From acfb2b7484d98d95a20ad21820c6c922b4e7cdb9 Mon Sep 17 00:00:00 2001
From: Patrick Walton <pcwalton@mimiga.net>
Date: Fri, 14 Nov 2014 19:07:28 -0800
Subject: [PATCH] Add a method to transform a point and a rect via an affine
 transformation

---
 src/matrix2d.rs | 23 ++++++++++++++++++++---
 src/rect.rs     |  5 +++++
 2 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/src/matrix2d.rs b/src/matrix2d.rs
index 7ed91d3..3afeb20 100644
--- a/src/matrix2d.rs
+++ b/src/matrix2d.rs
@@ -7,6 +7,10 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+use point::Point2D;
+use rect::Rect;
+use size::Size2D;
+
 use std::num::{One, Zero};
 
 pub struct Matrix2D<T> {
@@ -15,7 +19,7 @@ pub struct Matrix2D<T> {
     m31: T, m32: T
 }
 
-impl<T:Add<T,T> + Clone + Mul<T,T> + One + Zero> Matrix2D<T> {
+impl<T> Matrix2D<T> where T: Add<T,T> + Clone + Mul<T,T> + One + PartialOrd + Sub<T,T> + Zero {
     pub fn new(m11: T, m12: T, m21: T, m22: T, m31: T, m32: T) -> Matrix2D<T> {
         Matrix2D {
             m11: m11, m12: m12,
@@ -53,14 +57,27 @@ impl<T:Add<T,T> + Clone + Mul<T,T> + One + Zero> Matrix2D<T> {
                              _0.clone(), _1.clone(),
                              _0.clone(), _0.clone());
     }
-        
+
     pub fn to_array(&self) -> [T, ..6] {
         [
             self.m11.clone(), self.m12.clone(),
             self.m21.clone(), self.m22.clone(),
             self.m31.clone(), self.m32.clone()
         ]
-    } 
+    }
 
+    #[inline]
+    pub fn transform_point(&self, point: &Point2D<T>) -> Point2D<T> {
+        Point2D(self.m11 * point.x + self.m21 * point.y + self.m31,
+                self.m21 * point.x + self.m22 * point.y + self.m32)
+    }
+
+    #[inline]
+    pub fn transform_rect(&self, rect: &Rect<T>) -> Rect<T> {
+        let upper_left = self.transform_point(&rect.origin);
+        let lower_right = self.transform_point(&rect.max_point());
+        Rect(upper_left.clone(),
+             Size2D(lower_right.x - upper_left.x, lower_right.y - upper_left.y))
+    }
 }
 
diff --git a/src/rect.rs b/src/rect.rs
index 348f86e..556ed57 100644
--- a/src/rect.rs
+++ b/src/rect.rs
@@ -63,6 +63,11 @@ impl<T: Clone + PartialOrd + Add<T,T> + Sub<T,T>> Rect<T> {
         self.origin.y.clone()
     }
 
+    #[inline]
+    pub fn max_point(&self) -> Point2D<T> {
+        Point2D(self.max_x(), self.max_y())
+    }
+
     #[inline]
     pub fn intersection(&self, other: &Rect<T>) -> Option<Rect<T>> {
         if !self.intersects(other) {