The expo now has all that is needed to apply a suitable theme, so drop
this unnecessary code. Any further tweaks can be added to the generic
expo code.

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

Apply the theme, calculate dimensions, highlight the menu and arrange
the scene correctly, so that everything is ready to go when the expo
is rendered.

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

Some callers may wish to add items later as they are discovered. Split
the setup code into its own function, to permit this.

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

Rather than returning a bootflow, return the index of the bootflow. This
will allow callers to do their own translation to bootflows or some
other data structure.

Also return a special code when the user tries to move the pointer, so
that the caller can cancel the boot-menu timeout, if this is in use.

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

The menu is currently quite basic. Make use of some recently added
features in expo, to:

- Show proper prompts
- Highlight the current item
- Centre text
- Use multi-line text instead of two independent lines
- Put a box around the items

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

The gap is intended to separate options which are on different bootdevs,
but most of the time there is only one. So drop this gap.

Keep the code around in case it becomes useful to have it in the style,
or based on some other mechanism.

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

For USB devices we use the string 'usb_mass_storage' which is a bit
verbose. Use 'USB' instead.

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

Use the measurement info to write each line of text separately, thus
respecting word-wrapping and newlines.

Fix up the comment for scene_obj_render() while we are here.

Since a lineedit does not support alignment, add a special case to just
display the text if there is no measurement. This happens assuming the
lineedit is initially empty.

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

Refactor bootflow_menu_add_all() to call a new bootflow_menu_add() to
add each of its bootflows.

Move the last_bootdev value into struct menu_priv to make this work.

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

Split the iteration piece of this function into bootflow_menu_add_all()
so that it is possible for the caller to be in control of adding items
to the menu.

Move the expo_destroy() call into the caller.

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