ui/gfx/transform.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef UI_GFX_TRANSFORM_H_
   6 #define UI_GFX_TRANSFORM_H_
   7
   8 #include <string>
   9
  10 #include "base/compiler_specific.h"
  11 #include "third_party/skia/include/utils/SkMatrix44.h"
  12 #include "ui/gfx/gfx_export.h"
  13 #include "ui/gfx/vector2d_f.h"
  14
  15 namespace gfx {
  16
  17 class BoxF;
  18 class RectF;
  19 class Point;
  20 class Point3F;
  21 class Vector3dF;
  22
  23 // 4x4 transformation matrix. Transform is cheap and explicitly allows
  24 // copy/assign.
  25 class GFX_EXPORT Transform {
  26  public:
  27
  28   enum SkipInitialization {
  29     kSkipInitialization
  30   };
  31
  32   Transform() : matrix_(SkMatrix44::kIdentity_Constructor) {}
  33
  34   // Skips initializing this matrix to avoid overhead, when we know it will be
  35   // initialized before use.
  36   Transform(SkipInitialization)
  37       : matrix_(SkMatrix44::kUninitialized_Constructor) {}
  38   Transform(const Transform& rhs) : matrix_(rhs.matrix_) {}
  39   // Initialize with the concatenation of lhs * rhs.
  40   Transform(const Transform& lhs, const Transform& rhs)
  41       : matrix_(lhs.matrix_, rhs.matrix_) {}
  42   // Constructs a transform from explicit 16 matrix elements. Elements
  43   // should be given in row-major order.
  44   Transform(SkMScalar col1row1,
  45             SkMScalar col2row1,
  46             SkMScalar col3row1,
  47             SkMScalar col4row1,
  48             SkMScalar col1row2,
  49             SkMScalar col2row2,
  50             SkMScalar col3row2,
  51             SkMScalar col4row2,
  52             SkMScalar col1row3,
  53             SkMScalar col2row3,
  54             SkMScalar col3row3,
  55             SkMScalar col4row3,
  56             SkMScalar col1row4,
  57             SkMScalar col2row4,
  58             SkMScalar col3row4,
  59             SkMScalar col4row4);
  60   // Constructs a transform from explicit 2d elements. All other matrix
  61   // elements remain the same as the corresponding elements of an identity
  62   // matrix.
  63   Transform(SkMScalar col1row1,
  64             SkMScalar col2row1,
  65             SkMScalar col1row2,
  66             SkMScalar col2row2,
  67             SkMScalar x_translation,
  68             SkMScalar y_translation);
  69   ~Transform() {}
  70
  71   bool operator==(const Transform& rhs) const { return matrix_ == rhs.matrix_; }
  72   bool operator!=(const Transform& rhs) const { return matrix_ != rhs.matrix_; }
  73
  74   // Resets this transform to the identity transform.
  75   void MakeIdentity() { matrix_.setIdentity(); }
  76
  77   // Applies the current transformation on a 2d rotation and assigns the result
  78   // to |this|.
  79   void Rotate(double degrees) { RotateAboutZAxis(degrees); }
  80
  81   // Applies the current transformation on an axis-angle rotation and assigns
  82   // the result to |this|.
  83   void RotateAboutXAxis(double degrees);
  84   void RotateAboutYAxis(double degrees);
  85   void RotateAboutZAxis(double degrees);
  86   void RotateAbout(const Vector3dF& axis, double degrees);
  87
  88   // Applies the current transformation on a scaling and assigns the result
  89   // to |this|.
  90   void Scale(SkMScalar x, SkMScalar y);
  91   void Scale3d(SkMScalar x, SkMScalar y, SkMScalar z);
  92   gfx::Vector2dF Scale2d() const {
  93     return gfx::Vector2dF(matrix_.get(0, 0), matrix_.get(1, 1));
  94   }
  95
  96   // Applies the current transformation on a translation and assigns the result
  97   // to |this|.
  98   void Translate(SkMScalar x, SkMScalar y);
  99   void Translate3d(SkMScalar x, SkMScalar y, SkMScalar z);
 100
 101   // Applies the current transformation on a skew and assigns the result
 102   // to |this|.
 103   void SkewX(double angle_x);
 104   void SkewY(double angle_y);
 105
 106   // Applies the current transformation on a perspective transform and assigns
 107   // the result to |this|.
 108   void ApplyPerspectiveDepth(SkMScalar depth);
 109
 110   // Applies a transformation on the current transformation
 111   // (i.e. 'this = this * transform;').
 112   void PreconcatTransform(const Transform& transform);
 113
 114   // Applies a transformation on the current transformation
 115   // (i.e. 'this = transform * this;').
 116   void ConcatTransform(const Transform& transform);
 117
 118   // Returns true if this is the identity matrix.
 119   bool IsIdentity() const { return matrix_.isIdentity(); }
 120
 121   // Returns true if the matrix is either identity or pure translation.
 122   bool IsIdentityOrTranslation() const {
 123     return !(matrix_.getType() & ~SkMatrix44::kTranslate_Mask);
 124   }
 125
 126   // Returns true if the matrix is either identity or pure translation,
 127   // allowing for an amount of inaccuracy as specified by the parameter.
 128   bool IsApproximatelyIdentityOrTranslation(SkMScalar tolerance) const;
 129
 130   // Returns true if the matrix is either a positive scale and/or a translation.
 131   bool IsPositiveScaleOrTranslation() const {
 132     if (!IsScaleOrTranslation())
 133       return false;
 134     return matrix_.get(0, 0) > 0.0 && matrix_.get(1, 1) > 0.0 &&
 135            matrix_.get(2, 2) > 0.0;
 136   }
 137
 138   // Returns true if the matrix is either identity or pure, non-fractional
 139   // translation.
 140   bool IsIdentityOrIntegerTranslation() const;
 141
 142   // Returns true if the matrix had only scaling components.
 143   bool IsScale2d() const {
 144     return !(matrix_.getType() & ~SkMatrix44::kScale_Mask);
 145   }
 146
 147   // Returns true if the matrix is has only scaling and translation components.
 148   bool IsScaleOrTranslation() const {
 149     int mask = SkMatrix44::kScale_Mask | SkMatrix44::kTranslate_Mask;
 150     return (matrix_.getType() & ~mask) == 0;
 151   }
 152
 153   // Returns true if axis-aligned 2d rects will remain axis-aligned after being
 154   // transformed by this matrix.
 155   bool Preserves2dAxisAlignment() const;
 156
 157   // Returns true if the matrix has any perspective component that would
 158   // change the w-component of a homogeneous point.
 159   bool HasPerspective() const {
 160     return (matrix_.getType() & SkMatrix44::kPerspective_Mask) != 0;
 161   }
 162
 163   // Returns true if this transform is non-singular.
 164   bool IsInvertible() const { return matrix_.invert(NULL); }
 165
 166   // Returns true if a layer with a forward-facing normal of (0, 0, 1) would
 167   // have its back side facing frontwards after applying the transform.
 168   bool IsBackFaceVisible() const;
 169
 170   // Inverts the transform which is passed in. Returns true if successful.
 171   bool GetInverse(Transform* transform) const WARN_UNUSED_RESULT;
 172
 173   // Transposes this transform in place.
 174   void Transpose();
 175
 176   // Set 3rd row and 3rd colum to (0, 0, 1, 0). Note that this flattening
 177   // operation is not quite the same as an orthographic projection and is
 178   // technically not a linear operation.
 179   //
 180   // One useful interpretation of doing this operation:
 181   //  - For x and y values, the new transform behaves effectively like an
 182   //    orthographic projection was added to the matrix sequence.
 183   //  - For z values, the new transform overrides any effect that the transform
 184   //    had on z, and instead it preserves the z value for any points that are
 185   //    transformed.
 186   //  - Because of linearity of transforms, this flattened transform also
 187   //    preserves the effect that any subsequent (multiplied from the right)
 188   //    transforms would have on z values.
 189   //
 190   void FlattenTo2d();
 191
 192   // Returns the x and y translation components of the matrix.
 193   Vector2dF To2dTranslation() const;
 194
 195   // Applies the transformation to the point.
 196   void TransformPoint(Point3F* point) const;
 197
 198   // Applies the transformation to the point.
 199   void TransformPoint(Point* point) const;
 200
 201   // Applies the reverse transformation on the point. Returns true if the
 202   // transformation can be inverted.
 203   bool TransformPointReverse(Point3F* point) const;
 204
 205   // Applies the reverse transformation on the point. Returns true if the
 206   // transformation can be inverted. Rounds the result to the nearest point.
 207   bool TransformPointReverse(Point* point) const;
 208
 209   // Applies transformation on the given rect. After the function completes,
 210   // |rect| will be the smallest axis aligned bounding rect containing the
 211   // transformed rect.
 212   void TransformRect(RectF* rect) const;
 213
 214   // Applies the reverse transformation on the given rect. After the function
 215   // completes, |rect| will be the smallest axis aligned bounding rect
 216   // containing the transformed rect. Returns false if the matrix cannot be
 217   // inverted.
 218   bool TransformRectReverse(RectF* rect) const;
 219
 220   // Applies transformation on the given box. After the function completes,
 221   // |box| will be the smallest axis aligned bounding box containing the
 222   // transformed box.
 223   void TransformBox(BoxF* box) const;
 224
 225   // Applies the reverse transformation on the given box. After the function
 226   // completes, |box| will be the smallest axis aligned bounding box
 227   // containing the transformed box. Returns false if the matrix cannot be
 228   // inverted.
 229   bool TransformBoxReverse(BoxF* box) const;
 230
 231   // Decomposes |this| and |from|, interpolates the decomposed values, and
 232   // sets |this| to the reconstituted result. Returns false if either matrix
 233   // can't be decomposed. Uses routines described in this spec:
 234   // http://www.w3.org/TR/css3-3d-transforms/.
 235   //
 236   // Note: this call is expensive since we need to decompose the transform. If
 237   // you're going to be calling this rapidly (e.g., in an animation) you should
 238   // decompose once using gfx::DecomposeTransforms and reuse your
 239   // DecomposedTransform.
 240   bool Blend(const Transform& from, double progress);
 241
 242   // Returns |this| * |other|.
 243   Transform operator*(const Transform& other) const {
 244     return Transform(*this, other);
 245   }
 246
 247   // Sets |this| = |this| * |other|
 248   Transform& operator*=(const Transform& other) {
 249     PreconcatTransform(other);
 250     return *this;
 251   }
 252
 253   // Returns the underlying matrix.
 254   const SkMatrix44& matrix() const { return matrix_; }
 255   SkMatrix44& matrix() { return matrix_; }
 256
 257   std::string ToString() const;
 258
 259  private:
 260   void TransformPointInternal(const SkMatrix44& xform,
 261                               Point* point) const;
 262
 263   void TransformPointInternal(const SkMatrix44& xform,
 264                               Point3F* point) const;
 265
 266   SkMatrix44 matrix_;
 267
 268   // copy/assign are allowed.
 269 };
 270
 271 }  // namespace gfx
 272
 273 #endif  // UI_GFX_TRANSFORM_H_