I-beam cursor color changing based on the background

[Jasper St. Pierre]

Most desktop CRTCs support a XOR key in their ROP, since it was
required by Windows for such a long time. I don't think Linux has
support for that in KMS, nor for similar things like alpha keying as
well. Perhaps we'll get it as a plane property at some point.

I don't know of any mobile/embedded chipsets that support XOR keying,
since it's not 1996.

On Thu, Oct 15, 2015 at 8:30 AM, Bill Spitzak <spitzak at gmail.com> wrote:
> That's xor of the color bits. The blue/red is due to xor'ing with the
> subpixel antialiasing. It is more obvious if you put the cursor over a solid
> colored area where you will see strange colors.
>
> It cannot be achieved with Porter-Duff combinations. I am not sure if OpenGL
> or DirectX supports it. I am also suspicious that overlay hardware designed
> for cursors may not support it either.
>
> This would either require adding something to Wayland to enable xor of a
> cursor, or (more likely) you will have to just set the cursor to blank and
> draw the desired graphics yourself.
>
> Linux programs seem to use a white insertion bar with a black outline, so it
> is visible against all backgrounds. This is despite the fact that X11 still
> supports xor cursors, everybody dropped that as obsolete. OS/X appears to
> use a black insertion bar with a very thin white outline (ie
> partially-transparent white pixels). Both of these work with normal
> compositing.
>
>
> On 10/14/2015 06:13 AM, John Doerthy wrote:
>>
>> Hi,
>> Could you please comment on this issue, if you are currently working on
>> the Windows-like implementation of the I-beam cursor (cursor for text
>> selection) in the graphical interface?
>> In Windows, the I-beam cursor, change color based on the background. So,
>> most of the time it's black, but when you are on the dark background its
>> color cahnges and not only that, but if part of the cursor is on the
>> white background and part on the dark background, only the affected
>> areas of teh I-beam cursor change the color. Plus if you are over a text
>> the part of the cursor that overlays some character has a slightly blue
>> or red color (as you can see in the screenshots below)
>> Here are some real world examples(screenshots) from Windows 7:
>> http://imgur.com/a/IxG7w
>> Thank for your response how far are you guys in implementing this feature.
>> John
>>
>>
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>
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-- 
  Jasper