ios - 动态居中的 UIImagepicker 取景器已放大至全屏

Question

我正在为 iPhone 5 制作一个全屏摄像头，并使用以下代码来缩放 4:3 摄像头以填充整个屏幕，即 2:3 比例。左右两侧从屏幕上溢出。

我必须将cameraView向下移动71点才能使其与屏幕居中。否则，底部会有一个黑条。我不太清楚为什么。因为我不知道为什么会发生这种情况，所以我无法弄清楚如何动态编码调整以适应 iPhone 6 和 6 Plus。

感谢任何帮助。

// get the screen size
CGSize screenSize = [[UIScreen mainScreen] bounds].size;

// establish the height to width ratio of the camera
float heightRatio = 4.0f / 3.0f;

// calculate the height of the camera based on the screen width
float cameraHeight = screenSize.width * heightRatio;

// calculate the ratio that the camera height needs to be scaled by
float ratio = screenSize.height / cameraHeight;

//This slots the preview exactly in the middle of the screen by moving it down 71 points (for iphone 5)
CGAffineTransform translate = CGAffineTransformMakeTranslation(0.0, 71.0);
self.camera.cameraViewTransform = translate;

CGAffineTransform scale = CGAffineTransformScale(translate, ratio, ratio);
self.camera.cameraViewTransform = scale;

Answer 1

这终于在我脑海中响起了。因为我们知道相机的长度始终与屏幕宽度相同:

//按4:3比例获取相机高度

int cameraViewHeight = SCREEN_WIDTH * 1.333;

int adjustedYPosition = (SCREEN_HEIGHT - cameraViewHeight) / 2;

CGAffineTransform translate = CGAffineTransformMakeTranslation(0, adjustedYPosition);
self.imagePicker.cameraViewTransform = translate;