backend: add new property: BORDER_WIDTH

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>

src/backend/backend.c

@@ -350,6 +350,17 @@ void paint_all_new(session_t *ps, struct managed_win *t, bool ignore_damage) {
 				ps->backend_data->ops->set_image_property(
 				    ps->backend_data, IMAGE_PROPERTY_BORDER_COLOR,
 				    w->win_image, &border_color);
+
+				int border_width = w->g.border_width;
+				if (border_width == 0) {
+					// Some WM has borders implemented as WM frames
+					border_width = min3(w->frame_extents.left,
+					                    w->frame_extents.right,
+					                    w->frame_extents.bottom);
+				}
+				ps->backend_data->ops->set_image_property(
+				    ps->backend_data, IMAGE_PROPERTY_BORDER_WIDTH,
+				    w->win_image, &border_width);
 			}
 		}
 

src/backend/backend.h

@@ -61,6 +61,9 @@ enum image_properties {
 	// Border color
 	// 1 struct color, default: black
 	IMAGE_PROPERTY_BORDER_COLOR,
+	// Border width
+	// 1 int, default: 0
+	IMAGE_PROPERTY_BORDER_WIDTH,
 };
 
 enum image_operations {

src/backend/backend_common.c

@@ -452,6 +452,7 @@ bool default_set_image_property(backend_t *base attr_unused, enum image_properti
 	case IMAGE_PROPERTY_CORNER_RADIUS: tex->corner_radius = dargs[0]; break;
 	case IMAGE_PROPERTY_MAX_BRIGHTNESS: tex->max_brightness = dargs[0]; break;
 	case IMAGE_PROPERTY_BORDER_COLOR: tex->border_color = *(struct color *)arg; break;
+	case IMAGE_PROPERTY_BORDER_WIDTH: tex->border_width = *(int *)arg; break;
 	}
 
 	return true;

src/backend/backend_common.h

@@ -42,6 +42,7 @@ struct backend_image {
 	int ewidth, eheight;
 	bool color_inverted;
 	struct color border_color;
+	int border_width;
 };
 
 bool build_shadow(xcb_connection_t *, xcb_drawable_t, double opacity, int width,

src/utils.h

@@ -134,6 +134,7 @@ static inline int attr_const normalize_i_range(int i, int min, int max) {
 
 #define min2(a, b) ((a) > (b) ? (b) : (a))
 #define max2(a, b) ((a) > (b) ? (a) : (b))
+#define min3(a, b, c) min2(a, min2(b, c))
 
 /// clamp `val` into interval [min, max]
 #define clamp(val, min, max) max2(min2(val, max), min)