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prevent incorrect shifting of window when dragging onto monitor with different DPI #4119

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prevent incorrect shifting of window when dragging onto monitor with different DPI #4119

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1 change: 1 addition & 0 deletions src/changelog/unreleased.md
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Original file line number Diff line number Diff line change
Expand Up @@ -195,6 +195,7 @@ changelog entry.
- Renamed "super" key to "meta", to match the naming in the W3C specification.
`NamedKey::Super` still exists, but it's non-functional and deprecated, `NamedKey::Meta` should be used instead.
- Move `IconExtWindows` into `WinIcon`.
- On Windows, prevent incorrect shifting when dragging window onto a monitor with different DPI.
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@kchibisov kchibisov Aug 12, 2025

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I'd assume that it's talking only about Windows 11?


### Removed

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33 changes: 2 additions & 31 deletions src/platform_impl/windows/dark_mode.rs
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Expand Up @@ -3,9 +3,8 @@
use std::{ffi::c_void, ptr};

use windows_sys::core::PCSTR;
use windows_sys::Win32::Foundation::{BOOL, HWND, NTSTATUS, S_OK};
use windows_sys::Win32::Foundation::{BOOL, HWND, S_OK};
use windows_sys::Win32::System::LibraryLoader::{GetProcAddress, LoadLibraryA};
use windows_sys::Win32::System::SystemInformation::OSVERSIONINFOW;
use windows_sys::Win32::UI::Accessibility::{HCF_HIGHCONTRASTON, HIGHCONTRASTA};
use windows_sys::Win32::UI::Controls::SetWindowTheme;
use windows_sys::Win32::UI::WindowsAndMessaging::{SystemParametersInfoA, SPI_GETHIGHCONTRAST};
Expand All @@ -14,38 +13,10 @@ use super::util;
use crate::utils::Lazy;
use crate::window::Theme;

static WIN10_BUILD_VERSION: Lazy<Option<u32>> = Lazy::new(|| {
type RtlGetVersion = unsafe extern "system" fn(*mut OSVERSIONINFOW) -> NTSTATUS;
let handle = get_function!("ntdll.dll", RtlGetVersion);

if let Some(rtl_get_version) = handle {
unsafe {
let mut vi = OSVERSIONINFOW {
dwOSVersionInfoSize: 0,
dwMajorVersion: 0,
dwMinorVersion: 0,
dwBuildNumber: 0,
dwPlatformId: 0,
szCSDVersion: [0; 128],
};

let status = (rtl_get_version)(&mut vi);

if status >= 0 && vi.dwMajorVersion == 10 && vi.dwMinorVersion == 0 {
Some(vi.dwBuildNumber)
} else {
None
}
}
} else {
None
}
});

static DARK_MODE_SUPPORTED: Lazy<bool> = Lazy::new(|| {
// We won't try to do anything for windows versions < 17763
// (Windows 10 October 2018 update)
match *WIN10_BUILD_VERSION {
match *util::WIN10_BUILD_VERSION {
Some(v) => v >= 17763,
None => false,
}
Expand Down
188 changes: 98 additions & 90 deletions src/platform_impl/windows/event_loop.rs
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Expand Up @@ -90,6 +90,7 @@ use crate::platform_impl::platform::window_state::{
CursorFlags, ImeState, WindowFlags, WindowState,
};
use crate::platform_impl::platform::{raw_input, util, wrap_device_id};
use crate::platform_impl::windows::util::WIN10_BUILD_VERSION;
use crate::platform_impl::Window;
use crate::utils::Lazy;
use crate::window::{
Expand Down Expand Up @@ -2307,103 +2308,110 @@ unsafe fn public_window_callback_inner(
}

let new_outer_rect: RECT;
{
let suggested_ul =
(suggested_rect.left + margin_left, suggested_rect.top + margin_top);

let mut conservative_rect = RECT {
left: suggested_ul.0,
top: suggested_ul.1,
right: suggested_ul.0 + new_physical_surface_size.width as i32,
bottom: suggested_ul.1 + new_physical_surface_size.height as i32,
};
if WIN10_BUILD_VERSION.is_some_and(|version| version < 22000) {
// The window position needs adjustment on Windows 10.
{
let suggested_ul =
(suggested_rect.left + margin_left, suggested_rect.top + margin_top);

let mut conservative_rect = RECT {
left: suggested_ul.0,
top: suggested_ul.1,
right: suggested_ul.0 + new_physical_surface_size.width as i32,
bottom: suggested_ul.1 + new_physical_surface_size.height as i32,
};

conservative_rect = window_flags
.adjust_rect(window, conservative_rect)
.unwrap_or(conservative_rect);

// If we're dragging the window, offset the window so that the cursor's
// relative horizontal position in the title bar is preserved.
if dragging_window {
let bias = {
let cursor_pos = {
let mut pos = unsafe { mem::zeroed() };
unsafe { GetCursorPos(&mut pos) };
pos
conservative_rect = window_flags
.adjust_rect(window, conservative_rect)
.unwrap_or(conservative_rect);

// If we're dragging the window, offset the window so that the cursor's
// relative horizontal position in the title bar is preserved.
if dragging_window {
let bias = {
let cursor_pos = {
let mut pos = unsafe { mem::zeroed() };
unsafe { GetCursorPos(&mut pos) };
pos
};
let suggested_cursor_horizontal_ratio =
(cursor_pos.x - suggested_rect.left) as f64
/ (suggested_rect.right - suggested_rect.left) as f64;

(cursor_pos.x
- (suggested_cursor_horizontal_ratio
* (conservative_rect.right - conservative_rect.left) as f64)
as i32)
- conservative_rect.left
};
let suggested_cursor_horizontal_ratio = (cursor_pos.x - suggested_rect.left)
as f64
/ (suggested_rect.right - suggested_rect.left) as f64;

(cursor_pos.x
- (suggested_cursor_horizontal_ratio
* (conservative_rect.right - conservative_rect.left) as f64)
as i32)
- conservative_rect.left
};
conservative_rect.left += bias;
conservative_rect.right += bias;
}
conservative_rect.left += bias;
conservative_rect.right += bias;
}

// Check to see if the new window rect is on the monitor with the new DPI factor.
// If it isn't, offset the window so that it is.
let new_dpi_monitor = unsafe { MonitorFromWindow(window, MONITOR_DEFAULTTONULL) };
let conservative_rect_monitor =
unsafe { MonitorFromRect(&conservative_rect, MONITOR_DEFAULTTONULL) };
new_outer_rect = if conservative_rect_monitor == new_dpi_monitor {
conservative_rect
} else {
let get_monitor_rect = |monitor| {
let mut monitor_info = MONITORINFO {
cbSize: mem::size_of::<MONITORINFO>() as _,
..unsafe { mem::zeroed() }
// Check to see if the new window rect is on the monitor with the new DPI
// factor. If it isn't, offset the window so that it is.
let new_dpi_monitor =
unsafe { MonitorFromWindow(window, MONITOR_DEFAULTTONULL) };
let conservative_rect_monitor =
unsafe { MonitorFromRect(&conservative_rect, MONITOR_DEFAULTTONULL) };
new_outer_rect = if conservative_rect_monitor == new_dpi_monitor {
conservative_rect
} else {
let get_monitor_rect = |monitor| {
let mut monitor_info = MONITORINFO {
cbSize: mem::size_of::<MONITORINFO>() as _,
..unsafe { mem::zeroed() }
};
unsafe { GetMonitorInfoW(monitor, &mut monitor_info) };
monitor_info.rcMonitor
};
unsafe { GetMonitorInfoW(monitor, &mut monitor_info) };
monitor_info.rcMonitor
};
let wrong_monitor = conservative_rect_monitor;
let wrong_monitor_rect = get_monitor_rect(wrong_monitor);
let new_monitor_rect = get_monitor_rect(new_dpi_monitor);

// The direction to nudge the window in to get the window onto the monitor with
// the new DPI factor. We calculate this by seeing which monitor edges are
// shared and nudging away from the wrong monitor based on those.
#[allow(clippy::bool_to_int_with_if)]
let delta_nudge_to_dpi_monitor = (
if wrong_monitor_rect.left == new_monitor_rect.right {
-1
} else if wrong_monitor_rect.right == new_monitor_rect.left {
1
} else {
0
},
if wrong_monitor_rect.bottom == new_monitor_rect.top {
1
} else if wrong_monitor_rect.top == new_monitor_rect.bottom {
-1
} else {
0
},
);
let wrong_monitor = conservative_rect_monitor;
let wrong_monitor_rect = get_monitor_rect(wrong_monitor);
let new_monitor_rect = get_monitor_rect(new_dpi_monitor);

// The direction to nudge the window in to get the window onto the monitor
// with the new DPI factor. We calculate this by seeing which monitor edges
// are shared and nudging away from the wrong monitor based on those.
#[allow(clippy::bool_to_int_with_if)]
let delta_nudge_to_dpi_monitor = (
if wrong_monitor_rect.left == new_monitor_rect.right {
-1
} else if wrong_monitor_rect.right == new_monitor_rect.left {
1
} else {
0
},
if wrong_monitor_rect.bottom == new_monitor_rect.top {
1
} else if wrong_monitor_rect.top == new_monitor_rect.bottom {
-1
} else {
0
},
);

let abort_after_iterations = new_monitor_rect.right - new_monitor_rect.left
+ new_monitor_rect.bottom
- new_monitor_rect.top;
for _ in 0..abort_after_iterations {
conservative_rect.left += delta_nudge_to_dpi_monitor.0;
conservative_rect.right += delta_nudge_to_dpi_monitor.0;
conservative_rect.top += delta_nudge_to_dpi_monitor.1;
conservative_rect.bottom += delta_nudge_to_dpi_monitor.1;

if unsafe { MonitorFromRect(&conservative_rect, MONITOR_DEFAULTTONULL) }
== new_dpi_monitor
{
break;
let abort_after_iterations = new_monitor_rect.right - new_monitor_rect.left
+ new_monitor_rect.bottom
- new_monitor_rect.top;
for _ in 0..abort_after_iterations {
conservative_rect.left += delta_nudge_to_dpi_monitor.0;
conservative_rect.right += delta_nudge_to_dpi_monitor.0;
conservative_rect.top += delta_nudge_to_dpi_monitor.1;
conservative_rect.bottom += delta_nudge_to_dpi_monitor.1;

if unsafe { MonitorFromRect(&conservative_rect, MONITOR_DEFAULTTONULL) }
== new_dpi_monitor
{
break;
}
}
}

conservative_rect
};
conservative_rect
};
Comment on lines +2312 to +2410
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@kchibisov kchibisov Aug 12, 2025

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From what I can see this hasn't changed at all and all that got added is the new_outer_rect part, could this windows10 handling be somehow extracted to a function, while you shift the code anyway, so it'll be a bit more readable?

}
} else {
// The suggested position is fine w/o adjustment on Windows 11.
new_outer_rect = suggested_rect
}

unsafe {
Expand Down
31 changes: 30 additions & 1 deletion src/platform_impl/windows/util.rs
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Expand Up @@ -6,9 +6,10 @@ use std::sync::atomic::{AtomicBool, Ordering};
use std::{io, mem, ptr};

use windows_sys::core::{HRESULT, PCWSTR};
use windows_sys::Win32::Foundation::{BOOL, HANDLE, HMODULE, HWND, POINT, RECT};
use windows_sys::Win32::Foundation::{BOOL, HANDLE, HMODULE, HWND, NTSTATUS, POINT, RECT};
use windows_sys::Win32::Graphics::Gdi::{ClientToScreen, HMONITOR};
use windows_sys::Win32::System::LibraryLoader::{GetProcAddress, LoadLibraryA};
use windows_sys::Win32::System::SystemInformation::OSVERSIONINFOW;
use windows_sys::Win32::System::SystemServices::IMAGE_DOS_HEADER;
use windows_sys::Win32::UI::HiDpi::{
DPI_AWARENESS_CONTEXT, MONITOR_DPI_TYPE, PROCESS_DPI_AWARENESS,
Expand Down Expand Up @@ -251,6 +252,34 @@ pub type GetPointerDeviceRects = unsafe extern "system" fn(
pub type GetPointerTouchInfo =
unsafe extern "system" fn(pointer_id: u32, touch_info: *mut POINTER_TOUCH_INFO) -> BOOL;

pub(crate) static WIN10_BUILD_VERSION: Lazy<Option<u32>> = Lazy::new(|| {
type RtlGetVersion = unsafe extern "system" fn(*mut OSVERSIONINFOW) -> NTSTATUS;
let handle = get_function!("ntdll.dll", RtlGetVersion);

if let Some(rtl_get_version) = handle {
unsafe {
let mut vi = OSVERSIONINFOW {
dwOSVersionInfoSize: 0,
dwMajorVersion: 0,
dwMinorVersion: 0,
dwBuildNumber: 0,
dwPlatformId: 0,
szCSDVersion: [0; 128],
};

Comment on lines +255 to +269
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@kchibisov kchibisov Aug 12, 2025

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I'd assume that got moved just for the sake of it not being in dark_mode.rs, if so, split it to a separate commit.

let status = (rtl_get_version)(&mut vi);

if status >= 0 && vi.dwMajorVersion == 10 && vi.dwMinorVersion == 0 {
Some(vi.dwBuildNumber)
} else {
None
}
}
} else {
None
}
});

pub(crate) static GET_DPI_FOR_WINDOW: Lazy<Option<GetDpiForWindow>> =
Lazy::new(|| get_function!("user32.dll", GetDpiForWindow));
pub(crate) static ADJUST_WINDOW_RECT_EX_FOR_DPI: Lazy<Option<AdjustWindowRectExForDpi>> =
Expand Down
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