jflib-plat 0.1.0

// linux_gpuout -- what lib/gpu's images need from the window system: dmabuf buffers on a window,
// through JFLib's own Wayland and X11 code (programs against glibc only; docs/GPU.md "Ausgabe unter
// Linux").  No libwayland, no libxcb: Vulkan's surfaces would want a pointer from them, so the GPU
// draws into images of its own and this code hands them to the window.
//
//   win_gpu_child(w) -> NativeWindow   what the display accepts for window w (format + modifier
//                                      pairs, its render device) and the window's size: None = the
//                                      CPU path.  The name is the Windows presenter's, whose child
//                                      window this stands for; a Linux window needs no child: one
//                                      wl_surface or X window takes shared memory and dmabufs in turn
//   win_gpu_child_show, win_release_kept, win_in_sizemove, win_display_adapter, win_remote_session
//                                      nothing to do or know here
//   gpu_buf_new(w, &GpuBufDesc) -> handle     a buffer of window w from its planes (takes the fds);
//                                      0: refused.  On Wayland its answer comes later: PENDING first
//   gpu_buf_state(w, handle) -> GPU_BUF_*     FREE: nobody reads it, it is not the one on the window
//   gpu_buf_free(w, handle)            the buffer goes (also while it is on the window: what it shows
//                                      stays, as long as nobody writes the memory)
//   gpu_can_show(w) -> bool            a new frame is welcome now: the last commit has been answered
//                                      (the frame callback, PresentCompleteNotify; 1 s at most)
//   gpu_show(w, handle, rects)         the buffer, finished by the GPU, goes on the window (at once, or
//                                      as soon as the window can take it); rects: what changed against
//                                      the last one, None = all.  From now on window w shows through
//                                      buffers, until the next win_present.
//   gpu_next_look(w) -> time_us        when a frame that cannot go on yet should look again; the wait
//                                      returns earlier when the answer comes
//   gpu_wait(deadline_us)              pump the display until the deadline, also with events queued
//                                      (they stay queued; a plain wait would not read the socket)
//
// Only the thread of the window loop calls these (the backends are single-threaded: linux_disp.rs).
//
// No wrong frame can show:
//   * a buffer goes to the window only after the GPU has finished it (lib/gpu: Swapchain::flush
//     looks at the timeline without waiting).  So nothing depends on implicit sync: at the attach no
//     fence is pending on the buffer, on any compositor, kernel or driver.
//   * a buffer is drawn into only after the compositor gave it back (wl_buffer.release,
//     PresentIdleNotify) and no read of it is pending on its dma-buf (poll POLLOUT: the compositor's
//     GPU may still be reading it when the release arrives), and never while it is the newest.
//   * win_present ends the buffers' turn: a frame still on its way is dropped, shared memory shows
//     the whole frame.
// Test aids: win_test_image(w) reads what the window system holds where it can (X11: GetImage).

use alloc::vec::Vec;

use super::disp::{disp_backend, BK_WAYLAND, BK_X11};

/// a buffer's state (gpu_buf_state)
pub const GPU_BUF_PENDING: u32 = 0;
pub const GPU_BUF_FREE: u32 = 1;
pub const GPU_BUF_BUSY: u32 = 2;
pub const GPU_BUF_FAILED: u32 = 3;

/// what a display accepts as buffers
#[derive(Clone, Debug, Default)]
pub struct GpuCaps {
    /// the device it renders with (dev_t of a node of the DRM device), when it says so
    pub device: Option<u64>,
    /// DRM fourcc and modifier
    pub formats: Vec<(u32, u64)>,
}

/// a plane of a buffer: a dma-buf (owned: closed once sent), its offset and row pitch
#[derive(Clone, Copy, Debug)]
pub struct GpuPlane {
    pub fd: i32,
    pub offset: u32,
    pub stride: u32,
}

/// a buffer of memory the GPU drew into
#[derive(Clone, Debug)]
pub struct GpuBufDesc {
    pub w: i32,
    pub h: i32,
    pub fourcc: u32,
    pub modifier: u64,
    pub planes: Vec<GpuPlane>,
}

/// the Linux form of the handles lib/gpu gets for a window (Windows: HWND, HINSTANCE)
#[derive(Clone, Debug)]
pub struct NativeWindow {
    pub caps: GpuCaps,
    pub size: (i32, i32),
}

pub fn win_gpu_child(w: i32) -> Option<NativeWindow> {
    if crate::env("jfgui_GPU_DMABUF").as_deref() == Some("0") {
        return None; // (tests: a display without them)
    }
    let caps = match disp_backend() {
        BK_WAYLAND => super::wl::gpuw::gpu_caps(),
        BK_X11 => super::x11::gpux::gpu_caps(w),
        _ => None,
    }?;
    if caps.formats.is_empty() {
        return None;
    }
    Some(NativeWindow { caps, size: crate::win_size(w) })
}

pub fn win_gpu_child_show(_w: i32, _show: bool) {}

pub fn win_release_kept(_w: i32) {}

/// no child now, but it may come (the host or the next frame wakes the loop): only Android
pub fn win_gpu_child_later(_w: i32) -> bool {
    false
}

/// the window still shows on its child alone: here always
pub fn win_gpu_child_alone(_w: i32) -> bool {
    true
}

/// how the output came up (GPU_STATE_*): Android keeps it across runs
pub fn gpu_out_state(_state: u32) {}

/// a thread for the output's jobs
pub fn gpu_thread_spawn(stack: usize, f: alloc::boxed::Box<dyn FnOnce() + Send>) -> Option<crate::Thread> {
    crate::thread_spawn(stack, f)
}

pub fn win_in_sizemove() -> bool {
    false
}

/// the GPU that drives the window's monitor: not known here, the display's device decides (GpuCaps)
pub fn win_display_adapter(_w: i32) -> Option<(u32, u32)> {
    None
}

pub fn win_remote_session() -> bool {
    false
}

pub fn gpu_buf_new(w: i32, d: &GpuBufDesc) -> u32 {
    if crate::env("jfgui_GPU_DMABUF").as_deref() == Some("refuse") {
        close_planes(d); // (tests: a display that refuses them)
        return 0;
    }
    match disp_backend() {
        BK_WAYLAND => super::wl::gpuw::gpu_buf_new(w, d),
        BK_X11 => super::x11::gpux::gpu_buf_new(w, d),
        _ => {
            close_planes(d);
            0
        }
    }
}

/// the descriptors of a buffer nobody takes
pub(crate) fn close_planes(d: &GpuBufDesc) {
    for p in &d.planes {
        // SAFETY: closes a descriptor the caller handed over.
        unsafe { rt::os::syscall3(rt::os::SYS_CLOSE, p.fd as usize, 0, 0) };
    }
}

pub fn gpu_buf_state(w: i32, h: u32) -> u32 {
    match disp_backend() {
        BK_WAYLAND => super::wl::gpuw::gpu_buf_state(w, h),
        BK_X11 => super::x11::gpux::gpu_buf_state(w, h),
        _ => GPU_BUF_FAILED,
    }
}

pub fn gpu_buf_free(w: i32, h: u32) {
    match disp_backend() {
        BK_WAYLAND => super::wl::gpuw::gpu_buf_free(w, h),
        BK_X11 => super::x11::gpux::gpu_buf_free(w, h),
        _ => {}
    }
}

pub fn gpu_can_show(w: i32) -> bool {
    match disp_backend() {
        BK_WAYLAND => super::wl::gpuw::gpu_can_show(w),
        BK_X11 => super::x11::gpux::gpu_can_show(w),
        _ => false,
    }
}

pub fn gpu_show(w: i32, h: u32, rects: Option<&[[i32; 4]]>) {
    match disp_backend() {
        BK_WAYLAND => super::wl::gpuw::gpu_show(w, h, rects),
        BK_X11 => super::x11::gpux::gpu_show(w, h, rects),
        _ => {}
    }
}

pub fn gpu_next_look(w: i32) -> u64 {
    match disp_backend() {
        BK_WAYLAND => super::wl::gpuw::gpu_next_look(w),
        BK_X11 => super::x11::gpux::gpu_next_look(w),
        _ => u64::MAX,
    }
}

pub fn gpu_wait(deadline_us: u64) {
    let now = crate::time_us();
    let ms = (deadline_us.saturating_sub(now).div_ceil(1000)).min(1000) as i32;
    match disp_backend() {
        BK_WAYLAND => super::wl::gpuw::gpu_pump(ms),
        BK_X11 => super::x11::gpux::gpu_pump(ms),
        _ => crate::sleep_ms(ms as u32),
    }
}

// ------------------------------------------------------------------ test aids, as on Windows

pub const WT_PIXEL: u32 = 1;
pub const WT_REDRAW: u32 = 2;
pub const WT_MOVE: u32 = 3;
pub const WT_DPI: u32 = 4;
pub const WT_POPUP_RECT: u32 = 7;
pub const WT_NOANIM: u32 = 16;
pub const WT_FROM_POINT: u32 = 17;
pub const WT_SHOW: u32 = 18;

/// (tests)
///   WT_PIXEL      the colour the window system holds at client pixel a[0], a[1] of window w: X11
///                 GetImage, Wayland the last shared memory buffer; -1: no way to know (Wayland on
///                 GPU buffers: a client cannot read a window back)
///   WT_MOVE       a[0], a[1], a[2], a[3]: the window's rectangle; win_set_rect reports nothing back
///                 here, the event a size change has on Windows comes from this aid
///   WT_DPI        a[0]: the dpi as if the compositor preferred that scale (Wayland with a viewport,
///                 else -1: X11 has one dpi for the display and no second size)
///   WT_SHOW       a[0] = 7 minimised, 4 back: X11 through the window manager; Wayland can minimise, but
///                 no client can undo that: 4 does what the compositor's next activation does here
///   WT_POPUP_RECT popup slot w is shown: 1, else -1
///   WT_NOANIM, WT_FROM_POINT  nothing to turn off; nobody tells a client what lies on top of its
///                 window: it counts as ours
pub fn win_test(op: u32, w: i32, a: [i32; 4]) -> i64 {
    match op {
        WT_PIXEL => match disp_backend() {
            BK_WAYLAND => match super::wl::gpuw::gpu_test_shm(w) {
                Some((iw, ih, px)) if a[0] >= 0 && a[1] >= 0 && a[0] < iw && a[1] < ih => {
                    let o = (a[1] as usize * iw as usize + a[0] as usize) * 4;
                    px[o] as i64 | (px[o + 1] as i64) << 8 | (px[o + 2] as i64) << 16
                }
                _ => -1,
            },
            BK_X11 => super::x11::gpux::gpu_test_pixel(w, a[0], a[1]),
            _ => -1,
        },
        WT_MOVE => {
            crate::win_set_rect(w, a[0], a[1], a[2], a[3]);
            crate::evq_push(crate::Event { typ: crate::E_RESIZE, x: a[2], y: a[3], win: w as u8, ..crate::Event::default() });
            1
        }
        WT_DPI => match disp_backend() {
            BK_WAYLAND => super::wl::gpuw::gpu_test_dpi(w, a[0]),
            _ => -1,
        },
        WT_SHOW => {
            if a[0] == 7 {
                crate::win_cmd(w, crate::WCMD_MINIMIZE);
            } else if disp_backend() == BK_WAYLAND {
                super::wl::gpuw::gpu_test_unminimize(w);
            } else {
                crate::win_cmd(w, crate::WCMD_RESTORE);
            }
            1
        }
        WT_POPUP_RECT => match disp_backend() {
            BK_WAYLAND => super::wl::gpuw::gpu_test_popup(w),
            BK_X11 => super::x11::gpux::gpu_test_popup(w),
            _ => -1,
        },
        _ => 1,
    }
}

/// (tests) what the window system holds for window w: (w, h, rows of w * 4 bytes): X11 reads it
/// back (GetImage; also a buffer on the window), Wayland has no way to: None
pub fn win_test_image(w: i32) -> Option<(i32, i32, Vec<u8>)> {
    match disp_backend() {
        BK_X11 => super::x11::gpux::gpu_test_image(w),
        _ => None,
    }
}

/// (tests) a part of the screen: no client on Linux can read it without asking the user
pub fn win_test_screen(_x: i32, _y: i32, _w: i32, _h: i32) -> Option<Vec<u8>> {
    None
}

/// (tests) nothing to send to: Windows' messages
pub fn win_test_send(_w: i32, _msg: u32, _wp: usize, _lp: isize) -> isize {
    0
}

/// (tests) (CPU time of this process so far in us, its resident bytes, its anonymous resident bytes)
pub fn win_test_usage() -> (u64, u64, u64) {
    let mut ts = [0i64; 2];
    // SAFETY: CLOCK_PROCESS_CPUTIME_ID into a timespec.
    unsafe { rt::os::syscall3(rt::os::SYS_CLOCK_GETTIME, 2, ts.as_mut_ptr() as usize, 0) };
    let cpu = ts[0] as u64 * 1_000_000 + ts[1] as u64 / 1000;
    let (mut rss, mut anon) = (0, 0);
    if let Some(b) = super::sys::read_file_raw("/proc/self/status") {
        for ln in b.split(|&c| c == b'\n') {
            let val = |n: &[u8]| {
                ln.strip_prefix(n).map_or(0u64, |r| r.iter().filter(|c| c.is_ascii_digit()).fold(0, |v, c| v * 10 + (c - b'0') as u64) * 1024)
            };
            rss = rss.max(val(b"VmRSS:"));
            anon = anon.max(val(b"RssAnon:"));
        }
    }
    (cpu, rss as u64, anon as u64)
}

/// (bench: jfgui_WL_FEEDBACK=1 on Wayland) the commits since the last call and when each reached the
/// screen (wp_presentation): (time of the commit, time on the screen; 0: discarded), time_us
pub fn gpu_test_presented() -> Vec<(u64, u64)> {
    match disp_backend() {
        BK_WAYLAND => super::wl::gpuw::gpu_test_presented(),
        _ => Vec::new(),
    }
}