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/gfx_export.h"
  14 #include "ui/gfx/vector2d_f.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 identity or pure translation,
 126   // allowing for an amount of inaccuracy as specified by the parameter.
 127   bool IsApproximatelyIdentityOrTranslation(SkMScalar tolerance) const;
 128
 129   // Returns true if the matrix is either a positive scale and/or a translation.
 130   bool IsPositiveScaleOrTranslation() const {
 131     if (!IsScaleOrTranslation())
 132       return false;
 133     return matrix_.get(0, 0) > 0.0 && matrix_.get(1, 1) > 0.0 &&
 134            matrix_.get(2, 2) > 0.0;
 135   }
 136
 137   // Returns true if the matrix is either identity or pure, non-fractional
 138   // translation.
 139   bool IsIdentityOrIntegerTranslation() const;
 140
 141   // Returns true if the matrix had only scaling components.
 142   bool IsScale2d() const {
 143     return !(matrix_.getType() & ~SkMatrix44::kScale_Mask);
 144   }
 145
 146   // Returns true if the matrix is has only scaling and translation components.
 147   bool IsScaleOrTranslation() const { return matrix_.isScaleTranslate(); }
 148
 149   // Returns true if axis-aligned 2d rects will remain axis-aligned after being
 150   // transformed by this matrix.
 151   bool Preserves2dAxisAlignment() const;
 152
 153   // Returns true if the matrix has any perspective component that would
 154   // change the w-component of a homogeneous point.
 155   bool HasPerspective() const { return matrix_.hasPerspective(); }
 156
 157   // Returns true if this transform is non-singular.
 158   bool IsInvertible() const { return matrix_.invert(NULL); }
 159
 160   // Returns true if a layer with a forward-facing normal of (0, 0, 1) would
 161   // have its back side facing frontwards after applying the transform.
 162   bool IsBackFaceVisible() const;
 163
 164   // Inverts the transform which is passed in. Returns true if successful.
 165   bool GetInverse(Transform* transform) const WARN_UNUSED_RESULT;
 166
 167   // Transposes this transform in place.
 168   void Transpose();
 169
 170   // Set 3rd row and 3rd colum to (0, 0, 1, 0). Note that this flattening
 171   // operation is not quite the same as an orthographic projection and is
 172   // technically not a linear operation.
 173   //
 174   // One useful interpretation of doing this operation:
 175   //  - For x and y values, the new transform behaves effectively like an
 176   //    orthographic projection was added to the matrix sequence.
 177   //  - For z values, the new transform overrides any effect that the transform
 178   //    had on z, and instead it preserves the z value for any points that are
 179   //    transformed.
 180   //  - Because of linearity of transforms, this flattened transform also
 181   //    preserves the effect that any subsequent (multiplied from the right)
 182   //    transforms would have on z values.
 183   //
 184   void FlattenTo2d();
 185
 186   // Returns the x and y translation components of the matrix.
 187   Vector2dF To2dTranslation() const;
 188
 189   // Applies the transformation to the point.
 190   void TransformPoint(Point3F* point) const;
 191
 192   // Applies the transformation to the point.
 193   void TransformPoint(Point* point) const;
 194
 195   // Applies the reverse transformation on the point. Returns true if the
 196   // transformation can be inverted.
 197   bool TransformPointReverse(Point3F* point) const;
 198
 199   // Applies the reverse transformation on the point. Returns true if the
 200   // transformation can be inverted. Rounds the result to the nearest point.
 201   bool TransformPointReverse(Point* point) const;
 202
 203   // Applies transformation on the given rect. After the function completes,
 204   // |rect| will be the smallest axis aligned bounding rect containing the
 205   // transformed rect.
 206   void TransformRect(RectF* rect) const;
 207
 208   // Applies the reverse transformation on the given rect. After the function
 209   // completes, |rect| will be the smallest axis aligned bounding rect
 210   // containing the transformed rect. Returns false if the matrix cannot be
 211   // inverted.
 212   bool TransformRectReverse(RectF* rect) const;
 213
 214   // Applies transformation on the given box. After the function completes,
 215   // |box| will be the smallest axis aligned bounding box containing the
 216   // transformed box.
 217   void TransformBox(BoxF* box) const;
 218
 219   // Applies the reverse transformation on the given box. After the function
 220   // completes, |box| will be the smallest axis aligned bounding box
 221   // containing the transformed box. Returns false if the matrix cannot be
 222   // inverted.
 223   bool TransformBoxReverse(BoxF* box) const;
 224
 225   // Decomposes |this| and |from|, interpolates the decomposed values, and
 226   // sets |this| to the reconstituted result. Returns false if either matrix
 227   // can't be decomposed. Uses routines described in this spec:
 228   // http://www.w3.org/TR/css3-3d-transforms/.
 229   //
 230   // Note: this call is expensive since we need to decompose the transform. If
 231   // you're going to be calling this rapidly (e.g., in an animation) you should
 232   // decompose once using gfx::DecomposeTransforms and reuse your
 233   // DecomposedTransform.
 234   bool Blend(const Transform& from, double progress);
 235
 236   // Returns |this| * |other|.
 237   Transform operator*(const Transform& other) const {
 238     return Transform(*this, other);
 239   }
 240
 241   // Sets |this| = |this| * |other|
 242   Transform& operator*=(const Transform& other) {
 243     PreconcatTransform(other);
 244     return *this;
 245   }
 246
 247   // Returns the underlying matrix.
 248   const SkMatrix44& matrix() const { return matrix_; }
 249   SkMatrix44& matrix() { return matrix_; }
 250
 251   std::string ToString() const;
 252
 253  private:
 254   void TransformPointInternal(const SkMatrix44& xform,
 255                               Point* point) const;
 256
 257   void TransformPointInternal(const SkMatrix44& xform,
 258                               Point3F* point) const;
 259
 260   SkMatrix44 matrix_;
 261
 262   // copy/assign are allowed.
 263 };
 264
 265 // This is declared here for use in gtest-based unit tests but is defined in
 266 // the gfx_test_support target. Depend on that to use this in your unit test.
 267 // This should not be used in production code - call ToString() instead.
 268 void PrintTo(const Transform& transform, ::std::ostream* os);
 269
 270 }  // namespace gfx
 271
 272 #endif  // UI_GFX_TRANSFORM_H_