ladybird/Libraries/LibGfx/AffineTransform.cpp

/*
 * Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <AK/LogStream.h>
#include <AK/Optional.h>
#include <LibGfx/AffineTransform.h>
#include <LibGfx/FloatRect.h>
#include <LibGfx/Rect.h>

namespace Gfx {

bool AffineTransform::is_identity() const
{
    return m_values[0] == 1 && m_values[1] == 0 && m_values[2] == 0 && m_values[3] == 1 && m_values[4] == 0 && m_values[5] == 0;
}

static float hypotenuse(float x, float y)
{
    // FIXME: This won't handle overflow :(
    return sqrt(x * x + y * y);
}

float AffineTransform::x_scale() const
{
    return hypotenuse(m_values[0], m_values[1]);
}

float AffineTransform::y_scale() const
{
    return hypotenuse(m_values[2], m_values[3]);
}

AffineTransform& AffineTransform::scale(float sx, float sy)
{
    m_values[0] *= sx;
    m_values[1] *= sx;
    m_values[2] *= sy;
    m_values[3] *= sy;
    return *this;
}

AffineTransform& AffineTransform::translate(float tx, float ty)
{
    m_values[4] += tx * m_values[0] + ty * m_values[2];
    m_values[5] += tx * m_values[1] + ty * m_values[3];
    return *this;
}

void AffineTransform::map(float unmapped_x, float unmapped_y, float& mapped_x, float& mapped_y) const
{
    mapped_x = (m_values[0] * unmapped_x + m_values[2] * unmapped_y + m_values[4]);
    mapped_y = (m_values[1] * unmapped_x + m_values[3] * unmapped_y + m_values[5]);
}

IntPoint AffineTransform::map(const IntPoint& point) const
{
    float mapped_x;
    float mapped_y;
    map(point.x(), point.y(), mapped_x, mapped_y);
    return IntPoint(roundf(mapped_x), roundf(mapped_y));
}

FloatPoint AffineTransform::map(const FloatPoint& point) const
{
    float mapped_x;
    float mapped_y;
    map(point.x(), point.y(), mapped_x, mapped_y);
    return FloatPoint(mapped_x, mapped_y);
}

IntSize AffineTransform::map(const IntSize& size) const
{
    return IntSize(roundf(size.width() * x_scale()), roundf(y_scale()));
}

FloatSize AffineTransform::map(const FloatSize& size) const
{
    return { size.width() * x_scale(), size.height() * y_scale() };
}

IntRect AffineTransform::map(const IntRect& rect) const
{
    return enclosing_int_rect(map(FloatRect(rect)));
}

template<typename T>
static T smallest_of(T p1, T p2, T p3, T p4)
{
    return min(min(p1, p2), min(p3, p4));
}

template<typename T>
static T largest_of(T p1, T p2, T p3, T p4)
{
    return max(max(p1, p2), max(p3, p4));
}

FloatRect AffineTransform::map(const FloatRect& rect) const
{
    FloatPoint p1 = map(rect.top_left());
    FloatPoint p2 = map(rect.top_right().translated(1, 0));
    FloatPoint p3 = map(rect.bottom_right().translated(1, 1));
    FloatPoint p4 = map(rect.bottom_left().translated(0, 1));
    float left = smallest_of(p1.x(), p2.x(), p3.x(), p4.x());
    float top = smallest_of(p1.y(), p2.y(), p3.y(), p4.y());
    float right = largest_of(p1.x(), p2.x(), p3.x(), p4.x());
    float bottom = largest_of(p1.y(), p2.y(), p3.y(), p4.y());
    return { left, top, right - left, bottom - top };
}

const LogStream& operator<<(const LogStream& stream, const AffineTransform& value)
{
    if (value.is_identity())
        return stream << "{ Identity }";

    return stream << "{ "
                  << value.a() << ", "
                  << value.b() << ", "
                  << value.c() << ", "
                  << value.d() << ", "
                  << value.e() << ", "
                  << value.f() << " }";
}

}