Question

我想知道是否可以设置相机输入的不透明度？例如，如果我在相机下面有图层，我想通过相机层显示..

我像这样使用相机：

- (void)addVideoPreviewLayer {
    [self setPreviewLayer:[[[AVCaptureVideoPreviewLayer alloc] initWithSession:[self captureSession]] autorelease]];
    [[self previewLayer] setVideoGravity:AVLayerVideoGravityResizeAspectFill];

}

- (void)addVideoInput {
    AVCaptureDevice *videoDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];   
    if (videoDevice) {
        NSError *error;
        AVCaptureDeviceInput *videoIn = [AVCaptureDeviceInput deviceInputWithDevice:videoDevice error:&error];
        if (!error) {
            if ([[self captureSession] canAddInput:videoIn])
                [[self captureSession] addInput:videoIn];
            else
                NSLog(@"Couldn't add video input");     
        }
        else
            NSLog(@"Couldn't create video input");
    }
    else
        NSLog(@"Couldn't create video capture device");
}

通过以下方式解雇：

[self setCaptureManager:[[CaptureSessionManager alloc] init]];
[[self captureManager] addVideoInput];
[[self captureManager] addVideoPreviewLayer];
CGRect layerRect = [[[self view] layer] bounds];
[[[self captureManager] previewLayer] setBounds:layerRect];
[[[self captureManager] previewLayer] setPosition:CGPointMake(CGRectGetMidX(layerRect),
    CGRectGetMidY(layerRect))];
[[[self view] layer] addSublayer:[[self captureManager] previewLayer]];

有可能吗？如果是的话，怎么办呢？

Answer 1

previewLayer不像普通的CALayers那样合成，所以改变它的不透明度并不起作用也就不足为奇了。

您可以尝试做的是使用此代码（http://developer.apple.com/library/ios/#qa/qa1702/_index.html）实时捕获来自相机的输入，转换它是一个UIImage，并将该图像粘贴到UIImageView中。我发现使用AVCaptureSessionPresetMedium的会话设置，您应该能够以20-30 fps更新UIImageView，这可能足以满足您的目标。

iPhone 4相机不透明度

1 个答案: