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