Re: address@hidden: problem with transparent PNG image display]

[Chris Moore]

Chong Yidong <address@hidden> writes:

>> From: Chris Moore <address@hidden>
>>
>> Using M-x set-background-colour RET and you'll see the background
>> of the image changes with the background.
>
> Umm, no it doesn't (check again).

Hmmm, that's right.  I thought I saw it change.  Maybe I was doing a
C-x C-v RET to get it to change.

> The png code in Emacs fills in the image background with the current
> frame background iff this background color is unspecified.

I don't think that's quite true.  The behaviour seems to be a little
more complex than that.  For example (where image.png is a transparent
PNG in the current directory with unspecified background colour):

  $ emacs -Q

  M-x set-background-color RET blue RET
  C-x b xxx RET
  C-x i image.png RET
  M-x image-mode RET    -> blue background, as expected.

  M-x set-background-color RET red RET
  C-x b yyy RET
  C-x i image.png RET
  M-x image-mode RET    -> blue background, not red.

> I think this bug should be removed from FOR-RELEASE.  Someone
> should, however, work on this after the release.

Agreed.