gecko-dev/gfx/2d/Matrix.h

173 lines
4.0 KiB
C++

/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef MOZILLA_GFX_MATRIX_H_
#define MOZILLA_GFX_MATRIX_H_
#include "Types.h"
#include "Rect.h"
#include "Point.h"
#include <math.h>
namespace mozilla {
namespace gfx {
class Matrix
{
public:
Matrix()
: _11(1.0f), _12(0)
, _21(0), _22(1.0f)
, _31(0), _32(0)
{}
Matrix(Float a11, Float a12, Float a21, Float a22, Float a31, Float a32)
: _11(a11), _12(a12)
, _21(a21), _22(a22)
, _31(a31), _32(a32)
{}
Float _11, _12;
Float _21, _22;
Float _31, _32;
Point operator *(const Point &aPoint) const
{
Point retPoint;
retPoint.x = aPoint.x * _11 + aPoint.y * _21 + _31;
retPoint.y = aPoint.x * _12 + aPoint.y * _22 + _32;
return retPoint;
}
Size operator *(const Size &aSize) const
{
Size retSize;
retSize.width = aSize.width * _11 + aSize.height * _21;
retSize.height = aSize.width * _12 + aSize.height * _22;
return retSize;
}
GFX2D_API Rect TransformBounds(const Rect& rect) const;
// Apply a scale to this matrix. This scale will be applied -before- the
// existing transformation of the matrix.
Matrix &Scale(Float aX, Float aY)
{
_11 *= aX;
_12 *= aX;
_21 *= aY;
_22 *= aY;
return *this;
}
Matrix &Translate(Float aX, Float aY)
{
_31 += _11 * aX + _21 * aY;
_32 += _12 * aX + _22 * aY;
return *this;
}
bool Invert()
{
// Compute co-factors.
Float A = _22;
Float B = -_21;
Float C = _21 * _32 - _22 * _31;
Float D = -_12;
Float E = _11;
Float F = _31 * _12 - _11 * _32;
Float det = Determinant();
if (!det) {
return false;
}
Float inv_det = 1 / det;
_11 = inv_det * A;
_12 = inv_det * D;
_21 = inv_det * B;
_22 = inv_det * E;
_31 = inv_det * C;
_32 = inv_det * F;
return true;
}
Float Determinant() const
{
return _11 * _22 - _12 * _21;
}
GFX2D_API static Matrix Rotation(Float aAngle);
Matrix operator*(const Matrix &aMatrix) const
{
Matrix resultMatrix;
resultMatrix._11 = this->_11 * aMatrix._11 + this->_12 * aMatrix._21;
resultMatrix._12 = this->_11 * aMatrix._12 + this->_12 * aMatrix._22;
resultMatrix._21 = this->_21 * aMatrix._11 + this->_22 * aMatrix._21;
resultMatrix._22 = this->_21 * aMatrix._12 + this->_22 * aMatrix._22;
resultMatrix._31 = this->_31 * aMatrix._11 + this->_32 * aMatrix._21 + aMatrix._31;
resultMatrix._32 = this->_31 * aMatrix._12 + this->_32 * aMatrix._22 + aMatrix._32;
return resultMatrix;
}
/* Returns true if the other matrix is fuzzy-equal to this matrix.
* Note that this isn't a cheap comparison!
*/
bool operator==(const Matrix& other) const
{
return FuzzyEqual(_11, other._11) && FuzzyEqual(_12, other._12) &&
FuzzyEqual(_21, other._21) && FuzzyEqual(_22, other._22) &&
FuzzyEqual(_31, other._31) && FuzzyEqual(_32, other._32);
}
bool operator!=(const Matrix& other) const
{
return !(*this == other);
}
/* Returns true if the matrix is a rectilinear transformation (i.e.
* grid-aligned rectangles are transformed to grid-aligned rectangles)
*/
bool IsRectilinear() const {
if (FuzzyEqual(_12, 0) && FuzzyEqual(_21, 0)) {
return true;
} else if (FuzzyEqual(_22, 0) && FuzzyEqual(_11, 0)) {
return true;
}
return false;
}
/* Returns true if the matrix is an identity matrix.
*/
bool IsIdentity() const
{
return _11 == 1.0f && _12 == 0.0f &&
_21 == 0.0f && _22 == 1.0f &&
_31 == 0.0f && _32 == 0.0f;
}
private:
static bool FuzzyEqual(Float aV1, Float aV2) {
// XXX - Check if fabs does the smart thing and just negates the sign bit.
return fabs(aV2 - aV1) < 1e-6;
}
};
}
}
#endif /* MOZILLA_GFX_MATRIX_H_ */