Question

我正在尝试开发一个裁剪图像的应用程序。通过在图像上触摸两次（topLeft point，bottomRight point）来创建要裁剪的矩形。当用户点击时，屏幕上会显示一个红色矩形以查看裁剪区域。

然后用这个矩形，我想裁剪图像。但我面临一个问题，作物不起作用，给我不好的结果。

在我的代码下面：

@objc
func tap(_ sender: UITapGestureRecognizer) {
    let location = sender.location(in: sourceImageView)

    print(#function + ":: location: \(location)")

    if location1 == nil {
        location1 = location
    } else if location2 == nil {
        location2 = location

        print("Processing to crop the image...")
        guard let _topLeft = location1,
            let _bottomRight = location2 else {
                fatalError("Processing failed...")
        }
        let _topRight = CGPoint(x: _bottomRight.x, y: _topLeft.y)
        let _bottomLeft = CGPoint(x: _topLeft.x, y: _bottomRight.y)
        let _width = _topLeft.distance(point: _topRight)
        let _height = _topLeft.distance(point: _bottomLeft)
        let cropArea = CGRect(origin: _topLeft, size: CGSize(width: _width, height: _height))

        // Displaying red rectangle on the source image          
        let outline = CALayer()
        outline.frame = cropArea
        outline.borderWidth = 2.0
        outline.borderColor = UIColor.red.cgColor
        sourceImageView.layer.addSublayer(outline)

        guard let sourceImage = sourceImageView.image,
            let sourceCGImage = sourceImage.cgImage else {
            fatalError("Cannot get CG Image from source img")
        }

        let viewSize = self.view.frame.size

        let imageViewScaleWidth = viewSize.width / CGFloat(sourceCGImage.width)
        let imageViewScaleHeight = viewSize.height / CGFloat(sourceCGImage.height)

        let scale = 1 / min(imageViewScaleWidth, imageViewScaleHeight)
        let scaleWidth = 1 / imageViewScaleWidth
        let scaleHeight = 1 / imageViewScaleHeight


        let newWidth = cropArea.height * scale
        let newHeight = cropArea.width * scale
        let newXCord = (cropArea.topLeft.x * scale) + newHeight
        let newYCord = (cropArea.topLeft.y * scale)


        let newCropArea = CGRect(origin: CGPoint(x: newXCord,
                                                 y: newYCord),
                                 size: CGSize(width: newHeight,
                                              height: newWidth))

        guard let croppedSourceImage = sourceCGImage.cropping(to: newCropArea) else {
            print("Cannot crop the current image.")
            return
        }
    }
}

我认为我的问题来自源图像上的矩形投影。

由于

编辑：

public extension CGPoint {
    /// Distance between two points.
    ///
    /// - Parameter point: A `CGPoint` instance.
    public func distance(point p: CGPoint) -> CGFloat {
        return sqrt(pow((p.x - x), 2) + pow((p.y - y), 2))
    }
}

在屏幕坐标上裁剪来自CGRect的图像

0 个答案: