Customize the Annotation Selection Knobs in Swift for iOS

1
//
2
//  Copyright © 2016-2025 PSPDFKit GmbH. All rights reserved.
3
//
4
//  The Nutrient sample applications are licensed with a modified BSD license.
5
//  Please see License for details. This notice may not be removed from this file.
6
//
7

8
import PSPDFKit
9
import PSPDFKitUI
10

11
class SelectionKnobsExample: Example, PDFViewControllerDelegate {
12

13
    override init() {
14
        super.init()
15
        title = "Custom Selection Knobs Example"
16
        contentDescription = "Shows how to remove, reposition and style the selection knobs."
17
        category = .viewCustomization
18
    }
19

20
    override func invoke(with delegate: ExampleRunnerDelegate) -> UIViewController {
21
        let document = AssetLoader.document(for: .annualReport)
22

23
        // Add free text
24
        let freeText = FreeTextAnnotation()
25
        freeText.fontSize = 30
26
        freeText.contents = "I am example text. Drag me!"
27
        freeText.boundingBox = CGRect(x: 50, y: 250, width: 300, height: 300)
28
        freeText.sizeToFit()
29
        freeText.color = .blue
30
        freeText.absolutePageIndex = 0
31
        document.add(annotations: [freeText])
32

33
        let pdfController = PDFViewController(document: document, delegate: self) {
34
            $0.overrideClass(ResizableView.self, with: OnePointResizableView.self)
35
        }
36

37
        let appearance = ResizableView.appearance()
38
        appearance.selectionBorderWidth = 3
39
        appearance.cornerRadius = 6
40

41
        return pdfController
42
    }
43

44
    // MARK: PDFViewControllerDelegate
45

46
    internal func pdfViewController(_ pdfController: PDFViewController, didConfigurePageView pageView: PDFPageView, forPageAt pageIndex: Int) {
47
        if pageView.pageIndex == 0 {
48
            pageView.selectedAnnotations = pdfController.document?.annotationsForPage(at: 0, type: .freeText)
49
        }
50
    }
51

52
    // MARK: - Resizable view customization
53

54
    class OnePointResizableView: ResizableView {
55

56
        // MARK: Lifecycle
57

58
        override init(frame: CGRect) {
59
            super.init(frame: frame)
60
            removeAndTintKnobs()
61
        }
62

63
        required init?(coder aDecoder: NSCoder) {
64
            super.init(coder: aDecoder)
65
            removeAndTintKnobs()
66
        }
67

68
        // MARK: Knob customization
69

70
        func removeAndTintKnobs() {
71
            // Remove all knobs but the bottom right one.
72
            let unwantedKnobs: [OuterKnob] = [.topLeft, .topMiddle, .topRight, .middleLeft, .middleRight, .bottomLeft, .bottomMiddle]
73
            for knobType in unwantedKnobs {
74
                // `outerKnob(ofType:)` will only return nil if passed the type `.unknown`.
75
                outerKnob(ofType: knobType)!.removeFromSuperview()
76
            }
77
            // Use a custom tint color.
78
            tintColor = UIColor(red: 1, green: 0.622, blue: 0, alpha: 1)
79
        }
80

81
        override func centerPoint(for knobType: ResizableView.OuterKnob, inFrame frame: CGRect) -> CGPoint {
82
            var point = super.centerPoint(for: knobType, inFrame: frame)
83
            if knobType == .bottomRight {
84
                point.x += 10
85
                point.y += 10
86
            }
87
            return point
88
        }
89

90
        override func newKnobView(for type: KnobType) -> UIView & KnobView {
91
            return SquareKnobView(type: type)
92
        }
93
    }
94

95
    // MARK: - Custom knob view
96

97
    class SquareKnobView: UIView, KnobView {
98

99
        // MARK: Lifecycle
100

101
        convenience init(type: KnobType) {
102
            self.init()
103
            self.type = type
104
            frame = CGRect(origin: CGPoint.zero, size: knobSize)
105
            setUpShape()
106
        }
107

108
        // MARK: View
109

110
        override var bounds: CGRect {
111
            didSet {
112
                updatePaths()
113
            }
114
        }
115

116
        override func tintColorDidChange() {
117
            super.tintColorDidChange()
118
            updateColors()
119
        }
120

121
        // MARK: Layer
122

123
        override class var layerClass: AnyClass {
124
            return CAShapeLayer.self
125
        }
126

127
        var shapeLayer: CAShapeLayer {
128
            return layer as! CAShapeLayer
129
        }
130

131
        func setUpShape() {
132
            let layer = shapeLayer
133
            layer.strokeColor = UIColor.white.cgColor
134
            layer.shadowColor = UIColor.black.cgColor
135
            layer.shadowOffset = CGSize(width: 0, height: 1)
136
            layer.shadowOpacity = 0.4
137
            layer.shadowRadius = 1
138
            updateColors()
139
        }
140

141
        func updateColors() {
142
            let layer = shapeLayer
143
            layer.fillColor = tintColor.cgColor
144
            layer.strokeColor = UIColor(white: type == .outer ? 1 : 0.9, alpha: 1).cgColor
145
        }
146

147
        func updatePaths() {
148
            // The bounds change when zooming. Keep the dimensions proportional
149
            // to bounds to end up with the same apparent size.
150
            let width = min(bounds.width, bounds.height) / 6.0
151
            let layer = shapeLayer
152
            layer.path = UIBezierPath(roundedRect: bounds, cornerRadius: width).cgPath
153
            layer.shadowPath = layer.path
154
            layer.lineWidth = width
155
        }
156

157
        // MARK: PSPDFKnobView
158

159
        var type = KnobType.outer {
160
            didSet {
161
                updateColors()
162
            }
163
        }
164

165
        let knobSize = CGSize(width: 12, height: 12)
166
    }
167
}