254792 - Keep XBM images at 1-bit

Status: RESOLVED WONTFIX

(Core Graveyard :: GFX, defect)

Description

[Aaron Kaluszka]

XBMs are currently converted from 1-bit to 32-bit, quite a waste of memory.
Whenever bug 38447 is fixed and XBMs are supported as cursors, this will also
waste CPU by converting from 1-bit to 32-bit and back to 1-bit (particularly for
GTK <2.4 since that only supports 1-bit cursors.  In short, this is like bug
143046 for GIFs, and depends on those changes.  That only covers RGB, and more
work may need to be done for optimizing the alpha channel for binary
transparency.  Since the alpha channel and RGB data are held in two separate
variables, it may be that XBMs can only be optimized to 2-bit, but that's far
superior to 32-bit.  I suppose we'll need bugs for optimizing all of the other
image formats as well.

Comment 1

[Alfred Kayser]

In Cairo we could do the following:
in gfxImageFrame, add a format A1, using the CAIRO_FORMAT_A1, where the image data is a 1bit alpha, and then draw the image using a foreground and background (=transparent?) color.

But I am not sure if it worth the trouble.

Comment 2

[Aaron Kaluszka]

XBM support was removed.