iphone - iphone 表格中的一些图像会自动旋转

Question

我在相册表中有包含照片的数据库。我得到数组中的所有图像并显示在表格中。问题是很少有图像旋转 90 度。

这是 cellForRow 方法中的内容。

AlbumInformation * temp=[albumInfoArray objectAtIndex:indexPath.row];
cell.albumPicImageView.image=temp.albumPictureClass;
return cell;

我得到所有图像，但很少旋转。

请帮忙。

提前致谢

Answer 1

请参考以下示例。在 PhotoDisplayViewController.m 测试中有以下两种情况，您将自动得到答案，无需任何人解释。

案例 1：使用 UIImageOrientation

ALAssetRepresentation *assetRepresentation = [asset defaultRepresentation];

    UIImage *fullScreenImage = [UIImage imageWithCGImage:[assetRepresentation fullScreenImage] scale:[assetRepresentation scale] orientation:(UIImageOrientation)[assetRepresentation orientation]];

案例 2：没有 UIImageOrientation

ALAssetRepresentation *assetRepresentation = [asset defaultRepresentation];

    UIImage *fullScreenImage = [UIImage imageWithCGImage:[assetRepresentation fullScreenImage] scale:[assetRepresentation scale] orientation:nil];

当您从断言中阅读时，有一些方向，例如以下

 UIImageOrientationUp,            // default orientation
    UIImageOrientationDown,          // 180 deg rotation
    UIImageOrientationLeft,          // 90 deg CCW
    UIImageOrientationRight,         // 90 deg CW
    UIImageOrientationUpMirrored,    // as above but image mirrored along other axis. horizontal flip
    UIImageOrientationDownMirrored,  // horizontal flip
    UIImageOrientationLeftMirrored,  // vertical flip
    UIImageOrientationRightMirrored, // vertical flip

所以请下载通过这个示例演示

MyImagePicker 演示

注意：如果要显示所有专辑，则需要更改 RootViewController.m 中的代码，如下所示

NSUInteger groupTypes = ALAssetsGroupAlbum | ALAssetsGroupEvent | ALAssetsGroupFaces|ALAssetsGroupLibrary|ALAssetsGroupSavedPhotos|ALAssetsGroupPhotoStream;

Answer 2

UIImage 有一个分配属性“imageOrientation”；所以这个方法可以帮助你

• (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;  
  

  }