gfx/thebes/gfxMatrix.h
 author Gregory Szorc Tue, 24 Sep 2013 15:05:43 -0700 changeset 162321 b51710e0e485a5c4edccd438ddb2a46bd7f0e91f parent 144845 8fed67bc814d173ddba7083a1a6e6669456b7a2e child 163896 47b5355992adc942e1a059c572703becc40bcdb0 permissions -rw-r--r--
Bug 901990 - Part 3: Don't purge _tests during PGO builds; r=glandium CLOSED TREE
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/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* 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 GFX_MATRIX_H
#define GFX_MATRIX_H

#include "gfxPoint.h"
#include "gfxTypes.h"
#include "gfxRect.h"
#include "nsMathUtils.h"

// XX - I don't think this class should use gfxFloat at all,
// but should use 'double' and be called gfxDoubleMatrix;
// we can then typedef that to gfxMatrix where we typedef
// double to be gfxFloat.

/**
* A matrix that represents an affine transformation. Projective
* transformations are not supported. This matrix looks like:
*
* / a  b  0 \
* | c  d  0 |
* \ tx ty 1 /
*
* So, transforming a point (x, y) results in:
*
*           / a  b  0 \   / a * x + c * y + tx \ T
* (x y 1) * | c  d  0 | = | b * x + d * y + ty |
*           \ tx ty 1 /   \         1          /
*
*/
struct gfxMatrix {
double xx; double yx;
double xy; double yy;
double x0; double y0;

public:
/**
* Initializes this matrix as the identity matrix.
*/
gfxMatrix() { Reset(); }

/**
* Initializes the matrix from individual components. See the class
* description for the layout of the matrix.
*/
gfxMatrix(gfxFloat a, gfxFloat b, gfxFloat c, gfxFloat d, gfxFloat tx, gfxFloat ty) :
xx(a),  yx(b),
xy(c),  yy(d),
x0(tx), y0(ty) { }

/**
* Post-multiplies m onto the matrix.
*/
const gfxMatrix& operator *= (const gfxMatrix& m) {
return Multiply(m);
}

/**
* Multiplies *this with m and returns the result.
*/
gfxMatrix operator * (const gfxMatrix& m) const {
return gfxMatrix(*this).Multiply(m);
}

/* Returns true if the other matrix is fuzzy-equal to this matrix.
* Note that this isn't a cheap comparison!
*/
bool operator==(const gfxMatrix& other) const
{
return FuzzyEqual(xx, other.xx) && FuzzyEqual(yx, other.yx) &&
FuzzyEqual(xy, other.xy) && FuzzyEqual(yy, other.yy) &&
FuzzyEqual(x0, other.x0) && FuzzyEqual(y0, other.y0);
}

bool operator!=(const gfxMatrix& other) const
{
return !(*this == other);
}

// matrix operations
/**
* Resets this matrix to the identity matrix.
*/
const gfxMatrix& Reset();

bool IsIdentity() const {
return xx == 1.0 && yx == 0.0 &&
xy == 0.0 && yy == 1.0 &&
x0 == 0.0 && y0 == 0.0;
}

/**
* Inverts this matrix, if possible. Otherwise, the matrix is left
* unchanged.
*
* XXX should this do something with the return value of
* cairo_matrix_invert?
*/
const gfxMatrix& Invert();

/**
* Check if matrix is singular (no inverse exists).
*/
bool IsSingular() const {
// if the determinant (ad - bc) is zero it's singular
return (xx * yy) == (yx * xy);
}

/**
* Scales this matrix. The scale is pre-multiplied onto this matrix,
* i.e. the scaling takes place before the other transformations.
*/
const gfxMatrix& Scale(gfxFloat x, gfxFloat y);

/**
* Translates this matrix. The translation is pre-multiplied onto this matrix,
* i.e. the translation takes place before the other transformations.
*/
const gfxMatrix& Translate(const gfxPoint& pt);

/**
* Rotates this matrix. The rotation is pre-multiplied onto this matrix,
* i.e. the translation takes place after the other transformations.
*
*/

/**
* Multiplies the current matrix with m.
* This is a post-multiplication, i.e. the transformations of m are
* applied _after_ the existing transformations.
*
* XXX is that difference (compared to Rotate etc) a good thing?
*/
const gfxMatrix& Multiply(const gfxMatrix& m);

/**
* Multiplies the current matrix with m.
* This is a pre-multiplication, i.e. the transformations of m are
* applied _before_ the existing transformations.
*/
const gfxMatrix& PreMultiply(const gfxMatrix& m);

/**
* Transforms a point according to this matrix.
*/
gfxPoint Transform(const gfxPoint& point) const;

/**
* Transform a distance according to this matrix. This does not apply
* any translation components.
*/
gfxSize Transform(const gfxSize& size) const;

/**
* Transforms both the point and distance according to this matrix.
*/
gfxRect Transform(const gfxRect& rect) const;

gfxRect TransformBounds(const gfxRect& rect) const;

/**
* Returns the translation component of this matrix.
*/
gfxPoint GetTranslation() const {
return gfxPoint(x0, y0);
}

/**
* Returns true if the matrix is anything other than a straight
* translation by integers.
*/
bool HasNonIntegerTranslation() const {
return HasNonTranslation() ||
!FuzzyEqual(x0, floor(x0 + 0.5)) ||
!FuzzyEqual(y0, floor(y0 + 0.5));
}

/**
* Returns true if the matrix has any transform other
* than a straight translation
*/
bool HasNonTranslation() const {
return !FuzzyEqual(xx, 1.0) || !FuzzyEqual(yy, 1.0) ||
!FuzzyEqual(xy, 0.0) || !FuzzyEqual(yx, 0.0);
}

/**
* Returns true if the matrix only has an integer translation.
*/
bool HasOnlyIntegerTranslation() const {
return !HasNonIntegerTranslation();
}

/**
* Returns true if the matrix has any transform other
* than a translation or a -1 y scale (y axis flip)
*/
bool HasNonTranslationOrFlip() const {
return !FuzzyEqual(xx, 1.0) ||
(!FuzzyEqual(yy, 1.0) && !FuzzyEqual(yy, -1.0)) ||
!FuzzyEqual(xy, 0.0) || !FuzzyEqual(yx, 0.0);
}

/**
* Returns true if the matrix has any transform other
* than a translation or scale; this is, if there is
* no rotation.
*/
bool HasNonAxisAlignedTransform() const {
return !FuzzyEqual(xy, 0.0) || !FuzzyEqual(yx, 0.0);
}

/**
* Computes the determinant of this matrix.
*/
double Determinant() const {
return xx*yy - yx*xy;
}

/* Computes the scale factors of this matrix; that is,
* the amounts each basis vector is scaled by.
* The xMajor parameter indicates if the larger scale is
* to be assumed to be in the X direction or not.
*/
gfxSize ScaleFactors(bool xMajor) const {
double det = Determinant();

if (det == 0.0)
return gfxSize(0.0, 0.0);

gfxSize sz = xMajor ? gfxSize(1.0, 0.0) : gfxSize(0.0, 1.0);
sz = Transform(sz);

double major = sqrt(sz.width * sz.width + sz.height * sz.height);
double minor = 0.0;

// ignore mirroring
if (det < 0.0)
det = - det;

if (major)
minor = det / major;

if (xMajor)
return gfxSize(major, minor);

return gfxSize(minor, major);
}

/**
* Snap matrix components that are close to integers
* to integers. In particular, components that are integral when
* converted to single precision are set to those integers.
*/
void NudgeToIntegers(void);

/**
* Returns true if matrix is multiple of 90 degrees rotation with flipping,
* scaling and translation.
*/
bool PreservesAxisAlignedRectangles() const {
return ((FuzzyEqual(xx, 0.0) && FuzzyEqual(yy, 0.0))
|| (FuzzyEqual(xy, 0.0) && FuzzyEqual(yx, 0.0)));
}

/**
* Returns true if the matrix has non-integer scale
*/
bool HasNonIntegerScale() const {
return !FuzzyEqual(xx, floor(xx + 0.5)) ||
!FuzzyEqual(yy, floor(yy + 0.5));
}

private:
static bool FuzzyEqual(gfxFloat aV1, gfxFloat aV2) {
return fabs(aV2 - aV1) < 1e-6;
}
};

#endif /* GFX_MATRIX_H */
```