问题
这听起来很疯狂。我正在制作一个绘图应用程序，我希望用户能够绘制比屏幕更大或更小的图像。因此，当用户从他的照片库中选择图像时，它将被放入滚动视图中的图像视图中。用户绘制与所选图像尺寸相同的图像视图，并在另一个上方的另一个滚动视图中绘制。两个滚动视图的滚动是同步的，因此当您绘制时滚动图形显示在图像上方（在正确的位置）。然而，出于某种原因，当用户选择长图像时（例如400 x 2000），图形在图像的顶部工作，但是当您向下滚动以绘制时，您绘制的线条将显示在顶部。我无法弄清楚出了什么问题...我的代码在下面。
关于守则
cameraStill是包含图片的图片视图
drawable是图片的高度
myScroll是图片的滚动视图
mainImageView，tempImageView，undo1，undo2，undo3是绘图图层
drawScroll是绘图图层的滚动视图
图片选择
func imagePickerController(picker: UIImagePickerController, didFinishPickingImage image: UIImage!, editingInfo: [NSObject : AnyObject]!) {
self.dismissViewControllerAnimated(true, completion: { () -> Void in
})
if (image != nil) {
self.cameraStill.contentMode = UIViewContentMode.ScaleAspectFit
cameraStill.frame = CGRectMake(0, 0, screenWidth, screenWidth*(image.size.height/image.size.width))
// change uiimageivews size
mainImageView.frame = CGRectMake(0, 0, screenWidth, screenWidth*(image.size.height/image.size.width))
tempImageView.frame = CGRectMake(0, 0, screenWidth, screenWidth*(image.size.height/image.size.width))
undo1.frame = CGRectMake(0, 0, screenWidth, screenWidth*(image.size.height/image.size.width))
undo2.frame = CGRectMake(0, 0, screenWidth, screenWidth*(image.size.height/image.size.width))
undo3.frame = CGRectMake(0, 0, screenWidth, screenWidth*(image.size.height/image.size.width))
drawable = screenWidth*(image.size.height/image.size.width)
myScroll.contentSize = CGSize(width: screenWidth,height: screenWidth*(image.size.height/image.size.width))
drawScroll.contentSize = CGSize(width: screenWidth,height: screenWidth*(image.size.height/image.size.width))
if (screenWidth*(image.size.height/image.size.width) > (screenHeight-130)) {
myScroll.scrollEnabled = true
drawScroll.scrollEnabled = true
}
else {
myScroll.scrollEnabled = false
drawScroll.scrollEnabled = false
cameraStill.center = CGPoint(x: screenWidth/2, y: (screenHeight-130)/2)
mainImageView.center = CGPoint(x: screenWidth/2, y: (screenHeight-130)/2)
tempImageView.center = CGPoint(x: screenWidth/2, y: (screenHeight-130)/2)
undo1.center = CGPoint(x: screenWidth/2, y: (screenHeight-130)/2)
undo2.center = CGPoint(x: screenWidth/2, y: (screenHeight-130)/2)
undo3.center = CGPoint(x: screenWidth/2, y: (screenHeight-130)/2)
}
self.camera!.stopCamera()
}
//drawView.alpha = 1.0
}
图纸
override func touchesBegan(touches: Set<NSObject>, withEvent event: UIEvent) {
println("began")
if (drawingEnabled == true) {
c1 = 3
closeAllExtras()
swiped = false
if let touch = touches.first as? UITouch {
lastPoint = touch.locationInView(self.view)
}
}
}
func drawLineFrom(fromPoint: CGPoint, toPoint: CGPoint) {
//if (fromPoint.y > 50 && fromPoint.y < screenHeight-80 && toPoint.y > 50 && toPoint.y < screenHeight-80) {
// 1
UIGraphicsBeginImageContext(CGSize(width: view.frame.size.width,height: drawable))
let context = UIGraphicsGetCurrentContext()
tempImageView.image?.drawInRect(CGRect(x: 0, y: 0, width: view.frame.size.width, height: drawable))
// 2
CGContextMoveToPoint(context, fromPoint.x, fromPoint.y)
CGContextAddLineToPoint(context, toPoint.x, toPoint.y)
// 3
CGContextSetLineCap(context, kCGLineCapRound)
CGContextSetLineWidth(context, brushWidth)
CGContextSetRGBStrokeColor(context, red, green, blue, 1.0)
CGContextSetBlendMode(context, kCGBlendModeNormal)
// 4
CGContextStrokePath(context)
// 5
tempImageView.image = UIGraphicsGetImageFromCurrentImageContext()
tempImageView.alpha = opacity
UIGraphicsEndImageContext()
//}
}
override func touchesMoved(touches: Set<NSObject>, withEvent event: UIEvent) {
// 6
if (drawingEnabled == true) {
swiped = true
if let touch = touches.first as? UITouch {
let currentPoint = touch.locationInView(view)
drawLineFrom(lastPoint, toPoint: currentPoint)
// 7
lastPoint = currentPoint
}
}
}
func mergeViewContext(v1 : UIImageView, v2: UIImageView) {
UIGraphicsBeginImageContext(v1.frame.size)
v1.image?.drawInRect(CGRect(x: 0, y: 0, width: view.frame.size.width, height: drawable), blendMode: kCGBlendModeNormal, alpha: 1.0)
v2.image?.drawInRect(CGRect(x: 0, y: 0, width: view.frame.size.width, height: drawable), blendMode: kCGBlendModeNormal, alpha: 1.0)
v1.image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
v2.image = nil
}
override func touchesEnded(touches: Set<NSObject>, withEvent event: UIEvent) {
if (drawingEnabled == true) {
if !swiped {
// draw a single point
drawLineFrom(lastPoint, toPoint: lastPoint)
}
mergeViewContext(mainImageView, v2: undo1)
undo1.image = undo2.image
undo2.image = nil
undo2.image = undo3.image
undo3.image = nil
UIGraphicsBeginImageContext(undo3.frame.size)
undo3.image?.drawInRect(CGRect(x: 0, y: 0, width: view.frame.size.width, height: drawable), blendMode: kCGBlendModeNormal, alpha: 1.0)
tempImageView.image?.drawInRect(CGRect(x: 0, y: 0, width: view.frame.size.width, height: drawable), blendMode: kCGBlendModeNormal, alpha: opacity)
undo3.image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
tempImageView.image = nil
}
同步两个滚动视图
func scrollViewDidScroll(scrollView: UIScrollView) {
if (scrollView == drawScroll) {
var offset = scrollView.contentOffset
myScroll.setContentOffset(offset, animated: false)
}
}
答案 0 :(得分：1)
我通过使用滚动视图的偏移量更正以下值来实现它。但是，我得到了一些模糊的长图像和一个非常奇怪的错误与短的图像。不知道出了什么问题。
CGContextMoveToPoint(context, fromPoint.x, fromPoint.y)
CGContextAddLineToPoint(context, toPoint.x, toPoint.y)