tree 06b67c8c00684ce487684b7761d08c7733e9bde8
parent e38b7e7d902f117dba50ac850fcd132b1b256d18
author Chip Davis <cdavis@codeweavers.com> 1565142151 -0500
committer Chip Davis <cdavis@codeweavers.com> 1565295295 -0500

MVKSwapchain: Add handling for compositeAlpha.

Set the `opaque` property of the `CAMetalLayer` based on this. In the
past, we did nothing; this actually corresponds to
`VK_COMPOSITE_ALPHA_INHERIT_BIT_KHR`.

Drop support for premultiplied alpha. In Core Animation, this is managed
by the `contents` of the layer. Most layers use a `CGImage` or an
`NSImage` for their contents; the `AlphaInfo` property of a `CGImage`
determines whether or not it uses premultiplied alpha. However,
`CAMetalLayer` doesn't use a `CGImage`, but a custom opaque Core
Foundation object which ostensibly vends images to be displayed by the
layer. I don't know which kind of alpha it uses, but since most
applications render postmultiplied colors I'm going to assume that
premultiplied alpha isn't supported yet.