winit/platform_impl/linux/x11/util/
randr.rs

Help
1use std::str::FromStr;
2use std::{env, str};
3
4use super::*;
5use crate::dpi::validate_scale_factor;
6use crate::platform_impl::platform::x11::{monitor, VideoModeHandle};
7
8use tracing::warn;
9use x11rb::protocol::randr::{self, ConnectionExt as _};
10
11/// Represents values of `WINIT_HIDPI_FACTOR`.
12pub enum EnvVarDPI {
13    Randr,
14    Scale(f64),
15    NotSet,
16}
17
18pub fn calc_dpi_factor(
19    (width_px, height_px): (u32, u32),
20    (width_mm, height_mm): (u64, u64),
21) -> f64 {
22    // See http://xpra.org/trac/ticket/728 for more information.
23    if width_mm == 0 || height_mm == 0 {
24        warn!("XRandR reported that the display's 0mm in size, which is certifiably insane");
25        return 1.0;
26    }
27
28    let ppmm = ((width_px as f64 * height_px as f64) / (width_mm as f64 * height_mm as f64)).sqrt();
29    // Quantize 1/12 step size
30    let dpi_factor = ((ppmm * (12.0 * 25.4 / 96.0)).round() / 12.0).max(1.0);
31    assert!(validate_scale_factor(dpi_factor));
32    if dpi_factor <= 20. {
33        dpi_factor
34    } else {
35        1.
36    }
37}
38
39impl XConnection {
40    // Retrieve DPI from Xft.dpi property
41    pub fn get_xft_dpi(&self) -> Option<f64> {
42        // Try to get it from XSETTINGS first.
43        if let Some(xsettings_screen) = self.xsettings_screen() {
44            match self.xsettings_dpi(xsettings_screen) {
45                Ok(Some(dpi)) => return Some(dpi),
46                Ok(None) => {},
47                Err(err) => {
48                    tracing::warn!("failed to fetch XSettings: {err}");
49                },
50            }
51        }
52
53        self.database().get_string("Xft.dpi", "").and_then(|s| f64::from_str(s).ok())
54    }
55
56    pub fn get_output_info(
57        &self,
58        resources: &monitor::ScreenResources,
59        crtc: &randr::GetCrtcInfoReply,
60    ) -> Option<(String, f64, Vec<VideoModeHandle>)> {
61        let output_info = match self
62            .xcb_connection()
63            .randr_get_output_info(crtc.outputs[0], x11rb::CURRENT_TIME)
64            .map_err(X11Error::from)
65            .and_then(|r| r.reply().map_err(X11Error::from))
66        {
67            Ok(output_info) => output_info,
68            Err(err) => {
69                warn!("Failed to get output info: {:?}", err);
70                return None;
71            },
72        };
73
74        let bit_depth = self.default_root().root_depth;
75        let output_modes = &output_info.modes;
76        let resource_modes = resources.modes();
77
78        let modes = resource_modes
79            .iter()
80            // XRROutputInfo contains an array of mode ids that correspond to
81            // modes in the array in XRRScreenResources
82            .filter(|x| output_modes.iter().any(|id| x.id == *id))
83            .map(|mode| {
84                VideoModeHandle {
85                    size: (mode.width.into(), mode.height.into()),
86                    refresh_rate_millihertz: monitor::mode_refresh_rate_millihertz(mode)
87                        .unwrap_or(0),
88                    bit_depth: bit_depth as u16,
89                    native_mode: mode.id,
90                    // This is populated in `MonitorHandle::video_modes` as the
91                    // video mode is returned to the user
92                    monitor: None,
93                }
94            })
95            .collect();
96
97        let name = match str::from_utf8(&output_info.name) {
98            Ok(name) => name.to_owned(),
99            Err(err) => {
100                warn!("Failed to get output name: {:?}", err);
101                return None;
102            },
103        };
104        // Override DPI if `WINIT_X11_SCALE_FACTOR` variable is set
105        let deprecated_dpi_override = env::var("WINIT_HIDPI_FACTOR").ok();
106        if deprecated_dpi_override.is_some() {
107            warn!(
108                "The WINIT_HIDPI_FACTOR environment variable is deprecated; use \
109                 WINIT_X11_SCALE_FACTOR"
110            )
111        }
112        let dpi_env = env::var("WINIT_X11_SCALE_FACTOR").ok().map_or_else(
113            || EnvVarDPI::NotSet,
114            |var| {
115                if var.to_lowercase() == "randr" {
116                    EnvVarDPI::Randr
117                } else if let Ok(dpi) = f64::from_str(&var) {
118                    EnvVarDPI::Scale(dpi)
119                } else if var.is_empty() {
120                    EnvVarDPI::NotSet
121                } else {
122                    panic!(
123                        "`WINIT_X11_SCALE_FACTOR` invalid; DPI factors must be either normal \
124                         floats greater than 0, or `randr`. Got `{var}`"
125                    );
126                }
127            },
128        );
129
130        let scale_factor = match dpi_env {
131            EnvVarDPI::Randr => calc_dpi_factor(
132                (crtc.width.into(), crtc.height.into()),
133                (output_info.mm_width as _, output_info.mm_height as _),
134            ),
135            EnvVarDPI::Scale(dpi_override) => {
136                if !validate_scale_factor(dpi_override) {
137                    panic!(
138                        "`WINIT_X11_SCALE_FACTOR` invalid; DPI factors must be either normal \
139                         floats greater than 0, or `randr`. Got `{dpi_override}`",
140                    );
141                }
142                dpi_override
143            },
144            EnvVarDPI::NotSet => {
145                if let Some(dpi) = self.get_xft_dpi() {
146                    dpi / 96.
147                } else {
148                    calc_dpi_factor(
149                        (crtc.width.into(), crtc.height.into()),
150                        (output_info.mm_width as _, output_info.mm_height as _),
151                    )
152                }
153            },
154        };
155
156        Some((name, scale_factor, modes))
157    }
158
159    pub fn set_crtc_config(
160        &self,
161        crtc_id: randr::Crtc,
162        mode_id: randr::Mode,
163    ) -> Result<(), X11Error> {
164        let crtc =
165            self.xcb_connection().randr_get_crtc_info(crtc_id, x11rb::CURRENT_TIME)?.reply()?;
166
167        self.xcb_connection()
168            .randr_set_crtc_config(
169                crtc_id,
170                crtc.timestamp,
171                x11rb::CURRENT_TIME,
172                crtc.x,
173                crtc.y,
174                mode_id,
175                crtc.rotation,
176                &crtc.outputs,
177            )?
178            .reply()
179            .map(|_| ())
180            .map_err(Into::into)
181    }
182
183    pub fn get_crtc_mode(&self, crtc_id: randr::Crtc) -> Result<randr::Mode, X11Error> {
184        Ok(self.xcb_connection().randr_get_crtc_info(crtc_id, x11rb::CURRENT_TIME)?.reply()?.mode)
185    }
186}
winit/platform_impl/linux/x11/util/randr.rs

winit/platform_impl/linux/x11/util/
randr.rs
