Re: redisplay system of emacs

[Jan Djärv]

alin.s skrev:
> An improvement in redisplay for X can be done by defining in the edit area of
> every window a subwindow for every character. For a window of geometry
> 200x70 of characters, it would be 1400 windows registered in X-server.

You are mad.  Everything would be 1400 times more.  1400 times more calls to 
the X server, 1400 times more GC:s created, 1400 times more events from the X 
server, 1400 times more Xft structures (XftDraws for example) created.
Emacs would be at least 1400 times slower.

> The advantage is that redisplay would work automatically; every character
> has associated its own expose event; the event PointerMotionMask would
> simply signify LeaveWindow and EnterWindow; so it will always be able to be
> captured without resource consuming.

But Emacs still needs to figure out what character that is in that window in 
order to redraw it.

> To say more, in order to clear a character it would require no computation,
> but only a simply call of XClearWindow().
>
> Every window could have its own font.

So say we have 1400 windows each with a different font with a different size? 
 How do you purpose we lay this out?  Instead of laying out characters we are 
now laying out windows.  Same problem, but with an enormous overhead.

> And to say more, an image of high dimension will be divided in many
> subwindows, and emacs will be able to display images normally, not as a huge
> glyph.

Again, making the display of an image to be so much slower, because instead of 
one (ideally), call to the X server, we now have one per window.  And what a 
nightmare to figure out what part of an image that needs to be redrawn and 
moved if the user changes the size of the Emacs frame...

> And finally, because this structure is identical to the geometry of the
> console, the code for X and console can be unified in many places.

Not very likely.

Did 1:st of April arrive early?

        Jan D.