[mythtv-users] ProjectGrayhem-wide theme version 1.2

[Bruce Markey]

Justin Hornsby wrote:
> I was dreading this.

We take it for granted that a TV picture fills the screen, The
illusion is that the picture size is identical to the screen
size but this is impossible. The raster size is larger than the
screen and the rough edges are cutoff by the cowl. A TV tube has
slightly curved edges and rounded corners. This is the traditional
shape of a TV screen:

http://upload.wikimedia.org/wikipedia/en/7/75/Television.png

Imagine ProjectGrayhem displayed on this TV, especially the icons
in the upper right corner. Modern tubes and cowls do a better job
of giving the illusion that the picture is rectangular but the
issue still exists. Another factor is that the picture can't be
perfectly centered so there needs to be enough overscan to cover
the middle of all edges and there may be more overscan on one side
than the other or top or bottom.

> On the minus side, people who have displays which don't overscan will

All several billion TVs that have ever been made since the '40s
are supposed to overscan unless they are misadjusted or broken.
TV production, broadcasters and devices designed for TV display
have all agreed to follow the SMPTE standards for several decades
so that picture elements and text will fit for all TVs. If you
look at TV graphics, VCR OSDs, the TV's own OSD, DVD menus, video
game consoles, commercial DVRs, they all follow this standard. A
common trick is to have graphic elements that flow off the screen
but if you look at the text, it all falls within the smae margins
from the edge.

> I thought that's why myth had the facility to scale the GUI.

It's ironic that myth is a TV application that wasn't designed to
be displayed on a TV =). We should have started by insisting that
the SMPTE margins were used but this hasn't been the case. The
setup wizard pages are particularly bad (but this doesn't mean that
themes and OSD themes have to be just as bad too). Myth GUI size is
actually a hack in response to the self imposed problem. The GUI
size can be tweaked and centered to try to match the edges of the
GUI to the edges of an individual screen so that GUI elements near
the edge won't be cutoff. However, if the GUI has little or no
margin space, it is difficult to impossible to match it perfectly
and there is nothing that can be done for elements in the corners
if the screen has rounded corners. None of this would be necessary
if we adhered to the action safe and title safe areas. For OSDs,
there is no GUI size adjustment (nor should there be) and we need
to be more strict about the margins. These are much easier to fix
than the GUI pages.

The problem comes from the fact that if a theme designer doesn't
think about a TV screen, they tend to think of the rectangular window
on their desktop as the space they have to work with. They should
actually see it as blacked out as least 2%-3% on all sides with
curved corners. [A related problem is that fonts chosen from two
feet in front of a monitor may not be readable on a 19" screen
from ten feet away.]

Any action, movement, or object that is supposed to be seen should
be 5% in from the edge and any text that needs to be read should be
10% in. However, 10% is probably overkill these day. Tickers like
CNN usually fall in the space between 5 and 10 percent. So, for
an 800x600 GUI design, graphics that don't flow off the edge should
fall inside 40-760 and 30-570. Something right at 40,30 or 760,570
may still be cutoff on some screens but that's the TV's problem.
You've done your part... that's why there is a standard =). Text
should be further in if possible but really, having a margin of
at least 30 or 40 solves most of the problem.

--  bjm