1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
use std::{env, slice, str::FromStr};

use super::{
    ffi::{CurrentTime, RRCrtc, RRMode, Success, XRRCrtcInfo, XRRScreenResources},
    *,
};
use crate::platform_impl::platform::x11::monitor;
use crate::{dpi::validate_scale_factor, platform_impl::platform::x11::VideoMode};

/// Represents values of `WINIT_HIDPI_FACTOR`.
pub enum EnvVarDPI {
    Randr,
    Scale(f64),
    NotSet,
}

pub fn calc_dpi_factor(
    (width_px, height_px): (u32, u32),
    (width_mm, height_mm): (u64, u64),
) -> f64 {
    // See http://xpra.org/trac/ticket/728 for more information.
    if width_mm == 0 || height_mm == 0 {
        warn!("XRandR reported that the display's 0mm in size, which is certifiably insane");
        return 1.0;
    }

    let ppmm = ((width_px as f64 * height_px as f64) / (width_mm as f64 * height_mm as f64)).sqrt();
    // Quantize 1/12 step size
    let dpi_factor = ((ppmm * (12.0 * 25.4 / 96.0)).round() / 12.0).max(1.0);
    assert!(validate_scale_factor(dpi_factor));
    if dpi_factor <= 20. {
        dpi_factor
    } else {
        1.
    }
}

impl XConnection {
    // Retrieve DPI from Xft.dpi property
    pub unsafe fn get_xft_dpi(&self) -> Option<f64> {
        (self.xlib.XrmInitialize)();
        let resource_manager_str = (self.xlib.XResourceManagerString)(self.display);
        if resource_manager_str.is_null() {
            return None;
        }
        if let Ok(res) = ::std::ffi::CStr::from_ptr(resource_manager_str).to_str() {
            let name: &str = "Xft.dpi:\t";
            for pair in res.split('\n') {
                if let Some(stripped) = pair.strip_prefix(name) {
                    return f64::from_str(stripped).ok();
                }
            }
        }
        None
    }
    pub unsafe fn get_output_info(
        &self,
        resources: *mut XRRScreenResources,
        crtc: *mut XRRCrtcInfo,
    ) -> Option<(String, f64, Vec<VideoMode>)> {
        let output_info =
            (self.xrandr.XRRGetOutputInfo)(self.display, resources, *(*crtc).outputs.offset(0));
        if output_info.is_null() {
            // When calling `XRRGetOutputInfo` on a virtual monitor (versus a physical display)
            // it's possible for it to return null.
            // https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=816596
            let _ = self.check_errors(); // discard `BadRROutput` error
            return None;
        }

        let screen = (self.xlib.XDefaultScreen)(self.display);
        let bit_depth = (self.xlib.XDefaultDepth)(self.display, screen);

        let output_modes =
            slice::from_raw_parts((*output_info).modes, (*output_info).nmode as usize);
        let resource_modes = slice::from_raw_parts((*resources).modes, (*resources).nmode as usize);

        let modes = resource_modes
            .iter()
            // XRROutputInfo contains an array of mode ids that correspond to
            // modes in the array in XRRScreenResources
            .filter(|x| output_modes.iter().any(|id| x.id == *id))
            .map(|mode| {
                VideoMode {
                    size: (mode.width, mode.height),
                    refresh_rate_millihertz: monitor::mode_refresh_rate_millihertz(mode)
                        .unwrap_or(0),
                    bit_depth: bit_depth as u16,
                    native_mode: mode.id,
                    // This is populated in `MonitorHandle::video_modes` as the
                    // video mode is returned to the user
                    monitor: None,
                }
            })
            .collect();

        let name_slice = slice::from_raw_parts(
            (*output_info).name as *mut u8,
            (*output_info).nameLen as usize,
        );
        let name = String::from_utf8_lossy(name_slice).into();
        // Override DPI if `WINIT_X11_SCALE_FACTOR` variable is set
        let deprecated_dpi_override = env::var("WINIT_HIDPI_FACTOR").ok();
        if deprecated_dpi_override.is_some() {
            warn!(
	            "The WINIT_HIDPI_FACTOR environment variable is deprecated; use WINIT_X11_SCALE_FACTOR"
	        )
        }
        let dpi_env = env::var("WINIT_X11_SCALE_FACTOR").ok().map_or_else(
            || EnvVarDPI::NotSet,
            |var| {
                if var.to_lowercase() == "randr" {
                    EnvVarDPI::Randr
                } else if let Ok(dpi) = f64::from_str(&var) {
                    EnvVarDPI::Scale(dpi)
                } else if var.is_empty() {
                    EnvVarDPI::NotSet
                } else {
                    panic!(
                        "`WINIT_X11_SCALE_FACTOR` invalid; DPI factors must be either normal floats greater than 0, or `randr`. Got `{var}`"
                    );
                }
            },
        );

        let scale_factor = match dpi_env {
            EnvVarDPI::Randr => calc_dpi_factor(
                ((*crtc).width, (*crtc).height),
                ((*output_info).mm_width as _, (*output_info).mm_height as _),
            ),
            EnvVarDPI::Scale(dpi_override) => {
                if !validate_scale_factor(dpi_override) {
                    panic!(
                        "`WINIT_X11_SCALE_FACTOR` invalid; DPI factors must be either normal floats greater than 0, or `randr`. Got `{dpi_override}`",
                    );
                }
                dpi_override
            }
            EnvVarDPI::NotSet => {
                if let Some(dpi) = self.get_xft_dpi() {
                    dpi / 96.
                } else {
                    calc_dpi_factor(
                        ((*crtc).width, (*crtc).height),
                        ((*output_info).mm_width as _, (*output_info).mm_height as _),
                    )
                }
            }
        };

        (self.xrandr.XRRFreeOutputInfo)(output_info);
        Some((name, scale_factor, modes))
    }

    #[must_use]
    pub fn set_crtc_config(&self, crtc_id: RRCrtc, mode_id: RRMode) -> Option<()> {
        unsafe {
            let mut major = 0;
            let mut minor = 0;
            (self.xrandr.XRRQueryVersion)(self.display, &mut major, &mut minor);

            let root = (self.xlib.XDefaultRootWindow)(self.display);
            let resources = if (major == 1 && minor >= 3) || major > 1 {
                (self.xrandr.XRRGetScreenResourcesCurrent)(self.display, root)
            } else {
                (self.xrandr.XRRGetScreenResources)(self.display, root)
            };

            let crtc = (self.xrandr.XRRGetCrtcInfo)(self.display, resources, crtc_id);
            let status = (self.xrandr.XRRSetCrtcConfig)(
                self.display,
                resources,
                crtc_id,
                CurrentTime,
                (*crtc).x,
                (*crtc).y,
                mode_id,
                (*crtc).rotation,
                (*crtc).outputs.offset(0),
                1,
            );

            (self.xrandr.XRRFreeCrtcInfo)(crtc);
            (self.xrandr.XRRFreeScreenResources)(resources);

            if status == Success as i32 {
                Some(())
            } else {
                None
            }
        }
    }

    pub fn get_crtc_mode(&self, crtc_id: RRCrtc) -> RRMode {
        unsafe {
            let mut major = 0;
            let mut minor = 0;
            (self.xrandr.XRRQueryVersion)(self.display, &mut major, &mut minor);

            let root = (self.xlib.XDefaultRootWindow)(self.display);
            let resources = if (major == 1 && minor >= 3) || major > 1 {
                (self.xrandr.XRRGetScreenResourcesCurrent)(self.display, root)
            } else {
                (self.xrandr.XRRGetScreenResources)(self.display, root)
            };

            let crtc = (self.xrandr.XRRGetCrtcInfo)(self.display, resources, crtc_id);
            let mode = (*crtc).mode;
            (self.xrandr.XRRFreeCrtcInfo)(crtc);
            (self.xrandr.XRRFreeScreenResources)(resources);
            mode
        }
    }
}