在SwiftUI中根据矩形裁剪图像
我有一个可以使用DragGesture()拖动的图像。我想裁剪矩形区域内可见的图像。这是我的密码在SwiftUI中根据矩形裁剪图像,swift,swiftui,Swift,Swiftui,我有一个可以使用DragGesture()拖动的图像。我想裁剪矩形区域内可见的图像。这是我的密码 struct CropImage: View { @State private var currentPosition: CGSize = .zero @State private var newPosition: CGSize = .zero var body: some View { VStack { ZStack {
struct CropImage: View {
@State private var currentPosition: CGSize = .zero
@State private var newPosition: CGSize = .zero
var body: some View {
VStack {
ZStack {
Image("test_pic")
.resizable()
.scaledToFit()
.offset(x: self.currentPosition.width, y: self.currentPosition.height)
Rectangle()
.fill(Color.black.opacity(0.3))
.frame(width: UIScreen.screenWidth * 0.7 , height: UIScreen.screenHeight/5)
.overlay(Rectangle().stroke(Color.white, lineWidth: 3))
}
.gesture(DragGesture()
.onChanged { value in
self.currentPosition = CGSize(width: value.translation.width + self.newPosition.width, height: value.translation.height + self.newPosition.height)
}
.onEnded { value in
self.currentPosition = CGSize(width: value.translation.width + self.newPosition.width, height: value.translation.height + self.newPosition.height)
self.newPosition = self.currentPosition
})
Button ( action : {
// how to crop the image according to rectangle area
} ) {
Text("Crop Image")
.padding(.all, 10)
.background(Color.blue)
.foregroundColor(.white)
.shadow(color: .gray, radius: 1)
.padding(.top, 50)
}
}
}
}
为了便于理解
以下是使用
.clipShape
的可能方法。使用Xcode 11.4/iOS 13.4进行测试
多亏了,我实现了一个轻量级的swiftUI库来裁剪图像
神奇之处如下:
public var body: some View {
GeometryReader { proxy in
// ...
Button(action: {
// how to crop the image according to rectangle area
if self.tempResult == nil {
self.cropTheImageWithImageViewSize(proxy.size)
}
self.resultImage = self.tempResult
}) {
Text("Crop Image")
.padding(.all, 10)
.background(Color.blue)
.foregroundColor(.white)
.shadow(color: .gray, radius: 1)
.padding(.top, 50)
}
}
}
func cropTheImageWithImageViewSize(_ size: CGSize) {
let imsize = inputImage.size
let scale = max(inputImage.size.width / size.width,
inputImage.size.height / size.height)
let zoomScale = self.scale
let currentPositionWidth = self.dragAmount.width * scale
let currentPositionHeight = self.dragAmount.height * scale
let croppedImsize = CGSize(width: (self.cropSize.width * scale) / zoomScale, height: (self.cropSize.height * scale) / zoomScale)
let xOffset = (( imsize.width - croppedImsize.width) / 2.0) - (currentPositionWidth / zoomScale)
let yOffset = (( imsize.height - croppedImsize.height) / 2.0) - (currentPositionHeight / zoomScale)
let croppedImrect: CGRect = CGRect(x: xOffset, y: yOffset, width: croppedImsize.width, height: croppedImsize.height)
if let cropped = inputImage.cgImage?.cropping(to: croppedImrect) {
//uiimage here can write to data in png or jpeg
let croppedIm = UIImage(cgImage: cropped)
tempResult = croppedIm
result = Image(uiImage: croppedIm)
}
}
很酷,但如何获得图像?比如说,如果我想在UserDefaults中保存图像以供临时使用,实际上我正在寻找Rect区域的pngData/jpgData。也许是矩形区域的截图!
public var body: some View {
GeometryReader { proxy in
// ...
Button(action: {
// how to crop the image according to rectangle area
if self.tempResult == nil {
self.cropTheImageWithImageViewSize(proxy.size)
}
self.resultImage = self.tempResult
}) {
Text("Crop Image")
.padding(.all, 10)
.background(Color.blue)
.foregroundColor(.white)
.shadow(color: .gray, radius: 1)
.padding(.top, 50)
}
}
}
func cropTheImageWithImageViewSize(_ size: CGSize) {
let imsize = inputImage.size
let scale = max(inputImage.size.width / size.width,
inputImage.size.height / size.height)
let zoomScale = self.scale
let currentPositionWidth = self.dragAmount.width * scale
let currentPositionHeight = self.dragAmount.height * scale
let croppedImsize = CGSize(width: (self.cropSize.width * scale) / zoomScale, height: (self.cropSize.height * scale) / zoomScale)
let xOffset = (( imsize.width - croppedImsize.width) / 2.0) - (currentPositionWidth / zoomScale)
let yOffset = (( imsize.height - croppedImsize.height) / 2.0) - (currentPositionHeight / zoomScale)
let croppedImrect: CGRect = CGRect(x: xOffset, y: yOffset, width: croppedImsize.width, height: croppedImsize.height)
if let cropped = inputImage.cgImage?.cropping(to: croppedImrect) {
//uiimage here can write to data in png or jpeg
let croppedIm = UIImage(cgImage: cropped)
tempResult = croppedIm
result = Image(uiImage: croppedIm)
}
}