Rename IntrinsicSizes to ContentSizes

components/layout_2020/sizing.rs

@@ -0,0 +1,80 @@
+/* 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/. */
+
+//! https://drafts.csswg.org/css-sizing/
+
+use crate::style_ext::ComputedValuesExt;
+use style::properties::ComputedValues;
+use style::values::computed::{Length, LengthPercentage, Percentage};
+use style::Zero;
+
+#[derive(Clone, Debug)]
+pub(crate) struct ContentSizes {
+    pub min_content: Length,
+    pub max_content: Length,
+}
+
+/// https://drafts.csswg.org/css-sizing/#intrinsic-sizes
+impl ContentSizes {
+    pub fn zero() -> Self {
+        Self {
+            min_content: Length::zero(),
+            max_content: Length::zero(),
+        }
+    }
+
+    /// Relevant to outer intrinsic inline sizes, for percentages from padding and margin.
+    pub fn adjust_for_pbm_percentages(&mut self, percentages: Percentage) {
+        // " Note that this may yield an infinite result, but undefined results
+        //   (zero divided by zero) must be treated as zero. "
+        if self.max_content.px() == 0. {
+            // Avoid a potential `NaN`.
+            // Zero is already the result we want regardless of `denominator`.
+        } else {
+            let denominator = (1. - percentages.0).max(0.);
+            self.max_content = Length::new(self.max_content.px() / denominator);
+        }
+    }
+}
+
+/// https://dbaron.org/css/intrinsic/#outer-intrinsic
+pub(crate) fn outer_inline_content_sizes(
+    style: &ComputedValues,
+    get_inner_intrinsic_sizes: &dyn Fn() -> ContentSizes,
+) -> (ContentSizes, Percentage) {
+    // FIXME: account for 'min-width', 'max-width', 'box-sizing'
+
+    let specified = style.box_size().inline;
+    // Percentages for 'width' are treated as 'auto'
+    let specified = specified.map(|lp| lp.as_length());
+    // The (inner) min/max-content are only used for 'auto'
+    let mut outer = match specified.non_auto().flatten() {
+        None => get_inner_intrinsic_sizes(),
+        Some(length) => ContentSizes {
+            min_content: length,
+            max_content: length,
+        },
+    };
+
+    let mut pbm_lengths = Length::zero();
+    let mut pbm_percentages = Percentage::zero();
+    let padding = style.padding();
+    let border = style.border_width();
+    let margin = style.margin();
+    pbm_lengths += border.inline_start;
+    pbm_lengths += border.inline_end;
+    let mut add = |x: LengthPercentage| {
+        pbm_lengths += x.length_component();
+        pbm_percentages += x.percentage_component();
+    };
+    add(padding.inline_start);
+    add(padding.inline_end);
+    margin.inline_start.non_auto().map(&mut add);
+    margin.inline_end.non_auto().map(&mut add);
+
+    outer.min_content += pbm_lengths;
+    outer.max_content += pbm_lengths;
+
+    (outer, pbm_percentages)
+}