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```
```use Context;
use math::{
multiply,
shear,
scale,
orient,
translate,
Matrix2d,
Vec2d,
Scalar,
};

/// Implemented by contexts that can transform.
pub trait Transformed: Sized {
/// Appends transform to the current one.
fn append_transform(self, transform: Matrix2d) -> Self;

/// Prepends transform to the current one.
fn prepend_transform(self, transform: Matrix2d) -> Self;

/// Translate x an y in local coordinates.
fn trans(self, x: Scalar, y: Scalar) -> Self;

/// Rotates degrees in local coordinates.
#[inline(always)]
fn rot_deg(self, angle: Scalar) -> Self {
}

/// Rotate radians in local coordinates.
fn rot_rad(self, angle: Scalar) -> Self;

/// Orients x axis to look at point locally.
///
/// Leaves x axis unchanged if the point to
/// look at is the origin.
fn orient(self, x: Scalar, y: Scalar) -> Self;

/// Scales in local coordinates.
fn scale(self, sx: Scalar, sy: Scalar) -> Self;

/// Scales in both directions in local coordinates.
#[inline(always)]
fn zoom(self, s: Scalar) -> Self {
self.scale(s, s)
}

/// Flips vertically in local coordinates.
#[inline(always)]
fn flip_v(self) -> Self {
self.scale(1.0, -1.0)
}

/// Flips horizontally in local coordinates.
#[inline(always)]
fn flip_h(self) -> Self {
self.scale(-1.0, 1.0)
}

/// Flips horizontally and vertically in local coordinates.
#[inline(always)]
fn flip_hv(self) -> Self {
self.scale(-1.0, -1.0)
}

/// Shears in local coordinates.
fn shear(self, v: Vec2d) -> Self;
}

impl Transformed for Matrix2d {
#[inline(always)]
fn append_transform(self, transform: Matrix2d) -> Self {
multiply(self, transform)
}

#[inline(always)]
fn prepend_transform(self, transform: Matrix2d) -> Self {
multiply(transform, self)
}

#[inline(always)]
fn trans(self, x: Scalar, y: Scalar) -> Self {
let trans = translate([x, y]);
multiply(self, trans)
}

#[inline(always)]
fn rot_rad(self, angle: Scalar) -> Self {
multiply(self, rot)
}

#[inline(always)]
fn orient(self, x: Scalar, y: Scalar) -> Self {
let orient = orient(x, y);
multiply(self, orient)
}

#[inline(always)]
fn scale(self, sx: Scalar, sy: Scalar) -> Self {
let scale = scale(sx, sy);
multiply(self, scale)
}

#[inline(always)]
fn shear(self, v: Vec2d) -> Self {
let shear = shear(v);
multiply(self, shear)
}
}

impl Transformed for Context {
#[inline(always)]
fn append_transform(mut self, transform: Matrix2d) -> Self {
self.transform = self.transform.append_transform(transform);
self
}

#[inline(always)]
fn prepend_transform(mut self, transform: Matrix2d) -> Self {
self.transform = self.transform.prepend_transform(transform);
self
}

#[inline(always)]
fn trans(mut self, x: Scalar, y: Scalar) -> Self {
self.transform = self.transform.trans(x, y);
self
}

#[inline(always)]
fn rot_rad(mut self, angle: Scalar) -> Self {
self
}

#[inline(always)]
fn orient(mut self, x: Scalar, y: Scalar) -> Self {
self.transform = self.transform.orient(x, y);
self
}

#[inline(always)]
fn scale(mut self, sx: Scalar, sy: Scalar) -> Self {
self.transform = self.transform.scale(sx, sy);
self
}

#[inline(always)]
fn shear(mut self, v: Vec2d) -> Self {
self.transform = self.transform.shear(v);
self
}
}
```