internal static void TransformRect(ref RectF rect, ref MatrixF matrix)
{
if (rect.IsEmpty)
{
return;
}
MatrixTypes matrixType = matrix._type;
// If the matrix is identity, don't worry.
if (matrixType == MatrixTypes.TRANSFORM_IS_IDENTITY)
{
return;
}
// Scaling
if (0 != (matrixType & MatrixTypes.TRANSFORM_IS_SCALING))
{
rect._x *= matrix._m11;
rect._y *= matrix._m22;
rect._width *= matrix._m11;
rect._height *= matrix._m22;
// Ensure the width is always positive. For example, if there was a reflection about the
// y axis followed by a translation into the visual area, the width could be negative.
if (rect._width < 0.0)
{
rect._x += rect._width;
rect._width = -rect._width;
}
// Ensure the height is always positive. For example, if there was a reflection about the
// x axis followed by a translation into the visual area, the height could be negative.
if (rect._height < 0.0F)
{
rect._y += rect._height;
rect._height = -rect._height;
}
}
// Translation
if (0 != (matrixType & MatrixTypes.TRANSFORM_IS_TRANSLATION))
{
// X
rect._x += matrix._offsetX;
// Y
rect._y += matrix._offsetY;
}
if (matrixType == MatrixTypes.TRANSFORM_IS_UNKNOWN)
{
// Al Bunny implementation.
PointF point0 = matrix.Transform(rect.TopLeft);
PointF point1 = matrix.Transform(rect.TopRight);
PointF point2 = matrix.Transform(rect.BottomRight);
PointF point3 = matrix.Transform(rect.BottomLeft);
// Width and height is always positive here.
rect._x = Math.Min(Math.Min(point0.X, point1.X), Math.Min(point2.X, point3.X));
rect._y = Math.Min(Math.Min(point0.Y, point1.Y), Math.Min(point2.Y, point3.Y));
rect._width = Math.Max(Math.Max(point0.X, point1.X), Math.Max(point2.X, point3.X)) - rect._x;
rect._height = Math.Max(Math.Max(point0.Y, point1.Y), Math.Max(point2.Y, point3.Y)) - rect._y;
}
}
