Mozilla2:GFXMatrix

Matrix Class

Since we'll be doing scaling, translations and rotates, we need some sort of matrix class. This class is really just an affine transform and might should be renamed to indicate that.

The API

class Matrix {
private:
    double m0, m1, m2, m3, m4, m5;

public:
    Matrix() { }
    Matrix(const Matrix& m);
    Matrix(double a, double b, double c, double d, double tx, double ty);
    Matrix(const cairo_matrix_t* m);

    Matrix& operator=(const cairo_matrix_t* m);
    const Matrix& operator *= (const Matrix& m);
    Matrix operator * (const Matrix& m);

    const Matrix& reset();
    const Matrix& invert();
    const Matrix& scale(double x, double y);
    const Matrix& translate(double x, double y);
    const Matrix& rotate(double radians);
    const Matrix& multiply(const Matrix& m);
    void transformDistance(double *dx, double *dy) const;
    void transformPoint(double *x, double *y) const;
};

Notes

Cairo currently uses row vectors to transform points, which is less optimal than if we used column vectors.