在 UIImageView 中旋转图像-移动开发问题

Rotate image in UIImageView(在 UIImageView 中旋转图像)

本文介绍了在 UIImageView 中旋转图像的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

是否可以只旋转 UIImageView 中的图像?我正在寻找有关它的信息，但我只找到了如何旋转 UIImageVeiw 的信息.

Is it possible to rotate only image in UIImageView? I'm looking for information about it, but i only found information how rotate UIImageVeiw.

推荐答案

您可以使用以下代码旋转图像.请注意，这使用了一个 CGImageRef，您可以通过

You can rotate the image with the following code. Note, this uses a CGImageRef which you can get from a UIImage via

CGImageRef imageRef = [self CGImageRotatedByAngle:[image CGImage] angle:30];

获得旋转后的图像后，您可以将 ImageView 的图像设置为新的旋转图像，如下所示:

Once you get the rotated image, you can set the ImageView's image to your new rotated image like this:

UIImage* img = [UIImage imageWithCGImage: imageRef];
myImageView.image = img;

这是一个旋转 imageRef 的方法:

here is a method that will rotate the imageRef:

- (CGImageRef)CGImageRotatedByAngle:(CGImageRef)imgRef angle:(CGFloat)angle
{

    CGFloat angleInRadians = angle * (M_PI / 180);
    CGFloat width = CGImageGetWidth(imgRef);
    CGFloat height = CGImageGetHeight(imgRef);

    CGRect imgRect = CGRectMake(0, 0, width, height);
    CGAffineTransform transform = CGAffineTransformMakeRotation(angleInRadians);
    CGRect rotatedRect = CGRectApplyAffineTransform(imgRect, transform);

    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

    CGContextRef bmContext = CGBitmapContextCreate(NULL,
                                                   rotatedRect.size.width,
                                                   rotatedRect.size.height,
                                                   8,
                                                   0,
                                                   colorSpace,
                                                   kCGImageAlphaPremultipliedFirst);
    CGContextSetAllowsAntialiasing(bmContext, YES);
    CGContextSetShouldAntialias(bmContext, YES);
    CGContextSetInterpolationQuality(bmContext, kCGInterpolationHigh);
    CGColorSpaceRelease(colorSpace);
    CGContextTranslateCTM(bmContext,
                          +(rotatedRect.size.width/2),
                          +(rotatedRect.size.height/2));
    CGContextRotateCTM(bmContext, angleInRadians);
    CGContextTranslateCTM(bmContext,
                          -(rotatedRect.size.width/2),
                          -(rotatedRect.size.height/2));
    CGContextDrawImage(bmContext, CGRectMake(0, 0,
                                             rotatedRect.size.width,
                                             rotatedRect.size.height),
                       imgRef);



    CGImageRef rotatedImage = CGBitmapContextCreateImage(bmContext);
    CFRelease(bmContext);
    [(id)rotatedImage autorelease];

    return rotatedImage;
}

这篇关于在 UIImageView 中旋转图像的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持编程学习网！