Crosshairs

box.c

@@ -0,0 +1,19 @@
+#include "box.h"
+
+bool box_intersect(const struct slurp_box *a, const struct slurp_box *b) {
+	return a->x < b->x + b->width &&
+		a->x + a->width > b->x &&
+		a->y < b->y + b->height &&
+		a->height + a->y > b->y;
+}
+
+bool in_box(const struct slurp_box *box, int32_t x, int32_t y) {
+	return box->x <= x
+		&& box->x + box->width > x
+		&& box->y <= y
+		&& box->y + box->height > y;
+}
+
+int32_t box_size(const struct slurp_box *box) {
+	return box->width * box->height;
+}

include/box.h

@@ -0,0 +1,21 @@
+#ifndef _BOX_H
+#define _BOX_H
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <wayland-client.h>
+
+struct slurp_box {
+	int32_t x, y;
+	int32_t width, height;
+	char *label;
+	struct wl_list link;
+};
+
+bool box_intersect(const struct slurp_box *a, const struct slurp_box *b);
+
+bool in_box(const struct slurp_box *box, int32_t x, int32_t y);
+
+int32_t box_size(const struct slurp_box *box);
+
+#endif

include/slurp.h

@@ -5,20 +5,14 @@
 #include <stdint.h>
 #include <wayland-client.h>
 
+#include "box.h"
 #include "pool-buffer.h"
 #include "cursor-shape-v1-client-protocol.h"
 #include "wlr-layer-shell-unstable-v1-client-protocol.h"
 #include "xdg-output-unstable-v1-client-protocol.h"
 
 #define TOUCH_ID_EMPTY -1
 
-struct slurp_box {
-	int32_t x, y;
-	int32_t width, height;
-	char *label;
-	struct wl_list link;
-};
-
 struct slurp_selection {
 	struct slurp_output *current_output;
 	int32_t x, y;
@@ -56,6 +50,7 @@ struct slurp_state {
 	bool display_dimensions;
 	bool single_point;
 	bool restrict_selection;
+	bool crosshairs;
 	struct wl_list boxes; // slurp_box::link
 	bool fixed_aspect_ratio;
 	double aspect_ratio;  // h / w

main.c

@@ -25,24 +25,6 @@ static void noop() {
 
 static void set_output_dirty(struct slurp_output *output);
 
-bool box_intersect(const struct slurp_box *a, const struct slurp_box *b) {
-	return a->x < b->x + b->width &&
-		a->x + a->width > b->x &&
-		a->y < b->y + b->height &&
-		a->height + a->y > b->y;
-}
-
-static bool in_box(const struct slurp_box *box, int32_t x, int32_t y) {
-	return box->x <= x
-		&& box->x + box->width > x
-		&& box->y <= y
-		&& box->y + box->height > y;
-}
-
-static int32_t box_size(const struct slurp_box *box) {
-	return box->width * box->height;
-}
-
 static int max(int a, int b) {
 	return (a > b) ? a : b;
 }
@@ -91,12 +73,13 @@ static void seat_update_selection(struct slurp_seat *seat) {
 }
 
 static void seat_set_outputs_dirty(struct slurp_seat *seat) {
+	struct slurp_state *state = seat->state;
 	struct slurp_output *output;
 	wl_list_for_each(output, &seat->state->outputs, link) {
-		if (box_intersect(&output->logical_geometry,
-			&seat->pointer_selection.selection) ||
-				box_intersect(&output->logical_geometry,
-			&seat->touch_selection.selection)) {
+		struct slurp_box *geometry = &output->logical_geometry;
+		if (box_intersect(geometry, &seat->pointer_selection.selection) ||
+				box_intersect(geometry, &seat->touch_selection.selection) ||
+				(state->crosshairs && in_box(geometry, seat->pointer_selection.x, seat->pointer_selection.y))) {
 			set_output_dirty(output);
 		}
 	}
@@ -136,7 +119,7 @@ static void pointer_handle_enter(void *data, struct wl_pointer *wl_pointer,
 	}
 
 	// the places the cursor moved away from are also dirty
-	if (seat->pointer_selection.has_selection) {
+	if (seat->pointer_selection.has_selection || seat->state->crosshairs) {
 		seat_set_outputs_dirty(seat);
 	}
 
@@ -185,8 +168,10 @@ static void pointer_handle_leave(void *data, struct wl_pointer *wl_pointer,
 static void pointer_handle_motion(void *data, struct wl_pointer *wl_pointer,
 		uint32_t time, wl_fixed_t surface_x, wl_fixed_t surface_y) {
 	struct slurp_seat *seat = data;
+	struct slurp_state *state = seat->state;
+
 	// the places the cursor moved away from are also dirty
-	if (seat->pointer_selection.has_selection) {
+	if (seat->pointer_selection.has_selection || state->crosshairs) {
 		seat_set_outputs_dirty(seat);
 	}
 
@@ -201,7 +186,7 @@ static void pointer_handle_motion(void *data, struct wl_pointer *wl_pointer,
 		break;
 	}
 
-	if (seat->pointer_selection.has_selection) {
+	if (seat->pointer_selection.has_selection || state->crosshairs) {
 		seat_set_outputs_dirty(seat);
 	}
 }
@@ -351,8 +336,11 @@ static void keyboard_handle_modifiers(void *data, struct wl_keyboard *wl_keyboar
 		const uint32_t mods_latched, const uint32_t mods_locked,
 		const uint32_t group) {
 	struct slurp_seat *seat = data;
-	xkb_state_update_mask(seat->xkb_state, mods_depressed, mods_latched,
-			mods_locked, 0, 0, group);
+	// Avoid segfault if this is called before we initialize the keyboard state
+	if (seat->xkb_state) {
+		xkb_state_update_mask(seat->xkb_state, mods_depressed, mods_latched,
+				mods_locked, 0, 0, group);
+	}
 }
 
 static const struct wl_keyboard_listener keyboard_listener = {
@@ -586,6 +574,7 @@ static void send_frame(struct slurp_output *output) {
 
 	cairo_identity_matrix(output->current_buffer->cairo);
 	cairo_scale(output->current_buffer->cairo, output->scale, output->scale);
+	cairo_translate(output->current_buffer->cairo, -output->logical_geometry.x, -output->logical_geometry.y);
 
 	render(output);
 
@@ -713,7 +702,8 @@ static const char usage[] =
 	"  -o           Select a display output.\n"
 	"  -p           Select a single point.\n"
 	"  -r           Restrict selection to predefined boxes.\n"
-	"  -a w:h       Force aspect ratio.\n";
+	"  -a w:h       Force aspect ratio.\n"
+	"  -x           Display crosshairs across active display output.\n";
 
 uint32_t parse_color(const char *color) {
 	if (color[0] == '#') {
@@ -892,7 +882,7 @@ int main(int argc, char *argv[]) {
 	char *format = "%x,%y %wx%h\n";
 	bool output_boxes = false;
 	int w, h;
-	while ((opt = getopt(argc, argv, "hdb:c:s:B:w:proa:f:F:")) != -1) {
+	while ((opt = getopt(argc, argv, "hdb:c:s:B:w:proa:f:F:x")) != -1) {
 		switch (opt) {
 		case 'h':
 			printf("%s", usage);
@@ -949,6 +939,9 @@ int main(int argc, char *argv[]) {
 			state.fixed_aspect_ratio = true;
 			state.aspect_ratio = (double) h / w;
 			break;
+		case 'x':
+			state.crosshairs = true;
+			break;
 		default:
 			printf("%s", usage);
 			return EXIT_FAILURE;

meson.build

@@ -26,6 +26,7 @@ executable(
 		'main.c',
 		'pool-buffer.c',
 		'render.c',
+		'box.c',
 		protos_src,
 	],
 	dependencies: [

render.c

@@ -19,11 +19,6 @@ static void draw_rect(cairo_t *cairo, struct slurp_box *box, uint32_t color) {
 			box->width, box->height);
 }
 
-static void box_layout_to_output(struct slurp_box *box, struct slurp_output *output) {
-	box->x -= output->logical_geometry.x;
-	box->y -= output->logical_geometry.y;
-}
-
 void render(struct slurp_output *output) {
 	struct slurp_state *state = output->state;
 	struct pool_buffer *buffer = output->current_buffer;
@@ -39,9 +34,7 @@ void render(struct slurp_output *output) {
 	wl_list_for_each(choice_box, &state->boxes, link) {
 		if (box_intersect(&output->logical_geometry,
 					choice_box)) {
-			struct slurp_box b = *choice_box;
-			box_layout_to_output(&b, output);
-			draw_rect(cairo, &b, state->colors.choice);
+			draw_rect(cairo, choice_box, state->colors.choice);
 			cairo_fill(cairo);
 		}
 	}
@@ -51,6 +44,18 @@ void render(struct slurp_output *output) {
 		struct slurp_selection *current_selection =
 			slurp_seat_current_selection(seat);
 
+		if (!current_selection->has_selection && state->crosshairs) {
+			struct slurp_box *output_box = &output->logical_geometry;
+			if (in_box(output_box, current_selection->x, current_selection->y)) {
+
+				set_source_u32(cairo, state->colors.border);
+				cairo_rectangle(cairo, output_box->x, current_selection->y, output->logical_geometry.width, 1);
+				cairo_fill(cairo);
+				cairo_rectangle(cairo, current_selection->x, output->logical_geometry.y, 1, output->logical_geometry.height);
+				cairo_fill(cairo);
+			}
+		}
+
 		if (!current_selection->has_selection) {
 			continue;
 		}
@@ -59,15 +64,14 @@ void render(struct slurp_output *output) {
 			&current_selection->selection)) {
 			continue;
 		}
-		struct slurp_box b = current_selection->selection;
-		box_layout_to_output(&b, output);
+		struct slurp_box *sel_box = &current_selection->selection;
 
-		draw_rect(cairo, &b, state->colors.selection);
+		draw_rect(cairo, sel_box, state->colors.selection);
 		cairo_fill(cairo);
 
 		// Draw border
 		cairo_set_line_width(cairo, state->border_weight);
-		draw_rect(cairo, &b, state->colors.border);
+		draw_rect(cairo, sel_box, state->colors.border);
 		cairo_stroke(cairo);
 
 		if (state->display_dimensions) {
@@ -79,9 +83,9 @@ void render(struct slurp_output *output) {
 			// buffer of 12 can hold selections up to 99999x99999
 			char dimensions[12];
 			snprintf(dimensions, sizeof(dimensions), "%ix%i",
-				 b.width, b.height);
-			cairo_move_to(cairo, b.x + b.width + 10,
-				      b.y + b.height + 20);
+				 sel_box->width, sel_box->height);
+			cairo_move_to(cairo, sel_box->x + sel_box->width + 10,
+				      sel_box->y + sel_box->height + 20);
 			cairo_show_text(cairo, dimensions);
 		}
 	}

slurp.1.scd

@@ -73,6 +73,10 @@ held, the selection is moved instead of being resized.
 	Force selections to have the given aspect ratio. This constraint is not
 	applied to the predefined rectangles specified using *-o*.
 
+*-x*
+	Draw fullscreen crosshairs on the display output containing the cursor until
+	a selection is started. This help aligning the origin of the selection.
+
 # COLORS
 
 Colors may be specified in #RRGGBB or #RRGGBBAA format. The # is optional.