flutter::DlMatrixColorFilter Class Reference

#include <dl_color_filter.h>

Inheritance diagram for flutter::DlMatrixColorFilter:

Public Member Functions
	DlMatrixColorFilter (const float matrix[20])
	DlMatrixColorFilter (const DlMatrixColorFilter &filter)
	DlMatrixColorFilter (const DlMatrixColorFilter *filter)
DlColorFilterType	type () const override
size_t	size () const override
bool	modifies_transparent_black () const override
bool	can_commute_with_opacity () const override
std::shared_ptr< DlColorFilter >	shared () const override
const DlMatrixColorFilter *	asMatrix () const override
const float &	operator[] (int index) const
void	get_matrix (float matrix[20]) const
Public Member Functions inherited from flutter::DlColorFilter
virtual const DlBlendColorFilter *	asBlend () const
Public Member Functions inherited from flutter::DlAttribute< DlColorFilter, DlColorFilterType >
bool	operator== (DlColorFilter const &other) const
bool	operator!= (DlColorFilter const &other) const
virtual	~DlAttribute ()=default

Static Public Member Functions
static std::shared_ptr< DlColorFilter >	Make (const float matrix[20])

Protected Member Functions
bool	equals_ (const DlColorFilter &other) const override

Detailed Description

Definition at line 114 of file dl_color_filter.h.

Constructor & Destructor Documentation

DlMatrixColorFilter() [1/3]

flutter::DlMatrixColorFilter::DlMatrixColorFilter ( const float  matrix[20] )

inlineexplicit

Definition at line 116 of file dl_color_filter.h.

                                                       {
    memcpy(matrix_, matrix, sizeof(matrix_));
  }

DlMatrixColorFilter() [2/3]

flutter::DlMatrixColorFilter::DlMatrixColorFilter ( const DlMatrixColorFilter &  filter )

inline

Definition at line 119 of file dl_color_filter.h.

      : DlMatrixColorFilter(filter.matrix_) {}

DlMatrixColorFilter() [3/3]

flutter::DlMatrixColorFilter::DlMatrixColorFilter ( const DlMatrixColorFilter *  filter )

inlineexplicit

Definition at line 121 of file dl_color_filter.h.

      : DlMatrixColorFilter(filter->matrix_) {}

Member Function Documentation

asMatrix()

const DlMatrixColorFilter * flutter::DlMatrixColorFilter::asMatrix ( ) const

inlineoverridevirtual

Reimplemented from flutter::DlColorFilter.

Definition at line 136 of file dl_color_filter.h.

{ return this; }

can_commute_with_opacity()

bool flutter::DlMatrixColorFilter::can_commute_with_opacity ( ) const

overridevirtual

Reimplemented from flutter::DlColorFilter.

Definition at line 153 of file dl_color_filter.cc.

                                                         {
  // We need to check if:
  //   filter(color) * opacity == filter(color * opacity).
  //
  // filter(RGBA) = R' = [ R*m[ 0] + G*m[ 1] + B*m[ 2] + A*m[ 3] + m[ 4] ]
  //                G' = [ R*m[ 5] + G*m[ 6] + B*m[ 7] + A*m[ 8] + m[ 9] ]
  //                B' = [ R*m[10] + G*m[11] + B*m[12] + A*m[13] + m[14] ]
  //                A' = [ R*m[15] + G*m[16] + B*m[17] + A*m[18] + m[19] ]
  //
  // Applying the opacity only affects the alpha value since the operations
  // are performed on non-premultiplied colors. (If the data is stored in
  // premultiplied form, though, there may be rounding errors due to
  // premul->unpremul->premul conversions.)
 
  // We test for the successful cases and return false if they fail so that
  // we fail and return false if any matrix values are NaN.
 
  // If any of the alpha column are non-zero then the prior alpha affects
  // the result color, so applying opacity before the filter will change
  // the incoming alpha and therefore the colors that are produced.
  if (!(matrix_[3] == 0 &&    // A does not affect R'
        matrix_[8] == 0 &&    // A does not affect G'
        matrix_[13] == 0)) {  // A does not affect B'
    return false;
  }
 
  // Similarly, if any of the alpha row are non-zero then the prior colors
  // affect the result alpha in a way that prevents opacity from commuting
  // through the filter operation.
  if (!(matrix_[15] == 0 &&   // R does not affect A'
        matrix_[16] == 0 &&   // G does not affect A'
        matrix_[17] == 0 &&   // B does not affect A'
        matrix_[19] == 0)) {  // A' is not offset by an absolute value
    return false;
  }
 
  return true;
}

equals_()

bool flutter::DlMatrixColorFilter::equals_ ( const DlColorFilter &  other ) const

inlineoverrideprotectedvirtual

Implements flutter::DlAttribute< DlColorFilter, DlColorFilterType >.

Definition at line 144 of file dl_color_filter.h.

                                                          {
    FML_DCHECK(other.type() == DlColorFilterType::kMatrix);
    auto that = static_cast<DlMatrixColorFilter const*>(&other);
    return memcmp(matrix_, that->matrix_, sizeof(matrix_)) == 0;
  }

get_matrix()

void flutter::DlMatrixColorFilter::get_matrix ( float  matrix[20] ) const

inline

Definition at line 139 of file dl_color_filter.h.

                                          {
    memcpy(matrix, matrix_, sizeof(matrix_));
  }

Make()

std::shared_ptr< DlColorFilter > flutter::DlMatrixColorFilter::Make ( const float  matrix[20] )

static

Definition at line 127 of file dl_color_filter.cc.

                            {
  float product = 0;
  for (int i = 0; i < 20; i++) {
    product *= matrix[i];
  }
  // If any of the elements of the matrix are infinity or NaN, then
  // |product| will be NaN, otherwise 0.
  if (product == 0) {
    return std::make_shared<DlMatrixColorFilter>(matrix);
  }
  return nullptr;
}

modifies_transparent_black()

bool flutter::DlMatrixColorFilter::modifies_transparent_black ( ) const

overridevirtual

Implements flutter::DlColorFilter.

Definition at line 141 of file dl_color_filter.cc.

                                                           {
  // Values are considered in non-premultiplied form when the matrix is
  // applied, but we only care about this answer for whether it leaves
  // an incoming color with a transparent alpha as transparent on output.
  // Thus, we only need to consider the alpha part of the matrix equation,
  // which is the last row. Since the incoming alpha value is 0, the last
  // equation ends up becoming A' = matrix_[19]. Negative results will be
  // clamped to the range [0,1] so we only care about positive values.
  // Non-finite values are clamped to a zero alpha.
  return (std::isfinite(matrix_[19]) && matrix_[19] > 0);
}

operator[]()

const float & flutter::DlMatrixColorFilter::operator[] ( int  index ) const

inline

Definition at line 138 of file dl_color_filter.h.

{ return matrix_[index]; }

shared()

std::shared_ptr< DlColorFilter > flutter::DlMatrixColorFilter::shared ( ) const

inlineoverridevirtual

Implements flutter::DlAttribute< DlColorFilter, DlColorFilterType >.

Definition at line 132 of file dl_color_filter.h.

                                                       {
    return std::make_shared<DlMatrixColorFilter>(this);
  }

size()

size_t flutter::DlMatrixColorFilter::size ( ) const

inlineoverridevirtual

Implements flutter::DlAttribute< DlColorFilter, DlColorFilterType >.

Definition at line 127 of file dl_color_filter.h.

{ return sizeof(*this); }

type()

DlColorFilterType flutter::DlMatrixColorFilter::type ( ) const

inlineoverridevirtual

Implements flutter::DlAttribute< DlColorFilter, DlColorFilterType >.

Definition at line 126 of file dl_color_filter.h.

{ return DlColorFilterType::kMatrix; }

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The documentation for this class was generated from the following files:

• display_list/effects/dl_color_filter.h
• display_list/effects/dl_color_filter.cc