我深入研究了Core Animation,并在图层蒙版方面遇到了一些问题
出于研究原因,我尝试使用透明的东西制作一个复杂的UI层
此视图已放入ViewController
public class TestView : UIView
{
public TestView()
{
Layer.Delegate = this;
Frame = new CGRect(100f,200f, 100f, 100f);
}
public override void LayoutSublayersOfLayer(CALayer layer)
{
base.LayoutSublayersOfLayer(layer);
var bounds = Bounds;
var circleFrame = new CGRect(20, 20, 60, 60);
var imageFrame = new CGRect(30, 30, 40, 40);
Layer.BorderWidth = 5;
Layer.BorderColor = UIColor.Red.CGColor;
Layer.CornerRadius = 4;
var gradientLayer = new CAGradientLayer();
gradientLayer.Colors = new[] { UIColor.Green.CGColor, UIColor.Red.CGColor };
gradientLayer.Frame = bounds;
Layer.AddSublayer(gradientLayer);
var maskOfGradientLayer = new CAShapeLayer();
var path = UIBezierPath.FromRoundedRect(circleFrame, 30);
path.UsesEvenOddFillRule = true;
maskOfGradientLayer.Path = path.CGPath;
maskOfGradientLayer.FillRule = CAShapeLayer.FillRuleEvenOdd;
maskOfGradientLayer.FillColor = UIColor.Black.CGColor;
maskOfGradientLayer.Frame = bounds;
gradientLayer.Mask = maskOfGradientLayer;
var maskOfMaskLayer = new CAShapeLayer();
maskOfMaskLayer.Frame = imageFrame;
maskOfMaskLayer.FillColor = UIColor.Black.CGColor;
maskOfMaskLayer.Contents = Bundles.ImageOff.CGImage;
Layer.AddSublayer(maskOfMaskLayer);
}
}
我拥有的,这正是我想要的。
但是我也想可以使圆圈透明而不是黑色。
我试图像这样maskOfGradientLayer.Mask = maskOfMaskLayer.
但是,maskOfMaskLayer
这样无济于事!它不能像面膜一样工作。
我该怎么办?
答案 0 :(得分:0)
但是我也想可以使圆圈透明而不是黑色。
解决方案探索版:
您还可以使用 UIBezierPath 绘制所需内容,并将其设置为maskOfMaskLayer
:
var maskOfMaskLayer = new CAShapeLayer();
maskOfMaskLayer.Frame = imageFrame;
maskOfMaskLayer.FillColor = UIColor.Black.CGColor;
maskOfMaskLayer.Contents = Bundles.ImageOff.CGImage;
Layer.AddSublayer(maskOfMaskLayer);
重新添加以下代码:
UIBezierPath offCirclePath = new UIBezierPath();
// draw an arc
offCirclePath.AddArc(new CGPoint(50, 50), circleFrame.Width / 3, (nfloat)(1.75 * Math.PI), (nfloat)(1.25 * Math.PI), true);
//draw a line
offCirclePath.MoveTo(new CGPoint(50, 30));
offCirclePath.AddLineTo(new CGPoint(50, 45));
//set to maskOfMaskLayer
var maskOfMaskLayer = new CAShapeLayer();
maskOfMaskLayer.FillColor = UIColor.Clear.CGColor;
maskOfMaskLayer.Path = offCirclePath.CGPath;
maskOfMaskLayer.LineWidth = 5;
maskOfMaskLayer.StrokeColor = UIColor.White.CGColor;
maskOfMaskLayer.LineCap = new NSString("round");
Layer.AddSublayer(maskOfMaskLayer);
其他代码未更改。
但是我从一开始就考虑设置任何自定义图片。
解决方案二:(方向错误)
我已测试CAShapeLayer
不能具有此功能来更改图像的颜色。 CAShapeLayer Class
但是,我发现UIImageView
可以做到。它有一个TintColor
属性。该属性来自UiView。UIView.TintColor Property。
var maskOfMaskLayer = new CAShapeLayer();
maskOfMaskLayer.Frame = imageFrame;
maskOfMaskLayer.FillColor = UIColor.Black.CGColor;
maskOfMaskLayer.Contents = Bundles.ImageOff.CGImage;
Layer.AddSublayer(maskOfMaskLayer);
更改为:
UIImageView imageView = new UIImageView();
imageView.Frame = imageFrame;
imageView.Image = Bundles.ImageOff;
imageView.TintColor = UIColor.White;
AddSubview(imageView);
正确的解决方案:
很抱歉误解了真实的需求,我更新如下:
Layer.Mask = maskOfMaskLayer;
如果使用AddSublayer
只是覆盖了图层上的图像,而Layer.Mask
则是相反的效果,它仅显示覆盖该部分的背景,其余区域将为白色。 CALayer.Mask
答案 1 :(得分:0)
要做的全部是通过Core Graphics反转图像颜色,将任何颜色转换为透明,将任何颜色转换为透明。在这种情况下,黑色就足够了
public static UIImage GetRevertImage(UIImage image, CGRect rect, CGRect cropFrame)
{
UIGraphics.BeginImageContextWithOptions(rect.Size, false, 1);
UIColor.Black.SetColor();
UIGraphics.RectFill(rect);
image.Draw(cropFrame, CGBlendMode.DestinationOut, 1);
var newImage = UIGraphics.GetImageFromCurrentImageContext();
UIGraphics.EndImageContext();
return newImage;
}
并将遮罩层的遮罩设置为父层
Layer.Mask = maskOfMaskLayer;
代码的最终版本:
public class TestView : UIView
{
public TestView()
{
Layer.Delegate = this;
Frame = new CGRect(50f, 50f, 100f, 100f);
}
public override void LayoutSublayersOfLayer(CALayer layer)
{
base.LayoutSublayersOfLayer(layer);
var bounds = Bounds;
var circleFrame = new CGRect(20, 20, 60, 60);
var imageFrame = new CGRect(30, 30, 40, 40);
Layer.BorderWidth = 5;
Layer.BorderColor = UIColor.Red.CGColor;
Layer.CornerRadius = 4;
Layer.MasksToBounds = true;
var gradientLayer = new CAGradientLayer();
gradientLayer.Colors = new[] {UIColor.Green.CGColor, UIColor.Red.CGColor};
gradientLayer.Frame = bounds;
Layer.AddSublayer(gradientLayer);
var maskOfGradientLayer = new CAShapeLayer();
var path = UIBezierPath.FromRoundedRect(circleFrame, 30);
path.UsesEvenOddFillRule = true;
maskOfGradientLayer.Path = path.CGPath;
maskOfGradientLayer.FillRule = CAShapeLayer.FillRuleEvenOdd;
maskOfGradientLayer.FillColor = UIColor.Black.CGColor;
maskOfGradientLayer.Frame = bounds;
gradientLayer.Mask = maskOfGradientLayer;
var maskOfMaskLayer = new CALayer();
maskOfMaskLayer.Frame = bounds;
var image = UIImage.FromBundle("Turn");
var reversedImage = GetReverseImage(image, bounds, imageFrame);
maskOfMaskLayer.Contents = reversedImage.CGImage;
Layer.Mask = maskOfMaskLayer;
}
private static UIImage GetReverseImage(UIImage image, CGRect rect, CGRect cropFrame)
{
UIGraphics.BeginImageContextWithOptions(rect.Size, false, 1);
UIColor.Black.SetColor();
UIGraphics.RectFill(rect);
image.Draw(cropFrame, CGBlendMode.DestinationOut, 1);
var newImage = UIGraphics.GetImageFromCurrentImageContext();
UIGraphics.EndImageContext();
return newImage;
}
}