style/device/
mod.rs

1/* This Source Code Form is subject to the terms of the Mozilla Public
2 * License, v. 2.0. If a copy of the MPL was not distributed with this
3 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
4
5//! Media-query device and expression representation.
6
7use crate::color::AbsoluteColor;
8use crate::custom_properties::CssEnvironment;
9#[cfg(feature = "servo")]
10use crate::derives::*;
11use crate::properties::ComputedValues;
12use crate::values::computed::Length;
13use crate::values::computed::font::QueryFontMetricsFlags;
14use parking_lot::RwLock;
15use servo_arc::Arc;
16use std::mem;
17use std::sync::atomic::{AtomicBool, AtomicU32, Ordering};
18
19#[cfg(feature = "gecko")]
20use crate::device::gecko::ExtraDeviceData;
21#[cfg(feature = "servo")]
22use crate::device::servo::ExtraDeviceData;
23
24#[cfg(feature = "gecko")]
25pub mod gecko;
26#[cfg(feature = "servo")]
27pub mod servo;
28
29/// A device is a structure that represents the current media a given document
30/// is displayed in.
31///
32/// This is the struct against which media queries are evaluated, has a default
33/// values computed, and contains all the viewport rule state.
34///
35/// This structure also contains atomics used for computing root font-relative
36/// units. These atomics use relaxed ordering, since when computing the style
37/// of the root element, there can't be any other style being computed at the
38/// same time (given we need the style of the parent to compute everything else).
39///
40/// In Gecko, it wraps a pres context.
41#[cfg_attr(feature = "servo", derive(Debug, MallocSizeOf))]
42pub struct Device {
43    /// The default computed values for this Device.
44    #[cfg_attr(feature = "servo", ignore_malloc_size_of = "Arc is shared")]
45    default_values: Arc<ComputedValues>,
46    /// Current computed style of the root element, used for calculations of
47    /// root font-relative units.
48    #[cfg_attr(feature = "servo", ignore_malloc_size_of = "Arc")]
49    root_style: RwLock<Arc<ComputedValues>>,
50    /// Font size of the root element, used for rem units in other elements.
51    root_font_size: AtomicU32,
52    /// Line height of the root element, used for rlh units in other elements.
53    root_line_height: AtomicU32,
54    /// X-height of the root element, used for rex units in other elements.
55    root_font_metrics_ex: AtomicU32,
56    /// Cap-height of the root element, used for rcap units in other elements.
57    root_font_metrics_cap: AtomicU32,
58    /// Advance measure (ch) of the root element, used for rch units in other elements.
59    root_font_metrics_ch: AtomicU32,
60    /// Ideographic advance measure of the root element, used for ric units in other elements.
61    root_font_metrics_ic: AtomicU32,
62    /// Whether any styles computed in the document relied on the root font-size
63    /// by using rem units.
64    used_root_font_size: AtomicBool,
65    /// Whether any styles computed in the document relied on the root line-height
66    /// by using rlh units.
67    used_root_line_height: AtomicBool,
68    /// Whether any styles computed in the document relied on the root font metrics
69    /// by using rcap, rch, rex, or ric units. This is a lock instead of an atomic
70    /// in order to prevent concurrent writes to the root font metric values.
71    #[cfg_attr(feature = "servo", ignore_malloc_size_of = "Pure stack type")]
72    used_root_font_metrics: RwLock<bool>,
73    /// Whether any styles computed in the document relied on font metrics.
74    used_font_metrics: AtomicBool,
75    /// Whether any styles computed in the document relied on the viewport size
76    /// by using vw/vh/vmin/vmax units.
77    used_viewport_size: AtomicBool,
78    /// Whether any styles computed in the document relied on the viewport size
79    /// by using dvw/dvh/dvmin/dvmax units.
80    used_dynamic_viewport_size: AtomicBool,
81    /// The CssEnvironment object responsible of getting CSS environment
82    /// variables.
83    environment: CssEnvironment,
84    /// The body text color, used for the "tables inherit from body" quirk.
85    ///
86    /// <https://quirks.spec.whatwg.org/#the-tables-inherit-color-from-body-quirk>
87    body_text_color: RwLock<AbsoluteColor>,
88
89    /// Extra Gecko-specific or Servo-specific data.
90    extra: ExtraDeviceData,
91}
92
93impl Device {
94    /// Get the relevant environment to resolve `env()` functions.
95    #[inline]
96    pub fn environment(&self) -> &CssEnvironment {
97        &self.environment
98    }
99
100    /// Returns the default computed values as a reference, in order to match
101    /// Servo.
102    pub fn default_computed_values(&self) -> &ComputedValues {
103        &self.default_values
104    }
105
106    /// Returns the default computed values as an `Arc`.
107    pub fn default_computed_values_arc(&self) -> &Arc<ComputedValues> {
108        &self.default_values
109    }
110
111    /// Store a pointer to the root element's computed style, for use in
112    /// calculation of root font-relative metrics.
113    pub fn set_root_style(&self, style: &Arc<ComputedValues>) {
114        *self.root_style.write() = style.clone();
115    }
116
117    /// Get the font size of the root element (for rem)
118    pub fn root_font_size(&self) -> Length {
119        self.used_root_font_size.store(true, Ordering::Relaxed);
120        Length::new(f32::from_bits(self.root_font_size.load(Ordering::Relaxed)))
121    }
122
123    /// Set the font size of the root element (for rem), in zoom-independent CSS pixels.
124    pub fn set_root_font_size(&self, size: f32) {
125        self.root_font_size.store(size.to_bits(), Ordering::Relaxed)
126    }
127
128    /// Get the line height of the root element (for rlh)
129    pub fn root_line_height(&self) -> Length {
130        self.used_root_line_height.store(true, Ordering::Relaxed);
131        Length::new(f32::from_bits(
132            self.root_line_height.load(Ordering::Relaxed),
133        ))
134    }
135
136    /// Set the line height of the root element (for rlh), in zoom-independent CSS pixels.
137    pub fn set_root_line_height(&self, size: f32) {
138        self.root_line_height
139            .store(size.to_bits(), Ordering::Relaxed);
140    }
141
142    /// Get the x-height of the root element (for rex)
143    pub fn root_font_metrics_ex(&self) -> Length {
144        self.ensure_root_font_metrics_updated();
145        Length::new(f32::from_bits(
146            self.root_font_metrics_ex.load(Ordering::Relaxed),
147        ))
148    }
149
150    /// Set the x-height of the root element (for rex), in zoom-independent CSS pixels.
151    pub fn set_root_font_metrics_ex(&self, size: f32) -> bool {
152        let size = size.to_bits();
153        let previous = self.root_font_metrics_ex.swap(size, Ordering::Relaxed);
154        previous != size
155    }
156
157    /// Get the cap-height of the root element (for rcap)
158    pub fn root_font_metrics_cap(&self) -> Length {
159        self.ensure_root_font_metrics_updated();
160        Length::new(f32::from_bits(
161            self.root_font_metrics_cap.load(Ordering::Relaxed),
162        ))
163    }
164
165    /// Set the cap-height of the root element (for rcap), in zoom-independent CSS pixels.
166    pub fn set_root_font_metrics_cap(&self, size: f32) -> bool {
167        let size = size.to_bits();
168        let previous = self.root_font_metrics_cap.swap(size, Ordering::Relaxed);
169        previous != size
170    }
171
172    /// Get the advance measure of the root element (for rch)
173    pub fn root_font_metrics_ch(&self) -> Length {
174        self.ensure_root_font_metrics_updated();
175        Length::new(f32::from_bits(
176            self.root_font_metrics_ch.load(Ordering::Relaxed),
177        ))
178    }
179
180    /// Set the advance measure of the root element (for rch), in zoom-independent CSS pixels.
181    pub fn set_root_font_metrics_ch(&self, size: f32) -> bool {
182        let size = size.to_bits();
183        let previous = self.root_font_metrics_ch.swap(size, Ordering::Relaxed);
184        previous != size
185    }
186
187    /// Get the ideographic advance measure of the root element (for ric)
188    pub fn root_font_metrics_ic(&self) -> Length {
189        self.ensure_root_font_metrics_updated();
190        Length::new(f32::from_bits(
191            self.root_font_metrics_ic.load(Ordering::Relaxed),
192        ))
193    }
194
195    /// Set the ideographic advance measure of the root element (for ric), in zoom-independent CSS pixels.
196    pub fn set_root_font_metrics_ic(&self, size: f32) -> bool {
197        let size = size.to_bits();
198        let previous = self.root_font_metrics_ic.swap(size, Ordering::Relaxed);
199        previous != size
200    }
201
202    fn ensure_root_font_metrics_updated(&self) {
203        let mut guard = self.used_root_font_metrics.write();
204        let previously_computed = mem::replace(&mut *guard, true);
205        if !previously_computed {
206            self.update_root_font_metrics();
207        }
208    }
209
210    /// Compute the root element's font metrics, and returns a bool indicating whether
211    /// the font metrics have changed since the previous restyle.
212    pub fn update_root_font_metrics(&self) -> bool {
213        let root_style = self.root_style.read();
214        let root_effective_zoom = root_style.effective_zoom;
215        let root_font_size = (*root_style)
216            .get_font()
217            .slow_clone_font_size()
218            .computed_size();
219
220        let root_font_metrics = self.query_font_metrics(
221            root_style.writing_mode.is_upright(),
222            (*root_style).get_font(),
223            root_font_size,
224            QueryFontMetricsFlags::USE_USER_FONT_SET
225                | QueryFontMetricsFlags::NEEDS_CH
226                | QueryFontMetricsFlags::NEEDS_IC,
227            /* track_usage = */ false,
228        );
229
230        let mut root_font_metrics_changed = false;
231        root_font_metrics_changed |= self.set_root_font_metrics_ex(
232            root_effective_zoom.unzoom(root_font_metrics.x_height_or_default(root_font_size).px()),
233        );
234        root_font_metrics_changed |= self.set_root_font_metrics_ch(
235            root_effective_zoom.unzoom(
236                root_font_metrics
237                    .zero_advance_measure_or_default(
238                        root_font_size,
239                        root_style.writing_mode.is_upright(),
240                    )
241                    .px(),
242            ),
243        );
244        root_font_metrics_changed |= self.set_root_font_metrics_cap(
245            root_effective_zoom.unzoom(root_font_metrics.cap_height_or_default().px()),
246        );
247        root_font_metrics_changed |= self.set_root_font_metrics_ic(
248            root_effective_zoom.unzoom(root_font_metrics.ic_width_or_default(root_font_size).px()),
249        );
250
251        root_font_metrics_changed
252    }
253
254    /// Returns whether we ever looked up the root font size of the Device.
255    pub fn used_root_font_size(&self) -> bool {
256        self.used_root_font_size.load(Ordering::Relaxed)
257    }
258
259    /// Returns whether we ever looked up the root line-height of the device.
260    pub fn used_root_line_height(&self) -> bool {
261        self.used_root_line_height.load(Ordering::Relaxed)
262    }
263
264    /// Returns whether we ever looked up the root font metrics of the device.
265    pub fn used_root_font_metrics(&self) -> bool {
266        *self.used_root_font_metrics.read()
267    }
268
269    /// Returns whether we ever looked up the viewport size of the Device.
270    pub fn used_viewport_size(&self) -> bool {
271        self.used_viewport_size.load(Ordering::Relaxed)
272    }
273
274    /// Returns whether we ever looked up the dynamic viewport size of the Device.
275    pub fn used_dynamic_viewport_size(&self) -> bool {
276        self.used_dynamic_viewport_size.load(Ordering::Relaxed)
277    }
278
279    /// Returns whether font metrics have been queried.
280    pub fn used_font_metrics(&self) -> bool {
281        self.used_font_metrics.load(Ordering::Relaxed)
282    }
283
284    /// Returns the body text color.
285    pub fn body_text_color(&self) -> AbsoluteColor {
286        *self.body_text_color.read()
287    }
288
289    /// Sets the body text color for the "inherit color from body" quirk.
290    ///
291    /// <https://quirks.spec.whatwg.org/#the-tables-inherit-color-from-body-quirk>
292    pub fn set_body_text_color(&self, color: AbsoluteColor) {
293        *self.body_text_color.write() = color;
294    }
295
296    /// Applies text zoom to a font-size or line-height value (see nsStyleFont::ZoomText).
297    #[inline]
298    pub fn zoom_text(&self, size: Length) -> Length {
299        size.scale_by(self.text_zoom())
300    }
301
302    /// Un-apply text zoom.
303    #[inline]
304    pub fn unzoom_text(&self, size: Length) -> Length {
305        size.scale_by(1. / self.text_zoom())
306    }
307}
style/device/mod.rs

style/device/
mod.rs
