From ac503a47a71e2ab5d149a1bb9184d424609c7da7 Mon Sep 17 00:00:00 2001
From: Tony Crisci <tony@dubstepdish.com>
Date: Sat, 26 Aug 2017 11:55:24 -0400
Subject: [PATCH] intersect cursor and device regions

---
 include/wlr/types/wlr_geometry.h |  6 ++++
 types/wlr_cursor.c               | 33 ++++++++++++-------
 types/wlr_geometry.c             | 54 ++++++++++++++++++++++++++++++++
 3 files changed, 82 insertions(+), 11 deletions(-)

diff --git a/include/wlr/types/wlr_geometry.h b/include/wlr/types/wlr_geometry.h
index 3e218bed..7ac2f843 100644
--- a/include/wlr/types/wlr_geometry.h
+++ b/include/wlr/types/wlr_geometry.h
@@ -1,5 +1,6 @@
 #ifndef _WLR_TYPES_GEOMETRY_H
 #define _WLR_TYPES_GEOMETRY_H
+#include <stdbool.h>
 
 struct wlr_geometry {
 	int x, y;
@@ -9,4 +10,9 @@ struct wlr_geometry {
 void wlr_geometry_closest_boundary(struct wlr_geometry *geo, double x, double y,
 		int *dest_x, int *dest_y, double *distance);
 
+bool wlr_geometry_intersection(struct wlr_geometry *geo_a,
+		struct wlr_geometry *geo_b, struct wlr_geometry **dest);
+
+bool wlr_geometry_contains_point(struct wlr_geometry *geo, int x, int y);
+
 #endif
diff --git a/types/wlr_cursor.c b/types/wlr_cursor.c
index c0b2b6ae..28d9f8c9 100644
--- a/types/wlr_cursor.c
+++ b/types/wlr_cursor.c
@@ -147,19 +147,20 @@ void wlr_cursor_move(struct wlr_cursor *cur, struct wlr_input_device *dev,
 	double x = cur->x + delta_x;
 	double y = cur->y + delta_y;
 
-	// cursor geometry constraints
-	if (cur->state->mapped_geometry) {
-		int closest_x, closest_y;
-		wlr_geometry_closest_boundary(cur->state->mapped_geometry, x, y,
-			&closest_x, &closest_y, NULL);
-		x = closest_x;
-		y = closest_y;
-	}
+	// geometry constraints
+	struct wlr_geometry *constraints = NULL;
+	if (cur->state->mapped_geometry != NULL ||
+			c_device->mapped_geometry != NULL) {
+		constraints = calloc(1, sizeof(struct wlr_geometry));
+
+		if (!wlr_geometry_intersection(cur->state->mapped_geometry,
+				c_device->mapped_geometry, &constraints)) {
+			// TODO handle no possible movement
+			goto out;
+		}
 
-	// device constraints
-	if (c_device->mapped_geometry) {
 		int closest_x, closest_y;
-		wlr_geometry_closest_boundary(c_device->mapped_geometry, x, y,
+		wlr_geometry_closest_boundary(constraints, x, y,
 			&closest_x, &closest_y, NULL);
 		x = closest_x;
 		y = closest_y;
@@ -177,10 +178,20 @@ void wlr_cursor_move(struct wlr_cursor *cur, struct wlr_input_device *dev,
 		y = closest_y;
 	}
 
+	if (constraints && !wlr_geometry_contains_point(constraints, x, y)) {
+		// TODO handle no possible movement
+		goto out;
+	}
+
 	if (wlr_cursor_warp(cur, dev, x, y)) {
 		cur->x = x;
 		cur->y = y;
 	}
+
+out:
+	if (constraints) {
+		free(constraints);
+	}
 }
 
 static void handle_pointer_motion(struct wl_listener *listener, void *data) {
diff --git a/types/wlr_geometry.c b/types/wlr_geometry.c
index 8358d887..be4a80eb 100644
--- a/types/wlr_geometry.c
+++ b/types/wlr_geometry.c
@@ -1,7 +1,9 @@
 #include <limits.h>
 #include <stdlib.h>
 #include <math.h>
+#include <stdbool.h>
 #include <wlr/types/wlr_geometry.h>
+#include <wlr/util/log.h>
 
 static double get_distance(double x1, double y1, double x2, double y2) {
 	double distance;
@@ -34,3 +36,55 @@ void wlr_geometry_closest_boundary(struct wlr_geometry *geo, double x, double y,
 		*distance = get_distance(*dest_x, *dest_y, x, y);
 	}
 }
+
+#ifndef max
+#define max(a,b) ((a) > (b) ? (a) : (b))
+#endif
+
+#ifndef min
+#define min(a,b) ((a) < (b) ? (a) : (b))
+#endif
+
+static bool wlr_geometry_empty(struct wlr_geometry *geo) {
+	return geo == NULL || geo->width < 0 || geo->height < 0;
+}
+
+bool wlr_geometry_intersection(struct wlr_geometry *geo_a,
+		struct wlr_geometry *geo_b, struct wlr_geometry **geo_dest) {
+	struct wlr_geometry *dest = *geo_dest;
+	bool a_empty = wlr_geometry_empty(geo_a);
+	bool b_empty = wlr_geometry_empty(geo_b);
+
+	if (a_empty && b_empty) {
+		return false;
+	} else if (a_empty) {
+		dest->x = geo_b->x;
+		dest->y = geo_b->y;
+		dest->height = geo_b->height;
+		dest->width = geo_b->width;
+		return true;
+	} else if (b_empty) {
+		dest->x = geo_a->x;
+		dest->y = geo_a->y;
+		dest->height = geo_a->height;
+		dest->width = geo_a->width;
+		return true;
+	}
+
+	int x1 = max(geo_a->x, geo_b->x);
+	int y1 = max(geo_a->y, geo_b->y);
+	int x2 = min(geo_a->x + geo_a->width, geo_b->x + geo_b->width);
+	int y2 = min(geo_a->y + geo_a->height, geo_b->y + geo_b->height);
+
+	dest->x = x1;
+	dest->y = y1;
+	dest->width = x2 - x1;
+	dest->height = y2 - y1;
+
+	return !wlr_geometry_empty(dest);
+}
+
+bool wlr_geometry_contains_point(struct wlr_geometry *geo, int x, int y) {
+	return x >= geo->x && x <= geo->x + geo->width &&
+		y >= geo->y && y <= geo->y + geo->height;
+}