如何向 UIImage 或 UIImageView 或 UIView 添加外发光

发布于 2024-08-21 19:27:07 字数 161 浏览 5 评论 0原文

我想向 UIImage/UIImageView/UIView 添加褪色阴影/外发光，但我不知道 Core Graphics 完全没有。

编辑： 请帮助！

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梦罢 2024-08-28 19:27:07

采用 Cirrostratus 概述的方法，保留其缓存副本，然后在拖动时应用变换来更改图像的大小和/或位置。

（警告，这不是功能/测试代码，但应该让您开始）

-(UIImage*)addGlowToImage:(UIImage*)imageInput;
{
    CGRect newSize = imageInput.bounds;
    CGImageRef theImage = imageInput.CGImage;

    // expand the size to handle the "glow"
    newSize.size.width += 6.0;
    newSize.size.height += 6.0;
    UIGraphicsBeginImageContext(newSize);
    CGContextRef ctx = UIGraphicsGetCurrentContext();

    CGContextBeginTransparencyLayerWithRect(ctx, newSize, NULL);
    CGContextClearRect(ctx, newSize);

    // you can repeat this process to build glow.
    CGContextDrawImage(ctx, newSize, theImage); 
    CGContextSetAlpha(ctx, 0.2);  

    CGContextEndTransparencyLayer(ctx);

    // draw the original image into the context, offset to be centered;
    CGRect centerRect = inputImage.bounds;
    centerRect.origin.x += 3.0;
    centerRect.origin.y += 3.0;
    CGContextDrawImage(ctx, centerRect, theImage);

    result = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return result;
}

然后在您的方法中，在缩放时您会执行以下操作：

// assumes UIImage *cachedImage = [self addGlowToImage:origImage]; has been called already.
// assumes ivars for scale exists

    CGRect newRect = cachedImage.bounds;
    newRect.size.width += scale;
    newRect.size.height += scale;

    [cachedImage drawInRect:newRect];  // image will be scaled to fill destination rectangle.

一定要看看苹果文档。一个好的起点是 Quartz 2D 编程指南< /a>.

Take the approach outlined by Cirrostratus, keep a cached copy of it, and then apply a transform to change the size and/or position of the image while dragging.

(warning, this is not functional/tested code, but should get you started)

-(UIImage*)addGlowToImage:(UIImage*)imageInput;
{
    CGRect newSize = imageInput.bounds;
    CGImageRef theImage = imageInput.CGImage;

    // expand the size to handle the "glow"
    newSize.size.width += 6.0;
    newSize.size.height += 6.0;
    UIGraphicsBeginImageContext(newSize);
    CGContextRef ctx = UIGraphicsGetCurrentContext();

    CGContextBeginTransparencyLayerWithRect(ctx, newSize, NULL);
    CGContextClearRect(ctx, newSize);

    // you can repeat this process to build glow.
    CGContextDrawImage(ctx, newSize, theImage); 
    CGContextSetAlpha(ctx, 0.2);  

    CGContextEndTransparencyLayer(ctx);

    // draw the original image into the context, offset to be centered;
    CGRect centerRect = inputImage.bounds;
    centerRect.origin.x += 3.0;
    centerRect.origin.y += 3.0;
    CGContextDrawImage(ctx, centerRect, theImage);

    result = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return result;
}

Then in your method while scaling you would do something like:

// assumes UIImage *cachedImage = [self addGlowToImage:origImage]; has been called already.
// assumes ivars for scale exists

    CGRect newRect = cachedImage.bounds;
    newRect.size.width += scale;
    newRect.size.height += scale;

    [cachedImage drawInRect:newRect];  // image will be scaled to fill destination rectangle.

Definitely take a look at the apple docs. A good starting place is the Quartz 2D Programming Guide.

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夏日浅笑〃 2024-08-28 19:27:07

你可以使用这个，简单快捷，这可以使用 uiview、unbutton 等：

UIView *shadowView = [[UIView alloc] initWithFrame:CGRectMake(100, 66, 112, 112)];
shadowView.layer.shadowColor = [[UIColor blackColor] CGColor];
shadowView.layer.shadowOpacity = .4;
shadowView.layer.shadowOffset = CGSizeZero;
shadowView.layer.masksToBounds = NO;

如果你可以使用收音机，请添加以下内容：

shadowView.layer.shadowRadius = 10.0f;

You can use this, simple and fast, this works using uiview, unbutton, etc:

UIView *shadowView = [[UIView alloc] initWithFrame:CGRectMake(100, 66, 112, 112)];
shadowView.layer.shadowColor = [[UIColor blackColor] CGColor];
shadowView.layer.shadowOpacity = .4;
shadowView.layer.shadowOffset = CGSizeZero;
shadowView.layer.masksToBounds = NO;

if, you can use radios, add this:

shadowView.layer.shadowRadius = 10.0f;

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女中豪杰 2024-08-28 19:27:07

出于性能考虑，iPhone OS 不支持通常可以在 Cocoa 中使用的shadowColor、shadowOffset、shadowOpacity 和shadowRadius 属性。大多数人会多次复制他们想要发光的形状，每次都会降低不透明度并每次偏移一个像素以模拟发光的外观。如果您的辉光不需要很大，您就无法分辨出差异。

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