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/*
* Copyright (c) 2020-2022, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2022, Sam Atkins <atkinssj@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/ExtraMathConstants.h>
#include <LibWeb/HTML/Canvas/CanvasPath.h>
namespace Web::HTML {
void CanvasPath::close_path()
{
m_path.close();
}
void CanvasPath::move_to(float x, float y)
{
m_path.move_to({ x, y });
}
void CanvasPath::line_to(float x, float y)
{
m_path.line_to({ x, y });
}
void CanvasPath::quadratic_curve_to(float cx, float cy, float x, float y)
{
m_path.quadratic_bezier_curve_to({ cx, cy }, { x, y });
}
void CanvasPath::bezier_curve_to(double cp1x, double cp1y, double cp2x, double cp2y, double x, double y)
{
m_path.cubic_bezier_curve_to(Gfx::FloatPoint(cp1x, cp1y), Gfx::FloatPoint(cp2x, cp2y), Gfx::FloatPoint(x, y));
}
WebIDL::ExceptionOr<void> CanvasPath::arc(float x, float y, float radius, float start_angle, float end_angle, bool counter_clockwise)
{
if (radius < 0)
return WebIDL::IndexSizeError::create(m_self->realm(), DeprecatedString::formatted("The radius provided ({}) is negative.", radius));
return ellipse(x, y, radius, radius, 0, start_angle, end_angle, counter_clockwise);
}
WebIDL::ExceptionOr<void> CanvasPath::ellipse(float x, float y, float radius_x, float radius_y, float rotation, float start_angle, float end_angle, bool counter_clockwise)
{
if (radius_x < 0)
return WebIDL::IndexSizeError::create(m_self->realm(), DeprecatedString::formatted("The major-axis radius provided ({}) is negative.", radius_x));
if (radius_y < 0)
return WebIDL::IndexSizeError::create(m_self->realm(), DeprecatedString::formatted("The minor-axis radius provided ({}) is negative.", radius_y));
if (constexpr float tau = M_TAU; (!counter_clockwise && (end_angle - start_angle) >= tau)
|| (counter_clockwise && (start_angle - end_angle) >= tau)) {
start_angle = 0;
// FIXME: elliptical_arc_to() incorrectly handles the case where the start/end points are very close.
// So we slightly fudge the numbers here to correct for that.
end_angle = tau * 0.9999f;
} else {
start_angle = fmodf(start_angle, tau);
end_angle = fmodf(end_angle, tau);
}
// Then, figure out where the ends of the arc are.
// To do so, we can pretend that the center of this ellipse is at (0, 0),
// and the whole coordinate system is rotated `rotation` radians around the x axis, centered on `center`.
// The sign of the resulting relative positions is just whether our angle is on one of the left quadrants.
float sin_rotation;
float cos_rotation;
AK::sincos(rotation, sin_rotation, cos_rotation);
auto resolve_point_with_angle = [&](float angle) {
auto tan_relative = tanf(angle);
auto tan2 = tan_relative * tan_relative;
auto ab = radius_x * radius_y;
auto a2 = radius_x * radius_x;
auto b2 = radius_y * radius_y;
auto sqrt = sqrtf(b2 + a2 * tan2);
auto relative_x_position = ab / sqrt;
auto relative_y_position = ab * tan_relative / sqrt;
// Make sure to set the correct sign
// -1 if 0 ≤ θ < 90° or 270°< θ ≤ 360°
// 1 if 90° < θ< 270°
float sn = cosf(angle) >= 0 ? 1 : -1;
relative_x_position *= sn;
relative_y_position *= sn;
// Now rotate it (back) around the center point by 'rotation' radians, then move it back to our actual origin.
auto relative_rotated_x_position = relative_x_position * cos_rotation - relative_y_position * sin_rotation;
auto relative_rotated_y_position = relative_x_position * sin_rotation + relative_y_position * cos_rotation;
return Gfx::FloatPoint { relative_rotated_x_position + x, relative_rotated_y_position + y };
};
auto start_point = resolve_point_with_angle(start_angle);
auto end_point = resolve_point_with_angle(end_angle);
m_path.move_to(start_point);
auto delta_theta = end_angle - start_angle;
m_path.elliptical_arc_to(end_point, { radius_x, radius_y }, rotation, delta_theta > AK::Pi<float>, !counter_clockwise);
return {};
}
void CanvasPath::rect(float x, float y, float width, float height)
{
m_path.move_to({ x, y });
if (width == 0 || height == 0)
return;
m_path.line_to({ x + width, y });
m_path.line_to({ x + width, y + height });
m_path.line_to({ x, y + height });
m_path.close();
}
}
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