Add gfx::Transform::TransformBox and TransformBoxReverse

These new functions do what you'd expect (they transform the given box and
return the tightest axis align box containing the transformed result). I've also
added tests for Transform::TransformRect and TransformRectReverse and updated
their comments. Seems like this class has gotten a bit stale.

R=ajuma@chromium.org
BUG=None

Review URL: https://codereview.chromium.org/26116004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228215 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 28 insertions, 0 deletions

diff --git a/ui/gfx/transform.cc b/ui/gfx/transform.cc
index ac62006..59e6a60 100644
--- a/ui/gfx/transform.cc
+++ b/ui/gfx/transform.cc
@@ -11,6 +11,7 @@
 
 #include "base/logging.h"
 #include "base/strings/stringprintf.h"
+#include "ui/gfx/box_f.h"
 #include "ui/gfx/point.h"
 #include "ui/gfx/point3_f.h"
 #include "ui/gfx/rect.h"
@@ -428,6 +429,33 @@ bool Transform::TransformRectReverse(RectF* rect) const {
   return true;
 }
 
+void Transform::TransformBox(BoxF* box) const {
+  BoxF bounds;
+  bool first_point = true;
+  for (int corner = 0; corner < 8; ++corner) {
+    gfx::Point3F point = box->origin();
+    point += gfx::Vector3dF(corner & 1 ? box->width() : 0.f,
+                            corner & 2 ? box->height() : 0.f,
+                            corner & 4 ? box->depth() : 0.f);
+    TransformPoint(&point);
+    if (first_point) {
+      bounds.set_origin(point);
+      first_point = false;
+    } else {
+      bounds.ExpandTo(point);
+    }
+  }
+  *box = bounds;
+}
+
+bool Transform::TransformBoxReverse(BoxF* box) const {
+  gfx::Transform inverse = *this;
+  if (!GetInverse(&inverse))
+    return false;
+  inverse.TransformBox(box);
+  return true;
+}
+
 bool Transform::Blend(const Transform& from, double progress) {
   DecomposedTransform to_decomp;
   DecomposedTransform from_decomp;