Source/WebCore/svg/SVGTransformValue.h

/*
 * Copyright (C) 2004, 2005, 2008 Nikolas Zimmermann <zimmermann@kde.org>
 * Copyright (C) 2004, 2005 Rob Buis <buis@kde.org>
 * Copyright (C) 2019 Apple Inc. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

#pragma once

#include "FloatConversion.h"
#include "FloatPoint.h"
#include "FloatSize.h"
#include "SVGMatrix.h"
#include <wtf/NeverDestroyed.h>
#include <wtf/text/StringBuilder.h>

namespace WebCore {

class FloatSize;

class SVGTransformValue {
public:
    enum SVGTransformType {
        SVG_TRANSFORM_UNKNOWN = 0,
        SVG_TRANSFORM_MATRIX = 1,
        SVG_TRANSFORM_TRANSLATE = 2,
        SVG_TRANSFORM_SCALE = 3,
        SVG_TRANSFORM_ROTATE = 4,
        SVG_TRANSFORM_SKEWX = 5,
        SVG_TRANSFORM_SKEWY = 6
    };

    enum ConstructionMode {
        ConstructIdentityTransform,
        ConstructZeroTransform
    };
    
    static SVGTransformValue translateTransformValue(FloatSize delta)
    {
        return SVGTransformValue(SVG_TRANSFORM_TRANSLATE, AffineTransform::makeTranslation(delta));
    }

    static SVGTransformValue rotateTransformValue(float angleInDegrees, FloatPoint center)
    {
        auto result = SVGTransformValue(SVG_TRANSFORM_ROTATE, AffineTransform::makeRotation(angleInDegrees, center));
        result.m_angle = angleInDegrees;
        result.m_rotationCenter = center;
        return result;
    }

    static SVGTransformValue scaleTransformValue(FloatSize scale)
    {
        return SVGTransformValue(SVG_TRANSFORM_SCALE, AffineTransform::makeScale(scale));
    }

    SVGTransformValue(SVGTransformType type = SVG_TRANSFORM_MATRIX, const AffineTransform& transform = { })
        : m_type(type)
        , m_matrix(SVGMatrix::create(transform))
    {
    }

    SVGTransformValue(const SVGTransformValue& other)
        : m_type(other.m_type)
        , m_matrix(SVGMatrix::create(other.matrix()->value()))
        , m_angle(other.m_angle)
        , m_rotationCenter(other.m_rotationCenter)
    {
    }

    SVGTransformValue(SVGTransformType type, Ref<SVGMatrix>&& matrix, float angle, const FloatPoint& rotationCenter)
        : m_type(type)
        , m_matrix(WTFMove(matrix))
        , m_angle(angle)
        , m_rotationCenter(rotationCenter)
    {
    }

    SVGTransformValue(SVGTransformValue&& other)
        : m_type(other.m_type)
        , m_matrix(other.m_matrix.copyRef())
        , m_angle(other.m_angle)
        , m_rotationCenter(other.m_rotationCenter)
    {
    }

    SVGTransformValue& operator=(const SVGTransformValue& other)
    {
        m_type = other.m_type;
        m_matrix->setValue(other.m_matrix->value());
        m_angle = other.m_angle;
        m_rotationCenter = other.m_rotationCenter;
        return *this;
    }

    SVGTransformType type() const { return m_type; }
    const Ref<SVGMatrix>& matrix() const { return m_matrix; }
    float angle() const { return m_angle; }
    FloatPoint rotationCenter() const { return m_rotationCenter; }

    bool isValid() const { return m_type != SVG_TRANSFORM_UNKNOWN; }

    void setMatrix(const AffineTransform& matrix)
    {
        m_type = SVG_TRANSFORM_MATRIX;
        m_angle = 0;
        m_rotationCenter = { };
        m_matrix->setValue(matrix);
    }

    void matrixDidChange()
    {
        // The underlying matrix has been changed, alter the transformation type.
        // Spec: In case the matrix object is changed directly (i.e., without using the methods on the SVGTransform interface itself)
        // then the type of the SVGTransform changes to SVG_TRANSFORM_MATRIX.
        m_type = SVG_TRANSFORM_MATRIX;
        m_angle = 0;
        m_rotationCenter = { };
    }

    FloatPoint translate() const
    {
        return FloatPoint::narrowPrecision(m_matrix->e(), m_matrix->f());
    }

    void setTranslate(float tx, float ty)
    {
        m_type = SVG_TRANSFORM_TRANSLATE;
        m_angle = 0;
        m_rotationCenter = { };
        m_matrix->value() = AffineTransform::makeTranslation({ tx, ty });
    }

    FloatSize scale() const
    {
        return FloatSize::narrowPrecision(m_matrix->a(), m_matrix->d());
    }

    void setScale(float sx, float sy)
    {
        m_type = SVG_TRANSFORM_SCALE;
        m_angle = 0;
        m_rotationCenter = { };
        m_matrix->value() = AffineTransform::makeScale({ sx, sy });
    }

    void setRotate(float angleInDegrees, float cx, float cy)
    {
        m_type = SVG_TRANSFORM_ROTATE;
        m_angle = angleInDegrees;
        m_rotationCenter = { cx, cy };
        m_matrix->value() = AffineTransform::makeRotation(angleInDegrees, { cx, cy });
    }

    void setSkewX(float angle)
    {
        m_type = SVG_TRANSFORM_SKEWX;
        m_angle = angle;
        m_rotationCenter = FloatPoint();
        
        m_matrix->value().makeIdentity();
        m_matrix->value().skewX(angle);
    }

    void setSkewY(float angle)
    {
        m_type = SVG_TRANSFORM_SKEWY;
        m_angle = angle;
        m_rotationCenter = FloatPoint();
        
        m_matrix->value().makeIdentity();
        m_matrix->value().skewY(angle);
    }

    String valueAsString() const
    {
        StringBuilder builder;
        builder.append(prefixForTransfromType(m_type));
        switch (m_type) {
        case SVG_TRANSFORM_UNKNOWN:
            break;
        case SVG_TRANSFORM_MATRIX:
            appendMatrix(builder);
            break;
        case SVG_TRANSFORM_TRANSLATE:
            appendTranslate(builder);
            break;
        case SVG_TRANSFORM_SCALE:
            appendScale(builder);
            break;
        case SVG_TRANSFORM_ROTATE:
            appendRotate(builder);
            break;
        case SVG_TRANSFORM_SKEWX:
            appendSkewX(builder);
            break;
        case SVG_TRANSFORM_SKEWY:
            appendSkewY(builder);
            break;
        }
        return builder.toString();
    }

    static const char* prefixForTransfromType(SVGTransformType type)
    {
        switch (type) {
        case SVG_TRANSFORM_UNKNOWN:
            return "";
        case SVG_TRANSFORM_MATRIX:
            return "matrix(";
        case SVG_TRANSFORM_TRANSLATE:
            return "translate(";
        case SVG_TRANSFORM_SCALE:
            return "scale(";
        case SVG_TRANSFORM_ROTATE:
            return "rotate(";
        case SVG_TRANSFORM_SKEWX:
            return "skewX(";
        case SVG_TRANSFORM_SKEWY:
            return "skewY(";
        }
        ASSERT_NOT_REACHED();
        return "";
    }

private:
    static void appendFixedPrecisionNumbers(StringBuilder& builder)
    {
        builder.append(')');
    }

    template<typename Number, typename... Numbers>
    static void appendFixedPrecisionNumbers(StringBuilder& builder, Number number, Numbers... numbers)
    {
        if (builder.length() && builder[builder.length() - 1] != '(')
            builder.append(' ');
        // FIXME: Shortest form would be better, but fixed precision is required for now to smooth over precision errors caused by converting float to double and back since we use AffineTransform to store transforms.
        builder.append(FormattedNumber::fixedPrecision(number));
        appendFixedPrecisionNumbers(builder, numbers...);
    }

    void appendMatrix(StringBuilder& builder) const
    {
        appendFixedPrecisionNumbers(builder, m_matrix->a(), m_matrix->b(), m_matrix->c(), m_matrix->d(), m_matrix->e(), m_matrix->f());
    }

    void appendTranslate(StringBuilder& builder) const
    {
        appendFixedPrecisionNumbers(builder, m_matrix->e(), m_matrix->f());
    }

    void appendScale(StringBuilder& builder) const
    {
        appendFixedPrecisionNumbers(builder, m_matrix->value().xScale(), m_matrix->value().yScale());
    }

    void appendRotate(StringBuilder& builder) const
    {
        double angleInRad = deg2rad(m_angle);
        double cosAngle = std::cos(angleInRad);
        double sinAngle = std::sin(angleInRad);

        float cx = narrowPrecisionToFloat(cosAngle != 1 ? (m_matrix->e() * (1 - cosAngle) - m_matrix->f() * sinAngle) / (1 - cosAngle) / 2 : 0);
        float cy = narrowPrecisionToFloat(cosAngle != 1 ? (m_matrix->e() * sinAngle / (1 - cosAngle) + m_matrix->f()) / 2 : 0);

        if (cx || cy)
            appendFixedPrecisionNumbers(builder, m_angle, cx, cy);
        else
            appendFixedPrecisionNumbers(builder, m_angle);
    }

    void appendSkewX(StringBuilder& builder) const
    {
        appendFixedPrecisionNumbers(builder, m_angle);
    }

    void appendSkewY(StringBuilder& builder) const
    {
        appendFixedPrecisionNumbers(builder, m_angle);
    }

    SVGTransformType m_type { SVG_TRANSFORM_UNKNOWN };
    Ref<SVGMatrix> m_matrix;
    float m_angle { 0 };
    FloatPoint m_rotationCenter;
};

} // namespace WebCore