *shell_cmd = command + strlen(exec_prefix);
 		pid_t pid = fork();
diff --git a/rootston/output.c b/rootston/output.c
index a354ebf8..3e954989 100644
--- a/rootston/output.c
+++ b/rootston/output.c
@@ -202,6 +202,7 @@ struct render_data {
 	struct roots_output *output;
 	struct timespec *when;
 	pixman_region32_t *damage;
+	float alpha;
 };
 
 /**
@@ -296,7 +297,7 @@ static void render_surface(struct wlr_surface *surface, double lx, double ly,
 	pixman_box32_t *rects = pixman_region32_rectangles(&damage, &nrects);
 	for (int i = 0; i < nrects; ++i) {
 		scissor_output(output, &rects[i]);
-		wlr_render_with_matrix(renderer, surface->texture, &matrix);
+		wlr_render_with_matrix(renderer, surface->texture, &matrix, data->alpha);
 	}
 
 damage_finish:
@@ -355,7 +356,7 @@ static void render_decorations(struct roots_view *view,
 	float matrix[16];
 	wlr_matrix_project_box(&matrix, &box, WL_OUTPUT_TRANSFORM_NORMAL,
 		view->rotation, &output->wlr_output->transform_matrix);
-	float color[] = { 0.2, 0.2, 0.2, 1 };
+	float color[] = { 0.2, 0.2, 0.2, view->alpha };
 
 	int nrects;
 	pixman_box32_t *rects =
@@ -376,6 +377,7 @@ static void render_view(struct roots_view *view, struct render_data *data) {
 		return;
 	}
 
+	data->alpha = view->alpha;
 	render_decorations(view, data);
 	view_for_each_surface(view, render_surface, data);
 }
diff --git a/rootston/rootston.ini.example b/rootston/rootston.ini.example
index a6619767..6f29a35d 100644
--- a/rootston/rootston.ini.example
+++ b/rootston/rootston.ini.example
@@ -42,8 +42,10 @@ meta-key = Logo
 # - "exec" to execute a shell command
 # - "close" to close the current view
 # - "next_window" to cycle through windows
+# - "alpha" to cycle a window's alpha channel
 [bindings]
 Logo+Shift+e = exit
 Logo+q = close
 Logo+m = maximize
 Alt+Tab = next_window
+Ctrl+Shift+a = alpha
diff --git a/rootston/wl_shell.c b/rootston/wl_shell.c
index 44a65cf5..899df1c6 100644
--- a/rootston/wl_shell.c
+++ b/rootston/wl_shell.c
@@ -227,7 +227,7 @@ void handle_wl_shell_surface(struct wl_listener *listener, void *data) {
 	roots_surface->surface_commit.notify = handle_surface_commit;
 	wl_signal_add(&surface->surface->events.commit, &roots_surface->surface_commit);
 
-	struct roots_view *view = calloc(1, sizeof(struct roots_view));
+	struct roots_view *view = view_create();
 	if (!view) {
 		free(roots_surface);
 		return;
diff --git a/rootston/xdg_shell.c b/rootston/xdg_shell.c
index 8340de46..9368ce0b 100644
--- a/rootston/xdg_shell.c
+++ b/rootston/xdg_shell.c
@@ -333,7 +333,7 @@ void handle_xdg_shell_surface(struct wl_listener *listener, void *data) {
 	roots_surface->new_popup.notify = handle_new_popup;
 	wl_signal_add(&surface->events.new_popup, &roots_surface->new_popup);
 
-	struct roots_view *view = calloc(1, sizeof(struct roots_view));
+	struct roots_view *view = view_create();
 	if (!view) {
 		free(roots_surface);
 		return;
diff --git a/rootston/xdg_shell_v6.c b/rootston/xdg_shell_v6.c
index 8e6674ab..eda349cb 100644
--- a/rootston/xdg_shell_v6.c
+++ b/rootston/xdg_shell_v6.c
@@ -333,7 +333,7 @@ void handle_xdg_shell_v6_surface(struct wl_listener *listener, void *data) {
 	roots_surface->new_popup.notify = handle_new_popup;
 	wl_signal_add(&surface->events.new_popup, &roots_surface->new_popup);
 
-	struct roots_view *view = calloc(1, sizeof(struct roots_view));
+	struct roots_view *view = view_create();
 	if (!view) {
 		free(roots_surface);
 		return;
diff --git a/rootston/xwayland.c b/rootston/xwayland.c
index e9e0d5e0..f917fe5d 100644
--- a/rootston/xwayland.c
+++ b/rootston/xwayland.c
@@ -317,7 +317,7 @@ void handle_xwayland_surface(struct wl_listener *listener, void *data) {
 	wl_signal_add(&surface->surface->events.commit,
 		&roots_surface->surface_commit);
 
-	struct roots_view *view = calloc(1, sizeof(struct roots_view));
+	struct roots_view *view = view_create();
 	if (view == NULL) {
 		free(roots_surface);
 		return;