DrawingView

DrawingView is a customizable UIView subclass for drawing lines, filling shapes, and managing drawing actions with undo/redo functionality.

Overview

DrawingView provides an interactive drawing experience with support for various features such as adjustable line width, color selection, shape filling, and undo/redo operations. The view also includes functionality to save the drawing as a PNG file.

Properties

• lineWidth: CGFloat

  • The width of the lines drawn. Default is 5.0.

• lineColor: UIColor

  • The color of the lines drawn. Default is black.

• isErasing: Bool

  • When true, sets the drawing color to the background color for erasing. Default is false.

• fillColor: UIColor?

  • The color used to fill closed shapes. Default is nil.

• isFilling: Bool

  • When true, enables shape filling mode. Default is false.

• onUndoAvailabilityChanged: ((Bool) -> Void)?

  • Closure called when undo availability changes, passing a boolean indicating whether undo is available.

• onRedoAvailabilityChanged: ((Bool) -> Void)?

  • Closure called when redo availability changes, passing a boolean indicating whether redo is available.

• onSaveAndShare: ((URL) -> Void)?

  • Closure called with the URL of the saved drawing file when the drawing is saved and shared.

• onError: ((Error) -> Void)?

  • Closure called with an error if an operation fails.

Methods

• func undo()

  • Undoes the last drawing action (line or filled shape). Updates the display and the availability of undo/redo actions.

• func redo()

  • Redoes the last undone action (line or filled shape). Updates the display and the availability of undo/redo actions.

• func saveDrawing()

  • Saves the current drawing as a PNG file and invokes the onSaveAndShare closure with the file URL. If saving fails, invokes the onError closure with the encountered error.

Overrides

• override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?)

  • Handles the beginning of a touch event. Initializes a new line or handles filling a shape if isFilling is true.

• override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?)

  • Updates the current line with the new touch points and triggers a redraw.

• override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?)

  • Finalizes the current line and adds it to the list of lines. Updates the availability of undo/redo actions.

• override func touchesCancelled(_ touches: Set<UITouch>, with event: UIEvent?)

  • Handles cancelled touch events by treating them as ended touches.

• override func draw(_ rect: CGRect)

  • Draws the lines, filled shapes, and the current line onto the view's context.

Example Usage

let drawingView = DrawingView(frame: CGRect(x: 0, y: 0, width: 300, height: 300))
drawingView.lineWidth = 10.0
drawingView.lineColor = .blue
drawingView.isFilling = true
drawingView.fillColor = .red

drawingView.onUndoAvailabilityChanged = { isAvailable in
    // Update UI to reflect undo availability
}

drawingView.onRedoAvailabilityChanged = { isAvailable in
    // Update UI to reflect redo availability
}

drawingView.saveDrawing()
drawingView.onSaveAndShare = { fileURL in
    // Handle file URL for saved drawing (e.g., share via UIActivityViewController)
}

drawingView.onError = { error in
    // Handle error (e.g., show alert to user)
}

drawingView.undo()

drawingView.redo()

// Erase Mode
drawingView.isErasing = true
drawingView.isFilling = false

// Fill Mode
drawingView.isErasing = false
drawingView.isFilling = true

// Draw Mode
drawingView.isErasing = false
drawingView.isFilling = false