[Kde-accessibility] Mouse Scaling in KWin's Zoom Effecdt

[Sebastian Sauer]

Jeremy Whiting wrote:

>  On Wed, Nov 16, 2011 at 5:24 PM, Robert Cole <rkcole72984 at gmail.com>

>  wrote:

> > Hello, everyone.

> >

> > I am testing out openSUSE 12.1 in a virtual machine using VirtualBox

> > today. I decided to test out the Zoom effect of KWin to see how it

> > worked, as it is quite jumpy on my primary Linux Mint 11 machine. I was

> > amazed at how smooth the screen panned around while it was zoomed, and

> > this being in a virtual machine! My main reason for writing this message,

> > however, is that I found that the mouse pointer does not scale (at least

> > in the virtual machine) when zoomed in.

>

>  Interesting. I haven't played with the kwin zoom effect til today.

>  It's quite nice indeed.


Thanks :-)


>  I tried on my real machine, and the cursor

>  did scale, but I noticed it changed style.


The reason for this is that it's not the real mouse-pointer that is 
displayed. What we do is to hide the real mouse-pointer and then draw 
our own which is 1) optionally proper scaled to match the zoom-level 
and, even more important, 2) the position is adjusted to match to what 
is displayed at the screen. What is displayed at the screen is more or 
less a fake and not what X.org sees. So, the real mouse-position, which 
is controlled by X.org, would be displayed at a position that does not 
match to what is displayed. That is why we need to hide + draw our own 
and for that we are loading the cursor-theme. When that does not match 
to what was displayed before then no cursor-theme was set in which case 
we would need to fallback to the X.org default what we atm don't do.


So much for the background :-)


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