When starting a new text line, an assumption is made that the current
vertical position is a multiple of the character height. When this is
not true, characters can be written after the end of the framebuffer.

This can causes crashes and strange errors from QEMU.

Adjust the scrolling check when processing a newline character, to
avoid any problems.

Add some comments to make things a little clearer.

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

efi_console / UEFI applications (grub2, sd-boot, ...) pass UTF-8
character sequences to vidconsole which results in wrong glyphs for code
points outside of ASCII. The truetype console expects Unicode code
points and bitmap font based consoles expect code page 437 code points.
To support both convert UTF-8 to UTF-32 and pass Unicode code points in
vidconsole_ops.putc_xy(). These can be used directly in console_truetype
and after conversion to code page 437 in console_{normal,rotate}.

This fixes rendering of international, symbol and box drawing characters
used by UEFI applications.

Signed-off-by: Janne Grunau <j@jannau.net>

Add rudimentary support for displaying a cursor on a vidconsole. This
helps the user to see where text is being entered.

The implementation so far is very simple: the cursor is just a vertical
bar of fixed width and cannot be erased. To erase the cursor, the text
must be redrawn over it.

This is good enough for expo but will need enhancement to be useful for
the command-line console. For example, it could save and restore the
area behind the cursor.

For now, enable this only for expo, to reduce code size.

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

At present this is called only when a newline is detected, since this
indicates the start of a line of text being entered.

Export this function so it can be used by expo, which may start a new
text line itself, without first writing out a newline.

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

Text entry operates within a context which includes quite a bit of
information. For example, with Truetype fonts, each character in the
text string has a position stored, so that it is possible to
backspace to that character. This information is built up as strings
are drawn on the display.

For the command line, there is just a single context. It is created
when command-line entry starts and it is destroyed (or at least not
needed anymore) when the user presses <enter> to enter the command.

By contrast, expo needs to be able to switch in and out of a text-entry
context, since it is also displaying other objects in the scene.

Add a way to save and restore the entry context for a vidconsole. This
is only needed for the truetype vidconsole, so add a method for that,
storing the information in an abuf struct.

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

At present there is a method for measuring text, but if the actual text
string is not known, it cannot be used.

For text editor we want to set the size of the entry box to cover the
expected text size. Add the concept of a 'norminal' size with a method
to calculate that for the vidconsole.

If the method is not implemented, fall back to using the font size,
which is sufficient for fixed-width fonts.

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

For laying out text accurately it is necessary to know the width and
height of the text. Add a measure() method to the console API, so this
can be supported.

Add an implementation for truetype and a base implementation for the
normal console.

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

It is sometimes necessary to highlight some text in a different colour.
Add an easy way to do this and then restore the original console colours.

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

It is better to clear the console device rather than the video device,
since the console has the text display. We also need to reset the cursor
position with the console, but not with the video device.

Add a new function to handle this and update the 'cls' command to use it.

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

Since multiple vidconsole drivers exists, vidconsole_get_font_size()
implementation cannot longer live in vidconsole_uclass.c file.

Move current vidconsole_get_font_size logic to truetype driver ops.

Signed-off-by: Dzmitry Sankouski <dsankouski@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>