common/graphic-helpers: Add multi_rect

include/common/graphic-helpers.h

@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+struct wlr_scene_tree;
+struct wlr_scene_rect;
+struct wl_listener;
+
+struct multi_rect {
+	struct wlr_scene_tree *tree;
+	int line_width; /* read-only */
+
+	/* Private */
+	struct wlr_scene_rect *top[3];
+	struct wlr_scene_rect *bottom[3];
+	struct wlr_scene_rect *left[3];
+	struct wlr_scene_rect *right[3];
+	struct wl_listener destroy;
+};
+
+/**
+ * Create a new multi_rect.
+ * A multi_rect consists of 3 nested rectangular outlines.
+ * Each of the rectangular outlines is using the same @line_width
+ * but its own color based on the @colors argument.
+ *
+ * The multi-rect can be positioned by positioning multi_rect->tree->node.
+ *
+ * It can be destroyed by destroying its tree node (or one of its
+ * parent nodes). Once the tree node has been destroyed the struct
+ * will be free'd automatically.
+ */
+struct multi_rect *multi_rect_create(struct wlr_scene_tree *parent,
+		float *colors[3], int line_width);
+
+void multi_rect_set_size(struct multi_rect *rect, int width, int height);

src/common/graphic-helpers.c

@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <assert.h>
+#include <stdlib.h>
+#include <wlr/types/wlr_scene.h>
+#include "common/graphic-helpers.h"
+
+static void
+multi_rect_destroy_notify(struct wl_listener *listener, void *data)
+{
+	struct multi_rect *rect = wl_container_of(listener, rect, destroy);
+	free(rect);
+}
+
+struct multi_rect *
+multi_rect_create(struct wlr_scene_tree *parent, float *colors[3], int line_width)
+{
+	struct multi_rect *rect = calloc(1, sizeof(*rect));
+	rect->line_width = line_width;
+	rect->tree = wlr_scene_tree_create(parent);
+	rect->destroy.notify = multi_rect_destroy_notify;
+	wl_signal_add(&rect->tree->node.events.destroy, &rect->destroy);
+	for (size_t i = 0; i < 3; i++) {
+		rect->top[i] = wlr_scene_rect_create(rect->tree, 0, 0, colors[i]);
+		rect->right[i] = wlr_scene_rect_create(rect->tree, 0, 0, colors[i]);
+		rect->bottom[i] = wlr_scene_rect_create(rect->tree, 0, 0, colors[i]);
+		rect->left[i] = wlr_scene_rect_create(rect->tree, 0, 0, colors[i]);
+		wlr_scene_node_set_position(&rect->top[i]->node,
+			i * line_width, i * line_width);
+		wlr_scene_node_set_position(&rect->left[i]->node,
+			i * line_width, i * line_width);
+	}
+	return rect;
+}
+
+void
+multi_rect_set_size(struct multi_rect *rect, int width, int height)
+{
+	assert(rect);
+	int line_width = rect->line_width;
+
+	for (size_t i = 0; i < 3; i++) {
+
+		/* Reposition, top and left don't ever change */
+		wlr_scene_node_set_position(&rect->right[i]->node,
+			width - (i + 1) * line_width, i * line_width);
+		wlr_scene_node_set_position(&rect->bottom[i]->node,
+			i * line_width, height - (i + 1) * line_width);
+
+		/* Update sizes */
+		wlr_scene_rect_set_size(rect->top[i],
+			width - i * line_width * 2, line_width);
+		wlr_scene_rect_set_size(rect->bottom[i],
+			width - i * line_width * 2, line_width);
+		wlr_scene_rect_set_size(rect->left[i],
+			line_width, height - i * line_width * 2);
+		wlr_scene_rect_set_size(rect->right[i],
+			line_width, height - i * line_width * 2);
+	}
+}

src/common/meson.build

@@ -4,6 +4,7 @@ labwc_sources += files(
   'fd_util.c',
   'font.c',
   'grab-file.c',
+  'graphic-helpers.c',
   'nodename.c',
   'scaled_font_buffer.c',
   'scaled_scene_buffer.c',