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LibWeb: Factor out SVG path parsing from SVGPathElement

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Converting a Vector<PathInstruction> is now done by a free function so
that we can share this code with HTML::Path2D. :^)
This commit is contained in:
Andreas Kling 2022-11-29 14:06:41 +01:00
parent b716c14c32
commit 65d762130a
2 changed files with 27 additions and 21 deletions
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45
Userland/Libraries/LibWeb/SVG/SVGPathElement.cpp
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@ -99,15 +99,13 @@ void SVGPathElement::parse_attribute(FlyString const& name, String const& value)
}
}
Gfx::Path& SVGPathElement::get_path()
Gfx::Path path_from_path_instructions(Span<PathInstruction const> instructions)
{
if (m_path.has_value())
return m_path.value();
Gfx::Path path;
Gfx::FloatPoint previous_control_point;
PathInstructionType last_instruction = PathInstructionType::Invalid;
for (auto& instruction : m_instructions) {
for (auto& instruction : instructions) {
// If the first path element uses relative coordinates, we treat them as absolute by making them relative to (0, 0).
auto last_point = path.segments().is_empty() ? Gfx::FloatPoint { 0, 0 } : path.segments().last().point();
@ -181,24 +179,24 @@ Gfx::Path& SVGPathElement::get_path()
if (absolute) {
path.quadratic_bezier_curve_to(through, point);
m_previous_control_point = through;
previous_control_point = through;
} else {
auto control_point = through + last_point;
path.quadratic_bezier_curve_to(control_point, point + last_point);
m_previous_control_point = control_point;
previous_control_point = control_point;
}
break;
}
case PathInstructionType::SmoothQuadraticBezierCurve: {
clear_last_control_point = false;
if (m_previous_control_point.is_null()
if (previous_control_point.is_null()
|| ((last_instruction != PathInstructionType::QuadraticBezierCurve) && (last_instruction != PathInstructionType::SmoothQuadraticBezierCurve))) {
m_previous_control_point = last_point;
previous_control_point = last_point;
}
auto dx_end_control = last_point.dx_relative_to(m_previous_control_point);
auto dy_end_control = last_point.dy_relative_to(m_previous_control_point);
auto dx_end_control = last_point.dx_relative_to(previous_control_point);
auto dy_end_control = last_point.dy_relative_to(previous_control_point);
auto control_point = Gfx::FloatPoint { last_point.x() + dx_end_control, last_point.y() + dy_end_control };
Gfx::FloatPoint end_point = { data[0], data[1] };
@ -209,7 +207,7 @@ Gfx::Path& SVGPathElement::get_path()
path.quadratic_bezier_curve_to(control_point, end_point + last_point);
}
m_previous_control_point = control_point;
previous_control_point = control_point;
break;
}
@ -226,24 +224,24 @@ Gfx::Path& SVGPathElement::get_path()
}
path.cubic_bezier_curve_to(c1, c2, p2);
m_previous_control_point = c2;
previous_control_point = c2;
break;
}
case PathInstructionType::SmoothCurve: {
clear_last_control_point = false;
if (m_previous_control_point.is_null()
if (previous_control_point.is_null()
|| ((last_instruction != PathInstructionType::Curve) && (last_instruction != PathInstructionType::SmoothCurve))) {
m_previous_control_point = last_point;
previous_control_point = last_point;
}
// 9.5.2. Reflected control points https://svgwg.org/svg2-draft/paths.html#ReflectedControlPoints
// If the current point is (curx, cury) and the final control point of the previous path segment is (oldx2, oldy2),
// then the reflected point (i.e., (newx1, newy1), the first control point of the current path segment) is:
// (newx1, newy1) = (curx - (oldx2 - curx), cury - (oldy2 - cury))
auto reflected_previous_control_x = last_point.x() - m_previous_control_point.dx_relative_to(last_point);
auto reflected_previous_control_y = last_point.y() - m_previous_control_point.dy_relative_to(last_point);
auto reflected_previous_control_x = last_point.x() - previous_control_point.dx_relative_to(last_point);
auto reflected_previous_control_y = last_point.y() - previous_control_point.dy_relative_to(last_point);
Gfx::FloatPoint c1 = Gfx::FloatPoint { reflected_previous_control_x, reflected_previous_control_y };
Gfx::FloatPoint c2 = { data[0], data[1] };
Gfx::FloatPoint p2 = { data[2], data[3] };
@ -253,7 +251,7 @@ Gfx::Path& SVGPathElement::get_path()
}
path.cubic_bezier_curve_to(c1, c2, p2);
m_previous_control_point = c2;
previous_control_point = c2;
break;
}
case PathInstructionType::Invalid:
@ -261,12 +259,19 @@ Gfx::Path& SVGPathElement::get_path()
}
if (clear_last_control_point) {
m_previous_control_point = Gfx::FloatPoint {};
previous_control_point = Gfx::FloatPoint {};
}
last_instruction = instruction.type;
}
m_path = path;
return path;
}
Gfx::Path& SVGPathElement::get_path()
{
if (!m_path.has_value()) {
m_path = path_from_path_instructions(m_instructions);
}
return m_path.value();
}