[m-rev.] [PATCH 09/11] mercury_cairo: Add matrix.unpack.

[Peter Wang]

extras/graphics/mercury_cairo/cairo.matrix.m:
	Add `matrix.unpack' to return the components of a matrix.
---
 extras/graphics/mercury_cairo/cairo.matrix.m | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/extras/graphics/mercury_cairo/cairo.matrix.m b/extras/graphics/mercury_cairo/cairo.matrix.m
index fbd09e3..e78c95b 100644
--- a/extras/graphics/mercury_cairo/cairo.matrix.m
+++ b/extras/graphics/mercury_cairo/cairo.matrix.m
@@ -87,6 +87,12 @@
     %
 :- pred multiply(matrix::in, matrix::in, matrix::in, io::di, io::uo) is det.
 
+    % matrix.unpack(Matrix, XX, YX, XY, YY, X0, Y0, !IO):
+    % Return the six components of Matrix.
+    %
+:- pred unpack(matrix::in, float::out, float::out, float::out, float::out,
+    float::out, float::out, io::di, io::uo) is det.
+
     % matrix.transform_distance(Matrix, Dx0, Dy0, Dx, Dy, !IO):
     % Transforms the distance vector (Dx0, Dy0) by Matrix.
     %
@@ -211,6 +217,19 @@ invert(Matrix, !IO) :-
 ").
 
 :- pragma foreign_proc("C",
+    unpack(Matrix::in, Xx::out, Yx::out, Xy::out, Yy::out, X0::out, Y0::out,
+        _IO0::di, _IO::uo),
+    [promise_pure, will_not_call_mercury],
+"
+    Xx = Matrix->xx;
+    Yx = Matrix->yx;
+    Xy = Matrix->xy;
+    Yy = Matrix->yy;
+    X0 = Matrix->x0;
+    Y0 = Matrix->y0;
+").
+
+:- pragma foreign_proc("C",
    transform_distance(Matrix::in, Dx0::in, Dy0::in, Dx::out, Dy::out,
        _IO0::di, _IO::uo),
    [promise_pure, will_not_call_mercury],
-- 
2.1.2