UIImage分类调整大小，旋转等

最新推荐文章于 2021-03-10 09:09:16 发布

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本文演示了如何使用Objective-C编程语言绘制一个圆形，并通过旋转实现动态效果。包括使用CAKeyframeAnimation进行路径动画设置，以及利用UIKit框架中的方法进行图形绘制与旋转操作。

CGFloat degreesToRadians(CGFloat degrees)
{
    return degrees * M_PI / 180;
};

@interface UIImage (Rotate)

- (UIImage *)imageRotatedByDegrees:(CGFloat)degrees;

@end

@implementation UIImage (Rotate)

- (UIImage *)imageRotatedByDegrees:(CGFloat)degrees
{
    UIView *rotatedViewBox = [[UIView alloc] initWithFrame:CGRectMake(0, 0, self.size.width, self.size.height)];
    CGAffineTransform t = CGAffineTransformMakeRotation(degreesToRadians(degrees));
    rotatedViewBox.transform = t;
    CGSize rotatedSize = rotatedViewBox.frame.size;
    
    UIGraphicsBeginImageContext(rotatedSize);
    CGContextRef bitmap = UIGraphicsGetCurrentContext();
    
    CGContextTranslateCTM(bitmap, rotatedSize.width / 2, rotatedSize.height / 2);
    
    CGContextRotateCTM(bitmap, degreesToRadians(degrees));
    
    CGContextScaleCTM(bitmap, 1.0, -1.0);
    CGContextDrawImage(bitmap, CGRectMake(-self.size.width / 2, -self.size.height / 2, self.size.width, self.size.height), [self CGImage]);
    
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return newImage;
}

@end

- (UIImage *)resizeImage:(UIImage *)image scaledToSize:(CGSize)newSize
{
    UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
    [image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return newImage;
}

以下为绘制一个圆形，然后生成一个UIImageView，测试代码：

//start...

CAKeyframeAnimation* animation;
    animation = [CAKeyframeAnimation animation];	
	CGMutablePathRef path = CGPathCreateMutable();
	NSLog(@"原点%f, 原点%f",imgview.layer.position.x,imgview.layer.position.y);
	CGPathMoveToPoint(path, NULL,imgview.layer.position.x,imgview.layer.position.y);
	
	int p =  (int)[self getblank:tag];
	NSLog(@"旋转%d, num:%d", p, (int)num);
	float f = 2.0*M_PI  - 2.0*M_PI *p/PHOTONUM;
	float h = f + 2.0*M_PI *num/PHOTONUM;
	float centery = self.view.center.y - DY;
	float centerx = self.view.center.x;
	float tmpy = centery + RADIUS*cos(h);
	float tmpx = centerx - RADIUS*sin(h);
	imgview.center = CGPointMake(tmpx,tmpy);
    
	CGPathAddArc(path, nil, self.view.center.x, self.view.center.y - DY, RADIUS, f+ M_PI/2, f+ M_PI/2 + 2.0*M_PI *num/PHOTONUM,0);
    animation.path = path;
    
    //test start
    UIGraphicsBeginImageContext(self.view.bounds.size);
    CGContextRef gc = UIGraphicsGetCurrentContext();
    CGContextAddPath(gc, path);
    [[UIColor colorWithRed:(arc4random()%255/255) green:(arc4random()%255/255) blue:(arc4random()%255/255) alpha:1.0] setStroke];
    CGContextSetLineWidth(gc, 2);
    CGContextDrawPath(gc, kCGPathStroke);
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    UIImageView *imgview2 = [[UIImageView alloc] initWithImage:image];
    [self.view addSubview:imgview2];
    //test end
    
    CGPathRelease(path);

//end...