ios AVFoundation 点击​​聚焦 [英] ios AVFoundation tap to focus

问题描述

我正在尝试创建一个相机应用程序，它或多或少会像默认相机应用程序一样工作.目前对我不起作用的事情是点击聚焦.我希望相机聚焦并在我的触摸点上做任何事情，就像真正的相机应用一样.

I am trying to create a camera app which, would act like the default camera app more or less. The thing, which is not working for me at the moment, is tap to focus. I want the camera to focus and do whatever it does on my touched point, just like the real camera app does.

这是我的 viewDidLoad

Here's my viewDidLoad

- (void)viewDidLoad
{
    [super viewDidLoad];

    // Session
    _session = [[AVCaptureSession alloc] init];
    _session.sessionPreset = AVCaptureSessionPresetPhoto;

    // Input
    _videoDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    _videoInput = [AVCaptureDeviceInput deviceInputWithDevice:_videoDevice error:nil];

    // Output
    _frameOutput = [[AVCaptureVideoDataOutput alloc] init];
    _frameOutput.videoSettings = [NSDictionary dictionaryWithObject:AVVideoCodecJPEG forKey:AVVideoCodecKey];

    [_frameOutput setSampleBufferDelegate:self queue:dispatch_get_main_queue()];
    [_session addInput:_videoInput];
    [_session addOutput:_frameOutput];
    [_session startRunning];
};

这是让我的相机在点击时对焦的方法.

And here's the method that should make my camera focus stuff on click.

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {

    [touches enumerateObjectsUsingBlock:^(id obj, BOOL *stop) {
        UITouch *touch = obj;
        CGPoint touchPoint = [touch locationInView:touch.view];
        focusLayer.frame = CGRectMake((touchPoint.x-25), (touchPoint.y-25), 50, 50);

        if ([_videoDevice isFocusPointOfInterestSupported]) {
            NSError *error;
            if ([_videoDevice lockForConfiguration:&error]) {
                [_videoDevice setFocusPointOfInterest:touchPoint];
                [_videoDevice setExposurePointOfInterest:touchPoint];

                [_videoDevice setFocusMode:AVCaptureFocusModeAutoFocus];
                if ([_videoDevice isExposureModeSupported:AVCaptureExposureModeAutoExpose]){
                    [_videoDevice setExposureMode:AVCaptureExposureModeAutoExpose];
                }
                [_videoDevice unlockForConfiguration];
            }
        }


        // NSLog(@"x = %f, y = %f", touchPoint.x, touchPoint.y);
    }];
}

点击屏幕后什么都没有发生.

Nothing really happens once I click on the screen.

推荐答案

你必须使用类似下面的代码将 touchPoint 调整到 [0,1] 的范围:

You have to adjust the touchPoint to a range of [0,1] using something like the following code:

    CGRect screenRect = [[UIScreen mainScreen] bounds];
    screenWidth = screenRect.size.width;
    screenHeight = screenRect.size.height;  
    double focus_x = thisFocusPoint.center.x/screenWidth;
    double focus_y = thisFocusPoint.center.y/screenHeight;

    [[self captureManager].videoDevice lockForConfiguration:&error];
    [[self captureManager].videoDevice setFocusPointOfInterest:CGPointMake(focus_x,focus_y)];
    [[self captureManager].videoDevice unlockForConfiguration];

相关文档可在 Apple 中找到- AV Foundation 编程指南 - 请参阅媒体捕获部分，您可以在其中找到有关对焦模式的信息:

The documentation on this can be found in Apple - AV Foundation Programming Guidelines - see section Media Capture where you will find information on Focus Modes:

如果支持，您可以使用 focusPointOfInterest 设置焦点.您传递一个 CGPoint，其中 {0,0} 代表图片区域的左上角，{1,1} 代表横向模式下的右下角，主页按钮位于右侧——即使设备处于纵向模式也适用.

If it’s supported, you set the focal point using focusPointOfInterest. You pass a CGPoint where {0,0} represents the top left of the picture area, and {1,1} represents the bottom right in landscape mode with the home button on the right—this applies even if the device is in portrait mode.

这篇关于ios AVFoundation 点击​​聚焦的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！