The Tor Browser: gfx/thebes/gfxMatrix.h@b8a032363ba2 (annotated)

gfx/thebes/gfxMatrix.h@b8a032363ba2 (annotated)

gfx/thebes/gfxMatrix.h

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /* -*- 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"
 // 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.
      *
      * @param radians Angle in radians.
      */
     const gfxMatrix& Rotate(gfxFloat radians);
      /**
       * 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 */

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gfx/thebes/gfxMatrix.h@b8a032363ba2 (annotated)

gfx/thebes/gfxMatrix.h