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Override host monitor DPI for remote desktop sessions.

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We found that when we are using a remote desktop, the monitor DPI
reported by GetDpiForMonitor() may not make sense. For example, on
Chrome Remote Desktop we always get 25 DPI, while the standard DPI is
96. Because of that, the calculated guest DPI is also too low, and all
the UI elements in the guest appear very small.

This might be a flaw in Windows Remote Desktop Protocol. As a
workaround, we would just assume the monitor DPI is the standard value
if we find that KiwiVM is running in a remote session.

Bug: 273810154
Test: Ran B* in CRD and checked the Overlay UI size
Change-Id: Ie335fe8df394b19733bbee8f70931c29b836f3d3
Reviewed-on: https://chromium-review.googlesource.com/c/crosvm/crosvm/+/4804796
Reviewed-by: Vikram Auradkar <auradkar@google.com>
Commit-Queue: Kaiyi Li <kaiyili@google.com>
This commit is contained in:
Pujun Lun 2023-03-16 13:07:55 -07:00 committed by crosvm LUCI
parent de91419c01
commit a1c2173bbf
1 changed files with 39 additions and 5 deletions
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44
gpu_display/src/gpu_display_win/window.rs
View file

@ -779,7 +779,14 @@ pub struct MonitorInfo {
pub hmonitor: HMONITOR,
pub display_rect: Rect,
pub work_rect: Rect,
pub dpi: i32,
raw_dpi: i32,
// Whether we are running in a Remote Desktop Protocol (RDP) session. The monitor DPI returned
// by `GetDpiForMonitor()` may not make sense in that case. For example, the DPI is always 25
// under Chrome Remote Desktop, which is way lower than the standard DPI 96. This might be a
// flaw in RDP itself. We have to override the DPI in that case, otherwise the guest DPI
// calculated based on it would be too low as well.
// https://learn.microsoft.com/en-us/troubleshoot/windows-server/shell-experience/dpi-adjustment-unavailable-in-rdp
is_rdp_session: bool,
}
impl MonitorInfo {
@ -788,14 +795,33 @@ impl MonitorInfo {
pub unsafe fn new(hmonitor: HMONITOR) -> Result<Self> {
let monitor_info: MONITORINFO =
Self::get_monitor_info(hmonitor).context("When creating MonitorInfo")?;
// Docs state that apart from `GetSystemMetrics(SM_REMOTESESSION)`, we also need to check
// registry entries to see if we are running in a remote session that uses RemoteFX vGPU:
// https://learn.microsoft.com/en-us/windows/win32/termserv/detecting-the-terminal-services-environment
// However, RemoteFX vGPU was then removed because of security vulnerabilities:
// https://support.microsoft.com/en-us/topic/kb4570006-update-to-disable-and-remove-the-remotefx-vgpu-component-in-windows-bbdf1531-7188-2bf4-0de6-641de79f09d2
// So, we are only calling `GetSystemMetrics(SM_REMOTESESSION)` here until this changes in
// the future.
// Safe because no memory management is needed for arguments.
let is_rdp_session = unsafe { GetSystemMetrics(SM_REMOTESESSION) != 0 };
Ok(Self {
hmonitor,
display_rect: monitor_info.rcMonitor.to_rect(),
work_rect: monitor_info.rcWork.to_rect(),
dpi: Self::get_dpi(hmonitor),
raw_dpi: Self::get_monitor_dpi(hmonitor),
is_rdp_session,
})
}
pub fn get_dpi(&self) -> i32 {
if self.is_rdp_session {
// Override the DPI since the system may not tell us the correct value in RDP sessions.
DEFAULT_HOST_DPI
} else {
self.raw_dpi
}
}
/// Calls `GetMonitorInfoW()` internally.
/// # Safety
/// Caller is responsible for ensuring that `hmonitor` is a valid handle.
@ -811,7 +837,7 @@ impl MonitorInfo {
}
/// Calls `GetDpiForMonitor()` internally.
fn get_dpi(hmonitor: HMONITOR) -> i32 {
fn get_monitor_dpi(hmonitor: HMONITOR) -> i32 {
let mut dpi_x = 0;
let mut dpi_y = 0;
// This is always safe since `GetDpiForMonitor` won't crash if HMONITOR is invalid, but
@ -834,8 +860,16 @@ impl fmt::Debug for MonitorInfo {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(
f,
"{{hmonitor: {:p}, display_rect: {:?}, work_rect: {:?}, DPI: {}}}",
self.hmonitor, self.display_rect, self.work_rect, self.dpi,
"{{hmonitor: {:p}, display_rect: {:?}, work_rect: {:?}, DPI: {}{}}}",
self.hmonitor,
self.display_rect,
self.work_rect,
self.get_dpi(),
if self.is_rdp_session {
format!(" (raw value: {}, overriden due to RDP)", self.raw_dpi)
} else {
String::new()
}
)
}
}