在 iPad 上以纵向模式启动图像选择器

Question

我正在使用以下代码在我的 iPad 应用程序（使用 Cocos2D）中启动图像选择器：

UIImagePickerController * imagePickerController = [[UIImagePickerController alloc] init];

if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) { 

    imagePickerController.sourceType = UIImagePickerControllerSourceTypeCamera;
    imagePickerController.showsCameraControls = YES;
    imagePickerController.cameraCaptureMode = UIImagePickerControllerCameraCaptureModePhoto;
    imagePickerController.delegate = self;
    imagePickerController.cameraDevice = UIImagePickerControllerCameraDeviceFront;
    [self.view addSubview:imagePickerController.view];
    [self presentModalViewController:imagePickerController animated:YES];

}

我希望它一直以纵向模式启动，但它总是这样启动：

图片以纵向显示，图片选择器 UI 为横向模式。但是当我捕获图像时，它会顺时针旋转 90 度。

我希望图像选择器 UI 和拍摄的图像都处于纵向模式。我怎样才能解决这个问题 ？

Answer 1

你需要做三件事：

1. 告诉 viewController 只展示 imagePicker 支持纵向。
2. 告诉 imagePicker 不要旋转实时摄像机源。
3. 取消旋转捕获的图像。

imagePicker 直接接收设备方向更改的通知。为了防止实时摄像头随设备旋转，您可以通过告诉 UIDevice endGenerating 在 imagePicker 显示后的方向通知来阻止它接收这些通知：

while ([currentDevice isGeneratingDeviceOrientationNotifications])
        [currentDevice endGeneratingDeviceOrientationNotifications];

之所以把它放在一个循环中是因为imagePicker开始GeneratingDeviceOrientationNotifications，然后在它被关闭时结束它，使普通设备上的通知计数从1到2回到1。

imagePicker 关闭后，可以调用：

while (![currentDevice isGeneratingDeviceOrientationNotifications])
        [currentDevice beginGeneratingDeviceOrientationNotifications];

以便您的 ViewController 可以继续接收方向更改通知。

不幸的是，即使关闭此功能，图像仍会以正确的图像方向保存，因此在保存图像或对其进行任何操作之前，您必须通过以下方式删除应用的方向转换手动反击：

-(UIImage *)turnMeAround:(UIImage *)image{
    CGAffineTransform transform = CGAffineTransformIdentity;
    CGFloat scale = [[UIScreen mainScreen] scale]; //retina
    CGSize size = CGSizeMake(image.size.width*scale,image.size.height*scale);
    switch (image.imageOrientation) {
        case UIImageOrientationUp:
            return image;
        case UIImageOrientationDown:
            size = CGSizeMake(size.height,size.width);
            transform = CGAffineTransformRotate(transform, M_PI);
            break;
        case UIImageOrientationLeft:
            transform = CGAffineTransformRotate(transform, -M_PI_2);
            break;
        case UIImageOrientationRight:
            transform = CGAffineTransformRotate(transform, M_PI_2);
            break;
    }
    CGContextRef context = CGBitmapContextCreate(NULL, size.width, size.height, CGImageGetBitsPerComponent(image.CGImage), 0, CGImageGetColorSpace(image.CGImage), CGImageGetBitmapInfo(image.CGImage));
    CGContextConcatCTM(context, transform);
    CGContextDrawImage(context, CGRectMake(0,0,size.width,size.height), image.CGImage);
    CGImageRef ref = CGBitmapContextCreateImage(context);
    UIImage *upsideRight = [UIImage imageWithCGImage:ref];
    CGContextRelease(context);
    CGImageRelease(ref);
    return upsideRight;
}

Answer 2

非常感谢大家的帮助，但对我有用的方法如下：

所以我发现罪魁祸首是 Xcode 的 Cocos2D 模板。它在 RootViewController 中生成了以下代码：

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {

//
// There are 2 ways to support auto-rotation:
//  - The OpenGL / cocos2d way
//     - Faster, but doesn't rotate the UIKit objects
//  - The ViewController way
//    - A bit slower, but the UiKit objects are placed in the right place
//

#if GAME_AUTOROTATION==kGameAutorotationNone
//
// EAGLView won't be autorotated.
// Since this method should return YES in at least 1 orientation, 
// we return YES only in the Portrait orientation
//
return ( interfaceOrientation == UIInterfaceOrientationPortrait );

#elif GAME_AUTOROTATION==kGameAutorotationCCDirector
//
// EAGLView will be rotated by cocos2d
//
// Sample: Autorotate only in landscape mode
//
if( interfaceOrientation == UIInterfaceOrientationLandscapeLeft ) {
    [[CCDirector sharedDirector] setDeviceOrientation: kCCDeviceOrientationLandscapeRight];
} else if( interfaceOrientation == UIInterfaceOrientationLandscapeRight) {
    [[CCDirector sharedDirector] setDeviceOrientation: kCCDeviceOrientationLandscapeLeft];
}

// Since this method should return YES in at least 1 orientation, 
// we return YES only in the Portrait orientation
return ( interfaceOrientation == UIInterfaceOrientationPortrait );

#elif GAME_AUTOROTATION == kGameAutorotationUIViewController
//
// EAGLView will be rotated by the UIViewController
//
// Sample: Autorotate only in landscpe mode
//
// return YES for the supported orientations

return ( UIInterfaceOrientationIsLandscape( interfaceOrientation ) );

#else
#error Unknown value in GAME_AUTOROTATION

#endif // GAME_AUTOROTATION


// Shold not happen
return NO;
}

在上面的代码中我改变了这个：

return ( UIInterfaceOrientationIsLandscape( interfaceOrientation ) );

对此：

return ( UIInterfaceOrientationIsPortrait( interfaceOrientation ) );

这样就解决了。