[R] Query for semi-transparency support

[Jesse Brown]

Thanks for the pointer. I looked through the source and it seems that
this is hard-coded into the device-specific files.

Considering that, I can think of three ways I could achieve this behavior:

  1 - Using .Device in a switch statement
  2 - A try/catch construct that will trigger on warnings (possible?)
  3 - Check warnings() after the call in question and react accordingly

I'm still fairly new with the language so I'm not sure the second is
even possible and I'd think that the third would still cause problems
as state handling would be a mess. It would be interesting to hear of
any approach that I'm missing.

Thanks,

Jesse

On Mon, Aug 15, 2011 at 11:32 PM, baptiste auguie
<baptiste.auguie at googlemail.com> wrote:
> Here's a warning, but it sounds like it's at a deep (C, presumably) level,
>
> xfig()
> grid::grid.rect(gp=gpar(fill="red", alpha=0.5))
> Warning message:
> In grid.Call.graphics("L_rect", x$x, x$y, x$width, x$height,
> resolveHJust(x$just,  :
>  semi-transparency is not supported on this device: reported only once per page
>
> HTH,
>
> baptiste
>
> On 16 August 2011 15:25, Jesse Brown <jesse.r.brown at gmail.com> wrote:
>> In ?par there is the following line:
>>
>>  "Semi-transparent colors are available for use on devices that support them."
>>
>> I'm looking for a way to query for that support on the current device.
>> I'm pretty sure that this functionality exists at some level as I
>> remember seeing warnings to this effect but my searches have come up
>> empty. Is anyone familiar with a direct path to this information?
>>
>> Thank you,
>>
>> Jesse
>>
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>