Auto merge of #13157 - Manishearth:background-size, r=emilio

stylo: support background-size and corner gradients

Forgot to fix this in the midst of all other things fixed in #12945

<s>(not yet tested, need to figure out how to test bg-size with gradients)</s>

r? @bholley

<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/13157)
<!-- Reviewable:end -->

3 files changed, 133 insertions, 6 deletions

diff --git a/components/style/gecko_conversions.rs b/components/style/gecko_conversions.rs
index 71457a7dc3a..851dbe90947 100644
--- a/components/style/gecko_conversions.rs
+++ b/components/style/gecko_conversions.rs
@@ -14,7 +14,7 @@ use gecko_bindings::structs::nsStyleCoord_CalcValue;
 use gecko_bindings::sugar::ownership::{HasArcFFI, HasFFI};
 use properties::ComputedValues;
 use stylesheets::Stylesheet;
-use values::computed::{CalcLengthOrPercentage, LengthOrPercentage};
+use values::computed::{CalcLengthOrPercentage, LengthOrPercentage, LengthOrPercentageOrAuto};
 
 unsafe impl HasFFI for Stylesheet {
     type FFIType = RawServoStyleSheet;
@@ -72,6 +72,29 @@ impl From<LengthOrPercentage> for nsStyleCoord_CalcValue {
     }
 }
 
+impl LengthOrPercentageOrAuto {
+    pub fn to_calc_value(&self) -> Option<nsStyleCoord_CalcValue> {
+        match *self {
+            LengthOrPercentageOrAuto::Length(au) => {
+                Some(nsStyleCoord_CalcValue {
+                    mLength: au.0,
+                    mPercent: 0.0,
+                    mHasPercent: false,
+                })
+            },
+            LengthOrPercentageOrAuto::Percentage(pc) => {
+                Some(nsStyleCoord_CalcValue {
+                    mLength: 0,
+                    mPercent: pc,
+                    mHasPercent: true,
+                })
+            },
+            LengthOrPercentageOrAuto::Calc(calc) => Some(calc.into()),
+            LengthOrPercentageOrAuto::Auto => None,
+        }
+    }
+}
+
 impl From<nsStyleCoord_CalcValue> for LengthOrPercentage {
     fn from(other: nsStyleCoord_CalcValue) -> LengthOrPercentage {
         match (other.mHasPercent, other.mLength) {
diff --git a/components/style/properties/gecko.mako.rs b/components/style/properties/gecko.mako.rs
index 9d8191aad6b..ae801790653 100644
--- a/components/style/properties/gecko.mako.rs
+++ b/components/style/properties/gecko.mako.rs
@@ -999,7 +999,7 @@ fn static_assert() {
 <% skip_background_longhands = """background-color background-repeat
                                   background-image background-clip
                                   background-origin background-attachment
-                                  background-position""" %>
+                                  background-size background-position""" %>
 <%self:impl_trait style_struct_name="Background"
                   skip_longhands="${skip_background_longhands}"
                   skip_additionals="*">
@@ -1058,6 +1058,78 @@ fn static_assert() {
         }
     </%self:simple_background_array_property>
 
+    <%self:simple_background_array_property name="size" field_name="mSize">
+        use gecko_bindings::structs::nsStyleImageLayers_Size_Dimension;
+        use gecko_bindings::structs::nsStyleImageLayers_Size_DimensionType;
+        use gecko_bindings::structs::{nsStyleCoord_CalcValue, nsStyleImageLayers_Size};
+        use properties::longhands::background_size::single_value::computed_value::T;
+        use values::computed::LengthOrPercentageOrAuto;
+
+        let mut width = nsStyleCoord_CalcValue::new();
+        let mut height = nsStyleCoord_CalcValue::new();
+
+        let (w_type, h_type) = match servo {
+            T::Explicit(size) => {
+                let mut w_type = nsStyleImageLayers_Size_DimensionType::eAuto;
+                let mut h_type = nsStyleImageLayers_Size_DimensionType::eAuto;
+                if let Some(w) = size.width.to_calc_value() {
+                    width = w;
+                    w_type = nsStyleImageLayers_Size_DimensionType::eLengthPercentage;
+                }
+                if let Some(h) = size.height.to_calc_value() {
+                    height = h;
+                    h_type = nsStyleImageLayers_Size_DimensionType::eLengthPercentage;
+                }
+                (w_type, h_type)
+            }
+            T::Cover => (nsStyleImageLayers_Size_DimensionType::eCover,
+                         nsStyleImageLayers_Size_DimensionType::eCover),
+            T::Contain => (nsStyleImageLayers_Size_DimensionType::eContain,
+                         nsStyleImageLayers_Size_DimensionType::eContain),
+        };
+
+        nsStyleImageLayers_Size {
+            mWidth: nsStyleImageLayers_Size_Dimension { _base: width },
+            mHeight: nsStyleImageLayers_Size_Dimension { _base: height },
+            mWidthType: w_type as u8,
+            mHeightType: h_type as u8,
+        }
+    </%self:simple_background_array_property>
+
+    pub fn clone_background_size(&self) -> longhands::background_size::computed_value::T {
+        use gecko_bindings::structs::nsStyleCoord_CalcValue as CalcValue;
+        use gecko_bindings::structs::nsStyleImageLayers_Size_DimensionType as DimensionType;
+        use properties::longhands::background_size::single_value::computed_value::{ExplicitSize, T};
+        use values::computed::LengthOrPercentageOrAuto;
+
+        fn to_servo(value: CalcValue, ty: u8) -> LengthOrPercentageOrAuto {
+            if ty == DimensionType::eAuto as u8 {
+                LengthOrPercentageOrAuto::Auto
+            } else {
+                debug_assert!(ty == DimensionType::eLengthPercentage as u8);
+                LengthOrPercentageOrAuto::Calc(value.into())
+            }
+        }
+
+        longhands::background_size::computed_value::T(
+            self.gecko.mImage.mLayers.iter().map(|ref layer| {
+                if DimensionType::eCover as u8 == layer.mSize.mWidthType {
+                    debug_assert!(layer.mSize.mHeightType == DimensionType::eCover as u8);
+                    return T::Cover
+                }
+                if DimensionType::eContain as u8 == layer.mSize.mWidthType {
+                    debug_assert!(layer.mSize.mHeightType == DimensionType::eContain as u8);
+                    return T::Contain
+                }
+
+                T::Explicit(ExplicitSize {
+                    width: to_servo(layer.mSize.mWidth._base, layer.mSize.mWidthType),
+                    height: to_servo(layer.mSize.mHeight._base, layer.mSize.mHeightType),
+                })
+            }).collect()
+        )
+    }
+
     pub fn copy_background_position_from(&mut self, other: &Self) {
         self.gecko.mImage.mPositionXCount = cmp::min(1, other.gecko.mImage.mPositionXCount);
         self.gecko.mImage.mPositionYCount = cmp::min(1, other.gecko.mImage.mPositionYCount);
@@ -1120,6 +1192,7 @@ fn static_assert() {
         use gecko_bindings::structs::nsStyleCoord;
         use values::computed::Image;
         use values::specified::AngleOrCorner;
+        use values::specified::{HorizontalDirection, VerticalDirection};
         use cssparser::Color as CSSColor;
 
         unsafe {
@@ -1156,10 +1229,31 @@ fn static_assert() {
                                                  stop_count as u32)
                         };
 
-                        // TODO: figure out what gecko does in the `corner` case.
-                        if let AngleOrCorner::Angle(angle) = gradient.angle_or_corner {
-                            unsafe {
-                                (*gecko_gradient).mAngle.set(angle);
+                        match gradient.angle_or_corner {
+                            AngleOrCorner::Angle(angle) => {
+                                unsafe {
+                                    (*gecko_gradient).mAngle.set(angle);
+                                    (*gecko_gradient).mBgPosX.set_value(CoordDataValue::None);
+                                    (*gecko_gradient).mBgPosY.set_value(CoordDataValue::None);
+                                }
+                            }
+                            AngleOrCorner::Corner(horiz, vert) => {
+                                let percent_x = match horiz {
+                                    HorizontalDirection::Left => 0.0,
+                                    HorizontalDirection::Right => 1.0,
+                                };
+                                let percent_y = match vert {
+                                    VerticalDirection::Top => 0.0,
+                                    VerticalDirection::Bottom => 1.0,
+                                };
+
+                                unsafe {
+                                    (*gecko_gradient).mAngle.set_value(CoordDataValue::None);
+                                    (*gecko_gradient).mBgPosX
+                                                     .set_value(CoordDataValue::Percent(percent_x));
+                                    (*gecko_gradient).mBgPosY
+                                                     .set_value(CoordDataValue::Percent(percent_y));
+                                }
                             }
                         }
 
diff --git a/ports/geckolib/gecko_bindings/sugar/ns_style_coord.rs b/ports/geckolib/gecko_bindings/sugar/ns_style_coord.rs
index 881da7e0e39..b850142c0f6 100644
--- a/ports/geckolib/gecko_bindings/sugar/ns_style_coord.rs
+++ b/ports/geckolib/gecko_bindings/sugar/ns_style_coord.rs
@@ -40,6 +40,16 @@ impl CoordDataMut for nsStyleCoord {
     }
 }
 
+impl nsStyleCoord_CalcValue {
+    pub fn new() -> Self {
+        nsStyleCoord_CalcValue {
+            mLength: 0,
+            mPercent: 0.0,
+            mHasPercent: false,
+        }
+    }
+}
+
 impl nsStyleSides {
     #[inline]
     pub fn data_at(&self, index: usize) -> SidesData {