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feat(vdisplay/windows): topology=primary — keep physicals active, virtual primary

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Implements the deferred Windows primary-only CCD (Stage 2). set_virtual_primary_ccd
repositions the virtual output's source to (0,0) = primary and shifts the physical
display(s) to its right, ALL kept active — one atomic CCD SetDisplayConfig (not GDI
CDS_SET_PRIMARY, which storms MODE_CHANGE_IN_PROGRESS with another display live).
The manager's should_isolate() becomes topology_action() (3-way): extend (skip),
primary (set_virtual_primary_ccd), exclusive (isolate_displays_ccd). Restore-on-teardown
covers both. Validates the user's two scenarios on a physical-monitor .173.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
This commit is contained in:
Enrico Bühler
2026-07-05 09:17:41 +00:00
parent d73951414c
commit eda7cac78e
2 changed files with 122 additions and 26 deletions
Download Patch File Download Diff File Expand all files Collapse all files
crates/punktfunk-host/src/vdisplay/windows/manager.rs
+36 -22
View File
@@ -34,7 +34,7 @@ use windows::Win32::System::Threading::{
use super::{Mode, VirtualOutput};
use crate::win_display::{
force_extend_topology, isolate_displays_ccd, resolve_gdi_name, restore_displays_ccd,
set_active_mode, SavedConfig,
set_active_mode, set_virtual_primary_ccd, SavedConfig,
};
/// The per-backend REMOVE key the driver stamps on ADD and consumes on REMOVE. SudoVDA keys monitors by
@@ -633,20 +633,29 @@ impl VirtualDisplayManager {
tracing::info!(backend = self.driver.name(), "target {} -> {n}", added.target_id);
// ADD only advertises the mode; force it active so DXGI captures the requested size.
set_active_mode(n, mode);
// Make the virtual display the SOLE active output (default): an EXTENDED (non-primary) IDD
// isn't DWM-composited on this box → Desktop Duplication born-losts. Deactivating the other
// display(s) first via the atomic CCD path promotes the IDD to a composited primary with no
// MODE_CHANGE storm. Opt out with PUNKTFUNK_NO_ISOLATE=1.
if should_isolate() {
// SAFETY: `isolate_displays_ccd` is `unsafe` for its CCD topology FFI; it takes a
// `Copy` `u32` by value and returns an owned `SavedConfig` snapshot (no borrowed
// memory crosses). It runs under the `state` lock, the sole mutator of the topology.
// Apply the display-management topology (Stage 2). `Exclusive` (default) deactivates the
// other display(s) so the IDD is the SOLE composited primary — an EXTENDED (non-primary)
// IDD isn't DWM-composited on this box → Desktop Duplication born-losts. `Primary` keeps the
// physical display(s) ACTIVE and makes the IDD primary (repositioned to origin). `Extend`
// leaves it a plain extension. Both isolate + primary go through the atomic CCD path (no
// MODE_CHANGE storm). Opt out (extend) with PUNKTFUNK_NO_ISOLATE=1 / the console policy.
use crate::vdisplay::policy::Topology;
match topology_action() {
// SAFETY (both arms): the CCD helper is `unsafe` for its topology FFI; it takes a
// `Copy` `u32` by value and returns an owned `SavedConfig` (no borrowed memory crosses),
// and runs under the `state` lock, the sole mutator of the topology.
Topology::Exclusive => {
ccd_saved = unsafe { isolate_displays_ccd(added.target_id) };
} else {
}
Topology::Primary => {
ccd_saved = unsafe { set_virtual_primary_ccd(added.target_id) };
}
Topology::Extend | Topology::Auto => {
tracing::info!(
"display isolation skipped (topology=extend / PUNKTFUNK_NO_ISOLATE) — IDD stays extended"
"display topology=extend — IDD stays extended (no isolate / no primary)"
);
}
}
thread::sleep(Duration::from_millis(1500)); // let the topology settle before capture opens
}
None => tracing::warn!(
@@ -997,17 +1006,22 @@ fn linger_ms() -> u64 {
.unwrap_or(10_000)
}
/// Should a freshly-created monitor isolate the desktop to itself (disable the other displays)? The
/// console policy's effective topology wins when configured — `Extend` leaves the IDD extended,
/// `Exclusive`/`Primary` isolate (Stage 0 treats `Primary` as `Exclusive`); otherwise the legacy
/// `PUNKTFUNK_NO_ISOLATE` env knob (unset ⇒ isolate, matching today's default).
fn should_isolate() -> bool {
/// The effective display topology for a freshly-created monitor (never `Auto`): the console policy's
/// [`effective_topology`](crate::vdisplay::effective_topology) when configured, else the legacy
/// `PUNKTFUNK_NO_ISOLATE` env knob (`Extend`) / `Exclusive` (today's default). `Extend` leaves the IDD
/// extended; `Primary` makes it primary while keeping the physical(s) active; `Exclusive` disables the
/// physical(s) so the IDD is the sole composited desktop.
fn topology_action() -> crate::vdisplay::policy::Topology {
use crate::vdisplay::policy::Topology;
if let Some(eff) = crate::vdisplay::policy::prefs().configured_effective() {
return !matches!(
crate::vdisplay::resolve_topology(eff.topology),
Topology::Extend
);
if crate::vdisplay::policy::prefs()
.configured_effective()
.is_some()
{
return crate::vdisplay::effective_topology();
}
if std::env::var("PUNKTFUNK_NO_ISOLATE").is_ok() {
Topology::Extend
} else {
Topology::Exclusive
}
std::env::var("PUNKTFUNK_NO_ISOLATE").is_err()
}
crates/punktfunk-host/src/windows/win_display.rs
+83 -1
View File
@@ -18,11 +18,13 @@ use windows::Win32::Devices::Display::{
DisplayConfigGetDeviceInfo, DisplayConfigSetDeviceInfo, GetDisplayConfigBufferSizes,
QueryDisplayConfig, SetDisplayConfig, DISPLAYCONFIG_DEVICE_INFO_GET_ADVANCED_COLOR_INFO,
DISPLAYCONFIG_DEVICE_INFO_GET_SOURCE_NAME, DISPLAYCONFIG_DEVICE_INFO_SET_ADVANCED_COLOR_STATE,
DISPLAYCONFIG_GET_ADVANCED_COLOR_INFO, DISPLAYCONFIG_MODE_INFO, DISPLAYCONFIG_PATH_INFO,
DISPLAYCONFIG_GET_ADVANCED_COLOR_INFO, DISPLAYCONFIG_MODE_INFO,
DISPLAYCONFIG_MODE_INFO_TYPE_SOURCE, DISPLAYCONFIG_PATH_INFO,
DISPLAYCONFIG_SET_ADVANCED_COLOR_STATE, DISPLAYCONFIG_SOURCE_DEVICE_NAME,
QDC_ONLY_ACTIVE_PATHS, SDC_ALLOW_CHANGES, SDC_APPLY, SDC_FORCE_MODE_ENUMERATION,
SDC_SAVE_TO_DATABASE, SDC_TOPOLOGY_EXTEND, SDC_USE_SUPPLIED_DISPLAY_CONFIG,
};
use windows::Win32::Foundation::POINTL;
use windows::Win32::Graphics::Gdi::{
ChangeDisplaySettingsExW, EnumDisplaySettingsW, CDS_TEST, CDS_UPDATEREGISTRY, DEVMODEW,
DISP_CHANGE_SUCCESSFUL, DM_BITSPERPEL, DM_DISPLAYFREQUENCY, DM_PELSHEIGHT, DM_PELSWIDTH,
@@ -431,6 +433,86 @@ pub(crate) unsafe fn isolate_displays_ccd(keep_target_id: u32) -> Option<SavedCo
Some(saved)
}
/// **Primary (topology=primary)** — make the virtual output the PRIMARY display while KEEPING every
/// other display ACTIVE (unlike [`isolate_displays_ccd`], which deactivates them). Windows treats the
/// display whose source sits at the desktop origin `(0,0)` as primary, so we move the virtual's source
/// to `(0,0)` and shift every other active source to its right — all paths stay active. Done as ONE
/// atomic CCD `SetDisplayConfig` (NOT GDI `CDS_SET_PRIMARY`, which storms
/// `DXGI_ERROR_MODE_CHANGE_IN_PROGRESS` when another display is live — see [`set_active_mode`]).
/// Returns the original config to restore on teardown.
pub(crate) unsafe fn set_virtual_primary_ccd(keep_target_id: u32) -> Option<SavedConfig> {
let mut np = 0u32;
let mut nm = 0u32;
if GetDisplayConfigBufferSizes(QDC_ONLY_ACTIVE_PATHS, &mut np, &mut nm).is_err() {
return None;
}
let mut paths = vec![DISPLAYCONFIG_PATH_INFO::default(); np as usize];
let mut modes = vec![DISPLAYCONFIG_MODE_INFO::default(); nm as usize];
if QueryDisplayConfig(
QDC_ONLY_ACTIVE_PATHS,
&mut np,
paths.as_mut_ptr(),
&mut nm,
modes.as_mut_ptr(),
None,
)
.is_err()
{
return None;
}
paths.truncate(np as usize);
modes.truncate(nm as usize);
let saved = (paths.clone(), modes.clone());
// The virtual output's source width, to shift the physicals past it.
let virt_width = paths.iter().find_map(|p| {
if p.targetInfo.id != keep_target_id {
return None;
}
let idx = p.sourceInfo.modeInfoIdx as usize;
let m = modes.get(idx)?;
(m.infoType == DISPLAYCONFIG_MODE_INFO_TYPE_SOURCE)
.then(|| m.Anonymous.sourceMode.width as i32)
})?;
// Reposition each active path's SOURCE once: the virtual to (0,0) (= primary), the rest shifted
// right by the virtual's width (kept active, no overlap). Dedup source-mode indices (a cloned
// group would share one).
let mut done = std::collections::HashSet::new();
for p in paths.iter() {
let idx = p.sourceInfo.modeInfoIdx as usize;
if !done.insert(idx) {
continue;
}
let Some(m) = modes.get_mut(idx) else {
continue;
};
if m.infoType != DISPLAYCONFIG_MODE_INFO_TYPE_SOURCE {
continue;
}
if p.targetInfo.id == keep_target_id {
m.Anonymous.sourceMode.position = POINTL { x: 0, y: 0 };
} else {
m.Anonymous.sourceMode.position.x += virt_width;
}
}
let rc = SetDisplayConfig(
Some(paths.as_slice()),
Some(modes.as_slice()),
SDC_APPLY
| SDC_USE_SUPPLIED_DISPLAY_CONFIG
| SDC_ALLOW_CHANGES
| SDC_FORCE_MODE_ENUMERATION,
);
if rc == 0 {
tracing::info!("display primary (CCD): virtual target {keep_target_id} set PRIMARY at (0,0); physical display(s) kept ACTIVE, shifted right by {virt_width}px");
} else {
tracing::warn!("display primary (CCD): SetDisplayConfig failed rc={rc:#x} (virtual {keep_target_id} primary, physicals kept)");
}
Some(saved)
}
/// Restore the topology saved by [`isolate_displays_ccd`] (teardown, before the virtual output is
/// removed), re-activating the displays we deactivated.
// pub(crate) so vdisplay::pf_vdisplay can reuse this backend-neutral CCD restore helper.