在绘图应用swift中合并图像视图

Question

我正在开发绘图应用程序。我有三个图像视图-

imageView-包含基本图像

tempImageView-用于图形注释。drawLineFrom函数获取一个点，然后在tempImageView 上绘制线

func drawLineFrom(fromPoint: CGPoint, toPoint: CGPoint)
{
//print("drawLineFrom")
let mid1 = CGPoint(x:(prevPoint1.x + prevPoint2.x)*0.5, y:(prevPoint1.y + prevPoint2.y)*0.5)
let mid2 = CGPoint(x:(toPoint.x + prevPoint1.x)*0.5, y:(toPoint.y + prevPoint1.y)*0.5)
UIGraphicsBeginImageContextWithOptions(self.tempImageView.boundsSize, false, 0.0)
if let context = UIGraphicsGetCurrentContext()
{
tempImageView.image?.draw(in: CGRect(x: 0, y: 0, width: self.tempImageView.frame.size.width, height: self.tempImageView.frame.size.height))
let annotaionPath = UIBezierPath()
annotaionPath.move(to:  CGPoint(x: mid1.x, y: mid1.y))
annotaionPath.addQuadCurve(to: CGPoint(x:mid2.x,y:mid2.y), controlPoint: CGPoint(x:prevPoint1.x,y:prevPoint1.y))
annotaionPath.lineCapStyle = CGLineCap.round
annotaionPath.lineJoinStyle = CGLineJoin.round
annotaionPath.lineWidth = editorPanelView.brushWidth
context.setStrokeColor(editorPanelView.drawingColor.cgColor)
annotaionPath.stroke()
tempImageView.image = UIGraphicsGetImageFromCurrentImageContext()
tempImageView.alpha = editorPanelView.opacity
UIGraphicsEndImageContext()
}
}

drawingImageView-每次触摸结束方法后，我将tempImageView与drawingImage View合并，并设置tempImageView.image=nil。

override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?)
{
isDrawing = false
if !swiped
{
drawLineFrom(fromPoint: lastPoint, toPoint: lastPoint)
}
annotationArray.append(annotationsPoints)
annotationsPoints.removeAll()
// Merge tempImageView into drawingImageView
UIGraphicsBeginImageContext(drawingImageView.frame.size)
drawingImageView.image?.draw(in: CGRect(x: 0, y: 0, width: drawingImageView.frame.size.width, height: drawingImageView.frame.size.height), blendMode: CGBlendMode.normal, alpha: 1.0)
tempImageView.image?.draw(in: CGRect(x: 0, y: 0, width: drawingImageView.frame.size.width, height: drawingImageView.frame.size.height), blendMode: CGBlendMode.normal, alpha: editorPanelView.opacity)
drawingImageView.image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
tempImageView.image = nil
}

单击保存按钮时，

let drawingImage = self.drawingImageView.image
let combinedImage = self.imageView.combineWithOverlay(overlayImageView: self.drawingImageView)

我正在保存combinedImage。

问题是，当我将tempImage视图与工程图图像视图合并时，注释会变得模糊。我想保持同样的清晰。我找不到任何解决办法。任何帮助(即使只是朝着正确的方向踢(都将不胜感激。

Answer 1

我认为问题在于使用UIGraphicsBeginImageContext(drawingImageView.frame.size)。

它使用的默认比例是1.0，所以如果你使用的是视网膜屏幕，它会导致内容放大2到3倍，导致外观模糊。

您应该像在drawLineFrom中一样使用UIGraphicsBeginImageContextWithOptions，0.0将默认为屏幕比例。