Add option to force user to select a choice box.

include/slurp.h

@@ -14,8 +14,8 @@
 struct slurp_box {
 	int32_t x, y;
 	int32_t width, height;
-	struct wl_list link;
 	char *label;
+	struct wl_list link;
 };
 
 struct slurp_selection {
@@ -51,6 +51,7 @@ struct slurp_state {
 	uint32_t border_weight;
 	bool display_dimensions;
 	bool single_point;
+	bool restrict_selection;
 	struct wl_list boxes; // slurp_box::link
 
 	struct slurp_box result;

main.c

@@ -171,14 +171,19 @@ static void pointer_handle_motion(void *data, struct wl_pointer *wl_pointer,
 static void handle_selection_start(struct slurp_seat *seat,
 				   struct slurp_selection *current_selection) {
 	struct slurp_state *state = seat->state;
-	current_selection->has_selection = true;
 
 	if (state->single_point) {
 		state->result.x = current_selection->x;
 		state->result.y = current_selection->y;
 		state->result.width = state->result.height = 1;
 		state->running = false;
+	} else if (state->restrict_selection) {
+		if (current_selection->has_selection) {
+			state->result = current_selection->selection;
+			state->running = false;
+		}
 	} else {
+		current_selection->has_selection = true;
 		current_selection->anchor_x = current_selection->x;
 		current_selection->anchor_y = current_selection->y;
 	}
@@ -187,7 +192,7 @@ static void handle_selection_start(struct slurp_seat *seat,
 static void handle_selection_end(struct slurp_seat *seat,
 				 struct slurp_selection *current_selection) {
 	struct slurp_state *state = seat->state;
-	if (state->single_point) {
+	if (state->single_point || state->restrict_selection) {
 		return;
 	}
 	if (current_selection->has_selection) {
@@ -645,7 +650,8 @@ static const char usage[] =
 	"  -w n         Set border weight.\n"
 	"  -f s         Set output format.\n"
 	"  -o           Select a display output.\n"
-	"  -p           Select a single point.\n";
+	"  -p           Select a single point.\n"
+	"  -r           Restrict selection to predefined boxes.\n";
 
 uint32_t parse_color(const char *color) {
 	if (color[0] == '#') {
@@ -748,12 +754,13 @@ int main(int argc, char *argv[]) {
 		},
 		.border_weight = 2,
 		.display_dimensions = false,
+		.restrict_selection = false,
 	};
 
 	int opt;
 	char *format = "%x,%y %wx%h\n";
 	bool output_boxes = false;
-	while ((opt = getopt(argc, argv, "hdb:c:s:B:w:pof:")) != -1) {
+	while ((opt = getopt(argc, argv, "hdb:c:s:B:w:prof:")) != -1) {
 		switch (opt) {
 		case 'h':
 			printf("%s", usage);
@@ -792,12 +799,20 @@ int main(int argc, char *argv[]) {
 		case 'o':
 			output_boxes = true;
 			break;
+		case 'r':
+			state.restrict_selection = true;
+			break;
 		default:
 			printf("%s", usage);
 			return EXIT_FAILURE;
 		}
 	}
 
+	if (state.single_point && state.restrict_selection) {
+		fprintf(stderr, "-p and -r cannot be used together\n");
+		return EXIT_FAILURE;
+	}
+
 	wl_list_init(&state.boxes);
 	if (!isatty(STDIN_FILENO) && !state.single_point) {
 		char *line = NULL;

slurp.1.scd

@@ -14,8 +14,8 @@ slurp is a command-line utility to select a region from Wayland compositors
 which support the layer-shell protocol. It lets the user hold the pointer to
 select, or click to cancel the selection.
 
-If the standard input is not a TTY, slurp will read a list of predefined
-rectangles for quick selection. Each line must be in the form
+If the standard input is not a TTY or the -r option is used, slurp will read a
+list of predefined rectangles for quick selection. Each line must be in the form
 "<x>,<y> <width>x<height> [label]". The label is optional and can be any string
 that doesn't contain newlines. It can be accessed using the "%l" sequence in a
 format string.
@@ -58,6 +58,11 @@ held, the selection is moved instead of being resized.
 	Add predefined rectangles for all outputs, as if provided on standard input.
 	The label will be the name of the output.
 
+*-r*
+	Require the user to select one of the predefined rectangles. These can come
+	from standard input, if *-o* is used, the rectangles of all display outputs.
+	This option conflicts with *-p*.
+
 # COLORS
 
 Colors may be specified in #RRGGBB or #RRGGBBAA format. The # is optional.