1 files changed, 148 insertions, 0 deletions
diff --git a/servo/components/style_traits/viewport.rs b/servo/components/style_traits/viewport.rs
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+++ b/servo/components/style_traits/viewport.rs
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+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+//! Helper types for the `@viewport` rule.
+
+use crate::{CSSPixel, CssWriter, ParseError, PinchZoomFactor, ToCss};
+use cssparser::Parser;
+use euclid::Size2D;
+use std::fmt::{self, Write};
+
+define_css_keyword_enum! {
+    pub enum UserZoom {
+        Zoom = "zoom",
+        Fixed = "fixed",
+    }
+}
+
+define_css_keyword_enum! {
+    pub enum Orientation {
+        Auto = "auto",
+        Portrait = "portrait",
+        Landscape = "landscape",
+    }
+}
+
+/// A set of viewport descriptors:
+///
+/// <https://drafts.csswg.org/css-device-adapt/#viewport-desc>
+#[derive(Clone, Debug, PartialEq)]
+#[cfg_attr(feature = "servo", derive(Deserialize, Serialize, MallocSizeOf))]
+pub struct ViewportConstraints {
+    /// Width and height:
+    ///  * https://drafts.csswg.org/css-device-adapt/#width-desc
+    ///  * https://drafts.csswg.org/css-device-adapt/#height-desc
+    pub size: Size2D<f32, CSSPixel>,
+    /// <https://drafts.csswg.org/css-device-adapt/#zoom-desc>
+    pub initial_zoom: PinchZoomFactor,
+    /// <https://drafts.csswg.org/css-device-adapt/#min-max-width-desc>
+    pub min_zoom: Option<PinchZoomFactor>,
+    /// <https://drafts.csswg.org/css-device-adapt/#min-max-width-desc>
+    pub max_zoom: Option<PinchZoomFactor>,
+    /// <https://drafts.csswg.org/css-device-adapt/#user-zoom-desc>
+    pub user_zoom: UserZoom,
+    /// <https://drafts.csswg.org/css-device-adapt/#orientation-desc>
+    pub orientation: Orientation,
+}
+
+impl ToCss for ViewportConstraints {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
+        dest.write_str("@viewport { width: ")?;
+        self.size.width.to_css(dest)?;
+
+        dest.write_str("px; height: ")?;
+        self.size.height.to_css(dest)?;
+
+        dest.write_str("px; zoom: ")?;
+        self.initial_zoom.get().to_css(dest)?;
+
+        if let Some(min_zoom) = self.min_zoom {
+            dest.write_str("; min-zoom: ")?;
+            min_zoom.get().to_css(dest)?;
+        }
+
+        if let Some(max_zoom) = self.max_zoom {
+            dest.write_str("; max-zoom: ")?;
+            max_zoom.get().to_css(dest)?;
+        }
+
+        dest.write_str("; user-zoom: ")?;
+        self.user_zoom.to_css(dest)?;
+
+        dest.write_str("; orientation: ")?;
+        self.orientation.to_css(dest)?;
+        dest.write_str("; }")
+    }
+}
+
+/// <https://drafts.csswg.org/css-device-adapt/#descdef-viewport-zoom>
+#[derive(Clone, Copy, Debug, PartialEq, ToShmem)]
+#[cfg_attr(feature = "servo", derive(MallocSizeOf))]
+pub enum Zoom {
+    /// A number value.
+    Number(f32),
+    /// A percentage value.
+    Percentage(f32),
+    /// The `auto` keyword.
+    Auto,
+}
+
+impl ToCss for Zoom {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: fmt::Write,
+    {
+        match *self {
+            Zoom::Number(number) => number.to_css(dest),
+            Zoom::Auto => dest.write_str("auto"),
+            Zoom::Percentage(percentage) => {
+                (percentage * 100.).to_css(dest)?;
+                dest.write_char('%')
+            },
+        }
+    }
+}
+
+impl Zoom {
+    /// Parse a zoom value per:
+    ///
+    /// <https://drafts.csswg.org/css-device-adapt/#descdef-viewport-zoom>
+    pub fn parse<'i, 't>(input: &mut Parser<'i, 't>) -> Result<Zoom, ParseError<'i>> {
+        use crate::values::specified::AllowedNumericType::NonNegative;
+        use crate::ParsingMode;
+        use cssparser::Token;
+
+        let location = input.current_source_location();
+        match *input.next()? {
+            // TODO: This parse() method should take ParserContext as an
+            // argument, and pass ParsingMode owned by the ParserContext to
+            // is_ok() instead of using ParsingMode::DEFAULT directly.
+            // In order to do so, we might want to move these stuff into style::stylesheets::viewport_rule.
+            Token::Percentage { unit_value, .. }
+                if NonNegative.is_ok(ParsingMode::DEFAULT, unit_value) =>
+            {
+                Ok(Zoom::Percentage(unit_value))
+            },
+            Token::Number { value, .. } if NonNegative.is_ok(ParsingMode::DEFAULT, value) => {
+                Ok(Zoom::Number(value))
+            },
+            Token::Ident(ref value) if value.eq_ignore_ascii_case("auto") => Ok(Zoom::Auto),
+            ref t => Err(location.new_unexpected_token_error(t.clone())),
+        }
+    }
+
+    /// Get this zoom value as a float value. Returns `None` if the value is the
+    /// `auto` keyword.
+    #[inline]
+    pub fn to_f32(&self) -> Option<f32> {
+        match *self {
+            Zoom::Number(number) => Some(number as f32),
+            Zoom::Percentage(percentage) => Some(percentage as f32),
+            Zoom::Auto => None,
+        }
+    }
+}