1 files changed, 69 insertions, 0 deletions
diff --git a/src/base/Equation.cpp b/src/base/Equation.cpp
new file mode 100644
index 0000000..a97fca4
--- /dev/null
+++ b/src/base/Equation.cpp
@@ -0,0 +1,69 @@
+// -*- c-basic-offset: 4 -*-
+
+
+/*
+    Rosegarden
+    A sequencer and musical notation editor.
+
+    This program is Copyright 2000-2008
+        Guillaume Laurent   <[email protected]>,
+        Chris Cannam        <[email protected]>,
+        Richard Bown        <[email protected]>
+
+    The moral right of the authors to claim authorship of this work
+    has been asserted.
+
+    This program is free software; you can redistribute it and/or
+    modify it under the terms of the GNU General Public License as
+    published by the Free Software Foundation; either version 2 of the
+    License, or (at your option) any later version.  See the file
+    COPYING included with this distribution for more information.
+*/
+
+#include "Equation.h"
+
+namespace Rosegarden {
+
+void Equation::solve(Unknown u, double &y, double &m, double &x, double &c)
+{
+    switch(u) {
+    case Y: y = m*x + c; break;
+    case M: m = (y - c) / x; break;
+    case X: x = (y - c) / m; break;
+    case C: c = y - m*x; break;
+    }
+}
+
+void Equation::solve(Unknown u, int &y, double &m, int &x, int &c)
+{
+    switch(u) {
+    case Y: y = static_cast<int>(m*x) + c; break;
+    case M: m = static_cast<double>(y - c) / static_cast<double>(x); break;
+    case X: x = static_cast<int>(static_cast<float>(y - c) / m); break;
+    case C: c = y - static_cast<int>(m*x); break;
+    }
+}
+
+void Equation::solveForYByEndPoints(Point a, Point b, double x, double &y)
+{
+     double m, c, y1, x1;
+
+     m = static_cast<double>(b.y - a.y) / static_cast<double>(b.x - a.x);
+
+     x1 = a.x; y1 = a.y;
+     solve(C, y1, m, x1, c);
+     solve(Y, y, m, x, c);
+}
+
+void Equation::solveForYByEndPoints(Point a, Point b, int x, int &y)
+{
+     double m;
+     int c;
+
+     m = static_cast<double>(b.y - a.y) / static_cast<double>(b.x - a.x);
+
+     solve(C, a.y, m, a.x, c);
+     solve(Y, y, m, x, c);
+}
+
+}