概述
关于iOS调用摄像机来获取照片,通常我们都会调用UIImagePickerController来调用系统提供的相机来拍照,这个控件非常好用。但是有时UIImagePickerController控件无法满足我们的需求,例如我们需要更加复杂的OverlayerView,这时候我们就要自己构造一个摄像机控件了。
这需要使用AVFoundation.framework这个framework里面的组件了,所以我们先要导入这个头文件,另外还需要的组件官方文档是这么说的:
● An instance of AVCaptureDevice to represent the input device, such as a camera or microphone
● An instance of a concrete subclass of AVCaptureInput to configure the ports from the input device
● An instance of a concrete subclass of AVCaptureOutput to manage the output to a movie file or still image
● An instance of AVCaptureSession to coordinate the data flow from the input to the output
这里我只构造了一个具有拍照功能的照相机,至于录影和录音功能这里就不加说明了。
总结下来,我们需要以下的对象:
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@property
(nonatomic, strong) AVCaptureSession * session;
//AVCaptureSession对象来执行输入设备和输出设备之间的数据传递
@property
(nonatomic, strong) AVCaptureDeviceInput * videoInput;
//AVCaptureDeviceInput对象是输入流
@property
(nonatomic, strong) AVCaptureStillImageOutput * stillImageOutput;
//照片输出流对象,当然我的照相机只有拍照功能,所以只需要这个对象就够了
@property
(nonatomic, strong) AVCaptureVideoPreviewLayer * previewLayer;
//预览图层,来显示照相机拍摄到的画面
@property
(nonatomic, strong) UIBarButtonItem * toggleButton;
//切换前后镜头的按钮
@property
(nonatomic, strong) UIButton * shutterButton;
//拍照按钮
@property
(nonatomic, strong) UIView * cameraShowView;
//放置预览图层的View
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我的习惯是在init方法执行的时候创建这些对象,然后在viewWillAppear方法里加载预览图层。现在就让我们看一下代码就清楚了。
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- (
void
) initialSession
{
//这个方法的执行我放在init方法里了
self.session = [[AVCaptureSession alloc] init];
self.videoInput = [[AVCaptureDeviceInput alloc] initWithDevice:[self frontCamera] error:nil];
//[self fronCamera]方法会返回一个AVCaptureDevice对象,因为我初始化时是采用前摄像头,所以这么写,具体的实现方法后面会介绍
self.stillImageOutput = [[AVCaptureStillImageOutput alloc] init];
NSDictionary * outputSettings = [[NSDictionary alloc] initWithObjectsAndKeys:AVVideoCodecJPEG,AVVideoCodecKey, nil];
//这是输出流的设置参数AVVideoCodecJPEG参数表示以JPEG的图片格式输出图片
[self.stillImageOutput setOutputSettings:outputSettings];
if
([self.session canAddInput:self.videoInput]) {
[self.session addInput:self.videoInput];
}
if
([self.session canAddOutput:self.stillImageOutput]) {
[self.session addOutput:self.stillImageOutput];
}
}
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- (AVCaptureDevice *)cameraWithPosition:(AVCaptureDevicePosition) position {
NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
for
(AVCaptureDevice *device in devices) {
if
([device position] == position) {
return
device;
}
}
return
nil;
}
- (AVCaptureDevice *)frontCamera {
return
[self cameraWithPosition:AVCaptureDevicePositionFront];
}
- (AVCaptureDevice *)backCamera {
return
[self cameraWithPosition:AVCaptureDevicePositionBack];
}
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接下来在viewWillAppear方法里执行加载预览图层的方法
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- (
void
) setUpCameraLayer
{
if
(_cameraAvaible == NO)
return
;
if
(self.previewLayer == nil) {
self.previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:self.session];
UIView * view = self.cameraShowView;
CALayer * viewLayer = [view layer];
[viewLayer setMasksToBounds:YES];
CGRect bounds = [view bounds];
[self.previewLayer setFrame:bounds];
[self.previewLayer setVideoGravity:AVLayerVideoGravityResizeAspect];
[viewLayer insertSublayer:self.previewLayer below:[[viewLayer sublayers] objectAtIndex:
0
]];
}
}
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注意以下的方法,在viewDidAppear和viewDidDisappear方法中启动和关闭session
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- (
void
) viewDidAppear:(BOOL)animated
{
[
super
viewDidAppear:animated];
if
(self.session) {
[self.session startRunning];
}
}
- (
void
) viewDidDisappear:(BOOL)animated
{
[
super
viewDidDisappear: animated];
if
(self.session) {
[self.session stopRunning];
}
}
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接着我们就来实现切换前后镜头的按钮,按钮的创建我就不多说了
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- (
void
)toggleCamera {
NSUInteger cameraCount = [[AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo] count];
if
(cameraCount >
1
) {
NSError *error;
AVCaptureDeviceInput *newVideoInput;
AVCaptureDevicePosition position = [[_videoInput device] position];
if
(position == AVCaptureDevicePositionBack)
newVideoInput = [[AVCaptureDeviceInput alloc] initWithDevice:[self frontCamera] error:&error];
else
if
(position == AVCaptureDevicePositionFront)
newVideoInput = [[AVCaptureDeviceInput alloc] initWithDevice:[self backCamera] error:&error];
else
return
;
if
(newVideoInput != nil) {
[self.session beginConfiguration];
[self.session removeInput:self.videoInput];
if
([self.session canAddInput:newVideoInput]) {
[self.session addInput:newVideoInput];
[self setVideoInput:newVideoInput];
}
else
{
[self.session addInput:self.videoInput];
}
[self.session commitConfiguration];
}
else
if
(error) {
NSLog(@
"toggle carema failed, error = %@"
, error);
}
}
}
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这是切换镜头的按钮方法
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- (
void
) shutterCamera
{
AVCaptureConnection * videoConnection = [self.stillImageOutput connectionWithMediaType:AVMediaTypeVideo];
if
(!videoConnection) {
NSLog(@
"take photo failed!"
);
return
;
}
[self.stillImageOutput captureStillImageAsynchronouslyFromConnection:videoConnection completionHandler:^(CMSampleBufferRef imageDataSampleBuffer, NSError *error) {
if
(imageDataSampleBuffer == NULL) {
return
;
}
NSData * imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageDataSampleBuffer];
UIImage * image = [UIImage imageWithData:imageData];
NSLog(@
"image size = %@"
,NSStringFromCGSize(image.size));
}];
}
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这样自定义照相机的简单功能就完成了,如果你想要再添加其他复杂的功能,可以参考一下下面这篇文章,希望对你们有所帮助。
http://course.gdou.com/blog/Blog.pzs/archive/2011/12/14/10882.html
最后
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