/
dark_mode.rs
184 lines (151 loc) · 5.55 KB
/
dark_mode.rs
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/// This is a simple implementation of support for Windows Dark Mode,
/// which is inspired by the solution in https://github.com/ysc3839/win32-darkmode
use std::{ffi::c_void, ptr};
use windows_sys::Win32::{
Foundation::{BOOL, HWND, NTSTATUS, PSTR, S_OK},
System::{
LibraryLoader::{GetProcAddress, LoadLibraryA},
SystemInformation::OSVERSIONINFOW,
},
UI::{
Accessibility::{HCF_HIGHCONTRASTON, HIGHCONTRASTA},
Controls::SetWindowTheme,
WindowsAndMessaging::{SystemParametersInfoA, SPI_GETHIGHCONTRAST},
},
};
use crate::window::Theme;
use super::util;
lazy_static! {
static ref WIN10_BUILD_VERSION: Option<u32> = {
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 ref DARK_MODE_SUPPORTED: bool = {
// We won't try to do anything for windows versions < 17763
// (Windows 10 October 2018 update)
match *WIN10_BUILD_VERSION {
Some(v) => v >= 17763,
None => false
}
};
static ref DARK_THEME_NAME: Vec<u16> = util::encode_wide("DarkMode_Explorer");
static ref LIGHT_THEME_NAME: Vec<u16> = util::encode_wide("");
}
/// Attempt to set a theme on a window, if necessary.
/// Returns the theme that was picked
pub fn try_theme(hwnd: HWND, preferred_theme: Option<Theme>) -> Theme {
if *DARK_MODE_SUPPORTED {
let is_dark_mode = match preferred_theme {
Some(theme) => theme == Theme::Dark,
None => should_use_dark_mode(),
};
let theme = if is_dark_mode {
Theme::Dark
} else {
Theme::Light
};
let theme_name = match theme {
Theme::Dark => DARK_THEME_NAME.as_ptr(),
Theme::Light => LIGHT_THEME_NAME.as_ptr(),
};
let status = unsafe { SetWindowTheme(hwnd, theme_name, ptr::null()) };
if status == S_OK && set_dark_mode_for_window(hwnd, is_dark_mode) {
return theme;
}
}
Theme::Light
}
fn set_dark_mode_for_window(hwnd: HWND, is_dark_mode: bool) -> bool {
// Uses Windows undocumented API SetWindowCompositionAttribute,
// as seen in win32-darkmode example linked at top of file.
type SetWindowCompositionAttribute =
unsafe extern "system" fn(HWND, *mut WINDOWCOMPOSITIONATTRIBDATA) -> BOOL;
#[allow(clippy::upper_case_acronyms)]
type WINDOWCOMPOSITIONATTRIB = u32;
const WCA_USEDARKMODECOLORS: WINDOWCOMPOSITIONATTRIB = 26;
#[allow(non_snake_case)]
#[allow(clippy::upper_case_acronyms)]
#[repr(C)]
struct WINDOWCOMPOSITIONATTRIBDATA {
Attrib: WINDOWCOMPOSITIONATTRIB,
pvData: *mut c_void,
cbData: usize,
}
lazy_static! {
static ref SET_WINDOW_COMPOSITION_ATTRIBUTE: Option<SetWindowCompositionAttribute> =
get_function!("user32.dll", SetWindowCompositionAttribute);
}
if let Some(set_window_composition_attribute) = *SET_WINDOW_COMPOSITION_ATTRIBUTE {
unsafe {
// SetWindowCompositionAttribute needs a bigbool (i32), not bool.
let mut is_dark_mode_bigbool = BOOL::from(is_dark_mode);
let mut data = WINDOWCOMPOSITIONATTRIBDATA {
Attrib: WCA_USEDARKMODECOLORS,
pvData: &mut is_dark_mode_bigbool as *mut _ as _,
cbData: std::mem::size_of_val(&is_dark_mode_bigbool) as _,
};
let status = set_window_composition_attribute(hwnd, &mut data);
status != false.into()
}
} else {
false
}
}
fn should_use_dark_mode() -> bool {
should_apps_use_dark_mode() && !is_high_contrast()
}
fn should_apps_use_dark_mode() -> bool {
type ShouldAppsUseDarkMode = unsafe extern "system" fn() -> bool;
lazy_static! {
static ref SHOULD_APPS_USE_DARK_MODE: Option<ShouldAppsUseDarkMode> = {
unsafe {
const UXTHEME_SHOULDAPPSUSEDARKMODE_ORDINAL: PSTR = 132 as PSTR;
let module = LoadLibraryA("uxtheme.dll\0".as_ptr());
if module == 0 {
return None;
}
let handle = GetProcAddress(module, UXTHEME_SHOULDAPPSUSEDARKMODE_ORDINAL);
handle.map(|handle| std::mem::transmute(handle))
}
};
}
SHOULD_APPS_USE_DARK_MODE
.map(|should_apps_use_dark_mode| unsafe { (should_apps_use_dark_mode)() })
.unwrap_or(false)
}
fn is_high_contrast() -> bool {
let mut hc = HIGHCONTRASTA {
cbSize: 0,
dwFlags: 0,
lpszDefaultScheme: ptr::null(),
};
let ok = unsafe {
SystemParametersInfoA(
SPI_GETHIGHCONTRAST,
std::mem::size_of_val(&hc) as _,
&mut hc as *mut _ as _,
0,
)
};
ok != false.into() && util::has_flag(hc.dwFlags, HCF_HIGHCONTRASTON)
}