Iphone 如何防止自动旋转AVCapture层时出现“收缩到缩放”手势？

Objective-C，iPhone iOS 6.0

下面的代码很好地支持纵向，但当我尝试横向时，“收缩到缩放”自动将其旋转回笨拙的纵向模式，但在横向视图中

@implementation AVCapture
{
    CGFloat     beginGestureScale;
    CGFloat     effectiveScale;
}


- (id)initWithView:(UIView *)cameraView
{
    ......

    self.previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:self.captureSession];

    [self rotateToInterfaceOrientation:(UIInterfaceOrientation)[UIDevice currentDevice].orientation];

    [self.previewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];
    self.previewLayer.frame = cameraView.frame;
    [self.previewLayer setPosition:CGPointMake(CGRectGetMidX(cameraView.bounds), CGRectGetMidY(cameraView.bounds))];
    [cameraView.layer addSublayer:self.previewLayer];

    effectiveScale = 1.0;

    ......
}


- (void)rotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation
{
    CALayer *previewLayer = self.previewLayer;

    switch (toInterfaceOrientation)
    {
        case UIDeviceOrientationLandscapeLeft:
            previewLayer.transform = CATransform3DMakeRotation(M_PI+M_PI_2, 0, 0, 1); // 270 degress
            break;

        case UIDeviceOrientationLandscapeRight:
            previewLayer.transform = CATransform3DMakeRotation(M_PI_2, 0, 0, 1); // 270 degress
            break;

        case UIDeviceOrientationPortraitUpsideDown:
            previewLayer.transform = CATransform3DMakeRotation(M_PI, 0, 0, 1); // 270 degress
            break;

        default:
            previewLayer.transform = CATransform3DMakeRotation(0.0, 0, 0, 1); // 270 degress
            break;
    }

}



// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
#pragma mark Pinch to Zoom Gestures
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer
{
    if ( [gestureRecognizer isKindOfClass:[UIPinchGestureRecognizer class]] )
        beginGestureScale = effectiveScale;

    return YES;

}



- (void)handlePinchGesture:(UIPinchGestureRecognizer *)recognizer
{
    if ([recognizer numberOfTouches] < 2)
        return;


    BOOL allTouchesAreOnThePreviewLayer = YES;
    NSUInteger numTouches = [recognizer numberOfTouches], i;

    for (i=0; i<numTouches; ++i)
    {
        CGPoint location = [recognizer locationOfTouch:i inView:m_CameraView];
        CGPoint convertedLocation = [self.previewLayer convertPoint:location fromLayer:self.previewLayer.superlayer];

        if (![self.previewLayer containsPoint:convertedLocation])
        {
            allTouchesAreOnThePreviewLayer = NO;
            break;
        }
    }

    if (allTouchesAreOnThePreviewLayer)
    {
        effectiveScale = beginGestureScale * recognizer.scale;

        if (effectiveScale < 1.0)
            effectiveScale = 1.0;

        CGFloat maxScaleAndCropFactor = [[self.stillImageOutput connectionWithMediaType:AVMediaTypeVideo] videoMaxScaleAndCropFactor];

        if (effectiveScale > maxScaleAndCropFactor)
            effectiveScale = maxScaleAndCropFactor;

        [CATransaction begin];
        [CATransaction setAnimationDuration:.025];

        // Scale
        [self.previewLayer setAffineTransform:CGAffineTransformMakeScale(effectiveScale, effectiveScale)];

        [CATransaction commit];
    }

}

---

我似乎不知道如何保持我的转换。

类似的问题在这里得到了回答：

在我看来，由于您正在手动旋转previewLayer，因此需要相应地调整识别器，因为您正在使用缩放覆盖变换。这是因为转换是绝对的，或者至少我是这么认为的

使用我链接的问题中推荐的CGAffineTransformScale，在那里可以传递previewLayer的原始转换，以及所需的比例，怎么样

编辑 以下是解决此问题的文档： 在这里，您可以看到CGAffineTransformMakeScale用于创建转换，而CGAffineTransformScale用于更改转换，我相信这正是您所需要的

编辑2

解决了

发现： ... 更改预览层的方向不会更改捕获图片的方式。对于该AVCaptureConnection，需要使用setVideoOrientation:方法

。。和

所以我替换了这个：

[self rotateToInterfaceOrientation:(UIInterfaceOrientation)[UIDevice currentDevice].orientation];

为此：

[self.previewLayer.connection setVideoOrientation:[UIDevice currentDevice].orientation];

---

现在，在横向模式+收缩缩放模式下，一切正常：

我尝试过：[self.previewLayer setAffineTransform:cGrafineTransformScaleSelf.previewLayer.affineTransform，effectiveScale，effectiveScale]；但是缩放会失去控制。你能描述一下什么是失去控制吗？变换和以前一样吗？当我捏着放大的时候，图像迅速放大到像素级，我似乎不能再缩小了。它不能用了，这不应该发生。有效规模的共同价值是什么？另外，如果我正确阅读了代码，为什么要将recognizer.scale与beginGestureScale相乘呢？原始代码不是我的，所以我正在修复它。有效规模急剧上升。这几乎就像需要对缩放进行限制一样。可能是因为我在使用previewLayer本身吗？

[self rotateToInterfaceOrientation:(UIInterfaceOrientation)[UIDevice currentDevice].orientation];

[self.previewLayer.connection setVideoOrientation:[UIDevice currentDevice].orientation];