Question

我正在尝试在imageView中“裁剪”图像。在以下意义上裁剪：如果用户向左平移，则图片从右侧向左侧裁剪。因此，当用户平移到右侧时，图片将完全显示，如果用户平移到最左侧，则图片不可见。

我尝试了以下内容：

@IBAction func handlePanGesture(recognizer: UIPanGestureRecognizer) {
    let translation = recognizer.translationInView(containerView)

    // Resize the image View
    let image = imageView.image!
    let hasAlpha = false
    let scale: CGFloat = 0.0

    let newRect = CGRectMake(0, 0, image.size.width - translation.x, image.size.height)
    UIGraphicsBeginImageContextWithOptions(newRect.size, !hasAlpha, scale)
    image.drawAtPoint(CGPointMake(-newRect.origin.x, -newRect.origin.y))
    let croppedImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    imageView.image = croppedImage

    recognizer.setTranslation(CGPointZero, inView: containerView)
}

这种作品。请参阅gif here（目前这只适用于左图）。

有人能指出我正确的方向吗？为什么图像高度不能保持不变，是因为contentMode设置为'Aspect Fit'？为什么只有在向左平移时才调整大小？ {4}} imageView的配置

感谢您的任何提示。

Answer 1

我按照以下方式解决了这个问题。

我将解释并发布以下代码。首先，我调整了图像大小以适应imageView。这样我就可以将contentMode设置为.Left。其次，我保留了两份图像。因此，一张图片可以从右到左裁剪，一张图片可以从左到右翻转到用户平底锅。我从上面的裁剪功能不起作用，所以我用CGImageCreateWithImageInRect(_:_:)裁剪它们。

以下是UIPanGestureRecognizer适用于我的代码：

@IBAction func handlePanGesture(recognizer: UIPanGestureRecognizer) {
    let translation = recognizer.translationInView(containerView)
    let imageLeft = googleImageView.image!
    let imageRef = CGImageCreateCopy(initiallyScaledImage?.CGImage)
    let imageRight = UIImage(CGImage: imageRef!, scale: (initiallyScaledImage?.scale)!, orientation: (initiallyScaledImage?.imageOrientation)!)

    if translation.x < 0 {
        let scale = imageLeft.scale
        let newRect = CGRectMake(0, 0, (imageLeft.size.width + translation.x) * scale, imageLeft.size.height * scale)
        let imageRef = CGImageCreateWithImageInRect(imageLeft.CGImage, newRect)

        if let croppedImage = imageRef {
            googleImageView.image = UIImage(CGImage: croppedImage, scale: scale, orientation: imageLeft.imageOrientation)
        }
    } else if translation.x > 0 {
        // Get the rect from above, add translation, set new picture
        let scale = imageRight.scale
        let newRect = CGRectMake(0, 0, (imageLeft.size.width + translation.x) * scale, imageRight.size.height * scale)
        let imageRef = CGImageCreateWithImageInRect(imageRight.CGImage, newRect)

        if let uncroppedImage = imageRef {
            googleImageView.image = UIImage(CGImage: uncroppedImage, scale: scale, orientation: imageRight.imageOrientation)
        }
    }

    recognizer.setTranslation(CGPointZero, inView: containerView)
}

使用PanGestureRecognizer在UIImageView内裁剪UIImage的右侧

1 个答案: