Mantis

Mantis is an iOS Image cropping library, which mimics the Photo App written in Swift and provides rich cropping interactions for your iOS/Mac app (Catalyst only).

🆕 What's New

Perspective Correction (Skew)

Mantis now supports Apple Photos–style perspective correction, allowing users to adjust horizontal and vertical skew in addition to straightening. When enabled, the slide dial displays three circular icon buttons — Straighten, Vertical, and Horizontal — letting users switch between adjustment modes with a single tap.

Real-time 3D perspective preview powered by CATransform3D
Accurate image export using CIPerspectiveCorrection
Full integration with existing features: undo/redo, flip, 90° rotation, and preset transformations

Appearance Mode

Mantis now supports light, dark, and system appearance modes. By default Mantis uses a dark appearance (backward compatible). You can switch to a light theme or let it follow the system setting.

.forceDark — Always dark (default)
.forceLight — Always light, similar to Apple Photos in light mode
.system — Follows the system light/dark mode setting

var config = Mantis.Config()
config.appearanceMode = .forceLight   // or .system
let cropViewController = Mantis.cropViewController(image: <Your Image>, config: config)

Demos

Mantis also provides rich crop shapes from the basic circle/square to polygon to arbitrary paths(We even provide a heart shape ❤️ 😏).

Requirements

iOS 12.0+
MacOS 10.15+
Xcode 10.0+

Install

<details> <summary>CocoaPods</summary>

pod 'Mantis', '~> 2.31.1'

</details> <details> <summary>Carthage</summary>

github "guoyingtao/Mantis"

</details> <details> <summary>Swift Packages</summary>

Repository: https://github.com/guoyingtao/Mantis.git
Rules: Version - Exact - 2.31.1

</details>

Usage

<details> <summary>Basic</summary>

Create a CropViewController from Mantis with default config

You need set (cropViewController or its navigation controller).modalPresentationStyle = .fullscreen for iOS 13+ when the cropViewController is presented

UIKit

    let cropViewController = Mantis.cropViewController(image: <Your Image>)
    cropViewController.delegate = self
    <Your ViewController>.present(cropViewController, animated: true)

SwiftUI

Create an ImageCropperView from Mantis with default config

struct MyView: View {
    @State private var image: UIImage?
    @State private var transformation: Transformation?
    @State private var cropInfo: CropInfo?

    var body: some View {
        ImageCropperView(
            image: $image,
            transformation: $transformation,
            cropInfo: $cropInfo
        )
    }
}

Note:
To start a crop operation programmatically, use the existing action binding(for ImageCropperView):
action = .crop
To receive the result of the crop (success or failure), use the new onCropCompleted callback.
This is especially useful because cropping may not complete instantly in all cases, so relying on this callback ensures you update your UI only after the operation finishes.

The caller needs to conform CropViewControllerDelegate

public protocol CropViewControllerDelegate: class {
    func cropViewControllerDidCrop(_ cropViewController: CropViewController, cropped: UIImage, transformation: Transformation, cropInfo: CropInfo)
    func cropViewControllerDidCancel(_ cropViewController: CropViewController, original: UIImage)
    
    // The implementation of the following functions are optional
    func cropViewControllerDidFailToCrop(_ cropViewController: CropViewController, original: UIImage)     
    func cropViewControllerDidBeginResize(_ cropViewController: CropViewController)
    func cropViewControllerDidEndResize(_ cropViewController: CropViewController, original: UIImage, cropInfo: CropInfo)    
}

</details> <details> <summary>CropToolbar mode</summary>

CropToolbar has two modes:
- normal mode
In normal mode, you can use a set of standard CropViewController photo editing features with "Cancel" and "Done" buttons.

let cropViewController = Mantis.cropViewController(image: <Your Image>)

embedded mode

This mode does not include "Cancel" and "Done" buttons, so you can embed CropViewController into another view controller

var config = Mantis.Config()
config.cropToolbarConfig.mode = .embedded
let cropViewController = Mantis.cropViewController(image: <Your Image>, config: config)

</details> <details> <summary>Add your own ratio</summary>

            // Add a custom ratio 1:2 for portrait orientation
            let config = Mantis.Config()
            config.addCustomRatio(byVerticalWidth: 1, andVerticalHeight: 2)            
            <Your Crop ViewController> = Mantis.cropViewController(image: <Your Image>, config: config)
            
            // Set the ratioOptions of the config if you don't want to keep all default ratios
            let config = Mantis.Config() 
            //config.ratioOptions = [.original, .square, .custom]
            config.ratioOptions = [.custom]
            config.addCustomRatio(byVerticalWidth: 1, andVerticalHeight: 2)            
            <Your Crop ViewController> = Mantis.cropViewController(image: <Your Image>, config: config)

If you always want to use only one fixed ratio, set Mantis.Config.presetFixedRatioType = alwaysUsingOnePresetFixedRatio

    <Your Crop ViewController>.config.presetFixedRatioType = .alwaysUsingOnePresetFixedRatio(ratio: 16.0 / 9.0)

When choose alwaysUsingOnePresetFixedRatio, fixed-ratio setting button does not show.

If you want to hide rotation control view, set Mantis.Config.cropViewConfig.showAttachedRotationControlView = false
If you want to use ratio list instead of presenter, set Mantis.CropToolbarConfig.ratioCandidatesShowType = .alwaysShowRatioList

public enum RatioCandidatesShowType {
    case presentRatioList
    case alwaysShowRatioList
}

If you build your custom toolbar you can add your own fixed ratio buttons

// set a custom fixed ratio
cropToolbarDelegate?.didSelectRatio(ratio: 9 / 16)

</details> <details> <summary>Crop shapes</summary>

If you want to set different crop shape, set Mantis.Config.cropViewConfig.cropShapeType

public enum CropShapeType {
    case rect
    case square
    case ellipse
    case circle(maskOnly: Bool = false)
    case diamond(maskOnly: Bool = false)
    case heart(maskOnly: Bool = false)
    case polygon(sides: Int, offset: CGFloat = 0, maskOnly: Bool = false)
    case path(points: [CGPoint], maskOnly: Bool = false)
}

</details> <details> <summary>Preset transformations</summary>

If you want to apply transformations when showing an image, set Mantis.Config.cropViewConfig.presetTransformationType

public enum PresetTransformationType {
    case none
    case presetInfo(info: Transformation)
    case presetNormalizedInfo(normalizedInfo: CGRect)
}

Please use the transformation information obtained previously from delegate method cropViewControllerDidCrop(_ cropViewController: CropViewController, cropped: UIImage, transformation: Transformation, , cropInfo: CropInfo).

</details> <details> <summary>Undo/Redo Support</summary>

Mantis offers full support for Undo, Redo, Revert to Original in both iOS and Catalyst.
If you want to add support for this feature, set Mantis.Config.enableUndoRedo = true
Catalyst menus for this feature are localized.

</details> <details> <summary>Perspective Correction (Skew) 🆕</summary>

Enable perspective correction to let users adjust horizontal and vertical skew, similar to the Apple Photos app.

var config = Mantis.Config()
config.cropViewConfig.enablePerspectiveCorrection = true
let cropViewController = Mantis.cropViewController(image: <Your Image>, config: config)

When enablePerspectiveCorrection is true, the slide dial is used by default (no need to set builtInRotationControlViewType explicitly) and automatically switches to withTypeSelector mode, showing three circular icon buttons (Straighten / Vertical / Horizontal) above the ruler.

Mantis

Install / Use

README

Mantis

🆕 What's New

Perspective Correction (Skew)

Appearance Mode

Demos

Requirements

Install

Usage

UIKit

SwiftUI