add code to Twips2d.rs

TODO: redo comments

swf/src/types/Twips2d.rs

@@ -1 +1,155 @@
+impl Twips2d {
+    /// There are 20 Twips2d in a pixel.
+    pub const TWIPS_PER_PIXEL: f64 = 20.0;
 
+    /// The `Twips2d` object with a value of `(0, 0)`.
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// assert_eq!(swf::Twips2d::ZERO.to_pixels(), (0.0, 0.0));
+    /// ```
+    pub const ZERO: Self = Self(Twips::ZERO,Twips::ZERO);
+
+    /// The `Twips2d` object with a value of `1` pixel.
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// assert_eq!(swf::Twips2d::ONE.to_pixels(), 1.0);
+    /// ```
+    pub const ONE: Self = Self(Twips::ONE,Twips::ONE);
+
+    /// Creates a new `Twips2d` object. Note that the `Twips2d` value is in Twips2d,
+    /// not pixels. Use the [`from_pixels`] method to convert from pixel units.
+    ///
+    /// [`from_pixels`]: Twips2d::from_pixels
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// use swf::Twips2d;
+    ///
+    /// let Twips2d = Twips2d::new(40,40);
+    /// ```
+    pub fn new<X: Into<i32>,Y: Into<i32>>(x: X,y: Y) -> Self {
+        Self( Twips::new(x.into()),Twips::new(y.into()))
+    }
+
+    /// Returns the values of Twips2d.
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// use swf::Twips2d;
+    ///
+    /// let Twips2d = Twips2d::new(47,47);
+    /// assert_eq!(Twips2d.get(), (47,47));
+    /// ```
+    pub const fn get(self) -> (i32,i32) {
+        (Twips::get(self.0),Twips::get(self.1))
+    }
+
+    /// Converts the given number of `pixels` into Twips2d.
+    ///
+    /// This may be a lossy conversion; any precision more than a twip (1/20 pixels) is truncated.
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// use swf::Twips2d;
+    ///
+    /// // 40 pixels is equivalent to 800 Twips.
+    /// let Twips2d = Twips2d::from_pixels(40.0);
+    /// assert_eq!(Twips2d.get(), 800);
+    ///
+    /// // Output is truncated if more precise than a twip (1/20 pixels).
+    /// let Twips2d = Twips2d::from_pixels(40.018);
+    /// assert_eq!(Twips2d.get(), 800);
+    /// ```
+    pub fn from_pixels(pixels:(f64,f64)) -> Self {
+        Self(Twips::new((pixels.0 * Self::TWIPS_PER_PIXEL)as i32),Twips::new((pixels.1 * Self::TWIPS_PER_PIXEL)as i32))
+    }
+
+    /// Converts this Twips2d value into pixel units.
+    ///
+    /// This is a lossless operation.
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// use swf::Twips2d;
+    ///
+    /// // 800 Twips2d is equivalent to 40 pixels.
+    /// let Twips2d = Twips2d::new(800);
+    /// assert_eq!(Twips2d.to_pixels(), 40.0);
+    ///
+    /// // Twips2d are sub-pixel: 713 Twips2d represent 35.65 pixels.
+    /// let Twips2d = Twips2d::new(713);
+    /// assert_eq!(Twips2d.to_pixels(), 35.65);
+    /// ```
+    pub fn to_pixels(self) -> (f64,f64) {
+        (f64::from(Twips::to_pixels(self.0)),f64::from(Twips::to_pixels(self.1)) )
+    }
+}
+
+impl std::ops::Add for Twips2d {
+    type Output = Self;
+    fn add(self, other: Self) -> Self {
+        Self(self.0 + other.0,self.1 + other.1)
+    }
+}
+
+impl std::ops::AddAssign for Twips2d {
+    fn add_assign(&mut self, other: Self){
+    self.0 += other.0;
+    self.1 += other.1;
+    }
+}
+
+impl std::ops::Sub for Twips2d {
+    type Output = Self;
+    fn sub(self, other: Self) -> Self {
+        Self(self.0 - other.0,self.1 - other.1)
+    }
+}
+
+impl std::ops::SubAssign for Twips2d {
+    fn sub_assign(&mut self, other: Self) {
+        self.0 -= other.0;
+        self.1 -= other.1;
+    }
+}
+
+impl std::ops::Mul<i32> for Twips2d {
+    type Output = Self;
+    fn mul(self, other: i32) -> Self {
+        Self(self.0 * other,self.1 * other)
+    }
+}
+
+impl std::ops::MulAssign<i32> for Twips2d {
+    fn mul_assign(&mut self, other: i32) {
+        self.0 *= other;
+        self.1 *= other;
+    }
+}
+
+impl std::ops::Div<i32> for Twips2d {
+    type Output = Self;
+    fn div(self, other: i32) -> Self {
+        Self(self.0 / other,self.1 / other)
+    }
+}
+impl std::ops::DivAssign<i32> for Twips2d {
+    fn div_assign(&mut self, other: i32) {
+        self.0 /= other;
+        self.1 /= other;
+    }
+}
+
+impl std::fmt::Display for Twips2d {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        write!(f, "( {} , {} )", self.to_pixels().0, self.to_pixels().1)
+    }
+}