SkConicalGradient::FocalData Struct Reference

#include <SkConicalGradient.h>

Public Member Functions
bool	set (SkScalar r0, SkScalar r1, SkMatrix *matrix)
bool	isFocalOnCircle () const
bool	isSwapped () const
bool	isWellBehaved () const
bool	isNativelyFocal () const

Public Attributes
SkScalar	fR1
SkScalar	fFocalX
bool	fIsSwapped

Detailed Description

Definition at line 28 of file SkConicalGradient.h.

Member Function Documentation

isFocalOnCircle()

bool SkConicalGradient::FocalData::isFocalOnCircle ( ) const

inline

Definition at line 44 of file SkConicalGradient.h.

{ return SkScalarNearlyZero(1 - fR1); }

isNativelyFocal()

bool SkConicalGradient::FocalData::isNativelyFocal ( ) const

inline

Definition at line 48 of file SkConicalGradient.h.

{ return SkScalarNearlyZero(fFocalX); }

isSwapped()

bool SkConicalGradient::FocalData::isSwapped ( ) const

inline

Definition at line 46 of file SkConicalGradient.h.

{ return fIsSwapped; }

isWellBehaved()

bool SkConicalGradient::FocalData::isWellBehaved ( ) const

inline

Definition at line 47 of file SkConicalGradient.h.

{ return !this->isFocalOnCircle() && fR1 > 1; }

set()

bool SkConicalGradient::FocalData::set	(	SkScalar	r0,
		SkScalar	r1,
		SkMatrix *	matrix
	)

Definition at line 33 of file SkConicalGradient.cpp.

                                                                               {
    fIsSwapped = false;
    fFocalX = sk_ieee_float_divide(r0, (r0 - r1));
    if (SkScalarNearlyZero(fFocalX - 1)) {
        // swap r0, r1
        matrix->postTranslate(-1, 0);
        matrix->postScale(-1, 1);
        std::swap(r0, r1);
        fFocalX = 0;  // because r0 is now 0
        fIsSwapped = true;
    }
 
    // Map {focal point, (1, 0)} to {(0, 0), (1, 0)}
    const SkPoint from[2]   = { {fFocalX, 0}, {1, 0} };
    const SkPoint to[2]     = { {0, 0}, {1, 0} };
    SkMatrix focalMatrix;
    if (!focalMatrix.setPolyToPoly(from, to, 2)) {
        return false;
    }
    matrix->postConcat(focalMatrix);
    fR1 = r1 / SkScalarAbs(1 - fFocalX);  // focalMatrix has a scale of 1/(1-f)
 
    // The following transformations are just to accelerate the shader computation by saving
    // some arithmatic operations.
    if (this->isFocalOnCircle()) {
        matrix->postScale(0.5, 0.5);
    } else {
        matrix->postScale(fR1 / (fR1 * fR1 - 1), 1 / sqrt(SkScalarAbs(fR1 * fR1 - 1)));
    }
    matrix->postScale(SkScalarAbs(1 - fFocalX), SkScalarAbs(1 - fFocalX));  // scale |1 - f|
    return true;
}

Member Data Documentation

fFocalX

SkScalar SkConicalGradient::FocalData::fFocalX

Definition at line 30 of file SkConicalGradient.h.

fIsSwapped

bool SkConicalGradient::FocalData::fIsSwapped

Definition at line 31 of file SkConicalGradient.h.

fR1

SkScalar SkConicalGradient::FocalData::fR1

Definition at line 29 of file SkConicalGradient.h.

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

• third_party/skia/src/shaders/gradients/SkConicalGradient.h
• third_party/skia/src/shaders/gradients/SkConicalGradient.cpp