DXR is a code search and navigation tool aimed at making sense of large projects. It supports full-text and regex searches as well as structural queries.

Implementation

Mercurial (5350524bb654)

VCS Links

Line Code
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310
/* -*- 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 "mozilla/Attributes.h"
#include "mozilla/gfx/MatrixFwd.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          /
 *
 */
class gfxMatrix {
public:
    double _11; double _12;
    double _21; double _22;
    double _31; double _32;

    /**
     * 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) :
        _11(a),  _12(b),
        _21(c),  _22(d),
        _31(tx), _32(ty) { }

    MOZ_ALWAYS_INLINE gfxMatrix Copy() const {
        return gfxMatrix(*this);
    }

    friend std::ostream& operator<<(std::ostream& stream, const gfxMatrix& m) {
      if (m.IsIdentity()) {
        return stream << "[identity]";
      }

      return stream << "["
             << m._11 << " " << m._12
             << m._21 << " " << m._22
             << m._31 << " " << m._32
             << "]";
    }

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

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

    /**
     * Multiplies *this with aMatrix and returns the result.
     */
    mozilla::gfx::Matrix4x4 operator * (const mozilla::gfx::Matrix4x4& aMatrix) const;

    /* 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(_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 gfxMatrix& other) const
    {
      return !(*this == other);
    }

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

    bool IsIdentity() const {
       return _11 == 1.0 && _12 == 0.0 &&
              _21 == 0.0 && _22 == 1.0 &&
              _31 == 0.0 && _32 == 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?
     */
    bool Invert();

    /**
     * Check if matrix is singular (no inverse exists).
     */
    bool IsSingular() const {
        // if the determinant (ad - bc) is zero it's singular
        return (_11 * _22) == (_12 * _21);
    }

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

    gfxMatrix& Translate(gfxFloat x, gfxFloat y) {
      return Translate(gfxPoint(x, y));
    }

    /**
     * Rotates this matrix. The rotation is pre-multiplied onto this matrix,
     * i.e. the translation takes place after the other transformations.
     *
     * @param radians Angle in radians.
     */
    gfxMatrix& Rotate(gfxFloat radians);

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

    static gfxMatrix Translation(gfxFloat aX, gfxFloat aY)
    {
        return gfxMatrix(1.0, 0.0, 0.0, 1.0, aX, aY);
    }

    static gfxMatrix Translation(gfxPoint aPoint)
    {
        return Translation(aPoint.x, aPoint.y);
    }

    static gfxMatrix Rotation(gfxFloat aAngle);

    static gfxMatrix Scaling(gfxFloat aX, gfxFloat aY)
    {
        return gfxMatrix(aX, 0.0, 0.0, aY, 0.0, 0.0);
    }

    /**
     * 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(_31, _32);
    }

    /**
     * Returns true if the matrix is anything other than a straight
     * translation by integers.
     */
    bool HasNonIntegerTranslation() const {
        return HasNonTranslation() ||
            !FuzzyEqual(_31, floor(_31 + 0.5)) ||
            !FuzzyEqual(_32, floor(_32 + 0.5));
    }

    /**
     * Returns true if the matrix has any transform other
     * than a straight translation
     */
    bool HasNonTranslation() const {
        return !FuzzyEqual(_11, 1.0) || !FuzzyEqual(_22, 1.0) ||
               !FuzzyEqual(_21, 0.0) || !FuzzyEqual(_12, 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(_11, 1.0) ||
               (!FuzzyEqual(_22, 1.0) && !FuzzyEqual(_22, -1.0)) ||
               !FuzzyEqual(_21, 0.0) || !FuzzyEqual(_12, 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(_21, 0.0) || !FuzzyEqual(_12, 0.0);
    }

    /**
     * Computes the determinant of this matrix.
     */
    double Determinant() const {
        return _11*_22 - _12*_21;
    }

    /* 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.
     */
    gfxMatrix& NudgeToIntegers(void);

    /**
     * Returns true if matrix is multiple of 90 degrees rotation with flipping,
     * scaling and translation.
     */
    bool PreservesAxisAlignedRectangles() const {
        return ((FuzzyEqual(_11, 0.0) && FuzzyEqual(_22, 0.0))
            || (FuzzyEqual(_21, 0.0) && FuzzyEqual(_12, 0.0)));
    }

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

#endif /* GFX_MATRIX_H */