Auto merge of #7795 - glennw:app-units-crate, r=SimonSapin

Split Au type into separate crate, with minimal dependencies.



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2 files changed, 170 insertions, 0 deletions

diff --git a/components/app_units/src/app_unit.rs b/components/app_units/src/app_unit.rs
new file mode 100644
index 00000000000..a94c2bac04b
--- /dev/null
+++ b/components/app_units/src/app_unit.rs
@@ -0,0 +1,154 @@
+/* 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 http://mozilla.org/MPL/2.0/. */
+
+use euclid::num::Zero;
+use rustc_serialize::{Encodable, Encoder};
+use std::default::Default;
+use std::fmt;
+use std::i32;
+use std::ops::{Add, Div, Mul, Neg, Rem, Sub};
+
+/// The number of app units in a pixel.
+pub const AU_PER_PX: i32 = 60;
+
+#[derive(Clone, Copy, Hash, PartialEq, PartialOrd, Eq, Ord, Deserialize, Serialize)]
+pub struct Au(pub i32);
+
+impl Default for Au {
+    #[inline]
+    fn default() -> Au {
+        Au(0)
+    }
+}
+
+impl Zero for Au {
+    #[inline]
+    fn zero() -> Au {
+        Au(0)
+    }
+}
+
+pub const MIN_AU: Au = Au(i32::MIN);
+pub const MAX_AU: Au = Au(i32::MAX);
+
+impl Encodable for Au {
+    fn encode<S: Encoder>(&self, e: &mut S) -> Result<(), S::Error> {
+        e.emit_f64(self.to_f64_px())
+    }
+}
+
+impl fmt::Debug for Au {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}px", self.to_f64_px())
+    }
+}
+
+impl Add for Au {
+    type Output = Au;
+
+    #[inline]
+    fn add(self, other: Au) -> Au {
+        Au(self.0.wrapping_add(other.0))
+    }
+}
+
+impl Sub for Au {
+    type Output = Au;
+
+    #[inline]
+    fn sub(self, other: Au) -> Au {
+        Au(self.0.wrapping_sub(other.0))
+    }
+
+}
+
+impl Mul<i32> for Au {
+    type Output = Au;
+
+    #[inline]
+    fn mul(self, other: i32) -> Au {
+        Au(self.0.wrapping_mul(other))
+    }
+}
+
+impl Div<i32> for Au {
+    type Output = Au;
+
+    #[inline]
+    fn div(self, other: i32) -> Au {
+        Au(self.0 / other)
+    }
+}
+
+impl Rem<i32> for Au {
+    type Output = Au;
+
+    #[inline]
+    fn rem(self, other: i32) -> Au {
+        Au(self.0 % other)
+    }
+}
+
+impl Neg for Au {
+    type Output = Au;
+
+    #[inline]
+    fn neg(self) -> Au {
+        Au(-self.0)
+    }
+}
+
+impl Au {
+    /// FIXME(pcwalton): Workaround for lack of cross crate inlining of newtype structs!
+    #[inline]
+    pub fn new(value: i32) -> Au {
+        Au(value)
+    }
+
+    #[inline]
+    pub fn scale_by(self, factor: f32) -> Au {
+        Au(((self.0 as f32) * factor) as i32)
+    }
+
+    #[inline]
+    pub fn from_px(px: i32) -> Au {
+        Au((px * AU_PER_PX) as i32)
+    }
+
+    /// Rounds this app unit down to the pixel towards zero and returns it.
+    #[inline]
+    pub fn to_px(self) -> i32 {
+        self.0 / AU_PER_PX
+    }
+
+    #[inline]
+    pub fn to_nearest_px(self) -> i32 {
+        ((self.0 as f64) / (AU_PER_PX as f64)).round() as i32
+    }
+
+    #[inline]
+    pub fn to_nearest_pixel(self, pixels_per_px: f32) -> f32 {
+        ((self.0 as f32) / (AU_PER_PX as f32) * pixels_per_px).round() / pixels_per_px
+    }
+
+    #[inline]
+    pub fn to_f32_px(self) -> f32 {
+        (self.0 as f32) / (AU_PER_PX as f32)
+    }
+
+    #[inline]
+    pub fn to_f64_px(self) -> f64 {
+        (self.0 as f64) / (AU_PER_PX as f64)
+    }
+
+    #[inline]
+    pub fn from_f32_px(px: f32) -> Au {
+        Au((px * (AU_PER_PX as f32)) as i32)
+    }
+
+    #[inline]
+    pub fn from_f64_px(px: f64) -> Au {
+        Au((px * (AU_PER_PX as f64)) as i32)
+    }
+}
diff --git a/components/app_units/src/lib.rs b/components/app_units/src/lib.rs
new file mode 100644
index 00000000000..2d1952dc3aa
--- /dev/null
+++ b/components/app_units/src/lib.rs
@@ -0,0 +1,16 @@
+/* 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 http://mozilla.org/MPL/2.0/. */
+
+#![feature(custom_derive)]
+#![feature(plugin)]
+
+#![plugin(serde_macros)]
+
+extern crate euclid;
+extern crate rustc_serialize;
+extern crate serde;
+
+mod app_unit;
+
+pub use app_unit::{Au, MIN_AU, MAX_AU, AU_PER_PX};