[Scummvm-tracker] [ScummVM :: Bugs] #13922: MacCursor not handling black in color cursors

[ScummVM :: Bugs]

#13922: MacCursor not handling black in color cursors
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Reporter:  sluicebox  |       Owner:  (none)
    Type:  defect     |      Status:  new
Priority:  normal     |   Component:  Common
 Version:             |  Resolution:
Keywords:             |        Game:  Quest for Glory 1
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Description changed by sluicebox:

Old description:

> `Common::MacCursor` doesn't handle black in color cursors (`crsr`
> resources). Black pixels aren't drawn because they're treated as
> transparent.
>
> This can be seen in the Run cursor in QFG1VGA-Mac. There are three black
> pixels, two of which are in the leg, and they're not drawn.
>
> The Mac format allows a full 256 palette plus a separate transparency
> mask but the `Common::Cursor` model requires one color to to be the
> transparency key color. `MacCursor` is hard-coded to return 0xff as the
> transparency key but color 0xff is always defined as black in Mac. There
> is no code that attempts to deal with this and so incoming 0xff pixels
> aren't drawn.

New description:

 `MacCursor` doesn't handle black in color cursors (`crsr` resources).
 Black pixels aren't drawn because they're treated as transparent.

 This can be seen in the Run cursor in QFG1VGA-Mac. There are three black
 pixels, two of which are in the leg, and they're not drawn.

 The Mac format allows a full 256 palette plus a separate transparency mask
 but the `Cursor` model requires one color to to be the transparency key.
 `MacCursor` is hard-coded to return 0xff as the transparency key but color
 0xff is always defined as black in Mac. There is no code that attempts to
 deal with this and so incoming 0xff pixels aren't drawn.

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Ticket URL: <https://bugs.scummvm.org/ticket/13922#comment:1>
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