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That the buffer is zeroed when `age == 0` is not guaranteed, e.g. on many platforms (Wayland, X11, Web), when we resize the buffer, we don't also clear it. We could technically guarantee something like "if the buffer's underlying data could not be reused, the buffer is zero-initialized", but that's not really useful to users (at least not unless we expose additional information in `Buffer::age`). This might also make it easier to use zero-copying on Android (might be able to avoid having to clear the buffer).
To help make it clear that the buffer isn't zero-initialize / catch
mistakes where the user was relying on it.
For example, drawing like this is incorrect:
```
// Fill with blue.
for (_, _, pixel) in buffer.pixels_iter() {
pixel.b = 0xff;
pixel.a = 0xff;
}
```
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Note that zero-initializing might have been useful in the past, because it corresponded to black, but it isn't really useful after #321, after that we panic when |
notgull
approved these changes
Mar 16, 2026
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That the buffer is zeroed when
age == 0is not guaranteed, e.g. on many platforms (Wayland, X11, Web), when we resize the buffer, we don't also clear it.We could technically guarantee something like "if the buffer's underlying data could not be reused, the buffer is zero-initialized", but that's not really useful to users (at least not unless we expose additional information in
Buffer::age).This might also make it easier to use zero-copying on Android (might be able to avoid having to clear the buffer if we can prove that the
MaybeUninitis actually initialized), see discussion in #331 (comment).To help a bit with catching mistakes like this in the future / documenting the state of affairs in the code, I've added a private
Pixel::INITwhich most backends initialize their buffers with.