scene_obj_find can return NULL but this is not checked for before
the return is dereferenced. Add a NULL check.

This issue was found by Smatch.

Also add a NULL check for str.

Signed-off-by: Andrew Goodbody <andrew.goodbody@linaro.org>
Reviewed-by: Tom Rini <trini@konsulko.com>

Expo normally uses a pointer to show the current item. Add support for
highlighting as well, since this makes it easier for the user to see the
current item.

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

In preparation for adding more text types, refactor the common fields
into a new structure. This will allow common code to be used.

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

At present labels are lined up vertically. Do the same with keys and
descriptions, since it looks nicer.

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

In some cases it is useful to obtain more than just two bounding boxes
from a menu, e.g. to line up all descriptions vertically.

Use an array to obtain bounding-box information and calculate it
separately for each item.

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

At present each object has a width and height and the bounding box is
implicit in that.

This is not flexible enough to handle objects which are larger than
their contents might need. For example, when centring a text object we
might want to have it stretch across the whole width of the display even
if the text itself does not need that much space.

Create a new 'dimensions' field and convert the existing width/height
into x1/y1 coordinates.

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

These coordinates are the top left values, so rename them to x0 and y0
in preparation for changing the width and height to x1 and y1

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

At present we assume that each object is a simple box and that it fills
the whole box.

This is quite limiting for text objects, which we may want to centre
within the box. We need a position within the box where drawing starts.

Rename the scene_dim struct to indicate that it is a bounding box.

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

At present when the user moves to a new menu item, the menu code
handles this immediately. This means it is not possible to use an expo
action to effect the same change.

Update this so that EXPOACT_POINT_ITEM is handled in cedit_do_action().

Expand the test to cover this.

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

Add functions to allow a caller to find out the current menu item and to
select a different one.

Update the event handling so that an attempt to change the current item
(e.g. by pressing the up-arrow key) is reported to the caller, since
this may be used to cancel an autoboot timeout.

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