UIView图层上的内部阴影效果?


92

我有以下CALayer:

CAGradientLayer *gradient = [CAGradientLayer layer];
gradient.frame = CGRectMake(8, 57, 296, 30);
gradient.cornerRadius = 3.0f;
gradient.colors = [NSArray arrayWithObjects:(id)[RGB(130, 0, 140) CGColor], (id)[RGB(108, 0, 120) CGColor], nil];
[self.layer insertSublayer:gradient atIndex:0];

我想为其添加一个内部阴影效果,但是我不确定如何执行此操作。我想我将需要绘制drawRect,但是这会在其他UIView对象的顶部添加该层,因为它应该是某些按钮后面的一个栏,所以我不知道该怎么做?

我可以添加另一层,但是同样,不确定如何实现内部阴影效果(如下所示:

在此处输入图片说明

感谢帮助...

Answers:


108

对于任何其他想知道如何根据Costique建议使用Core Graphics绘制内部阴影的人,这就是如何:(在iOS上根据需要进行调整)

在您的drawRect:方法中...

CGRect bounds = [self bounds];
CGContextRef context = UIGraphicsGetCurrentContext();
CGFloat radius = 0.5f * CGRectGetHeight(bounds);


// Create the "visible" path, which will be the shape that gets the inner shadow
// In this case it's just a rounded rect, but could be as complex as your want
CGMutablePathRef visiblePath = CGPathCreateMutable();
CGRect innerRect = CGRectInset(bounds, radius, radius);
CGPathMoveToPoint(visiblePath, NULL, innerRect.origin.x, bounds.origin.y);
CGPathAddLineToPoint(visiblePath, NULL, innerRect.origin.x + innerRect.size.width, bounds.origin.y);
CGPathAddArcToPoint(visiblePath, NULL, bounds.origin.x + bounds.size.width, bounds.origin.y, bounds.origin.x + bounds.size.width, innerRect.origin.y, radius);
CGPathAddLineToPoint(visiblePath, NULL, bounds.origin.x + bounds.size.width, innerRect.origin.y + innerRect.size.height);
CGPathAddArcToPoint(visiblePath, NULL,  bounds.origin.x + bounds.size.width, bounds.origin.y + bounds.size.height, innerRect.origin.x + innerRect.size.width, bounds.origin.y + bounds.size.height, radius);
CGPathAddLineToPoint(visiblePath, NULL, innerRect.origin.x, bounds.origin.y + bounds.size.height);
CGPathAddArcToPoint(visiblePath, NULL,  bounds.origin.x, bounds.origin.y + bounds.size.height, bounds.origin.x, innerRect.origin.y + innerRect.size.height, radius);
CGPathAddLineToPoint(visiblePath, NULL, bounds.origin.x, innerRect.origin.y);
CGPathAddArcToPoint(visiblePath, NULL,  bounds.origin.x, bounds.origin.y, innerRect.origin.x, bounds.origin.y, radius);
CGPathCloseSubpath(visiblePath);

// Fill this path
UIColor *aColor = [UIColor redColor];
[aColor setFill];
CGContextAddPath(context, visiblePath);
CGContextFillPath(context);


// Now create a larger rectangle, which we're going to subtract the visible path from
// and apply a shadow
CGMutablePathRef path = CGPathCreateMutable();
//(when drawing the shadow for a path whichs bounding box is not known pass "CGPathGetPathBoundingBox(visiblePath)" instead of "bounds" in the following line:)
//-42 cuould just be any offset > 0
CGPathAddRect(path, NULL, CGRectInset(bounds, -42, -42));

// Add the visible path (so that it gets subtracted for the shadow)
CGPathAddPath(path, NULL, visiblePath);
CGPathCloseSubpath(path);

// Add the visible paths as the clipping path to the context
CGContextAddPath(context, visiblePath); 
CGContextClip(context);         


// Now setup the shadow properties on the context
aColor = [UIColor colorWithRed:0.0f green:0.0f blue:0.0f alpha:0.5f];
CGContextSaveGState(context);
CGContextSetShadowWithColor(context, CGSizeMake(0.0f, 1.0f), 3.0f, [aColor CGColor]);   

// Now fill the rectangle, so the shadow gets drawn
[aColor setFill];   
CGContextSaveGState(context);   
CGContextAddPath(context, path);
CGContextEOFillPath(context);

// Release the paths
CGPathRelease(path);    
CGPathRelease(visiblePath);

因此,基本上有以下步骤:

  1. 创建你的道路
  2. 设置所需的填充颜色,将此路径添加到上下文中,然后填充上下文
  3. 现在创建一个更大的矩形,该矩形可以绑定可见路径。在关闭此路径之前,请添加可见路径。然后关闭路径,以便创建一个形状,并从其中减去可见路径。您可能要研究填充方法(偶数/奇数的非零缠绕),具体取决于创建这些路径的方式。本质上,要将子路径添加到一起时要使其“减去”,您需要沿相反的方向(一个顺时针方向,另一个逆时针方向)绘制(或构造)它们。
  4. 然后,您需要将可见路径设置为上下文中的剪切路径,以免在屏幕之外绘制任何内容。
  5. 然后在上下文上设置阴影,包括阴影,模糊和颜色。
  6. 然后在大形状中填充孔。颜色无关紧要,因为如果您正确完成所有操作,就不会看到此颜色,而只会看到阴影。

谢谢,但是可以调整半径吗?它当前基于边界,但是我想改为基于设置的半径(例如5.0f)。使用上面的代码,它的舍入方式太多了。
runmad

2
@runmad好吧,您可以创建所需的任何可见CGPath,此处使用的示例只是为了简洁起见而选择的示例。如果您想创建一个圆角的矩形,则可以执行以下操作:CGPath visiblePath = [UIBezierPath bezierPathWithRoundedRect:rect cornerRadius:radius] .CGPath希望有帮助。
Daniel Thorpe

4
@DanielThorpe:+1是个不错的答案。我修复了圆角的矩形路径代码(更改半径时您断了),并简化了外部矩形路径代码。希望你不要介意。
Regexident 2012年

如何从四个方向(而不只是两个方向)正确设置内部阴影?
Protocole

@Protocole,您可以将偏移量设置为{0,0},但使用阴影半径为4.f。
Daniel Thorpe

47

我知道我参加这个聚会迟到了,但这本可以帮助我在旅途中尽早找到...

为了在信用到期的地方提供信用,这本质上是对丹尼尔·索普(Daniel Thorpe)关于Costique从较大区域中减去较小区域的解决方案的详细说明的修改。此版本适用于使用图层合成而不是覆盖的用户-drawRect:

CAShapeLayer级可以用来达到同样的效果:

CAShapeLayer* shadowLayer = [CAShapeLayer layer];
[shadowLayer setFrame:[self bounds]];

// Standard shadow stuff
[shadowLayer setShadowColor:[[UIColor colorWithWhite:0 alpha:1] CGColor]];
[shadowLayer setShadowOffset:CGSizeMake(0.0f, 0.0f)];
[shadowLayer setShadowOpacity:1.0f];
[shadowLayer setShadowRadius:5];

// Causes the inner region in this example to NOT be filled.
[shadowLayer setFillRule:kCAFillRuleEvenOdd];

// Create the larger rectangle path.
CGMutablePathRef path = CGPathCreateMutable();
CGPathAddRect(path, NULL, CGRectInset(bounds, -42, -42));

// Add the inner path so it's subtracted from the outer path.
// someInnerPath could be a simple bounds rect, or maybe
// a rounded one for some extra fanciness.
CGPathAddPath(path, NULL, someInnerPath);
CGPathCloseSubpath(path);

[shadowLayer setPath:path];
CGPathRelease(path);

[[self layer] addSublayer:shadowLayer];

在这一点上,如果您的父层没有对它的边界进行遮罩,您将看到遮罩层边缘周围的额外区域。如果您直接复制示例,这将是42像素的黑色。为了摆脱它,您可以简单地使用CAShapeLayer具有相同路径的另一个并将其设置为阴影层的蒙版:

CAShapeLayer* maskLayer = [CAShapeLayer layer];
[maskLayer setPath:someInnerPath];
[shadowLayer setMask:maskLayer];

我自己尚未对此进行基准测试,但我怀疑将这种方法与栅格化结合使用比覆盖更有效-drawRect:


3
someInnerPath?您能否再解释一下。
Moe 2012年

4
@Moe可以是您想要的任意CGPath。[[UIBezierPath pathWithRect:[shadowLayer bounds]] CGPath]是最简单的选择。
Matt Wilding

为此Matt欢呼:-)
Moe 2012年

我正在为shadowLayer.path得到一个黑色(外部)矩形,可以正确绘制内部阴影。我如何摆脱它(黑色的外部矩形)?看起来您只能在上下文中设置fillColor,并且您不使用它。
奥利维尔,2012年

11
这很好用!我上传了一些内容到github。试试看:) github.com/inamiy/YIInnerShadowView
inamiy 2012年

35

可以通过以下方法在Core Graphics中绘制内部阴影:在边界外制作一个大的矩形路径,减去边界大小的矩形路径,然后在生成的路径上填充“正常”阴影。

但是,由于您需要将其与渐变层结合使用,因此我认为一个更简单的解决方案是为内部阴影创建一个由9个部分组成的透明PNG图像,并将其拉伸为合适的大小。由9个部分组成的阴影图像如下所示(其大小为21x21像素):

替代文字

CALayer *innerShadowLayer = [CALayer layer];
innerShadowLayer.contents = (id)[UIImage imageNamed: @"innershadow.png"].CGImage;
innerShadowLayer.contentsCenter = CGRectMake(10.0f/21.0f, 10.0f/21.0f, 1.0f/21.0f, 1.0f/21.0f);

然后设置innerShadowLayer的框架,它应该适当地拉伸阴影。


是的,我想你是对的。只是希望该层尽可能平坦。我可以在Photoshop中使用内部阴影和渐变外观创建图像,使用图像时,我只是遇到颜色与设备上的颜色匹配高达100%的问题。
runmad 2010年

是的,这是所有渐变和阴影的问题,我无法尝试在iOS上重现这些Photoshop效果1:1。
Costique 2010年

29

在Swift中仅使用CALayer的简化版本:

import UIKit

final class FrameView : UIView {
    init() {
        super.init(frame: CGRect.zero)
        backgroundColor = UIColor.white
    }

    @available(*, unavailable)
    required init?(coder decoder: NSCoder) { fatalError("unavailable") }

    override func layoutSubviews() {
        super.layoutSubviews()
        addInnerShadow()
    }

    private func addInnerShadow() {
        let innerShadow = CALayer()
        innerShadow.frame = bounds
        // Shadow path (1pt ring around bounds)
        let path = UIBezierPath(rect: innerShadow.bounds.insetBy(dx: -1, dy: -1))
        let cutout = UIBezierPath(rect: innerShadow.bounds).reversing()
        path.append(cutout)
        innerShadow.shadowPath = path.cgPath
        innerShadow.masksToBounds = true
        // Shadow properties
        innerShadow.shadowColor = UIColor(white: 0, alpha: 1).cgColor // UIColor(red: 0.71, green: 0.77, blue: 0.81, alpha: 1.0).cgColor
        innerShadow.shadowOffset = CGSize.zero
        innerShadow.shadowOpacity = 1
        innerShadow.shadowRadius = 3
        // Add
        layer.addSublayer(innerShadow)
    }
}

请注意,innerShadow层不应具有不透明的背景颜色,因为它将在阴影前面呈现。


最后一行包含“图层”。这是哪里来的?
查理·塞利格曼

@CharlieSeligman这是父层,可以是任何层。您可以使用自定义图层或视图图层(UIView具有layer属性)。
Patrick Pijnappel

应该是let innerShadow = CALayer(); innerShadow.frame = bounds。没有适当的界限,就不会画出适当的阴影。无论如何
haik.ampardjian

@noir_eagle是的,虽然您可能想要设置它以layoutSubviews()使其保持同步
Patrick Pijnappel

对!无论在里面layoutSubviews()还是在里面draw(_ rect)
haik.ampardjian

24

有点a回,但它避免了使用图像(阅读:易于更改颜色,阴影半径等),并且仅几行代码。

  1. 添加一个UIImageView作为要放置阴影的UIView的第一个子视图。我使用IB,但是您可以通过编程来执行相同的操作。

  2. 假设对UIImageView的引用是“ innerShadow”

`

[[innerShadow layer] setMasksToBounds:YES];
[[innerShadow layer] setCornerRadius:12.0f];        
[[innerShadow layer] setBorderColor:[UIColorFromRGB(180, 180, 180) CGColor]];
[[innerShadow layer] setBorderWidth:1.0f];
[[innerShadow layer] setShadowColor:[UIColorFromRGB(0, 0, 0) CGColor]];
[[innerShadow layer] setShadowOffset:CGSizeMake(0, 0)];
[[innerShadow layer] setShadowOpacity:1];
[[innerShadow layer] setShadowRadius:2.0];

警告:您必须有边框,否则阴影不会出现。[UIColor clearColor]不起作用。在示例中,我使用了不同的颜色,但是您可以将其弄乱以使其具有与阴影开始处相同的颜色。:)

请参阅下面有关UIColorFromRGB宏的bbrame注释。


我省略了它,但假设您会在添加imageview的过程中执行此操作-确保将框架设置为与父UIView相同的矩形。如果使用的是IB,则要更改父视图的框架,请正确设置支柱和弹簧以使视图具有阴影大小。在代码中,应该有一个调整大小的蒙版,您可以或者做同样的事情,AFAIK。
jinglesthula 2011年

这是目前最简单的方法,但是请注意,CALayer阴影方法仅在iOS 3.2及更高版本中可用。我支持3.1,所以我将这些属性设置为if([layer
responsesToSelector

这似乎对我不起作用。至少在xcode 4.2和ios模拟器4.3上。要使阴影出现,我必须添加背景色...,此时阴影仅出现在外部。
Andrea

@Andrea-请记住我上面提到的警告。我认为背景颜色或边框可能具有“给它添加阴影的效果”相同的效果。至于它出现在外部,如果UIImageView不是该视图的子视图,则您可能希望它的内部阴影是它-我必须查看您的代码才能看到。
jinglesthula 2011年

只是为了纠正我以前的声明...代码实际上起作用了...我丢失了一些东西,但不幸的是我现在不记得了。:)所以...感谢您分享此代码段。
Andrea

17

迟到总比不到好...

这是另一种方法,可能不会比已经发布的方法更好,但是它很好而且很简单-

-(void)drawInnerShadowOnView:(UIView *)view
{
    UIImageView *innerShadowView = [[UIImageView alloc] initWithFrame:view.bounds];

    innerShadowView.contentMode = UIViewContentModeScaleToFill;
    innerShadowView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;

    [view addSubview:innerShadowView];

    [innerShadowView.layer setMasksToBounds:YES];

    [innerShadowView.layer setBorderColor:[UIColor lightGrayColor].CGColor];
    [innerShadowView.layer setShadowColor:[UIColor blackColor].CGColor];
    [innerShadowView.layer setBorderWidth:1.0f];

    [innerShadowView.layer setShadowOffset:CGSizeMake(0, 0)];
    [innerShadowView.layer setShadowOpacity:1.0];

    // this is the inner shadow thickness
    [innerShadowView.layer setShadowRadius:1.5];
}

@SomaMan是否可以只设置特定侧面的阴影?就像只有在顶或顶部/底部或顶部/右等
Mitesh Dobareeya

8

代替通过drawRect绘制内部阴影或将UIView添加到View。您可以直接将CALayer添加到边框,例如:如果我想要UIView V底部的内部阴影效果。

innerShadowOwnerLayer = [[CALayer alloc]init];
innerShadowOwnerLayer.frame = CGRectMake(0, V.frame.size.height+2, V.frame.size.width, 2);
innerShadowOwnerLayer.backgroundColor = [UIColor whiteColor].CGColor;

innerShadowOwnerLayer.shadowColor = [UIColor blackColor].CGColor;
innerShadowOwnerLayer.shadowOffset = CGSizeMake(0, 0);
innerShadowOwnerLayer.shadowRadius = 10.0;
innerShadowOwnerLayer.shadowOpacity = 0.7;

[V.layer addSubLayer:innerShadowOwnerLayer];

这为目标UIView添加了底部内部阴影


6

这是迅速,变化startPointendPoint相互融合的版本。

        let layer = CAGradientLayer()
        layer.startPoint    = CGPointMake(0.5, 0.0);
        layer.endPoint      = CGPointMake(0.5, 1.0);
        layer.colors        = [UIColor(white: 0.1, alpha: 1.0).CGColor, UIColor(white: 0.1, alpha: 0.5).CGColor, UIColor.clearColor().CGColor]
        layer.locations     = [0.05, 0.2, 1.0 ]
        layer.frame         = CGRectMake(0, 0, self.view.frame.width, 60)
        self.view.layer.insertSublayer(layer, atIndex: 0)

为我工作!谢谢。
iUser

5

这是您的解决方案,我已经从PaintCode导出了该解决方案:

-(void) drawRect:(CGRect)rect
{
    CGContextRef context = UIGraphicsGetCurrentContext();

    //// Shadow Declarations
    UIColor* shadow = UIColor.whiteColor;
    CGSize shadowOffset = CGSizeMake(0, 0);
    CGFloat shadowBlurRadius = 10;

    //// Rectangle Drawing
    UIBezierPath* rectanglePath = [UIBezierPath bezierPathWithRect: self.bounds];
    [[UIColor blackColor] setFill];
    [rectanglePath fill];

    ////// Rectangle Inner Shadow
    CGContextSaveGState(context);
    UIRectClip(rectanglePath.bounds);
    CGContextSetShadowWithColor(context, CGSizeZero, 0, NULL);

    CGContextSetAlpha(context, CGColorGetAlpha([shadow CGColor]));
    CGContextBeginTransparencyLayer(context, NULL);
    {
        UIColor* opaqueShadow = [shadow colorWithAlphaComponent: 1];
        CGContextSetShadowWithColor(context, shadowOffset, shadowBlurRadius, [opaqueShadow CGColor]);
        CGContextSetBlendMode(context, kCGBlendModeSourceOut);
        CGContextBeginTransparencyLayer(context, NULL);

        [opaqueShadow setFill];
        [rectanglePath fill];

        CGContextEndTransparencyLayer(context);
    }
    CGContextEndTransparencyLayer(context);
    CGContextRestoreGState(context);
}

3

我参加聚会很晚,但是我想回馈社区。.这是我写的一种方法,因为我提供了静态库而没有资源,所以删除了UITextField背景图像...我将其用于一个包含四个UITextField实例的PIN输入屏幕,该实例可以在ViewController中显示一个字符原始或(BOOL)[self isUsingBullets]或(BOOL)[self usingAsterisks]。该应用程序适用于iPhone / iPhone视网膜/ iPad / iPad视网膜,因此我不必提供四张图像...

#import <QuartzCore/QuartzCore.h>

- (void)setTextFieldInnerGradient:(UITextField *)textField
{

    [textField setSecureTextEntry:self.isUsingBullets];
    [textField setBackgroundColor:[UIColor blackColor]];
    [textField setTextColor:[UIColor blackColor]];
    [textField setBorderStyle:UITextBorderStyleNone];
    [textField setClipsToBounds:YES];

    [textField.layer setBorderColor:[[UIColor blackColor] CGColor]];
    [textField.layer setBorderWidth:1.0f];

    // make a gradient off-white background
    CAGradientLayer *gradient = [CAGradientLayer layer];
    CGRect gradRect = CGRectInset([textField bounds], 3, 3);    // Reduce Width and Height and center layer
    gradRect.size.height += 2;  // minimise Bottom shadow, rely on clipping to remove these 2 pts.

    gradient.frame = gradRect;
    struct CGColor *topColor = [UIColor colorWithWhite:0.6f alpha:1.0f].CGColor;
    struct CGColor *bottomColor = [UIColor colorWithWhite:0.9f alpha:1.0f].CGColor;
    // We need to use this fancy __bridge object in order to get the array we want.
    gradient.colors = [NSArray arrayWithObjects:(__bridge id)topColor, (__bridge id)bottomColor, nil];
    [gradient setCornerRadius:4.0f];
    [gradient setShadowOffset:CGSizeMake(0, 0)];
    [gradient setShadowColor:[[UIColor whiteColor] CGColor]];
    [gradient setShadowOpacity:1.0f];
    [gradient setShadowRadius:3.0f];

    // Now we need to Blur the edges of this layer "so it blends"
    // This rasterizes the view down to 4x4 pixel chunks then scales it back up using bilinear filtering...
    // it's EXTREMELY fast and looks ok if you are just wanting to blur a background view under a modal view.
    // To undo it, just set the rasterization scale back to 1.0 or turn off rasterization.
    [gradient setRasterizationScale:0.25];
    [gradient setShouldRasterize:YES];

    [textField.layer insertSublayer:gradient atIndex:0];

    if (self.usingAsterisks) {
        [textField setFont:[UIFont systemFontOfSize:80.0]];
    } else {
        [textField setFont:[UIFont systemFontOfSize:40.0]];
    }
    [textField setTextAlignment:UITextAlignmentCenter];
    [textField setEnabled:NO];
}

我希望这对某人有所帮助,因为这个论坛对我有所帮助。


3

检查的大文章中石英内阴影克里斯·埃默里至极解释了内阴影如何绘制PaintCode并给出了一个干净整洁的代码片段:

- (void)drawInnerShadowInContext:(CGContextRef)context
                        withPath:(CGPathRef)path
                     shadowColor:(CGColorRef)shadowColor
                          offset:(CGSize)offset
                      blurRadius:(CGFloat)blurRadius 
{
    CGContextSaveGState(context);

    CGContextAddPath(context, path);
    CGContextClip(context);

    CGColorRef opaqueShadowColor = CGColorCreateCopyWithAlpha(shadowColor, 1.0);

    CGContextSetAlpha(context, CGColorGetAlpha(shadowColor));
    CGContextBeginTransparencyLayer(context, NULL);
        CGContextSetShadowWithColor(context, offset, blurRadius, opaqueShadowColor);
        CGContextSetBlendMode(context, kCGBlendModeSourceOut);
        CGContextSetFillColorWithColor(context, opaqueShadowColor);
        CGContextAddPath(context, path);
        CGContextFillPath(context);
    CGContextEndTransparencyLayer(context);

    CGContextRestoreGState(context);

    CGColorRelease(opaqueShadowColor);
}

3

这是我在Swift 4.2中的解决方案。你想试试吗?

final class ACInnerShadowLayer : CAShapeLayer {

  var innerShadowColor: CGColor? = UIColor.black.cgColor {
    didSet { setNeedsDisplay() }
  }

  var innerShadowOffset: CGSize = .zero {
    didSet { setNeedsDisplay() }
  }

  var innerShadowRadius: CGFloat = 8 {
    didSet { setNeedsDisplay() }
  }

  var innerShadowOpacity: Float = 1 {
    didSet { setNeedsDisplay() }
  }

  override init() {
    super.init()

    masksToBounds = true
    contentsScale = UIScreen.main.scale

    setNeedsDisplay()
  }

  override init(layer: Any) {
      if let layer = layer as? InnerShadowLayer {
          innerShadowColor = layer.innerShadowColor
          innerShadowOffset = layer.innerShadowOffset
          innerShadowRadius = layer.innerShadowRadius
          innerShadowOpacity = layer.innerShadowOpacity
      }
      super.init(layer: layer)
  }

  required init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
  }

  override func draw(in ctx: CGContext) {
    ctx.setAllowsAntialiasing(true)
    ctx.setShouldAntialias(true)
    ctx.interpolationQuality = .high

    let colorspace = CGColorSpaceCreateDeviceRGB()

    var rect = bounds
    var radius = cornerRadius

    if borderWidth != 0 {
      rect = rect.insetBy(dx: borderWidth, dy: borderWidth)
      radius -= borderWidth
      radius = max(radius, 0)
    }

    let innerShadowPath = UIBezierPath(roundedRect: rect, cornerRadius: radius).cgPath
    ctx.addPath(innerShadowPath)
    ctx.clip()

    let shadowPath = CGMutablePath()
    let shadowRect = rect.insetBy(dx: -rect.size.width, dy: -rect.size.width)
    shadowPath.addRect(shadowRect)
    shadowPath.addPath(innerShadowPath)
    shadowPath.closeSubpath()

    if let innerShadowColor = innerShadowColor, let oldComponents = innerShadowColor.components {
      var newComponets = Array<CGFloat>(repeating: 0, count: 4) // [0, 0, 0, 0] as [CGFloat]
      let numberOfComponents = innerShadowColor.numberOfComponents

      switch numberOfComponents {
      case 2:
        newComponets[0] = oldComponents[0]
        newComponets[1] = oldComponents[0]
        newComponets[2] = oldComponents[0]
        newComponets[3] = oldComponents[1] * CGFloat(innerShadowOpacity)
      case 4:
        newComponets[0] = oldComponents[0]
        newComponets[1] = oldComponents[1]
        newComponets[2] = oldComponents[2]
        newComponets[3] = oldComponents[3] * CGFloat(innerShadowOpacity)
      default:
        break
      }

      if let innerShadowColorWithMultipliedAlpha = CGColor(colorSpace: colorspace, components: newComponets) {
        ctx.setFillColor(innerShadowColorWithMultipliedAlpha)
        ctx.setShadow(offset: innerShadowOffset, blur: innerShadowRadius, color: innerShadowColorWithMultipliedAlpha)
        ctx.addPath(shadowPath)
        ctx.fillPath(using: .evenOdd)
      }
    } 
  }
}

如果我没有将其用作单独的类,而是像在我的代码中使用那样,当我得到以下信息时,上下文(ctx)为零:let ctx = UIGraphicsGetCurrentContext
Mohsin Khubaib Ahmed 18/12/1

@MohsinKhubaibAhmed UIGraphicsGetCurrentContext 当某些视图将其上下文推入堆栈时,可以按方法获取当前上下文以进行获取。
阿科

@Arco旋转设备时遇到了一些麻烦。我添加了“覆盖便利init(layer:Any){self.init()}”。现在没有错误显示!
Yuma Technical Inc.

添加了init(layer:Any)来修复崩溃。
Nik Kov

2

在Swift中使用CALayer的可扩展解决方案

随着描述 InnerShadowLayer您还可以仅对特定边缘(不包括其他边缘)启用内部阴影。(例如,您只能在视图的左侧和顶部边缘启用内部阴影)

然后InnerShadowLayer,您可以使用以下方法将a添加到视图中:

init(...) {

    // ... your initialization code ...

    super.init(frame: .zero)
    layer.addSublayer(shadowLayer)
}

public override func layoutSubviews() {
    super.layoutSubviews()
    shadowLayer.frame = bounds
}

InnerShadowLayer 实施

/// Shadow is a struct defining the different kinds of shadows
public struct Shadow {
    let x: CGFloat
    let y: CGFloat
    let blur: CGFloat
    let opacity: CGFloat
    let color: UIColor
}

/// A layer that applies an inner shadow to the specified edges of either its path or its bounds
public class InnerShadowLayer: CALayer {
    private let shadow: Shadow
    private let edge: UIRectEdge

    public init(shadow: Shadow, edge: UIRectEdge) {
        self.shadow = shadow
        self.edge = edge
        super.init()
        setupShadow()
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    public override func layoutSublayers() {
        updateShadow()
    }

    private func setupShadow() {
        shadowColor = shadow.color.cgColor
        shadowOpacity = Float(shadow.opacity)
        shadowRadius = shadow.blur / 2.0
        masksToBounds = true
    }

    private func updateShadow() {
        shadowOffset = {
            let topWidth: CGFloat = 0
            let leftWidth = edge.contains(.left) ? shadow.y / 2 : 0
            let bottomWidth: CGFloat = 0
            let rightWidth = edge.contains(.right) ? -shadow.y / 2 : 0

            let topHeight = edge.contains(.top) ? shadow.y / 2 : 0
            let leftHeight: CGFloat = 0
            let bottomHeight = edge.contains(.bottom) ? -shadow.y / 2 : 0
            let rightHeight: CGFloat = 0

            return CGSize(width: [topWidth, leftWidth, bottomWidth, rightWidth].reduce(0, +),
                          height: [topHeight, leftHeight, bottomHeight, rightHeight].reduce(0, +))
        }()

        let insets = UIEdgeInsets(top: edge.contains(.top) ? -bounds.height : 0,
                                  left: edge.contains(.left) ? -bounds.width : 0,
                                  bottom: edge.contains(.bottom) ? -bounds.height : 0,
                                  right: edge.contains(.right) ? -bounds.width : 0)
        let path = UIBezierPath(rect: bounds.inset(by: insets))
        let cutout = UIBezierPath(rect: bounds).reversing()
        path.append(cutout)
        shadowPath = path.cgPath
    }
}

1

这段代码对我有用

class InnerDropShadowView: UIView {
    override func draw(_ rect: CGRect) {
        //Drawing code
        let context = UIGraphicsGetCurrentContext()
        //// Shadow Declarations
        let shadow: UIColor? = UIColor.init(hexString: "a3a3a3", alpha: 1.0) //UIColor.black.withAlphaComponent(0.6) //UIColor.init(hexString: "d7d7da", alpha: 1.0)
        let shadowOffset = CGSize(width: 0, height: 0)
        let shadowBlurRadius: CGFloat = 7.5
        //// Rectangle Drawing
        let rectanglePath = UIBezierPath(rect: bounds)
        UIColor.groupTableViewBackground.setFill()
        rectanglePath.fill()
        ////// Rectangle Inner Shadow
        context?.saveGState()
        UIRectClip(rectanglePath.bounds)
        context?.setShadow(offset: CGSize.zero, blur: 0, color: nil)
        context?.setAlpha((shadow?.cgColor.alpha)!)
        context?.beginTransparencyLayer(auxiliaryInfo: nil)
        do {
            let opaqueShadow: UIColor? = shadow?.withAlphaComponent(1)
            context?.setShadow(offset: shadowOffset, blur: shadowBlurRadius, color: opaqueShadow?.cgColor)
            context!.setBlendMode(.sourceOut)
            context?.beginTransparencyLayer(auxiliaryInfo: nil)
            opaqueShadow?.setFill()
            rectanglePath.fill()
            context!.endTransparencyLayer()
        }
        context!.endTransparencyLayer()
        context?.restoreGState()
    }
}

0

有一些代码在这里可以为你做这个。如果将视图中的图层(通过覆盖+ (Class)layerClass)更改为JTAInnerShadowLayer,则可以在init方法中将缩进图层上的内部阴影设置好,它将为您完成工作。如果您还想绘制原始内容,请确保setDrawOriginalImage:yes在缩进层上调用。有一个关于如何工作的一个博客帖子在这里


@MiteshDobareeya刚刚测试了两个链接,它们似乎工作正常(包括在私有选项卡中)。哪个链接导致了您的问题?
James Snook

您能否看一下内部影子代码的这种实现。它仅在ViewDidAppear方法中工作。并显示一些闪烁。drive.google.com/open?id=1VtCt7UFYteq4UteT0RoFRjMfFnbibD0E
Mitesh Dobareeya

0

使用渐变层:

UIView * mapCover = [UIView new];
mapCover.frame = map.frame;
[view addSubview:mapCover];

CAGradientLayer * vertical = [CAGradientLayer layer];
vertical.frame = mapCover.bounds;
vertical.colors = [NSArray arrayWithObjects:(id)[UIColor whiteColor].CGColor,
                        (id)[[UIColor whiteColor] colorWithAlphaComponent:0.0f].CGColor,
                        (id)[[UIColor whiteColor] colorWithAlphaComponent:0.0f].CGColor,
                        (id)[UIColor whiteColor].CGColor, nil];
vertical.locations = @[@0.01,@0.1,@0.9,@0.99];
[mapCover.layer insertSublayer:vertical atIndex:0];

CAGradientLayer * horizontal = [CAGradientLayer layer];
horizontal.frame = mapCover.bounds;
horizontal.colors = [NSArray arrayWithObjects:(id)[UIColor whiteColor].CGColor,
                     (id)[[UIColor whiteColor] colorWithAlphaComponent:0.0f].CGColor,
                     (id)[[UIColor whiteColor] colorWithAlphaComponent:0.0f].CGColor,
                     (id)[UIColor whiteColor].CGColor, nil];
horizontal.locations = @[@0.01,@0.1,@0.9,@0.99];
horizontal.startPoint = CGPointMake(0.0, 0.5);
horizontal.endPoint = CGPointMake(1.0, 0.5);
[mapCover.layer insertSublayer:horizontal atIndex:0];

0

有一个简单的解决方案-只需绘制法线阴影并旋转即可,就像这样

@objc func shadowView() -> UIView {
        let shadowView = UIView(frame: .zero)
        shadowView.backgroundColor = .white
        shadowView.layer.shadowColor = UIColor.grey.cgColor
        shadowView.layer.shadowOffset = CGSize(width: 0, height: 2)
        shadowView.layer.shadowOpacity = 1.0
        shadowView.layer.shadowRadius = 4
        shadowView.layer.compositingFilter = "multiplyBlendMode"
        return shadowView
    }

func idtm_addBottomShadow() {
        let shadow = shadowView()
        shadow.transform = transform.rotated(by: 180 * CGFloat(Double.pi))
        shadow.transform = transform.rotated(by: -1 * CGFloat(Double.pi))
        shadow.translatesAutoresizingMaskIntoConstraints = false
        addSubview(shadow)
        NSLayoutConstraint.activate([
            shadow.leadingAnchor.constraint(equalTo: leadingAnchor),
            shadow.trailingAnchor.constraint(equalTo: trailingAnchor),
            shadow.bottomAnchor.constraint(equalTo: bottomAnchor),
            shadow.heightAnchor.constraint(equalToConstant: 1),
            ])
    }
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