SwiftUI modifier that adds smooth pinch‑to‑zoom, panning, and double‑tap zoom with sensible clamping and optional haptics (iOS 17+). Includes a lightweight logging hook and programmatic centering support.

• iOS 16.0+ / macOS 11.0+
• Swift 5.9+

1. In Xcode: File → Add Package Dependencies…
2. Enter the repo URL for this package.
3. Add the ZoomableView library to your target.

Wrap your content in a GeometryReader to supply the container size, then apply .zoomable(...):

import SwiftUI
import ZoomableView

struct ContentView: View {
    var body: some View {
        GeometryReader { proxy in
            Image(.images)
                .resizable()
                .zoomable(
                    containerSize: proxy.size,
                    logger: ConsoleLogger() // optional
                )
        }
    }
}

struct ConsoleLogger: Logger {
    func log(_ message: String, level: LogLevel, file: String, function: String, line: Int) {
        print("[\(level.rawValue.uppercased())] \(message)")
    }
}

Pass a binding to focusPoint (in content coordinates). Setting it will center that point in the container; the value is cleared automatically.

@State private var focus: CGPoint?

GeometryReader { proxy in
    Image(.images)
        .resizable()
        .zoomable(
            containerSize: proxy.size,
            focusPoint: $focus,
            minZoomScale: 1,
            maxZoomScale: 4
        )
}

// Example: center on the middle of the image later
focus = CGPoint(x: imageSize.width / 2, y: imageSize.height / 2)

Double tap toggles between 1.0 scale and doubleTapZoomScale (default 2.0) anchored at the tap location. On iOS 17+ it emits selection haptics.

• containerSize: Required. Size of the viewport that should clamp panning.
• focusPoint: Optional binding for programmatic centering (cleared after use).
• minZoomScale / maxZoomScale: Clamps pinch zooming.
• doubleTapZoomScale: Target scale when toggling from the base scale.
• animationDuration: Duration for double-tap zoom and clamping animations.
• logger: Optional Logger to observe transforms and clamping.

Provide any Logger implementation to receive debug messages from gesture end and clamping logic. The protocol supplies debug, info, warning, and error helpers.

• Content is clamped to stay within the container; if the scaled content is smaller than the container, it recenters automatically.
• On macOS, gesture support depends on available input devices; pinch and double-tap behavior mirror iOS where supported.