Added zoom gesture to expanded view

JustScanIt.xcodeproj/project.pbxproj

@@ -7,6 +7,7 @@
 	objects = {
 
 /* Begin PBXBuildFile section */
+		46410F842C3D12B100FFBF7E /* ZoomableScrollView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 46410F832C3D12B100FFBF7E /* ZoomableScrollView.swift */; };
 		466989C72C34DC7A009884D1 /* JustScanItApp.swift in Sources */ = {isa = PBXBuildFile; fileRef = 466989C62C34DC7A009884D1 /* JustScanItApp.swift */; };
 		466989CB2C34DC7B009884D1 /* Assets.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = 466989CA2C34DC7B009884D1 /* Assets.xcassets */; };
 		466989CE2C34DC7B009884D1 /* Preview Assets.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = 466989CD2C34DC7B009884D1 /* Preview Assets.xcassets */; };
@@ -19,6 +20,7 @@
 /* End PBXBuildFile section */
 
 /* Begin PBXFileReference section */
+		46410F832C3D12B100FFBF7E /* ZoomableScrollView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ZoomableScrollView.swift; sourceTree = "<group>"; };
 		466989C32C34DC7A009884D1 /* JustScanIt.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = JustScanIt.app; sourceTree = BUILT_PRODUCTS_DIR; };
 		466989C62C34DC7A009884D1 /* JustScanItApp.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = JustScanItApp.swift; sourceTree = "<group>"; };
 		466989C82C34DC7A009884D1 /* MainView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MainView.swift; sourceTree = "<group>"; };
@@ -83,6 +85,7 @@
 			isa = PBXGroup;
 			children = (
 				466989D52C34DCE4009884D1 /* VNDocumentCameraViewControllerR.swift */,
+				46410F832C3D12B100FFBF7E /* ZoomableScrollView.swift */,
 			);
 			path = Controllers;
 			sourceTree = "<group>";
@@ -182,6 +185,7 @@
 				466989D92C35206E009884D1 /* Scan.swift in Sources */,
 				466989DF2C353FEC009884D1 /* SettingsView.swift in Sources */,
 				466989D62C34DCE4009884D1 /* VNDocumentCameraViewControllerR.swift in Sources */,
+				46410F842C3D12B100FFBF7E /* ZoomableScrollView.swift in Sources */,
 				466989DD2C35299D009884D1 /* ScanItemView.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;

JustScanIt/Controllers/ZoomableScrollView.swift

@@ -0,0 +1,162 @@
+//
+//  ZoomableScrollView.swift
+//  JustScanIt
+//
+//  Created by Pradyun Setti on 09/07/2024.
+//
+
+import Foundation
+import UIKit
+import SwiftUI
+
+class PinchZoomView: UIView {
+
+    weak var delegate: PinchZoomViewDelgate?
+
+    private(set) var scale: CGFloat = 0 {
+        didSet {
+            delegate?.pinchZoomView(self, didChangeScale: scale)
+        }
+    }
+
+    private(set) var anchor: UnitPoint = .center {
+        didSet {
+            delegate?.pinchZoomView(self, didChangeAnchor: anchor)
+        }
+    }
+
+    private(set) var offset: CGSize = .zero {
+        didSet {
+            delegate?.pinchZoomView(self, didChangeOffset: offset)
+        }
+    }
+
+    private(set) var isPinching: Bool = false {
+        didSet {
+            delegate?.pinchZoomView(self, didChangePinching: isPinching)
+        }
+    }
+
+    private var startLocation: CGPoint = .zero
+    private var location: CGPoint = .zero
+    private var numberOfTouches: Int = 0
+
+    init() {
+        super.init(frame: .zero)
+
+        let pinchGesture = UIPinchGestureRecognizer(target: self, action: #selector(pinch(gesture:)))
+        pinchGesture.cancelsTouchesInView = false
+        addGestureRecognizer(pinchGesture)
+    }
+
+    required init?(coder: NSCoder) {
+        fatalError()
+    }
+
+    @objc private func pinch(gesture: UIPinchGestureRecognizer) {
+
+        switch gesture.state {
+        case .began:
+            isPinching = true
+            startLocation = gesture.location(in: self)
+            anchor = UnitPoint(x: startLocation.x / bounds.width, y: startLocation.y / bounds.height)
+            numberOfTouches = gesture.numberOfTouches
+
+        case .changed:
+            if gesture.numberOfTouches != numberOfTouches {
+                // If the number of fingers being used changes, the start location needs to be adjusted to avoid jumping.
+                let newLocation = gesture.location(in: self)
+                let jumpDifference = CGSize(width: newLocation.x - location.x, height: newLocation.y - location.y)
+                startLocation = CGPoint(x: startLocation.x + jumpDifference.width, y: startLocation.y + jumpDifference.height)
+
+                numberOfTouches = gesture.numberOfTouches
+            }
+
+            scale = gesture.scale
+
+            location = gesture.location(in: self)
+            offset = CGSize(width: location.x - startLocation.x, height: location.y - startLocation.y)
+
+        case .ended, .cancelled, .failed:
+            isPinching = false
+            scale = 1.0
+            anchor = .center
+            offset = .zero
+        default:
+            break
+        }
+    }
+
+}
+
+protocol PinchZoomViewDelgate: AnyObject {
+    func pinchZoomView(_ pinchZoomView: PinchZoomView, didChangePinching isPinching: Bool)
+    func pinchZoomView(_ pinchZoomView: PinchZoomView, didChangeScale scale: CGFloat)
+    func pinchZoomView(_ pinchZoomView: PinchZoomView, didChangeAnchor anchor: UnitPoint)
+    func pinchZoomView(_ pinchZoomView: PinchZoomView, didChangeOffset offset: CGSize)
+}
+
+struct PinchZoom: UIViewRepresentable {
+
+    @Binding var scale: CGFloat
+    @Binding var anchor: UnitPoint
+    @Binding var offset: CGSize
+    @Binding var isPinching: Bool
+
+    func makeCoordinator() -> Coordinator {
+        Coordinator(self)
+    }
+
+    func makeUIView(context: Context) -> PinchZoomView {
+        let pinchZoomView = PinchZoomView()
+        pinchZoomView.delegate = context.coordinator
+        return pinchZoomView
+    }
+
+    func updateUIView(_ pageControl: PinchZoomView, context: Context) { }
+
+    class Coordinator: NSObject, PinchZoomViewDelgate {
+        var pinchZoom: PinchZoom
+
+        init(_ pinchZoom: PinchZoom) {
+            self.pinchZoom = pinchZoom
+        }
+
+        func pinchZoomView(_ pinchZoomView: PinchZoomView, didChangePinching isPinching: Bool) {
+            pinchZoom.isPinching = isPinching
+        }
+
+        func pinchZoomView(_ pinchZoomView: PinchZoomView, didChangeScale scale: CGFloat) {
+            pinchZoom.scale = scale
+        }
+
+        func pinchZoomView(_ pinchZoomView: PinchZoomView, didChangeAnchor anchor: UnitPoint) {
+            pinchZoom.anchor = anchor
+        }
+
+        func pinchZoomView(_ pinchZoomView: PinchZoomView, didChangeOffset offset: CGSize) {
+            pinchZoom.offset = offset
+        }
+    }
+}
+
+struct PinchToZoom: ViewModifier {
+    @State var scale: CGFloat = 1.0
+    @State var anchor: UnitPoint = .center
+    @State var offset: CGSize = .zero
+    @State var isPinching: Bool = false
+
+    func body(content: Content) -> some View {
+        content
+            .scaleEffect(scale, anchor: anchor)
+            .offset(offset)
+            .animation(.spring, value: isPinching)
+            .overlay(PinchZoom(scale: $scale, anchor: $anchor, offset: $offset, isPinching: $isPinching))
+    }
+}
+
+extension View {
+    func pinchToZoom() -> some View {
+        self.modifier(PinchToZoom())
+    }
+}

JustScanIt/View/MainView.swift

@@ -41,6 +41,7 @@ struct MainView: View {
     var body: some View {
         NavigationView {
             ScrollView {
+//                newScanButton
                 ForEach(scans, id: \.self) { scan in
                     ScanItemView(scan)
                 }
@@ -72,6 +73,18 @@ struct MainView: View {
         }
     }
     
+    var newScanButton: some View {
+        Button { showVNDocumentCameraView() } label: {
+            Text("New Scan")
+                .frame(maxWidth: .infinity)
+                .padding(12)
+                .foregroundStyle(.white)
+                .background(.blue)
+                .clipShape(RoundedRectangle(cornerRadius: 15))
+        }
+        .padding(.horizontal)
+    }
+    
     private func showVNDocumentCameraView() {
         Task { guard await isAuthorized else { return } }
         
@@ -95,5 +108,11 @@ struct MainView: View {
 }
 
 #Preview {
-    MainView()
+    let config = ModelConfiguration(isStoredInMemoryOnly: true)
+    let container = try! ModelContainer(for: Scan.self, configurations: config)
+    
+    let scan = Scan(images: [UIImage(systemName: "questionmark")!])
+    container.mainContext.insert(scan)
+    
+    return MainView().modelContainer(container)
 }

JustScanIt/View/ScanItemView.swift

@@ -96,6 +96,7 @@ struct ScanItemView: View {
                             .resizable()
                             .scaledToFit()
                             .frame(maxHeight: 400)
+                            .pinchToZoom()
                             .onTapGesture {
                                 withAnimation(.easeInOut(duration: 0.3)) {
                                     isZoomed = false