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 {
 124     return !(matrix_.getType() & ~SkMatrix44::kTranslate_Mask);
 125   }
 126
 127   // Returns true if the matrix is either identity or pure translation,
 128   // allowing for an amount of inaccuracy as specified by the parameter.
 129   bool IsApproximatelyIdentityOrTranslation(SkMScalar tolerance) const;
 130
 131   // Returns true if the matrix is either a positive scale and/or a translation.
 132   bool IsPositiveScaleOrTranslation() const {
 133     if (!IsScaleOrTranslation())
 134       return false;
 135     return matrix_.get(0, 0) > 0.0 && matrix_.get(1, 1) > 0.0 &&
 136            matrix_.get(2, 2) > 0.0;
 137   }
 138
 139   // Returns true if the matrix is either identity or pure, non-fractional
 140   // translation.
 141   bool IsIdentityOrIntegerTranslation() const;
 142
 143   // Returns true if the matrix had only scaling components.
 144   bool IsScale2d() const {
 145     return !(matrix_.getType() & ~SkMatrix44::kScale_Mask);
 146   }
 147
 148   // Returns true if the matrix is has only scaling and translation components.
 149   bool IsScaleOrTranslation() const {
 150     int mask = SkMatrix44::kScale_Mask | SkMatrix44::kTranslate_Mask;
 151     return (matrix_.getType() & ~mask) == 0;
 152   }
 153
 154   // Returns true if axis-aligned 2d rects will remain axis-aligned after being
 155   // transformed by this matrix.
 156   bool Preserves2dAxisAlignment() const;
 157
 158   // Returns true if the matrix has any perspective component that would
 159   // change the w-component of a homogeneous point.
 160   bool HasPerspective() const {
 161     return (matrix_.getType() & SkMatrix44::kPerspective_Mask) != 0;
 162   }
 163
 164   // Returns true if this transform is non-singular.
 165   bool IsInvertible() const { return matrix_.invert(NULL); }
 166
 167   // Returns true if a layer with a forward-facing normal of (0, 0, 1) would
 168   // have its back side facing frontwards after applying the transform.
 169   bool IsBackFaceVisible() const;
 170
 171   // Inverts the transform which is passed in. Returns true if successful.
 172   bool GetInverse(Transform* transform) const WARN_UNUSED_RESULT;
 173
 174   // Transposes this transform in place.
 175   void Transpose();
 176
 177   // Set 3rd row and 3rd colum to (0, 0, 1, 0). Note that this flattening
 178   // operation is not quite the same as an orthographic projection and is
 179   // technically not a linear operation.
 180   //
 181   // One useful interpretation of doing this operation:
 182   //  - For x and y values, the new transform behaves effectively like an
 183   //    orthographic projection was added to the matrix sequence.
 184   //  - For z values, the new transform overrides any effect that the transform
 185   //    had on z, and instead it preserves the z value for any points that are
 186   //    transformed.
 187   //  - Because of linearity of transforms, this flattened transform also
 188   //    preserves the effect that any subsequent (multiplied from the right)
 189   //    transforms would have on z values.
 190   //
 191   void FlattenTo2d();
 192
 193   // Returns the x and y translation components of the matrix.
 194   Vector2dF To2dTranslation() const;
 195
 196   // Applies the transformation to the point.
 197   void TransformPoint(Point3F* point) const;
 198
 199   // Applies the transformation to the point.
 200   void TransformPoint(Point* point) const;
 201
 202   // Applies the reverse transformation on the point. Returns true if the
 203   // transformation can be inverted.
 204   bool TransformPointReverse(Point3F* point) const;
 205
 206   // Applies the reverse transformation on the point. Returns true if the
 207   // transformation can be inverted. Rounds the result to the nearest point.
 208   bool TransformPointReverse(Point* point) const;
 209
 210   // Applies transformation on the given rect. After the function completes,
 211   // |rect| will be the smallest axis aligned bounding rect containing the
 212   // transformed rect.
 213   void TransformRect(RectF* rect) const;
 214
 215   // Applies the reverse transformation on the given rect. After the function
 216   // completes, |rect| will be the smallest axis aligned bounding rect
 217   // containing the transformed rect. Returns false if the matrix cannot be
 218   // inverted.
 219   bool TransformRectReverse(RectF* rect) const;
 220
 221   // Applies transformation on the given box. After the function completes,
 222   // |box| will be the smallest axis aligned bounding box containing the
 223   // transformed box.
 224   void TransformBox(BoxF* box) const;
 225
 226   // Applies the reverse transformation on the given box. After the function
 227   // completes, |box| will be the smallest axis aligned bounding box
 228   // containing the transformed box. Returns false if the matrix cannot be
 229   // inverted.
 230   bool TransformBoxReverse(BoxF* box) const;
 231
 232   // Decomposes |this| and |from|, interpolates the decomposed values, and
 233   // sets |this| to the reconstituted result. Returns false if either matrix
 234   // can't be decomposed. Uses routines described in this spec:
 235   // http://www.w3.org/TR/css3-3d-transforms/.
 236   //
 237   // Note: this call is expensive since we need to decompose the transform. If
 238   // you're going to be calling this rapidly (e.g., in an animation) you should
 239   // decompose once using gfx::DecomposeTransforms and reuse your
 240   // DecomposedTransform.
 241   bool Blend(const Transform& from, double progress);
 242
 243   // Returns |this| * |other|.
 244   Transform operator*(const Transform& other) const {
 245     return Transform(*this, other);
 246   }
 247
 248   // Sets |this| = |this| * |other|
 249   Transform& operator*=(const Transform& other) {
 250     PreconcatTransform(other);
 251     return *this;
 252   }
 253
 254   // Returns the underlying matrix.
 255   const SkMatrix44& matrix() const { return matrix_; }
 256   SkMatrix44& matrix() { return matrix_; }
 257
 258   std::string ToString() const;
 259
 260  private:
 261   void TransformPointInternal(const SkMatrix44& xform,
 262                               Point* point) const;
 263
 264   void TransformPointInternal(const SkMatrix44& xform,
 265                               Point3F* point) const;
 266
 267   SkMatrix44 matrix_;
 268
 269   // copy/assign are allowed.
 270 };
 271
 272 // This is declared here for use in gtest-based unit tests but is defined in
 273 // the gfx_test_support target. Depend on that to use this in your unit test.
 274 // This should not be used in production code - call ToString() instead.
 275 void PrintTo(const Transform& transform, ::std::ostream* os);
 276
 277 }  // namespace gfx
 278
 279 #endif  // UI_GFX_TRANSFORM_H_