expo: Begin implementation of a text editor

It is useful to be able to edit text, e.g. to allow the user to edit the
environment or the command-line arguments for the OS.

Add the beginnings of an implementation. Future work is needed to finish
this: keypress handling and scrolling. For now it just displays the
text.

Signed-off-by: Simon Glass <sjg@chromium.org>

1 files changed, 61 insertions, 0 deletions

diff --git a/boot/scene_textedit.c b/boot/scene_textedit.c
new file mode 100644
index 00000000000..8242eb39806
--- /dev/null
+++ b/boot/scene_textedit.c
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Implementation of a menu in a scene
+ *
+ * Copyright 2025 Google LLC
+ * Written by Simon Glass <sjg@chromium.org>
+ */
+
+#define LOG_CATEGORY	LOGC_EXPO
+
+#include <expo.h>
+#include <log.h>
+#include <linux/err.h>
+#include <linux/sizes.h>
+#include "scene_internal.h"
+
+enum {
+	INITIAL_SIZE	= SZ_4K,
+};
+
+int scene_texted(struct scene *scn, const char *name, uint id, uint str_id,
+		 struct scene_obj_txtedit **teditp)
+{
+	struct scene_obj_txtedit *ted;
+	char *buf;
+	int ret;
+
+	ret = scene_obj_add(scn, name, id, SCENEOBJT_TEXTEDIT,
+			    sizeof(struct scene_obj_txtedit),
+			    (struct scene_obj **)&ted);
+	if (ret < 0)
+		return log_msg_ret("obj", ret);
+
+	abuf_init(&ted->buf);
+	if (!abuf_realloc(&ted->buf, INITIAL_SIZE))
+		return log_msg_ret("buf", -ENOMEM);
+	buf = abuf_data(&ted->buf);
+	*buf = '\0';
+
+	ret = scene_txt_generic_init(scn->expo, &ted->gen, name, str_id, buf);
+	if (ret)
+		return log_msg_ret("teg", ret);
+	if (teditp)
+		*teditp = ted;
+
+	return ted->obj.id;
+}
+
+int scene_txted_set_font(struct scene *scn, uint id, const char *font_name,
+			 uint font_size)
+{
+	struct scene_obj_txtedit *ted;
+
+	ted = scene_obj_find(scn, id, SCENEOBJT_TEXTEDIT);
+	if (!ted)
+		return log_msg_ret("find", -ENOENT);
+	ted->gen.font_name = font_name;
+	ted->gen.font_size = font_size;
+
+	return 0;
+}