Implement unit tests and temporary MathUtil wrappers for transform functionality

cc/math_util.cc

Index: cc/math_util.cc
diff --git a/cc/math_util.cc b/cc/math_util.cc
index 606f67bf482b34e7ffbb9cdf35ffb2d039ccb401..27066004e8b72be582e2f4f7ae8a8ed0038f3a1a 100644
--- a/cc/math_util.cc
+++ b/cc/math_util.cc
@@ -395,4 +395,170 @@ gfx::Vector2dF MathUtil::projectVector(gfx::Vector2dF source, gfx::Vector2dF des
     return gfx::Vector2dF(projectedLength * destination.x(), projectedLength * destination.y());
 }
 
+bool MathUtil::isInvertible(const gfx::Transform& transform)
+{
+    const SkMatrix44& matrix = transform.matrix();
+    double determinant = matrix.determinant();
+
+    // TODO (shawnsingh): we may need to check fuzzy against an epsilon here instead?

[danakj, 2012/11/17 02:14:17]

Is something random going to break and cause a revert because of this? Why not
just use an epsilon now?

+    return determinant != 0;
+}
+
+bool MathUtil::isBackFaceVisible(const gfx::Transform&)
+{
+    DCHECK(false); // NOT YET IMPLEMENTED!!

[danakj, 2012/11/17 02:14:17]

NOTREACHED()

+    return false;
+}
+
+bool MathUtil::isIdentity(const gfx::Transform& transform)
+{
+    return transform.matrix().isIdentity();
+}
+
+bool MathUtil::isIdentityOrTranslation(const gfx::Transform& transform)
+{
+    const SkMatrix44& matrix = transform.matrix();
+
+    bool hasNoPerspective = !matrix.getDouble(3, 0) && !matrix.getDouble(3, 1) && !matrix.getDouble(3, 2) && (matrix.getDouble(3, 3) == 1);
+    bool hasNoRotationOrSkew = !matrix.getDouble(0, 1) && !matrix.getDouble(0, 2) && !matrix.getDouble(1, 0) &&
+        !matrix.getDouble(1, 2) && !matrix.getDouble(2, 0) && !matrix.getDouble(2, 1);
+    bool hasNoScale = matrix.getDouble(0, 0) == 1

[danakj, 2012/11/17 02:14:17]

nit: the line wrapping is inconsistent here.

+        && matrix.getDouble(1, 1) == 1
+        && matrix.getDouble(2, 2) == 1;
+
+    return hasNoPerspective && hasNoRotationOrSkew && hasNoScale;
+}
+
+bool MathUtil::hasPerspective(const gfx::Transform& transform)
+{
+    // Mathematically it is a bit too strict to expect the 4th element to be
+    // equal to 1. However, the only non-perspective case where this element
+    // becomes non-1 is when it was explicitly initialized. In that case it
+    // still causes us to have a nontrivial divide-by-w, so we count it as
+    // being perspective here.
+    const SkMatrix44& matrix = transform.matrix();
+    return matrix.getDouble(3, 0) || matrix.getDouble(3, 1) || matrix.getDouble(3, 2) || (matrix.getDouble(3, 3) != 1);
+}
+
+void MathUtil::makeIdentity(gfx::Transform* transform)
+{
+    transform->matrix().setIdentity();
+}
+
+void MathUtil::rotateEulerAngles(gfx::Transform* transform, double eulerX, double eulerY, double eulerZ)
+{
+    // TODO (shawnsingh): make this implementation faster and more accurate by
+    // hard-coding each matrix instead of calling rotateAxisAngle().
+    gfx::Transform rotationAboutX;
+    gfx::Transform rotationAboutY;
+    gfx::Transform rotationAboutZ;
+
+    MathUtil::rotateAxisAngle(&rotationAboutX, 1, 0, 0, eulerX);
+    MathUtil::rotateAxisAngle(&rotationAboutY, 0, 1, 0, eulerY);
+    MathUtil::rotateAxisAngle(&rotationAboutZ, 0, 0, 1, eulerZ);
+
+    gfx::Transform composite = rotationAboutZ * rotationAboutY * rotationAboutX;
+    transform->PreconcatTransform(composite);
+}
+
+void MathUtil::rotateAxisAngle(gfx::Transform* transform, double i, double j, double k, double degrees)
+{
+    // TODO (shawnsingh): fix gfx::Transform API to receive vector instead of
+    // point for the axis.
+    gfx::Point3F axis(i, j, k);
+    transform->PreconcatRotateAbout(axis, degrees);
+}
+
+gfx::Transform MathUtil::inverse(const gfx::Transform& transform)
+{
+    gfx::Transform result;
+    bool invertedSuccessfully = transform.GetInverse(&result);
+
+    if (invertedSuccessfully)
+        return result;
+
+    // If transform was un-invertible, then just return identity.
+    return gfx::Transform();
+}
+
+gfx::Transform MathUtil::to2dTransform(const gfx::Transform& transform)
+{
+    gfx::Transform result = transform;
+    SkMatrix44& matrix = result.matrix();
+    matrix.setDouble(0, 2, 0);
+    matrix.setDouble(1, 2, 0);
+    matrix.setDouble(2, 2, 1);
+    matrix.setDouble(3, 2, 0);
+
+    matrix.setDouble(2, 0, 0);
+    matrix.setDouble(2, 1, 0);
+    matrix.setDouble(2, 3, 0);
+
+    return result;
+}
+
+gfx::Transform MathUtil::toGfxTransform(const WebKit::WebTransformationMatrix&)
+{
+    DCHECK(false); // NOT YET IMPLEMENTED!!

[danakj, 2012/11/17 02:14:17]

NOTREACHED() but..

We're going to need this to even start the transition, so NOT IMPLEMENTED here
seems a bit funny. The right place to do this is in WebTransformationMatrix, so
I did this: https://bugs.webkit.org/show_bug.cgi?id=102575

Then you can remove this method and you'll get implicit conversions between
webkit/compositor_bindings and cc/

[shawnsingh, 2012/11/17 05:42:41]

OK I guess you've landed by now, but why is it implicit?  Shouldn't we be
forcing ourselves to be aware where the conversion is taking place?

The "not implemented" stuff was accidentally an oversight.  All the wrappers
here (including "not implemented") were going to be necessary for the migration
patch that I have.

[danakj, 2012/11/17 08:27:21]

It's in and waiting for roll.

Also, it's explicit for now. Once cc/ is completely converted we can switch it
to implicit, as the only place conversion will happen is in the
compositor_bindings, similar to Rect/Point/Size/Vector2d.

+    return gfx::Transform();
+}
+
+gfx::Transform MathUtil::createGfxTransform(double m11, double m12, double m13, double m14,
+                                            double m21, double m22, double m23, double m24,
+                                            double m31, double m32, double m33, double m34,
+                                            double m41, double m42, double m43, double m44)
+{
+    gfx::Transform result;
+    SkMatrix44& matrix = result.matrix();
+
+    // Initialize column 1
+    matrix.setDouble(0, 0, m11);
+    matrix.setDouble(1, 0, m12);
+    matrix.setDouble(2, 0, m13);
+    matrix.setDouble(3, 0, m14);
+
+    // Initialize column 2
+    matrix.setDouble(0, 1, m21);
+    matrix.setDouble(1, 1, m22);
+    matrix.setDouble(2, 1, m23);
+    matrix.setDouble(3, 1, m24);
+
+    // Initialize column 3
+    matrix.setDouble(0, 2, m31);
+    matrix.setDouble(1, 2, m32);
+    matrix.setDouble(2, 2, m33);
+    matrix.setDouble(3, 2, m34);
+
+    // Initialize column 4
+    matrix.setDouble(0, 3, m41);
+    matrix.setDouble(1, 3, m42);
+    matrix.setDouble(2, 3, m43);
+    matrix.setDouble(3, 3, m44);
+
+    return result;
+}
+
+gfx::Transform MathUtil::createGfxTransform(double a, double b, double c,
+                                            double d, double e, double f)
+{
+    gfx::Transform result;
+    SkMatrix44& matrix = result.matrix();
+    matrix.setDouble(0, 0, a);
+    matrix.setDouble(1, 0, b);
+    matrix.setDouble(0, 1, c);
+    matrix.setDouble(1, 1, d);
+    matrix.setDouble(0, 3, e);
+    matrix.setDouble(1, 3, f);
+
+    return result;
+}
+
+gfx::Transform operator*(const gfx::Transform& A, const gfx::Transform& B)
+{
+    // Compute A * B.
+    gfx::Transform result = A;
+    result.PreconcatTransform(B);
+    return result;
+}
+
 }  // namespace cc