LibGfx: Add method for copying a Path with a transform applied

The Web's CanvasRenderingContext2D needs a way to draw a path with a
transform applied to it, without modifying the original path, so here
it is. :^)

2 files changed, 46 insertions, 0 deletions

diff --git a/Userland/Libraries/LibGfx/Path.cpp b/Userland/Libraries/LibGfx/Path.cpp
index f84d071609..81209f5252 100644
--- a/Userland/Libraries/LibGfx/Path.cpp
+++ b/Userland/Libraries/LibGfx/Path.cpp
@@ -332,4 +332,48 @@ void Path::segmentize_path()
     m_bounding_box = Gfx::FloatRect { min_x, min_y, max_x - min_x, max_y - min_y };
 }
 
+Path Path::copy_transformed(Gfx::AffineTransform const& transform) const
+{
+    Path result;
+
+    for (auto const& segment : m_segments) {
+        switch (segment.type()) {
+        case Segment::Type::MoveTo:
+            result.move_to(transform.map(segment.point()));
+            break;
+        case Segment::Type::LineTo: {
+            result.line_to(transform.map(segment.point()));
+            break;
+        }
+        case Segment::Type::QuadraticBezierCurveTo: {
+            auto const& quadratic_segment = static_cast<QuadraticBezierCurveSegment const&>(segment);
+            result.quadratic_bezier_curve_to(transform.map(quadratic_segment.through()), transform.map(segment.point()));
+            break;
+        }
+        case Segment::Type::CubicBezierCurveTo: {
+            auto const& cubic_segment = static_cast<CubicBezierCurveSegment const&>(segment);
+            result.cubic_bezier_curve_to(transform.map(cubic_segment.through_0()), transform.map(cubic_segment.through_1()), transform.map(segment.point()));
+            break;
+        }
+        case Segment::Type::EllipticalArcTo: {
+            auto const& arc_segment = static_cast<EllipticalArcSegment const&>(segment);
+            result.elliptical_arc_to(
+                transform.map(segment.point()),
+                transform.map(arc_segment.center()),
+                transform.map(arc_segment.radii()),
+                arc_segment.x_axis_rotation(),
+                arc_segment.theta_1(),
+                arc_segment.theta_delta(),
+                arc_segment.large_arc(),
+                arc_segment.sweep());
+            break;
+        }
+        case Segment::Type::Invalid:
+            VERIFY_NOT_REACHED();
+        }
+    }
+
+    return result;
+}
+
 }
diff --git a/Userland/Libraries/LibGfx/Path.h b/Userland/Libraries/LibGfx/Path.h
index 7c0ba83090..662edb3732 100644
--- a/Userland/Libraries/LibGfx/Path.h
+++ b/Userland/Libraries/LibGfx/Path.h
@@ -243,6 +243,8 @@ public:
         return m_bounding_box.value();
     }
 
+    Path copy_transformed(AffineTransform const&) const;
+
     String to_string() const;
 
 private: