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如何制作一个小的uiimage并在其上手动设置像素？

发布于 2024-10-31 20:52:59 字数 99 浏览 2 评论 0原文

对于阴影，我想制作一个 1px x 2px UIImage 并手动将像素设置为某些 RGBA 值。

我该怎么做？我不想用小 png 污染我的包。

谢谢！

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旧话新听 2024-11-07 20:52:59

这是一种方法。首先分配用 RGB 值填充的内存，然后调用“imageWithBytes”函数。

您分配的内存应该是 4*宽度*高度字节。每个像素由四个字节描述，顺序为 A、R、G、B。

完成后不要忘记释放内存！

+ (UIImage*)imageWithBytes:(unsigned char*)data size:(CGSize)size
{
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    if (colorSpace == NULL)
    {
        NSLog(@"Could not create color space");
        return nil;
    }

    CGContextRef context = CGBitmapContextCreate(
        data, size.width, size.height, 8, size.width * 4, colorSpace,
        kCGImageAlphaPremultipliedFirst);

    CGColorSpaceRelease(colorSpace);

    if (context == NULL)
    {
        NSLog(@"Could not create context");
        return nil;
    }

    CGImageRef ref = CGBitmapContextCreateImage(context);
    if (ref == NULL)
    {
        NSLog(@"Could not create image");
        return nil;
    }

    CGContextRelease(context);

    UIImage* image = [UIImage imageWithCGImage:ref];
    CFRelease(ref);

    return image;   
}

Here is a way to do it. First you allocate memory that you fill up with your RGB values, then you call the 'imageWithBytes' function.

The memory you allocate should be 4*width*height bytes. Every pixel is described by four bytes, in the order A,R,G,B.

Don't forget to free the memory when you're done!

+ (UIImage*)imageWithBytes:(unsigned char*)data size:(CGSize)size
{
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    if (colorSpace == NULL)
    {
        NSLog(@"Could not create color space");
        return nil;
    }

    CGContextRef context = CGBitmapContextCreate(
        data, size.width, size.height, 8, size.width * 4, colorSpace,
        kCGImageAlphaPremultipliedFirst);

    CGColorSpaceRelease(colorSpace);

    if (context == NULL)
    {
        NSLog(@"Could not create context");
        return nil;
    }

    CGImageRef ref = CGBitmapContextCreateImage(context);
    if (ref == NULL)
    {
        NSLog(@"Could not create image");
        return nil;
    }

    CGContextRelease(context);

    UIImage* image = [UIImage imageWithCGImage:ref];
    CFRelease(ref);

    return image;   
}

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星軌x 2024-11-07 20:52:59

UIImage 扩展：

extension UIImage {

    class func imageWithColor(color: UIColor, size: CGSize) -> UIImage {

        let rect = CGRect(origin: CGPoint.zeroPoint, size: size)

        UIGraphicsBeginImageContext(rect.size)

        let context = UIGraphicsGetCurrentContext()

        CGContextSetFillColorWithColor(context, color.CGColor)
        CGContextFillRect(context, rect)

        let image = UIGraphicsGetImageFromCurrentImageContext()

        UIGraphicsEndImageContext()

        return image

    }

}

UIImage extension:

extension UIImage {

    class func imageWithColor(color: UIColor, size: CGSize) -> UIImage {

        let rect = CGRect(origin: CGPoint.zeroPoint, size: size)

        UIGraphicsBeginImageContext(rect.size)

        let context = UIGraphicsGetCurrentContext()

        CGContextSetFillColorWithColor(context, color.CGColor)
        CGContextFillRect(context, rect)

        let image = UIGraphicsGetImageFromCurrentImageContext()

        UIGraphicsEndImageContext()

        return image

    }

}

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囚我心虐我身 2024-11-07 20:52:59

UIImageView *imageView = [[UIImageView alloc] initWithFrame:yourFrame];
imageView.backgroundColor = [UIColor colorWithRed:redValue green:greenValue blue:blueValue alpha:alphaValue];
[self.view addSubview:imageView];
[imageView release];

希望这有帮助

UIImageView *imageView = [[UIImageView alloc] initWithFrame:yourFrame];
imageView.backgroundColor = [UIColor colorWithRed:redValue green:greenValue blue:blueValue alpha:alphaValue];
[self.view addSubview:imageView];
[imageView release];

Hope this helps

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