CGContextAddRect

CGContextAddRect is a Core Graphics function used to append a rectangle to the current path of a graphics context. It does not perform any drawing by itself; the rectangle is added to the path and will be rendered when you later stroke or fill the path, or when the path is used for clipping.

Prototype and parameters: void CGContextAddRect(CGContextRef c, CGRect rect). The context c is typically a graphics context obtained from UIGraphicsGetCurrentContext or a similar API, and rect is a CGRect specifying the rectangle in the context’s user space. The rectangle is incorporated into the current path with the current transformation matrix applied.

Path behavior and coordinate space: The rectangle is added as a closed subpath within the current path. If the current path is empty, the rectangle becomes the new path; otherwise it is appended to the existing path. All coordinates are in the context’s user space, and the current CTM (transformation matrix) of the context affects the final position and size when the path is rendered.

Rendering and related uses: After calling CGContextAddRect, you typically render by calling CGContextFillPath or CGContextStrokePath, or use the path for clipping via CGContextClipToPath or related clipping functions. The function is useful for constructing complex shapes by combining multiple rectangles.

Example: CGContextAddRect(context, CGRectMake(10, 20, 100, 50)); CGContextSetFillColorWithColor(context, UIColor.redColor.CGColor); CGContextFillPath(context);