ios - CGBitmapContextCreateImage 内存泄漏

Question

这行代码使用了 Quartz 框架中的 CGBitmapContextCreateImage，造成了严重的内存泄漏:

CGImageRef imgRef  = CGBitmapContextCreateImage(bitmapContext);

是否有任何替代方法或代码来代替它。

整个方法如下:

    - (void)captureImageWithCompletionHander:(void(^)(NSString *imageFilePath))completionHandler
    {
        dispatch_suspend(_captureQueue);
        AVCaptureConnection *videoConnection = nil;
        for (AVCaptureConnection *connection in self.stillImageOutput.connections)
    {
        for (AVCaptureInputPort *port in [connection inputPorts])
        {
            if ([[port mediaType] isEqual:AVMediaTypeVideo] )
            {
               videoConnection = connection;
               break;
            }
        }
    if (videoConnection) break;
    }
     __weak typeof(self) weakSelf = self;
     [self.stillImageOutput captureStillImageAsynchronouslyFromConnection:videoConnection completionHandler: ^(CMSampleBufferRef imageSampleBuffer, NSError *error)
    {
        if (error)
        {
          dispatch_resume(_captureQueue);
          return;
        }
        __block NSString *filePath = [NSTemporaryDirectory() stringByAppendingPathComponent:@"Image 1"];
     @autoreleasepool
     {
         NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageSampleBuffer];
         CIImage *ciImage = [[CIImage alloc] initWithData:imageData options:@{kCIImageColorSpace:[NSNull null]}];
         enhancedImage = [self filteredImageUsingContrastFilterOnImage:ciImage];
         if (weakSelf.isBorderDetectionEnabled && rectangleDetectionConfidenceHighEnough(_imageDedectionConfidence))
         {
             CIRectangleFeature *rectangleFeature = [self biggestRectangleInRectangles:[[self highAccuracyRectangleDetector] featuresInImage:enhancedImage]];
             if (rectangleFeature)
             {
                 [self correctPerspectiveForImageWithFeatures:rectangleFeature];
             }
         }
         CIFilter *transform = [CIFilter filterWithName:@"CIAffineTransform"];
         [transform setValue:enhancedImage forKey:kCIInputImageKey];
         NSValue *rotation = [NSValue valueWithCGAffineTransform:CGAffineTransformMakeRotation(-90 * (M_PI/180))];
         [transform setValue:rotation forKey:@"inputTransform"];
         enhancedImage = [transform outputImage];
         if (!enhancedImage || CGRectIsEmpty(enhancedImage.extent)) return;
         static CIContext *ctx = nil;
         if (!ctx)
         {
             ctx = [CIContext contextWithOptions:@{kCIContextWorkingColorSpace:[NSNull null]}];
         }
         CGSize bounds = enhancedImage.extent.size;
         bounds = CGSizeMake(floorf(bounds.width / 4) * 4,floorf(bounds.height / 4) * 4);
         CGRect extent = CGRectMake(enhancedImage.extent.origin.x, enhancedImage.extent.origin.y, bounds.width, bounds.height);
         static int bytesPerPixel = 8;
         uint rowBytes = bytesPerPixel * bounds.width;
         uint totalBytes = rowBytes * bounds.height;
         uint8_t *byteBuffer = (uint8_t *)malloc(totalBytes);
         CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
         [ctx render:enhancedImage toBitmap:byteBuffer rowBytes:rowBytes bounds:extent format:kCIFormatRGBA8 colorSpace:colorSpace];
         CGContextRef bitmapContext = CGBitmapContextCreate(byteBuffer,bounds.width,bounds.height,bytesPerPixel,rowBytes,colorSpace,kCGImageAlphaNoneSkipLast);
         free(byteBuffer);

         CGImageRef imgRef  = CGBitmapContextCreateImage(bitmapContext);

         CGContextRelease(bitmapContext);
         CGColorSpaceRelease(colorSpace);
         saveCGImageAsJPEGToFilePath(imgRef, filePath);
         CFRelease(imgRef);
         dispatch_async(dispatch_get_main_queue(), ^
                        {
                            completionHandler(filePath);
                            dispatch_resume(_captureQueue);
                        });
         _imageDedectionConfidence = 0.0f;
     }
 }];

Answer 1

您使用 CGBitmapContextCreateImage() 创建了一个 CGImage，但您还没有发布该 CGImage。

一旦你得到 UIImage 释放 CGImageRef 这将帮助你

从中获取图片

CGImageRef imgRef = CGBitmapContextCreateImage(bmContext);
image = [UIImage imageWithCGImage:imgRef];
CGImageRelease(imgRef);