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diff --git a/include/2geom/parallelogram.h b/include/2geom/parallelogram.h
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+/*
+ * Authors:
+ *   Thomas Holder
+ *   Sergei Izmailov
+ *
+ * Copyright 2020 Authors
+ *
+ * SPDX-License-Identifier: LGPL-2.1 or MPL-1.1
+ */
+
+#ifndef LIB2GEOM_SEEN_PARALLELOGRAM_H
+#define LIB2GEOM_SEEN_PARALLELOGRAM_H
+
+#include <2geom/affine.h>
+#include <2geom/rect.h>
+
+namespace Geom {
+
+/**
+ * Paralellogram, representing a linear transformation of a rectangle.
+ *
+ * Implements efficient "contains" and "intersects" operations.
+ */
+class Parallelogram {
+    Affine m_affine;
+
+    /// Transformed unit rectangle
+    Parallelogram(Affine const &affine)
+        : m_affine(affine)
+    {
+    }
+
+  public:
+    explicit Parallelogram(Rect const &rect)
+        : m_affine(rect.width(), 0, 0, rect.height(), rect.left(), rect.top())
+    {
+    }
+
+    Point corner(unsigned i) const;
+
+    Point midpoint() const { return Point(0.5, 0.5) * m_affine; }
+
+    /// Area (non-negative)
+    Coord area() const { return m_affine.descrim2(); }
+
+    /// Axis-aligned bounding box
+    Rect bounds() const;
+
+    bool intersects(Parallelogram const &) const;
+    bool intersects(Rect const &rect) const { return intersects(Parallelogram(rect)); }
+
+    bool contains(Point const &) const;
+    bool contains(Parallelogram const &) const;
+    bool contains(Rect const &rect) const { return contains(Parallelogram(rect)); }
+
+    /// Returns shorter side length
+    Coord minExtent() const;
+
+    /// Returns longer side length
+    Coord maxExtent() const;
+
+    /// Return a new transformed parallelogram
+    Parallelogram operator*(Affine const &affine) const { return m_affine * affine; }
+    Parallelogram &operator*=(Affine const &affine) { m_affine *= affine; return *this; }
+
+    /// True if this parallelogram does not have right angles
+    bool isSheared(Coord eps = EPSILON) const;
+};
+
+} // namespace Geom
+
+#endif
+
+/*
+  Local Variables:
+  mode:c++
+  c-file-style:"stroustrup"
+  c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
+  indent-tabs-mode:nil
+  fill-column:99
+  End:
+*/
+// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:fileencoding=utf-8:textwidth=99 :