text: // Copyright 2013 The Chromium Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  #ifndef CC_ANIMATION_TRANSFORM_OPERATIONS_H_
  #define CC_ANIMATION_TRANSFORM_OPERATIONS_H_
  
  #include <vector>
  
  #include "base/macros.h"
  #include "base/memory/scoped_ptr.h"
  #include "cc/animation/transform_operation.h"
  #include "cc/base/cc_export.h"
  #include "ui/gfx/transform.h"
  
  namespace gfx {
  class BoxF;
  struct DecomposedTransform;
  }
  
  namespace cc {
  
  // Transform operations are a decomposed transformation matrix. It can be
  // applied to obtain a gfx::Transform at any time, and can be blended
  // intelligently with other transform operations, so long as they represent the
  // same decomposition. For example, if we have a transform that is made up of
  // a rotation followed by skew, it can be blended intelligently with another
  // transform made up of a rotation followed by a skew. Blending is possible if
  // we have two dissimilar sets of transform operations, but the effect may not
  // be what was intended. For more information, see the comments for the blend
  // function below.
  class CC_EXPORT TransformOperations {
   public:
    TransformOperations();
    TransformOperations(const TransformOperations& other);
    ~TransformOperations();
  
    // Returns a transformation matrix representing these transform operations.
    gfx::Transform Apply() const;
  
    // Given another set of transform operations and a progress in the range
    // [0, 1], returns a transformation matrix representing the intermediate
    // value. If this->MatchesTypes(from), then each of the operations are
    // blended separately and then combined. Otherwise, the two sets of
    // transforms are baked to matrices (using apply), and the matrices are
    // then decomposed and interpolated. For more information, see
    // http://www.w3.org/TR/2011/WD-css3-2d-transforms-20111215/#matrix-decomposition.
    gfx::Transform Blend(const TransformOperations& from,
                         SkMScalar progress) const;
  
    // Sets |bounds| be the bounding box for the region within which |box| will
    // exist when it is transformed by the result of calling Blend on |from| and
    // with progress in the range [min_progress, max_progress]. If this region
    // cannot be computed, returns false.
    bool BlendedBoundsForBox(const gfx::BoxF& box,
                             const TransformOperations& from,
                             SkMScalar min_progress,
                             SkMScalar max_progress,
                             gfx::BoxF* bounds) const;
  
    // Returns true if these operations affect scale.
    bool AffectsScale() const;
  
    // Returns true if these operations are only translations.
    bool IsTranslation() const;
  
    // Returns false if the operations affect 2d axis alignment.
    bool PreservesAxisAlignment() const;
  
    // Returns true if this operation and its descendants have the same types
    // as other and its descendants.
    bool MatchesTypes(const TransformOperations& other) const;
  
    // Returns true if these operations can be blended. It will only return
    // false if we must resort to matrix interpolation, and matrix interpolation
    // fails (this can happen if either matrix cannot be decomposed).
    bool CanBlendWith(const TransformOperations& other) const;
  
    // If these operations have no more than one scale operation, and if the only
    // other operations are translations, sets |scale| to the scale component
    // of these operations. Otherwise, returns false.
    bool ScaleComponent(gfx::Vector3dF* scale) const;
  
    void AppendTranslate(SkMScalar x, SkMScalar y, SkMScalar z);
    void AppendRotate(SkMScalar x, SkMScalar y, SkMScalar z, SkMScalar degrees);
    void AppendScale(SkMScalar x, SkMScalar y, SkMScalar z);
    void AppendSkew(SkMScalar x, SkMScalar y);
    void AppendPerspective(SkMScalar depth);
    void AppendMatrix(const gfx::Transform& matrix);
    void AppendIdentity();
    bool IsIdentity() const;
  
   private:
    bool BlendInternal(const TransformOperations& from,
                       SkMScalar progress,
                       gfx::Transform* result) const;
  
    std::vector<TransformOperation> operations_;
  
    bool ComputeDecomposedTransform() const;
  
    // For efficiency, we cache the decomposed transform.
    mutable scoped_ptr<gfx::DecomposedTransform> decomposed_transform_;
    mutable bool decomposed_transform_dirty_;
  
    DISALLOW_ASSIGN(TransformOperations);
  };
  
  }  // namespace cc
  
  #endif  // CC_ANIMATION_TRANSFORM_OPERATIONS_H_
  