diff --git a/Userland/Libraries/LibGfx/Path.cpp b/Userland/Libraries/LibGfx/Path.cpp index 66431a7597..9caf5d0b8e 100644 --- a/Userland/Libraries/LibGfx/Path.cpp +++ b/Userland/Libraries/LibGfx/Path.cpp @@ -72,11 +72,7 @@ void Path::elliptical_arc_to(FloatPoint point, FloatSize radii, float x_axis_rot double x_axis_rotation_s; double x_axis_rotation_c; AK::sincos(static_cast(x_axis_rotation), x_axis_rotation_s, x_axis_rotation_c); - - // Find the last point - FloatPoint last_point { 0, 0 }; - if (!m_segments.is_empty()) - last_point = m_segments.last()->point(); + FloatPoint last_point = this->last_point(); // Step 1 of out-of-range radii correction if (rx == 0.0 || ry == 0.0) { @@ -160,6 +156,13 @@ void Path::elliptical_arc_to(FloatPoint point, FloatSize radii, float x_axis_rot theta_1, theta_delta); } +FloatPoint Path::last_point() +{ + FloatPoint last_point { 0, 0 }; + if (!m_segments.is_empty()) + last_point = m_segments.last()->point(); + return last_point; +} void Path::close() { @@ -383,6 +386,14 @@ void Path::add_path(Path const& other) invalidate_split_lines(); } +void Path::ensure_subpath(FloatPoint point) +{ + if (m_need_new_subpath && m_segments.is_empty()) { + move_to(point); + m_need_new_subpath = false; + } +} + template struct RoundTrip { RoundTrip(ReadonlySpan span) diff --git a/Userland/Libraries/LibGfx/Path.h b/Userland/Libraries/LibGfx/Path.h index 32a9dde008..8c519c31c4 100644 --- a/Userland/Libraries/LibGfx/Path.h +++ b/Userland/Libraries/LibGfx/Path.h @@ -153,6 +153,8 @@ public: elliptical_arc_to(point, { radius, radius }, 0, large_arc, sweep); } + FloatPoint last_point(); + void close(); void close_all_subpaths(); @@ -192,7 +194,7 @@ public: Path copy_transformed(AffineTransform const&) const; void add_path(Path const&); - + void ensure_subpath(FloatPoint point); DeprecatedString to_deprecated_string() const; Path stroke_to_fill(float thickness) const; @@ -217,6 +219,7 @@ private: Optional> m_split_lines {}; Optional m_bounding_box; + bool m_need_new_subpath = { true }; }; } diff --git a/Userland/Libraries/LibWeb/HTML/Canvas/CanvasPath.cpp b/Userland/Libraries/LibWeb/HTML/Canvas/CanvasPath.cpp index 3e6492397d..e7f9bed7d7 100644 --- a/Userland/Libraries/LibWeb/HTML/Canvas/CanvasPath.cpp +++ b/Userland/Libraries/LibWeb/HTML/Canvas/CanvasPath.cpp @@ -120,6 +120,78 @@ WebIDL::ExceptionOr CanvasPath::ellipse(float x, float y, float radius_x, return {}; } +// https://html.spec.whatwg.org/multipage/canvas.html#dom-context-2d-arcto +WebIDL::ExceptionOr CanvasPath::arc_to(double x1, double y1, double x2, double y2, double radius) +{ + // 1. If any of the arguments are infinite or NaN, then return. + if (!isfinite(x1) || !isfinite(y1) || !isfinite(x2) || !isfinite(y2) || !isfinite(radius)) + return {}; + + // 2. Ensure there is a subpath for (x1, y1). + auto transform = active_transform(); + m_path.ensure_subpath(transform.map(Gfx::FloatPoint { x1, y1 })); + + // 3. If radius is negative, then throw an "IndexSizeError" DOMException. + if (radius < 0) + return WebIDL::IndexSizeError::create(m_self->realm(), MUST(String::formatted("The radius provided ({}) is negative.", radius))); + + // 4. Let the point (x0, y0) be the last point in the subpath, + // transformed by the inverse of the current transformation matrix + // (so that it is in the same coordinate system as the points passed to the method). + // Point (x0, y0) + auto p0 = m_path.last_point(); + // Point (x1, y1) + auto p1 = transform.map(Gfx::FloatPoint { x1, y1 }); + // Point (x2, y2) + auto p2 = transform.map(Gfx::FloatPoint { x2, y2 }); + + // 5. If the point (x0, y0) is equal to the point (x1, y1), + // or if the point (x1, y1) is equal to the point (x2, y2), + // or if radius is zero, then add the point (x1, y1) to the subpath, + // and connect that point to the previous point (x0, y0) by a straight line. + if (p0 == p1 || p1 == p2 || radius == 0) { + m_path.line_to(p1); + return {}; + } + + auto v1 = Gfx::FloatVector2 { p0.x() - p1.x(), p0.y() - p1.y() }; + auto v2 = Gfx::FloatVector2 { p2.x() - p1.x(), p2.y() - p1.y() }; + auto cos_theta = v1.dot(v2) / (v1.length() * v2.length()); + // 6. Otherwise, if the points (x0, y0), (x1, y1), and (x2, y2) all lie on a single straight line, + // then add the point (x1, y1) to the subpath, + // and connect that point to the previous point (x0, y0) by a straight line. + if (-1 == cos_theta || 1 == cos_theta) { + m_path.line_to(p1); + return {}; + } + + // 7. Otherwise, let The Arc be the shortest arc given by circumference of the circle that has radius radius, + // and that has one point tangent to the half-infinite line that crosses the point (x0, y0) and ends at the point (x1, y1), + // and that has a different point tangent to the half-infinite line that ends at the point (x1, y1) and crosses the point (x2, y2). + // The points at which this circle touches these two lines are called the start and end tangent points respectively. + auto adjacent = radius / static_cast(tan(acos(cos_theta) / 2)); + auto factor1 = adjacent / static_cast(v1.length()); + auto x3 = static_cast(p1.x()) + factor1 * static_cast(p0.x() - p1.x()); + auto y3 = static_cast(p1.y()) + factor1 * static_cast(p0.y() - p1.y()); + auto start_tangent = Gfx::FloatPoint { x3, y3 }; + + auto factor2 = adjacent / static_cast(v2.length()); + auto x4 = static_cast(p1.x()) + factor2 * static_cast(p2.x() - p1.x()); + auto y4 = static_cast(p1.y()) + factor2 * static_cast(p2.y() - p1.y()); + auto end_tangent = Gfx::FloatPoint { x4, y4 }; + + // Connect the point (x0, y0) to the start tangent point by a straight line, adding the start tangent point to the subpath. + m_path.line_to(start_tangent); + + bool const large_arc = false; // always small since tangent points define arc endpoints and lines meet at (x1, y1) + auto cross_product = v1.x() * v2.y() - v1.y() * v2.x(); + bool const sweep = cross_product < 0; // right-hand rule, true means clockwise + + // and then connect the start tangent point to the end tangent point by The Arc, adding the end tangent point to the subpath. + m_path.arc_to(end_tangent, radius, large_arc, sweep); + return {}; +} + void CanvasPath::rect(float x, float y, float width, float height) { auto transform = active_transform(); diff --git a/Userland/Libraries/LibWeb/HTML/Canvas/CanvasPath.h b/Userland/Libraries/LibWeb/HTML/Canvas/CanvasPath.h index 6510239c15..e7811707bf 100644 --- a/Userland/Libraries/LibWeb/HTML/Canvas/CanvasPath.h +++ b/Userland/Libraries/LibWeb/HTML/Canvas/CanvasPath.h @@ -23,6 +23,7 @@ public: void line_to(float x, float y); void quadratic_curve_to(float cx, float cy, float x, float y); void bezier_curve_to(double cp1x, double cp1y, double cp2x, double cp2y, double x, double y); + WebIDL::ExceptionOr arc_to(double x1, double y1, double x2, double y2, double radius); void rect(float x, float y, float width, float height); WebIDL::ExceptionOr arc(float x, float y, float radius, float start_angle, float end_angle, bool counter_clockwise); WebIDL::ExceptionOr ellipse(float x, float y, float radius_x, float radius_y, float rotation, float start_angle, float end_angle, bool counter_clockwise); diff --git a/Userland/Libraries/LibWeb/HTML/Canvas/CanvasPath.idl b/Userland/Libraries/LibWeb/HTML/Canvas/CanvasPath.idl index 5ba418a91e..14b93bd405 100644 --- a/Userland/Libraries/LibWeb/HTML/Canvas/CanvasPath.idl +++ b/Userland/Libraries/LibWeb/HTML/Canvas/CanvasPath.idl @@ -5,7 +5,7 @@ interface mixin CanvasPath { undefined lineTo(unrestricted double x, unrestricted double y); undefined quadraticCurveTo(unrestricted double cpx, unrestricted double cpy, unrestricted double x, unrestricted double y); undefined bezierCurveTo(unrestricted double cp1x, unrestricted double cp1y, unrestricted double cp2x, unrestricted double cp2y, unrestricted double x, unrestricted double y); - // FIXME: undefined arcTo(unrestricted double x1, unrestricted double y1, unrestricted double x2, unrestricted double y2, unrestricted double radius); + undefined arcTo(unrestricted double x1, unrestricted double y1, unrestricted double x2, unrestricted double y2, unrestricted double radius); undefined rect(unrestricted double x, unrestricted double y, unrestricted double width, unrestricted double height); // FIXME: undefined roundRect(unrestricted double x, unrestricted double y, unrestricted double w, unrestricted double h, optional (unrestricted double or DOMPointInit or sequence<(unrestricted double or DOMPointInit)>) radii = 0); undefined arc(unrestricted double x, unrestricted double y, unrestricted double radius, unrestricted double startAngle, unrestricted double endAngle, optional boolean counterclockwise = false);