scrap: load the D3D compiler securely from System32

Signed-off-by: 21pages <sunboeasy@gmail.com>

libs/scrap/Cargo.toml

@@ -37,7 +37,7 @@ serde = {version="1.0", features=["derive"]}
 [dependencies.winapi]
 version = "0.3"
 default-features = true
-features = ["dxgi", "dxgi1_2", "dxgi1_5", "d3d11", "winuser", "winerror", "errhandlingapi", "libloaderapi"]
+features = ["dxgi", "dxgi1_2", "dxgi1_5", "dxgi1_6", "d3d11", "winuser", "winerror", "errhandlingapi", "libloaderapi"]
 
 [target.'cfg(target_os = "macos")'.dependencies]
 block = "0.1"

libs/scrap/src/dxgi/hdr.rs

@@ -0,0 +1,629 @@
+//! HDR desktop -> SDR normalization for Desktop Duplication frames.
+//!
+//! With HDR enabled Windows composes the desktop as linear scRGB in
+//! R16G16B16A16_FLOAT, and SDR "white" sits at the user's SDR content
+//! brightness (DISPLAYCONFIG_SDR_WHITE_LEVEL) rather than at 1.0. The legacy
+//! DuplicateOutput converts that to BGRA8 by clipping, which is the washed-out
+//! picture reported for HDR hosts. This pass divides by the SDR white level,
+//! clamps, and applies the sRGB transfer, so SDR content comes out exactly as
+//! it would from an SDR desktop.
+//!
+//! It is a normalization, not a tone map: anything brighter than SDR white
+//! (HDR video, HDR games) clips to white on the SDR viewer, where the local
+//! HDR display would show it brighter than white. A roll-off would have to
+//! move SDR white below 1.0 to make headroom, trading the accuracy of the SDR
+//! content this pass exists for, so it is deliberately not done.
+//!
+//! Windows 11 22H2 also composes Advanced Color SDR (WCG) desktops in FP16,
+//! but there 1.0 is the display's reference white rather than 80 nits and no
+//! SDR white level applies. IDXGIOutput6 tells the two apart, and for a
+//! non-HDR output the pass only applies the scRGB -> sRGB transfer.
+//!
+//! The conversion is automatic and stays on the controlled side on purpose:
+//! the controller renders through Flutter external textures, which are 8-bit
+//! on every desktop platform, so there is nothing to gain from sending HDR.
+//! Real HDR pass-through, if the renderer ever supports it, should follow the
+//! Sunshine/Moonlight pattern instead: an `hdr` capability bit advertised by
+//! the controller behind an explicit user toggle, negotiated like i444.
+
+use super::ComPtr;
+use hbb_common::log;
+use std::{
+    io, mem, ptr,
+    sync::{atomic::AtomicBool, OnceLock},
+    time::{Duration, Instant},
+};
+use winapi::{
+    ctypes::c_void,
+    shared::{
+        basetsd::SIZE_T,
+        dxgi::{CreateDXGIFactory1, IDXGIFactory1, IID_IDXGIFactory1, DXGI_OUTPUT_DESC},
+        dxgi1_2::IDXGIOutput1,
+        dxgi1_6::{IDXGIOutput6, IID_IDXGIOutput6, DXGI_OUTPUT_DESC1},
+        dxgiformat::DXGI_FORMAT_B8G8R8A8_UNORM,
+        dxgitype::{DXGI_COLOR_SPACE_RGB_FULL_G2084_NONE_P2020, DXGI_SAMPLE_DESC},
+        minwindef::{FALSE, LPCVOID, UINT, ULONG},
+        ntdef::{LONG, LPCSTR, WCHAR},
+        winerror::S_OK,
+    },
+    um::{
+        d3d11::*,
+        d3dcommon::{ID3DBlob, ID3DInclude, D3D_PRIMITIVE_TOPOLOGY_TRIANGLELIST, D3D_SHADER_MACRO},
+        libloaderapi::{GetProcAddress, LoadLibraryExW, LOAD_LIBRARY_SEARCH_SYSTEM32},
+        unknwnbase::IUnknown,
+        wingdi::{
+            DISPLAYCONFIG_DEVICE_INFO_GET_SOURCE_NAME, DISPLAYCONFIG_DEVICE_INFO_HEADER,
+            DISPLAYCONFIG_MODE_INFO, DISPLAYCONFIG_PATH_INFO, DISPLAYCONFIG_SOURCE_DEVICE_NAME,
+            DISPLAYCONFIG_TOPOLOGY_ID,
+        },
+        winnt::HRESULT,
+    },
+};
+
+/// Set once the tone-map can never work in this process (no d3dcompiler, the
+/// shaders do not compile). Capturers then stop asking DXGI for float frames.
+/// Device-specific failures are not recorded here; the capturer that hit one
+/// re-duplicates without the tone-map on its own.
+pub static UNAVAILABLE: AtomicBool = AtomicBool::new(false);
+
+/// Failures no capturer on this machine can recover from, as opposed to
+/// device-specific ones that a recreated capturer may not hit again.
+pub fn is_permanent(err: &io::Error) -> bool {
+    err.kind() == io::ErrorKind::Unsupported
+}
+
+const VS_SRC: &str = "\
+float4 main(uint id : SV_VertexID) : SV_Position {
+    float2 uv = float2((id << 1) & 2, id & 2);
+    return float4(uv * float2(2.0, -2.0) + float2(-1.0, 1.0), 0.0, 1.0);
+}";
+
+const PS_SRC: &str = "\
+Texture2D<float4> src : register(t0);
+cbuffer Params : register(b0) { float inv_sdr_white; float3 pad; };
+float4 main(float4 pos : SV_Position) : SV_Target {
+    float3 lin = saturate(src.Load(int3(pos.xy, 0)).rgb * inv_sdr_white);
+    float3 lo = lin * 12.92;
+    float3 hi = 1.055 * pow(lin, 1.0 / 2.4) - 0.055;
+    return float4(lerp(hi, lo, step(lin, 0.0031308)), 1.0);
+}";
+
+const OUTPUT_STATE_REFRESH: Duration = Duration::from_secs(1);
+
+pub struct HdrToSdr {
+    device: ComPtr<ID3D11Device>,
+    context: ComPtr<ID3D11DeviceContext>,
+    vs: ComPtr<ID3D11VertexShader>,
+    ps: ComPtr<ID3D11PixelShader>,
+    params: ComPtr<ID3D11Buffer>,
+    target: ComPtr<ID3D11Texture2D>,
+    rtv: ComPtr<ID3D11RenderTargetView>,
+    srv: ComPtr<ID3D11ShaderResourceView>,
+    // Texture `srv` was created for. The view keeps it alive, so the address
+    // cannot be recycled behind our back.
+    srv_source: *mut ID3D11Texture2D,
+    width: u32,
+    height: u32,
+    device_name: [WCHAR; 32],
+    // Advanced Color state is read from `output6`, which is re-enumerated from a
+    // fresh factory whenever `factory` stops being current.
+    factory: ComPtr<IDXGIFactory1>,
+    output6: ComPtr<IDXGIOutput6>,
+    is_hdr: bool,
+    // DISPLAYCONFIG units (1000 == 80 nits == scRGB 1.0). `None` when it could
+    // not be read, in which case 80 nits is assumed until it can.
+    sdr_white_level: Option<u32>,
+    queried_at: Instant,
+}
+
+impl HdrToSdr {
+    pub fn new(
+        device: *mut ID3D11Device,
+        context: *mut ID3D11DeviceContext,
+        output: *mut IDXGIOutput1,
+        device_name: &[WCHAR; 32],
+    ) -> io::Result<Self> {
+        unsafe {
+            if device.is_null() || context.is_null() {
+                return Err(other("no d3d11 device"));
+            }
+            (*device).AddRef();
+            let device = ComPtr(device);
+            (*context).AddRef();
+            let context = ComPtr(context);
+
+            let compile = load_d3d_compile()?;
+            let vs_code = compile_shader(compile, VS_SRC, b"vs_4_0\0")?;
+            let ps_code = compile_shader(compile, PS_SRC, b"ps_4_0\0")?;
+            let mut vs = ptr::null_mut();
+            check(
+                (*device.0).CreateVertexShader(
+                    (*vs_code.0).GetBufferPointer(),
+                    (*vs_code.0).GetBufferSize(),
+                    ptr::null_mut(),
+                    &mut vs,
+                ),
+                "CreateVertexShader",
+            )?;
+            let vs = ComPtr(vs);
+            let mut ps = ptr::null_mut();
+            check(
+                (*device.0).CreatePixelShader(
+                    (*ps_code.0).GetBufferPointer(),
+                    (*ps_code.0).GetBufferSize(),
+                    ptr::null_mut(),
+                    &mut ps,
+                ),
+                "CreatePixelShader",
+            )?;
+            let ps = ComPtr(ps);
+
+            // Not found leaves the factory null, so the first refresh enumerates
+            // again instead of trusting the capturer's possibly stale output.
+            let (factory, mut output6) = enumerate_output6(device_name);
+            if output6.is_null() {
+                output6 = query_output6(output as *mut IUnknown);
+            }
+            // Float frames are only requested where IDXGIOutput6 exists, so an
+            // unreadable description still comes from an HDR-capable stack.
+            let is_hdr = output_is_hdr(output6.0).unwrap_or(true);
+            let sdr_white_level = if is_hdr {
+                query_sdr_white_level(device_name)
+            } else {
+                None
+            };
+            if is_hdr && sdr_white_level.is_none() {
+                log::warn!(
+                    "HDR output but the SDR white level cannot be read (needs Windows 10 1709+), \
+                     assuming 80 nits until it can"
+                );
+            }
+            let init = params_data(sdr_white_level);
+            let desc = D3D11_BUFFER_DESC {
+                ByteWidth: mem::size_of_val(&init) as _,
+                Usage: D3D11_USAGE_DEFAULT,
+                BindFlags: D3D11_BIND_CONSTANT_BUFFER,
+                CPUAccessFlags: 0,
+                MiscFlags: 0,
+                StructureByteStride: 0,
+            };
+            let data = D3D11_SUBRESOURCE_DATA {
+                pSysMem: init.as_ptr() as _,
+                SysMemPitch: 0,
+                SysMemSlicePitch: 0,
+            };
+            let mut params = ptr::null_mut();
+            check(
+                (*device.0).CreateBuffer(&desc, &data, &mut params),
+                "CreateBuffer",
+            )?;
+            let params = ComPtr(params);
+            log::info!(
+                "scRGB desktop conversion ready, hdr {is_hdr}, sdr white level {sdr_white_level:?}"
+            );
+
+            Ok(Self {
+                device,
+                context,
+                vs,
+                ps,
+                params,
+                target: ComPtr(ptr::null_mut()),
+                rtv: ComPtr(ptr::null_mut()),
+                srv: ComPtr(ptr::null_mut()),
+                srv_source: ptr::null_mut(),
+                width: 0,
+                height: 0,
+                device_name: *device_name,
+                factory,
+                output6,
+                is_hdr,
+                sdr_white_level,
+                queried_at: Instant::now(),
+            })
+        }
+    }
+
+    /// Renders `source` (R16G16B16A16_FLOAT) into an owned B8G8R8A8_UNORM
+    /// texture of the same size and returns it. The texture stays valid until
+    /// the next call.
+    pub fn convert(
+        &mut self,
+        source: *mut ID3D11Texture2D,
+        desc: &D3D11_TEXTURE2D_DESC,
+    ) -> io::Result<*mut ID3D11Texture2D> {
+        unsafe {
+            self.refresh_output_state();
+            self.ensure_target(desc.Width, desc.Height)?;
+            self.ensure_source_view(source)?;
+
+            let ctx = self.context.0;
+            let rtv = self.rtv.0;
+            let srv = self.srv.0;
+            let params = self.params.0;
+            let viewport = D3D11_VIEWPORT {
+                TopLeftX: 0.0,
+                TopLeftY: 0.0,
+                Width: self.width as f32,
+                Height: self.height as f32,
+                MinDepth: 0.0,
+                MaxDepth: 1.0,
+            };
+            (*ctx).OMSetRenderTargets(1, &rtv, ptr::null_mut());
+            (*ctx).OMSetBlendState(ptr::null_mut(), &[0.0; 4], 0xffff_ffff);
+            (*ctx).OMSetDepthStencilState(ptr::null_mut(), 0);
+            (*ctx).RSSetState(ptr::null_mut());
+            (*ctx).RSSetViewports(1, &viewport);
+            (*ctx).IASetInputLayout(ptr::null_mut());
+            (*ctx).IASetPrimitiveTopology(D3D_PRIMITIVE_TOPOLOGY_TRIANGLELIST);
+            (*ctx).VSSetShader(self.vs.0, ptr::null(), 0);
+            (*ctx).PSSetShader(self.ps.0, ptr::null(), 0);
+            (*ctx).PSSetConstantBuffers(0, 1, &params);
+            (*ctx).PSSetShaderResources(0, 1, &srv);
+            (*ctx).Draw(3, 0);
+            // Unbind so the next frame's copy and the encoder never see the
+            // target as a live render target or the desktop image as a bound
+            // shader input.
+            let no_srv: *mut ID3D11ShaderResourceView = ptr::null_mut();
+            (*ctx).PSSetShaderResources(0, 1, &no_srv);
+            (*ctx).OMSetRenderTargets(0, ptr::null(), ptr::null_mut());
+            Ok(self.target.0)
+        }
+    }
+
+    unsafe fn ensure_target(&mut self, width: u32, height: u32) -> io::Result<()> {
+        if !self.target.is_null() && self.width == width && self.height == height {
+            return Ok(());
+        }
+        let desc = D3D11_TEXTURE2D_DESC {
+            Width: width,
+            Height: height,
+            MipLevels: 1,
+            ArraySize: 1,
+            Format: DXGI_FORMAT_B8G8R8A8_UNORM,
+            SampleDesc: DXGI_SAMPLE_DESC {
+                Count: 1,
+                Quality: 0,
+            },
+            Usage: D3D11_USAGE_DEFAULT,
+            BindFlags: D3D11_BIND_RENDER_TARGET | D3D11_BIND_SHADER_RESOURCE,
+            CPUAccessFlags: 0,
+            MiscFlags: D3D11_RESOURCE_MISC_SHARED,
+        };
+        let mut target = ptr::null_mut();
+        check(
+            (*self.device.0).CreateTexture2D(&desc, ptr::null(), &mut target),
+            "CreateTexture2D",
+        )?;
+        let target = ComPtr(target);
+        let mut rtv = ptr::null_mut();
+        check(
+            (*self.device.0).CreateRenderTargetView(target.0 as *mut _, ptr::null(), &mut rtv),
+            "CreateRenderTargetView",
+        )?;
+        self.rtv = ComPtr(rtv);
+        self.target = target;
+        self.width = width;
+        self.height = height;
+        Ok(())
+    }
+
+    unsafe fn ensure_source_view(&mut self, source: *mut ID3D11Texture2D) -> io::Result<()> {
+        if !self.srv.is_null() && self.srv_source == source {
+            return Ok(());
+        }
+        let mut srv = ptr::null_mut();
+        check(
+            (*self.device.0).CreateShaderResourceView(source as *mut _, ptr::null(), &mut srv),
+            "CreateShaderResourceView",
+        )?;
+        self.srv = ComPtr(srv);
+        self.srv_source = source;
+        Ok(())
+    }
+
+    // Advanced Color state is dynamic: HDR can be switched on or off, or a WCG
+    // desktop can turn into an HDR one, without the duplication being lost. An
+    // output's description is a snapshot, so once the factory is no longer
+    // current a new factory and output are needed to see the new state, as the
+    // GetDesc1 docs require.
+    unsafe fn refresh_output_state(&mut self) {
+        if self.queried_at.elapsed() < OUTPUT_STATE_REFRESH {
+            return;
+        }
+        self.queried_at = Instant::now();
+        if self.factory.is_null() || (*self.factory.0).IsCurrent() == FALSE {
+            let (factory, output6) = enumerate_output6(&self.device_name);
+            if !output6.is_null() {
+                self.factory = factory;
+                self.output6 = output6;
+            } else {
+                // Keep reading the old output, but enumerate again next time.
+                self.factory = ComPtr(ptr::null_mut());
+            }
+        }
+        let is_hdr = output_is_hdr(self.output6.0).unwrap_or(self.is_hdr);
+        let level = if is_hdr {
+            query_sdr_white_level(&self.device_name)
+        } else {
+            None
+        };
+        // A transiently unreadable level keeps the last known one.
+        if is_hdr == self.is_hdr && (level.is_none() || level == self.sdr_white_level) {
+            return;
+        }
+        log::info!(
+            "output changed: hdr {} -> {is_hdr}, sdr white level {:?} -> {level:?}",
+            self.is_hdr,
+            self.sdr_white_level
+        );
+        if is_hdr && level.is_none() {
+            log::warn!(
+                "HDR output but the SDR white level cannot be read, assuming 80 nits until it can"
+            );
+        }
+        self.is_hdr = is_hdr;
+        self.sdr_white_level = level;
+        let data = params_data(level);
+        (*self.context.0).UpdateSubresource(
+            self.params.0 as *mut _,
+            0,
+            ptr::null(),
+            data.as_ptr() as _,
+            0,
+            0,
+        );
+    }
+}
+
+// `None` is either a non-HDR (WCG) output, where 1.0 already is the display's
+// reference white, or an HDR output whose level is unknown; both use 1.0.
+fn params_data(sdr_white_level: Option<u32>) -> [f32; 4] {
+    [
+        1000.0 / sdr_white_level.unwrap_or(1000) as f32,
+        0.0,
+        0.0,
+        0.0,
+    ]
+}
+
+// FP16 desktop composition means either HDR (scene-referred, 1.0 == 80 nits)
+// or, since Windows 11 22H2, Advanced Color SDR (display-referred), and only
+// IDXGIOutput6 (Windows 10 1703) tells them apart. `None` when it cannot be
+// read right now.
+unsafe fn output_is_hdr(output6: *mut IDXGIOutput6) -> Option<bool> {
+    if output6.is_null() {
+        return None;
+    }
+    let mut desc: DXGI_OUTPUT_DESC1 = mem::zeroed();
+    if (*output6).GetDesc1(&mut desc) != S_OK {
+        return None;
+    }
+    Some(desc.ColorSpace == DXGI_COLOR_SPACE_RGB_FULL_G2084_NONE_P2020)
+}
+
+unsafe fn query_output6(object: *mut IUnknown) -> ComPtr<IDXGIOutput6> {
+    let mut output6: *mut IDXGIOutput6 = ptr::null_mut();
+    if !object.is_null() {
+        (*object).QueryInterface(
+            &IID_IDXGIOutput6,
+            &mut output6 as *mut *mut _ as *mut *mut _,
+        );
+    }
+    ComPtr(output6)
+}
+
+// A fresh factory sees the current display configuration; the output is found
+// by its GDI name because the outputs of a stale factory keep stale descriptions.
+// Returns both or neither: a non-null factory guarantees the output came from
+// its topology, so a caller that sees a null factory knows to enumerate again.
+unsafe fn enumerate_output6(
+    device_name: &[WCHAR; 32],
+) -> (ComPtr<IDXGIFactory1>, ComPtr<IDXGIOutput6>) {
+    let mut factory: *mut c_void = ptr::null_mut();
+    if CreateDXGIFactory1(&IID_IDXGIFactory1, &mut factory) != S_OK {
+        return (ComPtr(ptr::null_mut()), ComPtr(ptr::null_mut()));
+    }
+    let factory = ComPtr(factory as *mut IDXGIFactory1);
+    let mut adapter_index = 0;
+    loop {
+        let mut adapter = ptr::null_mut();
+        if (*factory.0).EnumAdapters1(adapter_index, &mut adapter) != S_OK {
+            break;
+        }
+        let adapter = ComPtr(adapter);
+        adapter_index += 1;
+        let mut output_index = 0;
+        loop {
+            let mut output = ptr::null_mut();
+            if (*adapter.0).EnumOutputs(output_index, &mut output) != S_OK {
+                break;
+            }
+            let output = ComPtr(output);
+            output_index += 1;
+            let mut desc: DXGI_OUTPUT_DESC = mem::zeroed();
+            if (*output.0).GetDesc(&mut desc) == S_OK && wide_eq(&desc.DeviceName, device_name) {
+                let output6 = query_output6(output.0 as *mut IUnknown);
+                if output6.is_null() {
+                    return (ComPtr(ptr::null_mut()), ComPtr(ptr::null_mut()));
+                }
+                return (factory, output6);
+            }
+        }
+    }
+    (ComPtr(ptr::null_mut()), ComPtr(ptr::null_mut()))
+}
+
+fn other(msg: impl Into<String>) -> io::Error {
+    io::Error::new(io::ErrorKind::Other, msg.into())
+}
+
+fn check(hr: HRESULT, what: &str) -> io::Result<()> {
+    if hr == S_OK {
+        Ok(())
+    } else {
+        Err(other(format!("{what} failed: {hr:#x}")))
+    }
+}
+
+// D3DCompile(pSrcData, SrcDataSize, pSourceName, pDefines, pInclude,
+//            pEntrypoint, pTarget, Flags1, Flags2, ppCode, ppErrorMsgs)
+type D3DCompileFn = unsafe extern "system" fn(
+    LPCVOID,
+    SIZE_T,
+    LPCSTR,
+    *const D3D_SHADER_MACRO,
+    *mut ID3DInclude,
+    LPCSTR,
+    LPCSTR,
+    UINT,
+    UINT,
+    *mut *mut ID3DBlob,
+    *mut *mut ID3DBlob,
+) -> HRESULT;
+
+static D3D_COMPILE: OnceLock<Result<D3DCompileFn, String>> = OnceLock::new();
+
+// Loaded once per process and kept: the compiler DLL is only needed on HDR
+// desktops, and an import-time link would make every install depend on it.
+fn load_d3d_compile() -> io::Result<D3DCompileFn> {
+    D3D_COMPILE
+        .get_or_init(|| unsafe { find_d3d_compile() })
+        .clone()
+        .map_err(|e| io::Error::new(io::ErrorKind::Unsupported, e))
+}
+
+unsafe fn find_d3d_compile() -> Result<D3DCompileFn, String> {
+    let name: Vec<u16> = "d3dcompiler_47.dll\0".encode_utf16().collect();
+    let module = LoadLibraryExW(name.as_ptr(), ptr::null_mut(), LOAD_LIBRARY_SEARCH_SYSTEM32);
+    if module.is_null() {
+        return Err("d3dcompiler_47.dll not available".into());
+    }
+    let f = GetProcAddress(module, b"D3DCompile\0".as_ptr() as _);
+    if f.is_null() {
+        return Err("D3DCompile not exported".into());
+    }
+    Ok(mem::transmute::<_, D3DCompileFn>(f))
+}
+
+unsafe fn compile_shader(
+    compile: D3DCompileFn,
+    src: &str,
+    target: &[u8],
+) -> io::Result<ComPtr<ID3DBlob>> {
+    let mut code = ptr::null_mut();
+    let mut errors = ptr::null_mut();
+    let hr = compile(
+        src.as_ptr() as _,
+        src.len(),
+        ptr::null(),
+        ptr::null(),
+        ptr::null_mut(),
+        b"main\0".as_ptr() as _,
+        target.as_ptr() as _,
+        0,
+        0,
+        &mut code,
+        &mut errors,
+    );
+    let errors = ComPtr(errors);
+    if hr != S_OK || code.is_null() {
+        let msg = if errors.is_null() {
+            String::new()
+        } else {
+            let bytes = std::slice::from_raw_parts(
+                (*errors.0).GetBufferPointer() as *const u8,
+                (*errors.0).GetBufferSize(),
+            );
+            String::from_utf8_lossy(bytes).into_owned()
+        };
+        if !code.is_null() {
+            (*(code as *mut IUnknown)).Release();
+        }
+        return Err(io::Error::new(
+            io::ErrorKind::Unsupported,
+            format!("D3DCompile failed: {hr:#x} {msg}"),
+        ));
+    }
+    Ok(ComPtr(code))
+}
+
+const DISPLAYCONFIG_DEVICE_INFO_GET_SDR_WHITE_LEVEL: u32 = 11;
+const QDC_ONLY_ACTIVE_PATHS: u32 = 2;
+
+#[repr(C)]
+#[allow(non_snake_case)]
+struct DISPLAYCONFIG_SDR_WHITE_LEVEL {
+    header: DISPLAYCONFIG_DEVICE_INFO_HEADER,
+    SDRWhiteLevel: ULONG,
+}
+
+#[link(name = "user32")]
+extern "system" {
+    fn GetDisplayConfigBufferSizes(
+        flags: u32,
+        numPathArrayElements: *mut u32,
+        numModeInfoArrayElements: *mut u32,
+    ) -> LONG;
+    fn QueryDisplayConfig(
+        flags: u32,
+        numPathArrayElements: *mut u32,
+        pathArray: *mut DISPLAYCONFIG_PATH_INFO,
+        numModeInfoArrayElements: *mut u32,
+        modeInfoArray: *mut DISPLAYCONFIG_MODE_INFO,
+        currentTopologyId: *mut DISPLAYCONFIG_TOPOLOGY_ID,
+    ) -> LONG;
+    fn DisplayConfigGetDeviceInfo(requestPacket: *mut DISPLAYCONFIG_DEVICE_INFO_HEADER) -> LONG;
+}
+
+/// SDR white level of the output whose GDI name is `device_name`
+/// (e.g. `\\.\DISPLAY1`), in DISPLAYCONFIG units (1000 == 80 nits). `None`
+/// when the query fails (before Windows 10 1709) or reports 0.
+fn query_sdr_white_level(device_name: &[WCHAR; 32]) -> Option<u32> {
+    unsafe {
+        let mut n_paths = 0u32;
+        let mut n_modes = 0u32;
+        if GetDisplayConfigBufferSizes(QDC_ONLY_ACTIVE_PATHS, &mut n_paths, &mut n_modes) != 0 {
+            return None;
+        }
+        let mut paths: Vec<DISPLAYCONFIG_PATH_INFO> = vec![mem::zeroed(); n_paths as usize];
+        let mut modes: Vec<DISPLAYCONFIG_MODE_INFO> = vec![mem::zeroed(); n_modes as usize];
+        if QueryDisplayConfig(
+            QDC_ONLY_ACTIVE_PATHS,
+            &mut n_paths,
+            paths.as_mut_ptr(),
+            &mut n_modes,
+            modes.as_mut_ptr(),
+            ptr::null_mut(),
+        ) != 0
+        {
+            return None;
+        }
+        for path in &paths[..n_paths as usize] {
+            let mut source: DISPLAYCONFIG_SOURCE_DEVICE_NAME = mem::zeroed();
+            source.header._type = DISPLAYCONFIG_DEVICE_INFO_GET_SOURCE_NAME;
+            source.header.size = mem::size_of::<DISPLAYCONFIG_SOURCE_DEVICE_NAME>() as _;
+            source.header.adapterId = path.sourceInfo.adapterId;
+            source.header.id = path.sourceInfo.id;
+            if DisplayConfigGetDeviceInfo(&mut source.header) != 0
+                || !wide_eq(&source.viewGdiDeviceName, device_name)
+            {
+                continue;
+            }
+            let mut white: DISPLAYCONFIG_SDR_WHITE_LEVEL = mem::zeroed();
+            white.header._type = DISPLAYCONFIG_DEVICE_INFO_GET_SDR_WHITE_LEVEL;
+            white.header.size = mem::size_of::<DISPLAYCONFIG_SDR_WHITE_LEVEL>() as _;
+            white.header.adapterId = path.targetInfo.adapterId;
+            white.header.id = path.targetInfo.id;
+            if DisplayConfigGetDeviceInfo(&mut white.header) == 0 && white.SDRWhiteLevel != 0 {
+                return Some(white.SDRWhiteLevel);
+            }
+        }
+        None
+    }
+}
+
+fn wide_eq(a: &[WCHAR], b: &[WCHAR]) -> bool {
+    let end = |s: &[WCHAR]| s.iter().position(|&c| c == 0).unwrap_or(s.len());
+    a[..end(a)] == b[..end(b)]
+}

libs/scrap/src/dxgi/mod.rs

@@ -1,18 +1,20 @@
 use std::{io, mem, ptr, slice};
 pub mod gdi;
 pub use gdi::CapturerGDI;
+pub mod hdr;
 pub mod mag;
 
 use winapi::{
     shared::{
         dxgi::*,
         dxgi1_2::*,
+        dxgi1_6::*,
+        dxgiformat::{DXGI_FORMAT_B8G8R8A8_UNORM, DXGI_FORMAT_R16G16B16A16_FLOAT},
         dxgitype::*,
         minwindef::{DWORD, FALSE, TRUE, UINT},
         ntdef::LONG,
         windef::{HMONITOR, RECT},
         winerror::*,
-        // dxgiformat::{DXGI_FORMAT, DXGI_FORMAT_B8G8R8A8_UNORM, DXGI_FORMAT_420_OPAQUE},
     },
     um::{
         d3d11::*, d3dcommon::D3D_DRIVER_TYPE_UNKNOWN, unknwnbase::IUnknown, wingdi::*,
@@ -58,6 +60,7 @@ pub struct Capturer {
     output_texture: bool,
     adapter_desc1: DXGI_ADAPTER_DESC1,
     rotate: Rotate,
+    hdr: Option<hdr::HdrToSdr>,
 }
 
 impl Capturer {
@@ -105,7 +108,7 @@ impl Capturer {
             }
         } else {
             res = wrap_hresult(unsafe {
-                let hres = (*display.inner.0).DuplicateOutput(device.0 as *mut _, &mut duplication);
+                let hres = Self::duplicate_output(&display, device.0, &mut duplication);
                 if hres != S_OK {
                     gdi_capturer = display.create_gdi();
                     println!("Fallback to GDI");
@@ -161,7 +164,8 @@ impl Capturer {
             device,
             context,
             duplication: ComPtr(duplication),
-            fastlane: desc.DesktopImageInSystemMemory == TRUE,
+            fastlane: desc.DesktopImageInSystemMemory == TRUE
+                && desc.ModeDesc.Format != DXGI_FORMAT_R16G16B16A16_FLOAT,
             surface: ComPtr(ptr::null_mut()),
             texture: ComPtr(ptr::null_mut()),
             width: display.width() as usize,
@@ -174,9 +178,102 @@ impl Capturer {
             output_texture: false,
             adapter_desc1,
             rotate,
+            hdr: None,
         })
     }
 
+    // Asks for the float desktop that HDR mode composes so it can be tone-mapped;
+    // the legacy call would hand back DXGI's clipped BGRA8 conversion instead.
+    // Only where IDXGIOutput6 (Windows 10 1703) exists, since that is what later
+    // tells an HDR desktop from a WCG one; Microsoft's duplication sample gates
+    // the float request the same way.
+    unsafe fn duplicate_output(
+        display: &Display,
+        device: *mut ID3D11Device,
+        duplication: &mut *mut IDXGIOutputDuplication,
+    ) -> HRESULT {
+        if !hdr::UNAVAILABLE.load(std::sync::atomic::Ordering::Relaxed) {
+            let mut output6: *mut IDXGIOutput6 = ptr::null_mut();
+            (*display.inner.0).QueryInterface(
+                &IID_IDXGIOutput6,
+                &mut output6 as *mut *mut _ as *mut *mut _,
+            );
+            if !output6.is_null() {
+                let output6 = ComPtr(output6);
+                let formats = [DXGI_FORMAT_R16G16B16A16_FLOAT, DXGI_FORMAT_B8G8R8A8_UNORM];
+                let hres = (*output6.0).DuplicateOutput1(
+                    device as *mut _,
+                    0,
+                    formats.len() as UINT,
+                    formats.as_ptr(),
+                    duplication,
+                );
+                if hres == S_OK {
+                    return hres;
+                }
+                hbb_common::log::warn!(
+                    "HDR DuplicateOutput1 failed: hr={:#x}, fallback=DuplicateOutput",
+                    hres as u32
+                );
+            }
+        }
+        (*display.inner.0).DuplicateOutput(device as *mut _, duplication)
+    }
+
+    unsafe fn tonemap(
+        &mut self,
+        source: *mut ID3D11Texture2D,
+        desc: &D3D11_TEXTURE2D_DESC,
+    ) -> io::Result<*mut ID3D11Texture2D> {
+        if self.hdr.is_none() {
+            match hdr::HdrToSdr::new(
+                self.device.0,
+                self.context.0,
+                self.display.inner.0,
+                &self.display.desc.DeviceName,
+            ) {
+                Ok(hdr) => self.hdr = Some(hdr),
+                Err(err) => return self.abandon_tonemap(err),
+            }
+        }
+        let converted = match self.hdr.as_mut() {
+            Some(hdr) => hdr.convert(source, desc),
+            None => Err(io::Error::new(io::ErrorKind::Other, "no tone-map")),
+        };
+        match converted {
+            Ok(texture) => Ok(texture),
+            Err(err) => self.abandon_tonemap(err),
+        }
+    }
+
+    // Drops the tone-map and re-duplicates the output the legacy way, so DXGI
+    // hands over clipped BGRA8 (the pre-HDR behaviour). If re-duplication fails,
+    // switch to GDI before returning. The caller sees WouldBlock and asks again.
+    unsafe fn abandon_tonemap<T>(&mut self, err: io::Error) -> io::Result<T> {
+        if hdr::is_permanent(&err) {
+            hdr::UNAVAILABLE.store(true, std::sync::atomic::Ordering::Relaxed);
+        }
+        hbb_common::log::error!("HDR tone-map failed, re-duplicating without it: {err}");
+        self.hdr = None;
+        (*self.duplication.0).ReleaseFrame();
+        self.duplication = ComPtr(ptr::null_mut());
+        let mut duplication = ptr::null_mut();
+        let result = wrap_hresult(
+            (*self.display.inner.0).DuplicateOutput(self.device.0 as *mut _, &mut duplication),
+        );
+        if let Err(err) = result {
+            if self.set_gdi() {
+                return Err(io::ErrorKind::WouldBlock.into());
+            }
+            return Err(err);
+        }
+        self.duplication = ComPtr(duplication);
+        let mut desc: DXGI_OUTDUPL_DESC = mem::zeroed();
+        (*duplication).GetDesc(&mut desc);
+        self.fastlane = desc.DesktopImageInSystemMemory == TRUE;
+        Err(io::ErrorKind::WouldBlock.into())
+    }
+
     fn create_rotations(
         device: *mut ID3D11Device,
         context: *mut ID3D11DeviceContext,
@@ -330,6 +427,9 @@ impl Capturer {
     }
 
     unsafe fn load_frame(&mut self, timeout: UINT) -> io::Result<(*const u8, i32)> {
+        if self.duplication.0.is_null() {
+            return Err(io::ErrorKind::AddrNotAvailable.into());
+        }
         let mut frame = ptr::null_mut();
         #[allow(invalid_value)]
         let mut info = mem::MaybeUninit::uninit().assume_init();
@@ -365,6 +465,12 @@ impl Capturer {
         let mut texture_desc = mem::MaybeUninit::uninit().assume_init();
         (*texture.0).GetDesc(&mut texture_desc);
 
+        let mut source = texture.0;
+        if texture_desc.Format == DXGI_FORMAT_R16G16B16A16_FLOAT {
+            source = self.tonemap(texture.0, &texture_desc)?;
+            (*source).GetDesc(&mut texture_desc);
+        }
+
         texture_desc.Usage = D3D11_USAGE_STAGING;
         texture_desc.BindFlags = 0;
         texture_desc.CPUAccessFlags = D3D11_CPU_ACCESS_READ;
@@ -385,7 +491,7 @@ impl Capturer {
             &mut surface as *mut *mut _ as *mut *mut _,
         );
 
-        (*self.context.0).CopyResource(readable.0 as *mut _, texture.0 as *mut _);
+        (*self.context.0).CopyResource(readable.0 as *mut _, source as *mut _);
 
         Ok(surface)
     }
@@ -492,6 +598,14 @@ impl Capturer {
             let texture = ComPtr(texture);
             self.texture = texture;
 
+            let mut frame_desc: D3D11_TEXTURE2D_DESC = mem::zeroed();
+            (*self.texture.0).GetDesc(&mut frame_desc);
+            if frame_desc.Format == DXGI_FORMAT_R16G16B16A16_FLOAT {
+                let converted = self.tonemap(self.texture.0, &frame_desc)?;
+                (*converted).AddRef();
+                self.texture = ComPtr(converted);
+            }
+
             let mut final_texture = self.texture.0 as *mut c_void;
             let mut rotation = match self.display.rotation() {
                 DXGI_MODE_ROTATION_ROTATE90 => 90,
@@ -575,6 +689,9 @@ impl Capturer {
     }
 
     fn unmap(&self) {
+        if self.duplication.0.is_null() {
+            return;
+        }
         unsafe {
             (*self.duplication.0).ReleaseFrame();
             if self.fastlane {