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LibWeb: Add elliptical curve support to svg path elements

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This commit is contained in:
Matthew Olsson 2020-07-21 23:46:39 -07:00 committed by Andreas Kling
parent 1cffde7635
commit 5985eac81d
1 changed files with 96 additions and 7 deletions
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103
Libraries/LibWeb/DOM/HTMLPathElement.cpp
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@ -439,7 +439,7 @@ void HTMLPathElement::paint(const SvgPaintingContext& context, Gfx::Painter& pai
path.move_to({ data[0], data[1] });
} else {
ASSERT(!path.segments().is_empty());
path.move_to(Gfx::FloatPoint { data[0], data[1] } + path.segments().last().point);
path.move_to(Gfx::FloatPoint { data[0], data[1] } + path.segments().last().point());
}
break;
case PathInstructionType::ClosePath:
@ -450,12 +450,12 @@ void HTMLPathElement::paint(const SvgPaintingContext& context, Gfx::Painter& pai
path.line_to({ data[0], data[1] });
} else {
ASSERT(!path.segments().is_empty());
path.line_to(Gfx::FloatPoint { data[0], data[1] } + path.segments().last().point);
path.line_to(Gfx::FloatPoint { data[0], data[1] } + path.segments().last().point());
}
break;
case PathInstructionType::HorizontalLine: {
ASSERT(!path.segments().is_empty());
auto last_point = path.segments().last().point;
auto last_point = path.segments().last().point();
if (absolute) {
path.line_to(Gfx::FloatPoint { data[0], last_point.y() });
} else {
@ -465,7 +465,7 @@ void HTMLPathElement::paint(const SvgPaintingContext& context, Gfx::Painter& pai
}
case PathInstructionType::VerticalLine: {
ASSERT(!path.segments().is_empty());
auto last_point = path.segments().last().point;
auto last_point = path.segments().last().point();
if (absolute) {
path.line_to(Gfx::FloatPoint{ last_point.x(), data[0] });
} else {
@ -473,27 +473,116 @@ void HTMLPathElement::paint(const SvgPaintingContext& context, Gfx::Painter& pai
}
break;
}
case PathInstructionType::EllipticalArc: {
double rx = data[0];
double ry = data[1];
double x_axis_rotation = data[2] * M_DEG2RAD;
double large_arc_flag = data[3];
double sweep_flag = data[4];
double x_axis_rotation_c = cos(x_axis_rotation);
double x_axis_rotation_s = sin(x_axis_rotation);
auto& last_point = path.segments().last().point();
Gfx::FloatPoint next_point;
if (absolute) {
next_point = { data[5], data[6] };
} else {
next_point = { data[5] + last_point.x(), data[6] + last_point.y() };
}
// Step 1 of out-of-range radii correction
if (rx == 0.0 || ry == 0.0) {
path.line_to(next_point);
break;
}
// Step 2 of out-of-range radii correction
if (rx < 0)
rx *= -1.0;
if (ry < 0)
ry *= -1.0;
// Find (cx, cy), theta_1, theta_delta
// Step 1: Compute (x1', y1')
auto x_avg = (last_point.x() - next_point.x()) / 2.0f;
auto y_avg = (last_point.y() - next_point.y()) / 2.0f;
auto x1p = x_axis_rotation_c * x_avg + x_axis_rotation_s * y_avg;
auto y1p = -x_axis_rotation_s * x_avg + x_axis_rotation_c * y_avg;
// Step 2: Compute (cx', cy')
double x1p_sq = pow(x1p, 2.0);
double y1p_sq = pow(y1p, 2.0);
double rx_sq = pow(rx, 2.0);
double ry_sq = pow(ry, 2.0);
// Step 3 of out-of-range radii correction
double lambda = x1p_sq / rx_sq + y1p_sq / ry_sq;
double multiplier;
if (lambda > 1.0) {
auto lambda_sqrt = sqrt(lambda);
rx *= lambda_sqrt;
ry *= lambda_sqrt;
multiplier = 0.0;
} else {
double numerator = rx_sq * ry_sq - rx_sq * y1p_sq - ry_sq * x1p_sq;
double denominator = rx_sq * y1p_sq + ry_sq * x1p_sq;
multiplier = sqrt(numerator / denominator);
}
if (large_arc_flag == sweep_flag)
multiplier *= -1.0;
double cxp = multiplier * rx * y1p / ry;
double cyp = multiplier * -ry * x1p / rx;
// Step 3: Compute (cx, cy) from (cx', cy')
x_avg = (last_point.x() + next_point.x()) / 2.0f;
y_avg = (last_point.y() + next_point.y()) / 2.0f;
double cx = x_axis_rotation_c * cxp - x_axis_rotation_s * cyp + x_avg;
double cy = x_axis_rotation_s * cxp + x_axis_rotation_c * cyp + y_avg;
double theta_1 = atan2((y1p - cyp) / ry, (x1p - cxp) / rx);
double theta_2 = atan2((-y1p - cyp) / ry, (-x1p - cxp) / rx);
auto theta_delta = theta_2 - theta_1;
if (sweep_flag == 0 && theta_delta > 0.0f) {
theta_delta -= M_TAU;
} else if (sweep_flag != 0 && theta_delta < 0) {
theta_delta += M_TAU;
}
path.elliptical_arc_to(next_point, { cx, cy }, { rx, ry }, x_axis_rotation, theta_1, theta_delta);
break;
}
case PathInstructionType::QuadraticBezierCurve:
if (absolute) {
path.quadratic_bezier_curve_to({ data[0], data[1] }, { data[2], data[3] });
} else {
ASSERT(!path.segments().is_empty());
auto last_point = path.segments().last().point;
auto last_point = path.segments().last().point();
path.quadratic_bezier_curve_to({ data[0] + last_point.x(), data[1] + last_point.y() }, { data[2] + last_point.x(), data[3] + last_point.y() });
}
break;
case PathInstructionType::Curve:
case PathInstructionType::SmoothCurve:
case PathInstructionType::SmoothQuadraticBezierCurve:
case PathInstructionType::EllipticalArc:
TODO();
case PathInstructionType::Invalid:
ASSERT_NOT_REACHED();
}
}
painter.fill_path(path, context.fill_color, Gfx::Painter::WindingRule::EvenOdd);
painter.stroke_path(path, context.stroke_color, context.stroke_width);
// Fills are computed as though all paths are closed (https://svgwg.org/svg2-draft/painting.html#FillProperties)
path.close();
painter.fill_path(path, context.fill_color, Gfx::Painter::WindingRule::EvenOdd);
}
}