QPainterPathcloseSubpath

QPainterPath is a class in the Qt GUI framework that represents a geometric path used by QPainter for rendering. It stores a sequence of connected segments, including straight lines, quadratic and cubic Bézier curves, and arc segments, and may contain multiple subpaths. The class is central to creating complex vector graphics, clipping regions, and hit-testing in Qt applications.

Path construction and modification: A path begins a subpath with moveTo(), then adds segments with lineTo(), quadTo(), cubicTo(), and arcTo(). A subpath can be closed with closeSubpath(), forming a closed figure. The path can be extended by adding existing paths or primitive shapes via addPath(), addRect(), addEllipse(), and similar helpers. The resulting QPainterPath can be combined, transformed, or reused for subsequent painting operations.

Properties and queries: The fill rule determines how the interior of overlapping segments is filled (e.g., Qt::OddEvenFill or Qt::WindingFill). The path can be tested and analyzed using methods such as contains(point) and intersects(rect). Paths can be transformed using transformed() with a QTransform or by applying other in-place operations.

Rendering and usage: In drawing code, a QPainter can render a path with drawPath(), or use a path as a clipping region via setClipPath(). QPainterPath is also used in hit-testing, clipping, and animations that rely on vector shapes, making it a versatile building block for vector graphics in Qt-based applications.