A safe interface to the Direct Rendering Manager.
The Direct Rendering Manager is a subsystem found on multiple Unix-based operating systems that provides a userspace API to graphics hardware. See the Wikipedia article for more details.
The DRM is accessed using ioctls
on a file representing a graphics card. These can normally be
found in /dev/dri, but can also be opened in other ways (ex. udev).
This crate does not provide a method of opening these files. Instead, the
user program must provide a way to access the file descriptor representing the
device through the AsFd
trait. Here is a basic example using File as a backend:
```rust /// A simple wrapper for a device node. pub struct Card(std::fs::File);
/// Implementing [AsFd] is a prerequisite to implementing the traits found
/// in this crate. Here, we are just calling [File::as_fd()] on the inner
/// [File].
impl AsFd for Card {
fn asfd(&self) -> BorrowedFd<'> {
self.0.as_fd()
}
}
/// Simple helper methods for opening a Card.
impl Card {
pub fn open(path: &str) -> Self {
let mut options = std::fs::OpenOptions::new();
options.read(true);
options.write(true);
Card(options.open(path).unwrap())
}
}
```
Finally, you can implement drm::Device to gain access to the basic DRM
functionality:
```rust impl drm::Device for Card {}
fn main() { let gpu = Card::open("/dev/dri/card0"); println!("{:#?}", gpu.get_driver().unwrap()); } ```
See drm::control::Device
as well as our mode-setting examples: atomic_modeset
and legacy_modeset
Rendering is done by creating and attaching framebuffers to crtcs.
A framebuffer is created from anything implementing Buffer like the always
available, but very limited, DumbBuffer.
For faster hardware-backed buffers, checkout gbm.rs.