[MBS] Check if ImmutableBitmap has alpha channel (MBS Xojo Plugin Mailinglist archive)
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|[MBS] MBS 7.5 with RB2010r4.1 - Garth Hjelte|
|[MBS] Check if ImmutableBitmap has alpha channel - Michael Diehr|
|[MBS] Improvements for new Picture object types - Michael Diehr|
|[MBS] Check if ImmutableBitmap has alpha channel|
|Date: 17.04.18 16:17 (Tue, 17 Apr 2018 08:17:58 -0700)|
|From: Michael Diehr|
With Supports HiDPI ON, Xojo loads pictures as ImmutableBitmaps, which always claim hasAlphaChannel=True regardless of the source file.
See here: https://forum.xojo.com/47184-picture-fromdata-gives-immutablebitmap-with-hasalphachannel-tru/last
Apparently this is stored internally as an NSImage, and once it's an NSImage there is no way to tell if the original file did or did not have alpha.
A brute-force workaround: get the copy of the mask, and see if all the pixels are zero.
Is there a fast way to do that in MBS?
Looks like PictureMBS.CompareImages might work, although I'd rather have a function that was fast and exited upon finding the first different pixel.
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