iphone - AVFoundation 对焦模式 iPad2

Question

我正在尝试在我的应用程序中实现自动对焦，并在 iPad2 中进行了测试。我的问题是，当我调用像 isFocusModeSupported:AVCaptureFocusModeContinouslyAutoFocus 这样的检查方法时，它总是返回 NO。不过，我可以通过设备中的其他相机应用程序点击进行对焦

devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
for (AVCaptureDevice *tempDevice in devices) {
    [tempDevice lockForConfiguration:nil];
    if ([tempDevice isFocusModeSupported:AVCaptureFocusModeAutoFocus]) {
        NSLog(@"Here");
    }

    if ([tempDevice isFocusModeSupported:AVCaptureFocusModeContinuousAutoFocus]) {
        NSLog(@"Here");
    }

    if ([tempDevice isFocusModeSupported:AVCaptureFocusModeLocked]) {
        NSLog(@"Here");
    }

    if ([tempDevice isFocusPointOfInterestSupported]) {
        NSLog(@"Here");
    }
    [tempDevice unlockForConfiguration];
}

Answer 1

今晚我只是在研究这个。据我所知，iPad 2 不进行对焦，而是进行曝光调整，因此在默认的相机应用程序中，点击屏幕会弹出一个矩形，其中点击发生指示要进行白点调整的区域。

也许我错了，但这就是我发现的，并且似乎已被您的 API(isFocusModeSupported:AVCaptureFocusModeContinouslyAutoFocus 返回 NO)测试所证实。

iPad 2 的摄像头相当弱——尤其是前置摄像头。我很惊讶苹果公司也提供了这个功能。

更新:这是来自最新的 AVCamDemo Apple 示例的代码，用于处理焦点+曝光+白点。我不认为这在 AVCam 示例中。 AVCamDemo 可能只能从开发人员中心下载 WWDC 代码 .dmg 包，而不是从网络上单独下载。 在我的 iPad 2 上，曝光代码永远不会被调用。//-来自 AVCamDemo:

- (BOOL) hasExposure
 {
AVCaptureDevice *device = [[self videoInput] device];

return  [device isExposureModeSupported:AVCaptureExposureModeLocked] ||
        [device isExposureModeSupported:AVCaptureExposureModeAutoExpose] ||
        [device isExposureModeSupported:AVCaptureExposureModeContinuousAutoExposure];
}

- (AVCaptureExposureMode) exposureMode
{
return [[[self videoInput] device] exposureMode];
}

- (void) setExposureMode:(AVCaptureExposureMode)exposureMode
{
if (exposureMode == 1) {
    exposureMode = 2;
}
AVCaptureDevice *device = [[self videoInput] device];
if ([device isExposureModeSupported:exposureMode] && [device exposureMode] != exposureMode) {
    NSError *error;
    if ([device lockForConfiguration:&error]) {
        [device setExposureMode:exposureMode];
        [device unlockForConfiguration];
    } else {
        id delegate = [self delegate];
        if ([delegate respondsToSelector:@selector(acquiringDeviceLockFailedWithError:)]) {
            [delegate acquiringDeviceLockFailedWithError:error];
        }
    }
}
}

- (BOOL) hasWhiteBalance
{
AVCaptureDevice *device = [[self videoInput] device];

return  [device isWhiteBalanceModeSupported:AVCaptureWhiteBalanceModeLocked] ||
        [device isWhiteBalanceModeSupported:AVCaptureWhiteBalanceModeAutoWhiteBalance];
}

- (AVCaptureWhiteBalanceMode) whiteBalanceMode
{
return [[[self videoInput] device] whiteBalanceMode];
}

- (void) setWhiteBalanceMode:(AVCaptureWhiteBalanceMode)whiteBalanceMode
{
if (whiteBalanceMode == 1) {
    whiteBalanceMode = 2;
}    
AVCaptureDevice *device = [[self videoInput] device];
if ([device isWhiteBalanceModeSupported:whiteBalanceMode] && [device whiteBalanceMode] != whiteBalanceMode) {
    NSError *error;
    if ([device lockForConfiguration:&error]) {
        [device setWhiteBalanceMode:whiteBalanceMode];
        [device unlockForConfiguration];
    } else {
        id delegate = [self delegate];
        if ([delegate respondsToSelector:@selector(acquiringDeviceLockFailedWithError:)]) {
            [delegate acquiringDeviceLockFailedWithError:error];
        }
    }
}
}

- (BOOL) hasFocus
{
AVCaptureDevice *device = [[self videoInput] device];

return  [device isFocusModeSupported:AVCaptureFocusModeLocked] ||
        [device isFocusModeSupported:AVCaptureFocusModeAutoFocus] ||
        [device isFocusModeSupported:AVCaptureFocusModeContinuousAutoFocus];
}

- (AVCaptureFocusMode) focusMode
{
return [[[self videoInput] device] focusMode];
}

- (void) setFocusMode:(AVCaptureFocusMode)focusMode
{


AVCaptureDevice *device = [[self videoInput] device];
if ([device isFocusModeSupported:focusMode] && [device focusMode] != focusMode) {
    NSError *error;

      printf(" setFocusMode    \n");
    if ([device lockForConfiguration:&error]) {
        [device setFocusMode:focusMode];
        [device unlockForConfiguration];
    } else {
        id delegate = [self delegate];
        if ([delegate respondsToSelector:@selector(acquiringDeviceLockFailedWithError:)]) {
            [delegate acquiringDeviceLockFailedWithError:error];
        }
    }    
}
}