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(, , 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, );
            transform = CGAffineTransformRotate(transform, M_PI_2);
            break;  

        case UIImageOrientationRight:
        case UIImageOrientationRightMirrored:
            transform = CGAffineTransformTranslate(transform, , 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, );
            transform = CGAffineTransformScale(transform, -, );
            break;  

        case UIImageOrientationLeftMirrored:
        case UIImageOrientationRightMirrored:
            transform = CGAffineTransformTranslate(transform, aImage.size.height, );
            transform = CGAffineTransformScale(transform, -, );
            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), ,
                                             CGImageGetColorSpace(aImage.CGImage),
                                             CGImageGetBitmapInfo(aImage.CGImage));
    CGContextConcatCTM(ctx, transform);
    switch (aImage.imageOrientation) {
        case UIImageOrientationLeft:
        case UIImageOrientationLeftMirrored:
        case UIImageOrientationRight:
        case UIImageOrientationRightMirrored:
            // Grr...
            CGContextDrawImage(ctx, CGRectMake(,,aImage.size.height,aImage.size.width), aImage.CGImage);
            break;  

        default:
            CGContextDrawImage(ctx, CGRectMake(,,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",@"")];
}