gfx/src/nsTransform2D.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef nsTransform2D_h___
   8 #define nsTransform2D_h___
   9
  10 #include "nsCoord.h"
  11
  12 class nsTransform2D
  13 {
  14 private:
  15  /**
  16   * This represents the following matrix (note that the order of row/column
  17   * indices is opposite to usual notation)
  18   *
  19   *      / m00   0   m20  \
  20   * M =  |  0   m11  m21  |
  21   *      \  0    0    1   /
  22   *
  23   * Transformation of a coordinate (x, y) is obtained by setting
  24   * v = (x, y, 1)^T and evaluating  M . v
  25   **/
  26
  27   float     m00, m11, m20, m21;
  28
  29 public:
  30   nsTransform2D(void)                         { m20 = m21 = 0.0f; m00 = m11 = 1.0f; }
  31
  32   ~nsTransform2D(void)                        { }
  33
  34  /**
  35   * set this transform to a translation
  36   *
  37   * @param      tx, x translation
  38   * @param      ty, y translation
  39   **/
  40
  41   void SetToTranslate(float tx, float ty)    { m00 = m11 = 1.0f; m20 = tx; m21 = ty; }
  42
  43  /**
  44   * get the translation portion of this transform
  45   *
  46   * @param      pt, Point to return translation values in
  47   **/
  48
  49   void GetTranslationCoord(nscoord *ptX, nscoord *ptY) const { *ptX = NSToCoordRound(m20); *ptY = NSToCoordRound(m21); }
  50
  51  /**
  52   * apply matrix to vector
  53   *
  54   * @param    pt Point to transform
  55   **/
  56
  57   void TransformCoord(nscoord *ptX, nscoord *ptY) const;
  58
  59  /**
  60   * apply matrix to rect
  61   *
  62   * @param    rect Rect to transform
  63   **/
  64
  65   void TransformCoord(nscoord *aX, nscoord *aY, nscoord *aWidth, nscoord *aHeight) const;
  66
  67  /**
  68   * add a scale to a Transform via x, y pair
  69   *
  70   * @param    ptX x value to add as x scale
  71   * @param    ptY y value to add as y scale
  72   **/
  73
  74   void AddScale(float ptX, float ptY) { m00 *= ptX; m11 *= ptY; }
  75
  76  /**
  77   * Set the scale (overriding any previous calls to AddScale, but leaving
  78   * any existing translation).
  79   *
  80   * @param    ptX x value to add as x scale
  81   * @param    ptY y value to add as y scale
  82   **/
  83
  84   void SetScale(float ptX, float ptY) { m00 = ptX; m11 = ptY; }
  85 };
  86
  87 #endif