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 <iosfwd>
   9 #include <string>
  10
  11 #include "base/compiler_specific.h"
  12 #include "third_party/skia/include/utils/SkMatrix44.h"
  13 #include "ui/gfx/geometry/vector2d_f.h"
  14 #include "ui/gfx/gfx_export.h"
  15
  16 namespace gfx {
  17
  18 class BoxF;
  19 class RectF;
  20 class Point;
  21 class Point3F;
  22 class Vector3dF;
  23
  24 // 4x4 transformation matrix. Transform is cheap and explicitly allows
  25 // copy/assign.
  26 class GFX_EXPORT Transform {
  27  public:
  28
  29   enum SkipInitialization {
  30     kSkipInitialization
  31   };
  32
  33   Transform() : matrix_(SkMatrix44::kIdentity_Constructor) {}
  34
  35   // Skips initializing this matrix to avoid overhead, when we know it will be
  36   // initialized before use.
  37   Transform(SkipInitialization)
  38       : matrix_(SkMatrix44::kUninitialized_Constructor) {}
  39   Transform(const Transform& rhs) : matrix_(rhs.matrix_) {}
  40   // Initialize with the concatenation of lhs * rhs.
  41   Transform(const Transform& lhs, const Transform& rhs)
  42       : matrix_(lhs.matrix_, rhs.matrix_) {}
  43   // Constructs a transform from explicit 16 matrix elements. Elements
  44   // should be given in row-major order.
  45   Transform(SkMScalar col1row1,
  46             SkMScalar col2row1,
  47             SkMScalar col3row1,
  48             SkMScalar col4row1,
  49             SkMScalar col1row2,
  50             SkMScalar col2row2,
  51             SkMScalar col3row2,
  52             SkMScalar col4row2,
  53             SkMScalar col1row3,
  54             SkMScalar col2row3,
  55             SkMScalar col3row3,
  56             SkMScalar col4row3,
  57             SkMScalar col1row4,
  58             SkMScalar col2row4,
  59             SkMScalar col3row4,
  60             SkMScalar col4row4);
  61   // Constructs a transform from explicit 2d elements. All other matrix
  62   // elements remain the same as the corresponding elements of an identity
  63   // matrix.
  64   Transform(SkMScalar col1row1,
  65             SkMScalar col2row1,
  66             SkMScalar col1row2,
  67             SkMScalar col2row2,
  68             SkMScalar x_translation,
  69             SkMScalar y_translation);
  70   ~Transform() {}
  71
  72   bool operator==(const Transform& rhs) const { return matrix_ == rhs.matrix_; }
  73   bool operator!=(const Transform& rhs) const { return matrix_ != rhs.matrix_; }
  74
  75   // Resets this transform to the identity transform.
  76   void MakeIdentity() { matrix_.setIdentity(); }
  77
  78   // Applies the current transformation on a 2d rotation and assigns the result
  79   // to |this|.
  80   void Rotate(double degrees) { RotateAboutZAxis(degrees); }
  81
  82   // Applies the current transformation on an axis-angle rotation and assigns
  83   // the result to |this|.
  84   void RotateAboutXAxis(double degrees);
  85   void RotateAboutYAxis(double degrees);
  86   void RotateAboutZAxis(double degrees);
  87   void RotateAbout(const Vector3dF& axis, double degrees);
  88
  89   // Applies the current transformation on a scaling and assigns the result
  90   // to |this|.
  91   void Scale(SkMScalar x, SkMScalar y);
  92   void Scale3d(SkMScalar x, SkMScalar y, SkMScalar z);
  93   gfx::Vector2dF Scale2d() const {
  94     return gfx::Vector2dF(matrix_.get(0, 0), matrix_.get(1, 1));
  95   }
  96
  97   // Applies the current transformation on a translation and assigns the result
  98   // to |this|.
  99   void Translate(SkMScalar x, SkMScalar y);
 100   void Translate3d(SkMScalar x, SkMScalar y, SkMScalar z);
 101
 102   // Applies the current transformation on a skew and assigns the result
 103   // to |this|.
 104   void SkewX(double angle_x);
 105   void SkewY(double angle_y);
 106
 107   // Applies the current transformation on a perspective transform and assigns
 108   // the result to |this|.
 109   void ApplyPerspectiveDepth(SkMScalar depth);
 110
 111   // Applies a transformation on the current transformation
 112   // (i.e. 'this = this * transform;').
 113   void PreconcatTransform(const Transform& transform);
 114
 115   // Applies a transformation on the current transformation
 116   // (i.e. 'this = transform * this;').
 117   void ConcatTransform(const Transform& transform);
 118
 119   // Returns true if this is the identity matrix.
 120   bool IsIdentity() const { return matrix_.isIdentity(); }
 121
 122   // Returns true if the matrix is either identity or pure translation.
 123   bool IsIdentityOrTranslation() const { return matrix_.isTranslate(); }
 124
 125   // Returns true if the matrix is either the identity or a 2d translation.
 126   bool IsIdentityOr2DTranslation() const {
 127     return matrix_.isTranslate() && matrix_.get(2, 3) == 0;
 128   }
 129
 130   // Returns true if the matrix is either identity or pure translation,
 131   // allowing for an amount of inaccuracy as specified by the parameter.
 132   bool IsApproximatelyIdentityOrTranslation(SkMScalar tolerance) const;
 133
 134   // Returns true if the matrix is either a positive scale and/or a translation.
 135   bool IsPositiveScaleOrTranslation() const {
 136     if (!IsScaleOrTranslation())
 137       return false;
 138     return matrix_.get(0, 0) > 0.0 && matrix_.get(1, 1) > 0.0 &&
 139            matrix_.get(2, 2) > 0.0;
 140   }
 141
 142   // Returns true if the matrix is either identity or pure, non-fractional
 143   // translation.
 144   bool IsIdentityOrIntegerTranslation() const;
 145
 146   // Returns true if the matrix had only scaling components.
 147   bool IsScale2d() const { return matrix_.isScale(); }
 148
 149   // Returns true if the matrix is has only scaling and translation components.
 150   bool IsScaleOrTranslation() const { return matrix_.isScaleTranslate(); }
 151
 152   // Returns true if axis-aligned 2d rects will remain axis-aligned after being
 153   // transformed by this matrix.
 154   bool Preserves2dAxisAlignment() const;
 155
 156   // Returns true if the matrix has any perspective component that would
 157   // change the w-component of a homogeneous point.
 158   bool HasPerspective() const { return matrix_.hasPerspective(); }
 159
 160   // Returns true if this transform is non-singular.
 161   bool IsInvertible() const { return matrix_.invert(NULL); }
 162
 163   // Returns true if a layer with a forward-facing normal of (0, 0, 1) would
 164   // have its back side facing frontwards after applying the transform.
 165   bool IsBackFaceVisible() const;
 166
 167   // Inverts the transform which is passed in. Returns true if successful.
 168   bool GetInverse(Transform* transform) const WARN_UNUSED_RESULT;
 169
 170   // Transposes this transform in place.
 171   void Transpose();
 172
 173   // Set 3rd row and 3rd colum to (0, 0, 1, 0). Note that this flattening
 174   // operation is not quite the same as an orthographic projection and is
 175   // technically not a linear operation.
 176   //
 177   // One useful interpretation of doing this operation:
 178   //  - For x and y values, the new transform behaves effectively like an
 179   //    orthographic projection was added to the matrix sequence.
 180   //  - For z values, the new transform overrides any effect that the transform
 181   //    had on z, and instead it preserves the z value for any points that are
 182   //    transformed.
 183   //  - Because of linearity of transforms, this flattened transform also
 184   //    preserves the effect that any subsequent (multiplied from the right)
 185   //    transforms would have on z values.
 186   //
 187   void FlattenTo2d();
 188
 189   // Returns true if the 3rd row and 3rd column are both (0, 0, 1, 0).
 190   bool IsFlat() const;
 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   void RoundTranslationComponents();
 243
 244   // Returns |this| * |other|.
 245   Transform operator*(const Transform& other) const {
 246     return Transform(*this, other);
 247   }
 248
 249   // Sets |this| = |this| * |other|
 250   Transform& operator*=(const Transform& other) {
 251     PreconcatTransform(other);
 252     return *this;
 253   }
 254
 255   // Returns the underlying matrix.
 256   const SkMatrix44& matrix() const { return matrix_; }
 257   SkMatrix44& matrix() { return matrix_; }
 258
 259   std::string ToString() const;
 260
 261  private:
 262   void TransformPointInternal(const SkMatrix44& xform,
 263                               Point* point) const;
 264
 265   void TransformPointInternal(const SkMatrix44& xform,
 266                               Point3F* point) const;
 267
 268   SkMatrix44 matrix_;
 269
 270   // copy/assign are allowed.
 271 };
 272
 273 // This is declared here for use in gtest-based unit tests but is defined in
 274 // the gfx_test_support target. Depend on that to use this in your unit test.
 275 // This should not be used in production code - call ToString() instead.
 276 void PrintTo(const Transform& transform, ::std::ostream* os);
 277
 278 }  // namespace gfx
 279
 280 #endif  // UI_GFX_TRANSFORM_H_