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#![allow(clippy::let_unit_value)] // `let () =` being used to constrain result type
use std::mem::ManuallyDrop;
use std::ptr::NonNull;
use std::sync::Once;
use std::thread;
use core_graphics_types::{
base::CGFloat,
geometry::{CGRect, CGSize},
};
use metal::foreign_types::ForeignType;
use objc::{
class,
declare::ClassDecl,
msg_send,
rc::{autoreleasepool, StrongPtr},
runtime::{Class, Object, Sel, BOOL, NO, YES},
sel, sel_impl,
};
use parking_lot::{Mutex, RwLock};
#[link(name = "QuartzCore", kind = "framework")]
extern "C" {
#[allow(non_upper_case_globals)]
static kCAGravityResize: *mut Object;
}
extern "C" fn layer_should_inherit_contents_scale_from_window(
_: &Class,
_: Sel,
_layer: *mut Object,
_new_scale: CGFloat,
_from_window: *mut Object,
) -> BOOL {
YES
}
static CAML_DELEGATE_REGISTER: Once = Once::new();
#[derive(Debug)]
pub struct HalManagedMetalLayerDelegate(&'static Class);
impl HalManagedMetalLayerDelegate {
pub fn new() -> Self {
let class_name = format!("HalManagedMetalLayerDelegate@{:p}", &CAML_DELEGATE_REGISTER);
CAML_DELEGATE_REGISTER.call_once(|| {
type Fun = extern "C" fn(&Class, Sel, *mut Object, CGFloat, *mut Object) -> BOOL;
let mut decl = ClassDecl::new(&class_name, class!(NSObject)).unwrap();
unsafe {
decl.add_class_method::<Fun>(
sel!(layer:shouldInheritContentsScale:fromWindow:),
layer_should_inherit_contents_scale_from_window,
);
}
decl.register();
});
Self(Class::get(&class_name).unwrap())
}
}
impl super::Surface {
fn new(layer: metal::MetalLayer) -> Self {
Self {
render_layer: Mutex::new(layer),
swapchain_format: RwLock::new(None),
extent: RwLock::new(wgt::Extent3d::default()),
main_thread_id: thread::current().id(),
present_with_transaction: false,
}
}
/// If not called on the main thread, this will panic.
#[allow(clippy::transmute_ptr_to_ref)]
pub unsafe fn from_view(view: NonNull<Object>) -> Self {
let layer = unsafe { Self::get_metal_layer(view) };
let layer = ManuallyDrop::new(layer);
// SAFETY: The layer is an initialized instance of `CAMetalLayer`, and
// we transfer the retain count to `MetalLayer` using `ManuallyDrop`.
let layer = unsafe { metal::MetalLayer::from_ptr(layer.cast()) };
Self::new(layer)
}
pub unsafe fn from_layer(layer: &metal::MetalLayerRef) -> Self {
let class = class!(CAMetalLayer);
let proper_kind: BOOL = msg_send![layer, isKindOfClass: class];
assert_eq!(proper_kind, YES);
Self::new(layer.to_owned())
}
/// Get or create a new `CAMetalLayer` associated with the given `NSView`
/// or `UIView`.
///
/// # Panics
///
/// If called from a thread that is not the main thread, this will panic.
///
/// # Safety
///
/// The `view` must be a valid instance of `NSView` or `UIView`.
pub(crate) unsafe fn get_metal_layer(view: NonNull<Object>) -> StrongPtr {
let is_main_thread: BOOL = msg_send![class!(NSThread), isMainThread];
if is_main_thread == NO {
panic!("get_metal_layer cannot be called in non-ui thread.");
}
// Ensure that the view is layer-backed.
// Views are always layer-backed in UIKit.
#[cfg(target_os = "macos")]
let () = msg_send![view.as_ptr(), setWantsLayer: YES];
let root_layer: *mut Object = msg_send![view.as_ptr(), layer];
// `-[NSView layer]` can return `NULL`, while `-[UIView layer]` should
// always be available.
assert!(!root_layer.is_null(), "failed making the view layer-backed");
// NOTE: We explicitly do not touch properties such as
// `layerContentsPlacement`, `needsDisplayOnBoundsChange` and
// `contentsGravity` etc. on the root layer, both since we would like
// to give the user full control over them, and because the default
// values suit us pretty well (especially the contents placement being
// `NSViewLayerContentsRedrawDuringViewResize`, which allows the view
// to receive `drawRect:`/`updateLayer` calls).
let is_metal_layer: BOOL = msg_send![root_layer, isKindOfClass: class!(CAMetalLayer)];
if is_metal_layer == YES {
// The view has a `CAMetalLayer` as the root layer, which can
// happen for example if user overwrote `-[NSView layerClass]` or
// the view is `MTKView`.
//
// This is easily handled: We take "ownership" over the layer, and
// render directly into that; after all, the user passed a view
// with an explicit Metal layer to us, so this is very likely what
// they expect us to do.
unsafe { StrongPtr::retain(root_layer) }
} else {
// The view does not have a `CAMetalLayer` as the root layer (this
// is the default for most views).
//
// This case is trickier! We cannot use the existing layer with
// Metal, so we must do something else. There are a few options:
//
// 1. Panic here, and require the user to pass a view with a
// `CAMetalLayer` layer.
//
// While this would "work", it doesn't solve the problem, and
// instead passes the ball onwards to the user and ecosystem to
// figure it out.
//
// 2. Override the existing layer with a newly created layer.
//
// If we overlook that this does not work in UIKit since
// `UIView`'s `layer` is `readonly`, and that as such we will
// need to do something different there anyhow, this is
// actually a fairly good solution, and was what the original
// implementation did.
//
// It has some problems though, due to:
//
// a. `wgpu` in our API design choosing not to register a
// callback with `-[CALayerDelegate displayLayer:]`, but
// instead leaves it up to the user to figure out when to
// redraw. That is, we rely on other libraries' callbacks
// telling us when to render.
//
// (If this were an API only for Metal, we would probably
// make the user provide a `render` closure that we'd call
// in the right situations. But alas, we have to be
// cross-platform here).
//
// b. Overwriting the `layer` on `NSView` makes the view
// "layer-hosting", see [wantsLayer], which disables drawing
// functionality on the view like `drawRect:`/`updateLayer`.
//
// These two in combination makes it basically impossible for
// crates like Winit to provide a robust rendering callback
// that integrates with the system's built-in mechanisms for
// redrawing, exactly because overwriting the layer would be
// implicitly disabling those mechanisms!
//
// [wantsLayer]: https://developer.apple.com/documentation/appkit/nsview/1483695-wantslayer?language=objc
//
// 3. Create a sublayer.
//
// `CALayer` has the concept of "sublayers", which we can use
// instead of overriding the layer.
//
// This is also the recommended solution on UIKit, so it's nice
// that we can use (almost) the same implementation for these.
//
// It _might_, however, perform ever so slightly worse than
// overriding the layer directly.
//
// 4. Create a new `MTKView` (or a custom view), and add it as a
// subview.
//
// Similar to creating a sublayer (see above), but also
// provides a bunch of event handling that we don't need.
//
// Option 3 seems like the most robust solution, so this is what
// we're going to do.
// Create a new sublayer.
let new_layer: *mut Object = msg_send![class!(CAMetalLayer), new];
let () = msg_send![root_layer, addSublayer: new_layer];
#[cfg(target_os = "macos")]
{
// Automatically resize the sublayer's frame to match the
// superlayer's bounds.
//
// Note that there is a somewhat hidden design decision in this:
// We define the `width` and `height` in `configure` to control
// the `drawableSize` of the layer, while `bounds` and `frame` are
// outside of the user's direct control - instead, though, they
// can control the size of the view (or root layer), and get the
// desired effect that way.
//
// We _could_ also let `configure` set the `bounds` size, however
// that would be inconsistent with using the root layer directly
// (as we may do, see above).
let width_sizable = 1 << 1; // kCALayerWidthSizable
let height_sizable = 1 << 4; // kCALayerHeightSizable
let mask: std::ffi::c_uint = width_sizable | height_sizable;
let () = msg_send![new_layer, setAutoresizingMask: mask];
}
// Specify the relative size that the auto resizing mask above
// will keep (i.e. tell it to fill out its superlayer).
let frame: CGRect = msg_send![root_layer, bounds];
let () = msg_send![new_layer, setFrame: frame];
// The gravity to use when the layer's `drawableSize` isn't the
// same as the bounds rectangle.
//
// The desired content gravity is `kCAGravityResize`, because it
// masks / alleviates issues with resizing when
// `present_with_transaction` is disabled, and behaves better when
// moving the window between monitors.
//
// Unfortunately, it also makes it harder to see changes to
// `width` and `height` in `configure`. When debugging resize
// issues, swap this for `kCAGravityTopLeft` instead.
let _: () = msg_send![new_layer, setContentsGravity: unsafe { kCAGravityResize }];
// Set initial scale factor of the layer. This is kept in sync by
// `configure` (on UIKit), and the delegate below (on AppKit).
let scale_factor: CGFloat = msg_send![root_layer, contentsScale];
let () = msg_send![new_layer, setContentsScale: scale_factor];
let delegate = HalManagedMetalLayerDelegate::new();
let () = msg_send![new_layer, setDelegate: delegate.0];
unsafe { StrongPtr::new(new_layer) }
}
}
pub(super) fn dimensions(&self) -> wgt::Extent3d {
let (size, scale): (CGSize, CGFloat) = unsafe {
let render_layer_borrow = self.render_layer.lock();
let render_layer = render_layer_borrow.as_ref();
let bounds: CGRect = msg_send![render_layer, bounds];
let contents_scale: CGFloat = msg_send![render_layer, contentsScale];
(bounds.size, contents_scale)
};
wgt::Extent3d {
width: (size.width * scale) as u32,
height: (size.height * scale) as u32,
depth_or_array_layers: 1,
}
}
}
impl crate::Surface for super::Surface {
type A = super::Api;
unsafe fn configure(
&self,
device: &super::Device,
config: &crate::SurfaceConfiguration,
) -> Result<(), crate::SurfaceError> {
log::debug!("build swapchain {:?}", config);
let caps = &device.shared.private_caps;
*self.swapchain_format.write() = Some(config.format);
*self.extent.write() = config.extent;
let render_layer = self.render_layer.lock();
let framebuffer_only = config.usage == crate::TextureUses::COLOR_TARGET;
let display_sync = match config.present_mode {
wgt::PresentMode::Fifo => true,
wgt::PresentMode::Immediate => false,
m => unreachable!("Unsupported present mode: {m:?}"),
};
let drawable_size = CGSize::new(config.extent.width as f64, config.extent.height as f64);
match config.composite_alpha_mode {
wgt::CompositeAlphaMode::Opaque => render_layer.set_opaque(true),
wgt::CompositeAlphaMode::PostMultiplied => render_layer.set_opaque(false),
_ => (),
}
// AppKit / UIKit automatically sets the correct scale factor for
// layers attached to a view. Our layer, however, may not be directly
// attached to a view; in those cases, we need to set the scale
// factor ourselves.
//
// For AppKit, we do so by adding a delegate on the layer with the
// `layer:shouldInheritContentsScale:fromWindow:` method returning
// `true` - this tells the system to automatically update the scale
// factor when it changes.
//
// For UIKit, we manually update the scale factor from the super layer
// here, if there is one.
//
// TODO: Is there a way that we could listen to such changes instead?
#[cfg(not(target_os = "macos"))]
{
let superlayer: *mut Object = msg_send![render_layer.as_ptr(), superlayer];
if !superlayer.is_null() {
let scale_factor: CGFloat = msg_send![superlayer, contentsScale];
let () = msg_send![render_layer.as_ptr(), setContentsScale: scale_factor];
}
}
let device_raw = device.shared.device.lock();
render_layer.set_device(&device_raw);
render_layer.set_pixel_format(caps.map_format(config.format));
render_layer.set_framebuffer_only(framebuffer_only);
render_layer.set_presents_with_transaction(self.present_with_transaction);
// opt-in to Metal EDR
// EDR potentially more power used in display and more bandwidth, memory footprint.
let wants_edr = config.format == wgt::TextureFormat::Rgba16Float;
if wants_edr != render_layer.wants_extended_dynamic_range_content() {
render_layer.set_wants_extended_dynamic_range_content(wants_edr);
}
// this gets ignored on iOS for certain OS/device combinations (iphone5s iOS 10.3)
render_layer.set_maximum_drawable_count(config.maximum_frame_latency as u64 + 1);
render_layer.set_drawable_size(drawable_size);
if caps.can_set_next_drawable_timeout {
let () = msg_send![*render_layer, setAllowsNextDrawableTimeout:false];
}
if caps.can_set_display_sync {
let () = msg_send![*render_layer, setDisplaySyncEnabled: display_sync];
}
Ok(())
}
unsafe fn unconfigure(&self, _device: &super::Device) {
*self.swapchain_format.write() = None;
}
unsafe fn acquire_texture(
&self,
_timeout_ms: Option<std::time::Duration>, //TODO
_fence: &super::Fence,
) -> Result<Option<crate::AcquiredSurfaceTexture<super::Api>>, crate::SurfaceError> {
let render_layer = self.render_layer.lock();
let (drawable, texture) = match autoreleasepool(|| {
render_layer
.next_drawable()
.map(|drawable| (drawable.to_owned(), drawable.texture().to_owned()))
}) {
Some(pair) => pair,
None => return Ok(None),
};
let swapchain_format = self.swapchain_format.read().unwrap();
let extent = self.extent.read();
let suf_texture = super::SurfaceTexture {
texture: super::Texture {
raw: texture,
format: swapchain_format,
raw_type: metal::MTLTextureType::D2,
array_layers: 1,
mip_levels: 1,
copy_size: crate::CopyExtent {
width: extent.width,
height: extent.height,
depth: 1,
},
},
drawable,
present_with_transaction: self.present_with_transaction,
};
Ok(Some(crate::AcquiredSurfaceTexture {
texture: suf_texture,
suboptimal: false,
}))
}
unsafe fn discard_texture(&self, _texture: super::SurfaceTexture) {}
}