ios - 设置使用 AVAssetImageGenerator ios 生成的缩略图的图像大小

Question

我正在使用 AVAssetImageGenerator 类来生成缩略图，但问题是我需要将该缩略图放入具有 UIImageView 大小的 UITableViewCell 中( 320,239)。我将 AVAssetImageGenerator 最大大小属性指定为 (320,239)，但我没有得到我指定的所需大小请提前感谢任何帮助。请查看以下代码以供快速引用。

    AVURLAsset *asset = [[AVURLAsset alloc] initWithURL:self.consenteeVideoUrl options:nil];

AVAssetImageGenerator *gen = [[AVAssetImageGenerator alloc] initWithAsset:asset];

gen.maximumSize = CGSizeMake(320, 239);

gen.apertureMode = AVAssetImageGeneratorApertureModeProductionAperture;

gen.appliesPreferredTrackTransform = YES;

CMTime time = CMTimeMakeWithSeconds(0.0, 600);

NSError *error = nil;

CMTime actualTime;

CGImageRef image = [gen copyCGImageAtTime:time actualTime:&actualTime error:&error];

UIImage *thumbnailImage = [[UIImage alloc] initWithCGImage:image];
//thumbnailImage = [CSUtilities imageWithImage:thumbnailImage scaledToSize:CGSizeMake(320, 239)];
CGImageRelease(image);

我从“stackoverflow”获得的另一个解决方案，但对我的场景没有太大帮助。`

AVURLAsset *asset=[[AVURLAsset alloc] initWithURL:self.consenteeVideoUrl options:nil];
AVAssetImageGenerator *generator = [[AVAssetImageGenerator alloc] initWithAsset:asset];
generator.appliesPreferredTrackTransform=TRUE;

CMTime thumbTime = CMTimeMakeWithSeconds(30,30);

AVAssetImageGeneratorCompletionHandler handler = ^(CMTime requestedTime, CGImageRef im, CMTime actualTime, AVAssetImageGeneratorResult result, NSError *error){
    if (result != AVAssetImageGeneratorSucceeded) {
        NSLog(@"couldn't generate thumbnail, error:%@", error);
    }

    UIImage *thumbnailImage = [[UIImage alloc] initWithCGImage:im];
    //save image to application directory...
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString *folderPath = [documentsDirectory stringByAppendingPathComponent:self.uniqueCodeString];
    if (![[NSFileManager defaultManager] fileExistsAtPath:folderPath])
        [[NSFileManager defaultManager] createDirectoryAtPath:folderPath  withIntermediateDirectories:NO attributes:nil error:&error];

    NSString *savedImagePath = [folderPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.png",self.uniqueCodeString]];
    NSData *imageData = UIImagePNGRepresentation(thumbnailImage);
    BOOL success = [imageData writeToFile:savedImagePath atomically:YES];
    if (success) {
        CSLog(@"sucess");
    }
    partnerEvent.thumbnailImageStr = [self getImagePath];
    [self.ibPartnerEventTableView reloadData];
 };

 CGSize maxSize = CGSizeMake(320, 239);
 generator.maximumSize = maxSize;
 [generator generateCGImagesAsynchronouslyForTimes:[NSArray arrayWithObject:[NSValue valueWithCMTime:thumbTime]] completionHandler:handler];

Answer 1

您的代码没有任何错误，但正如文档中所述

AVAssetImageGenerator scales images such that they fit within the defined bounding box. Images are never scaled up. The aspect ratio of the scaled image is defined by the apertureMode property.

由于 apertureMode 设置为 AVAssetImageGeneratorApertureModeProductionAperture 生成的图像保持纵横比。如果视频和尺寸集具有相同的宽高比，它只会适合最大尺寸，而指定尺寸不太可能发生这种情况。
尝试将 UIImageView contentMode 更改为 UIViewContentModeScaleAspectFill 一些内容可能会被裁剪，但您将填满整个 imageView