UIImageView 动画 / UIImage 方向

UIImage 方向

UIImage imageOrientation是相对当前屏幕的横竖屏来判断方向

如果本身是横屏, 照片也是横屏的话, 方向是正方向

        

        

BOOL b1 = (originalImage.imageOrientation == UIImageOrientationUp || originalImage.imageOrientation == UIImageOrientationDown);
BOOL b2 = (originalImage.imageOrientation == UIImageOrientationLeft || originalImage.imageOrientation == UIImageOrientationRight);
BOOL b3 = originalImage.imageOrientation == UIImageOrientationLeft;
BOOL b4 = originalImage.imageOrientation == UIImageOrientationRight;

横屏中, 正面照是:UIImageOrientationRight

upsidedown 照片是 UIImageOrientationLeft

//根据给定得图片，从其指定区域截取一张新得图片
-(UIImage *)getImageFromImage:(UIImage *)image rect:(CGRect)rect
{
    //开始上下文
    UIGraphicsBeginImageContext(rect.size);
    CGImageRef imageRef = image.CGImage;
    //创建子图像索引
    CGImageRef subImageRef = CGImageCreateWithImageInRect(imageRef, rect);
    //获取当前上下文
    CGContextRef context = UIGraphicsGetCurrentContext();
    
    //在当前上下文下, 定位为rect下, 画出子图像索引
    CGContextDrawImage(context,CGRectMake(0, 0, rect.size.width, rect.size.height), subImageRef);
    
    //创建图片对象, 根据图像索引
    UIImage *subImage = [[UIImage alloc] initWithCGImage:subImageRef];
    
    //销毁创建的子图像索引,不然会导致内存泄露
    CGImageRelease(subImageRef);
    //结束上下文
    UIGraphicsEndImageContext();
    return subImage;
}

被render成为新图片之后 uiimage默认的imageOrientation是正方向(UIImageOrientationUp)

图片方向转换

这几天写个拍照,或者从相册中选择照片,进行剪切,然后分享.结果出现了,剪切后图片颠倒或者旋转90度的问题.

找了很久才发现是忽略imageOrientation这个属性.

以下为解决方法:


[cpp] view plaincopy
+ (UIImage *)fixOrientation:(UIImage *)aImage {  
      
    // No-op if the orientation is already correct  
    if (aImage.imageOrientation == UIImageOrientationUp)   
        return aImage;  
      
    // We need to calculate the proper transformation to make the image upright.  
    // We do it in 2 steps: Rotate if Left/Right/Down, and then flip if Mirrored.  
    CGAffineTransform transform = CGAffineTransformIdentity;  
      
    switch (aImage.imageOrientation) {  
        case UIImageOrientationDown:  
        case UIImageOrientationDownMirrored:  
            transform = CGAffineTransformTranslate(transform, aImage.size.width, aImage.size.height);  
            transform = CGAffineTransformRotate(transform, M_PI);  
            break;  
              
        case UIImageOrientationLeft:  
        case UIImageOrientationLeftMirrored:  
            transform = CGAffineTransformTranslate(transform, aImage.size.width, 0);  
            transform = CGAffineTransformRotate(transform, M_PI_2);  
            break;  
              
        case UIImageOrientationRight:  
        case UIImageOrientationRightMirrored:  
            transform = CGAffineTransformTranslate(transform, 0, aImage.size.height);  
            transform = CGAffineTransformRotate(transform, -M_PI_2);  
            break;  
        default:  
            break;  
    }  
      
    switch (aImage.imageOrientation) {  
        case UIImageOrientationUpMirrored:  
        case UIImageOrientationDownMirrored:  
            transform = CGAffineTransformTranslate(transform, aImage.size.width, 0);  
            transform = CGAffineTransformScale(transform, -1, 1);  
            break;  
              
        case UIImageOrientationLeftMirrored:  
        case UIImageOrientationRightMirrored:  
            transform = CGAffineTransformTranslate(transform, aImage.size.height, 0);  
            transform = CGAffineTransformScale(transform, -1, 1);  
            break;  
        default:  
            break;  
    }  
      
    // Now we draw the underlying CGImage into a new context, applying the transform  
    // calculated above.  
    CGContextRef ctx = CGBitmapContextCreate(NULL, aImage.size.width, aImage.size.height,  
                                             CGImageGetBitsPerComponent(aImage.CGImage), 0,  
                                             CGImageGetColorSpace(aImage.CGImage),  
                                             CGImageGetBitmapInfo(aImage.CGImage));  
    CGContextConcatCTM(ctx, transform);  
    switch (aImage.imageOrientation) {  
        case UIImageOrientationLeft:  
        case UIImageOrientationLeftMirrored:  
        case UIImageOrientationRight:  
        case UIImageOrientationRightMirrored:  
            // Grr...  
            CGContextDrawImage(ctx, CGRectMake(0,0,aImage.size.height,aImage.size.width), aImage.CGImage);  
            break;  
              
        default:  
            CGContextDrawImage(ctx, CGRectMake(0,0,aImage.size.width,aImage.size.height), aImage.CGImage);  
            break;  
    }  
      
    // And now we just create a new UIImage from the drawing context  
    CGImageRef cgimg = CGBitmapContextCreateImage(ctx);  
    UIImage *img = [UIImage imageWithCGImage:cgimg];  
    CGContextRelease(ctx);  
    CGImageRelease(cgimg);  
    return img;  
}  

来源：http://blog.csdn.net/iukey/article/details/7308433

使用UIImageView来播放动画.

-(void)viewDidLoad
{
	[superviewDidLoad];

	self.title=NSLocalizedString(@"ImagesTitle",@"");
	//setupourUIImagewithagrouporarrayofimagestoanimate(orinourcaseaslideshow)	
	self.imageView.animationImages = [NSArrayarrayWithObjects:[UIImageimageNamed:@"scene1.jpg"],[UIImageimageNamed:@"scene2.jpg"],[UIImageimageNamed:@"scene3.jpg"],[UIImageimageNamed:@"scene4.jpg"],[UIImageimageNamed:@"scene5.jpg"],  nil  ];

	imageView.animationDuration=5.0;
	[self.imageViewstopAnimating];

	//Settheappropriateaccessibilitylabels.
	[self.imageViewsetIsAccessibilityElement:YES];
	[self.imageViewsetAccessibilityLabel:self.title];
	[self.slidersetAccessibilityLabel:NSLocalizedString(@"DurationSlider",@"")];
}