????在 AV Foundation ? 了解捕捉媒體 了解捕捉媒體的相關(guān)內(nèi)容，捕捉會話AVCaptureSession围段、捕捉設(shè)備????AVCaptureDevice 投放、捕捉設(shè)備的輸入AVCaptureDeviceInput和 捕捉設(shè)備的輸出AVCaptureOutput 以及視頻內(nèi)容的預(yù)覽 AVCaptureVideoPreviewLayer 圖層灸芳。
????iOS 相機(jī)應(yīng)用程序允許開發(fā)者從前置和后置攝像頭捕捉照片和電影烙样。這個示例代碼項目展示了如何在自己的相機(jī)應(yīng)用程序中利用內(nèi)置前后 iPhone 攝像頭的基本功能谒获。實現(xiàn)這些捕獲功能批狱。
開發(fā)相機(jī)應(yīng)用程序需要使用真機(jī)進(jìn)行編譯和測試精耐，在編寫代碼之前需要先處理隱私請求
設(shè)置預(yù)覽視圖
相機(jī)程序需要一個實時預(yù)覽的視圖卦停，其圖層為 AVCaptureVideoPreviewLayer惊完，關(guān)聯(lián)捕捉會話AVCaptureSession小槐，保持同步，AVCaptureSession 并處理屏幕觸控點(diǎn)轉(zhuǎn)換為攝像頭坐標(biāo)系的坐標(biāo)用于聚焦和曝光
- (id)initWithFrame:(CGRect)frame {
self = [super initWithFrame:frame];
if (self) {
[self setupView];
}
return self;
}
- (id)initWithCoder:(NSCoder *)coder {
self = [super initWithCoder:coder];
if (self) {
[self setupView];
}
return self;
}
+ (Class)layerClass {
//在UIView 重寫layerClass 類方法可以讓開發(fā)者創(chuàng)建視圖實例自定義圖層了下
//重寫layerClass方法并返回AVCaptureVideoPrevieLayer類對象
return [AVCaptureVideoPreviewLayer class];
}
- (AVCaptureSession*)session {
//重寫session方法，返回捕捉會話
return [(AVCaptureVideoPreviewLayer*)self.layer session];
}
- (void)setSession:(AVCaptureSession *)session {
//重寫session屬性的訪問方法骡显，在setSession:方法中訪問視圖layer屬性惫谤。
//AVCaptureVideoPreviewLayer 實例溜歪，并且設(shè)置AVCaptureSession 將捕捉數(shù)據(jù)直接輸出到圖層中蝴猪，并確保與會話狀態(tài)同步蛔糯。
[(AVCaptureVideoPreviewLayer*)self.layer setSession:session];
}
//關(guān)于UI的實現(xiàn)蚁飒，例如手勢淮逻，單擊爬早、雙擊 單擊聚焦筛严、雙擊曝光
- (void)setupView {
[(AVCaptureVideoPreviewLayer *)self.layer setVideoGravity:AVLayerVideoGravityResizeAspectFill];
_singleTapRecognizer =
[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleSingleTap:)];
_doubleTapRecognizer =
[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleDoubleTap:)];
_doubleTapRecognizer.numberOfTapsRequired = 2;
_doubleDoubleTapRecognizer =
[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleDoubleDoubleTap:)];
_doubleDoubleTapRecognizer.numberOfTapsRequired = 2;
_doubleDoubleTapRecognizer.numberOfTouchesRequired = 2;
[self addGestureRecognizer:_singleTapRecognizer];
[self addGestureRecognizer:_doubleTapRecognizer];
[self addGestureRecognizer:_doubleDoubleTapRecognizer];
[_singleTapRecognizer requireGestureRecognizerToFail:_doubleTapRecognizer];
_focusBox = [self viewWithColor:[UIColor colorWithRed:0.102 green:0.636 blue:1.000 alpha:1.000]];
_exposureBox = [self viewWithColor:[UIColor colorWithRed:1.000 green:0.421 blue:0.054 alpha:1.000]];
[self addSubview:_focusBox];
[self addSubview:_exposureBox];
}
- (void)handleSingleTap:(UIGestureRecognizer *)recognizer {
CGPoint point = [recognizer locationInView:self];
[self runBoxAnimationOnView:self.focusBox point:point];
if (self.delegate) {
[self.delegate tappedToFocusAtPoint:[self captureDevicePointForPoint:point]];
}
}
//私有方法 用于支持該類定義的不同觸摸處理方法。 將屏幕坐標(biāo)系上的觸控點(diǎn)轉(zhuǎn)換為攝像頭上的坐標(biāo)系點(diǎn)
- (CGPoint)captureDevicePointForPoint:(CGPoint)point {
AVCaptureVideoPreviewLayer *layer =
(AVCaptureVideoPreviewLayer *)self.layer;
return [layer captureDevicePointOfInterestForPoint:point];
}
- (void)handleDoubleTap:(UIGestureRecognizer *)recognizer {
CGPoint point = [recognizer locationInView:self];
[self runBoxAnimationOnView:self.exposureBox point:point];
if (self.delegate) {
[self.delegate tappedToExposeAtPoint:[self captureDevicePointForPoint:point]];
}
}
- (void)handleDoubleDoubleTap:(UIGestureRecognizer *)recognizer {
[self runResetAnimation];
if (self.delegate) {
[self.delegate tappedToResetFocusAndExposure];
}
}
- (void)runBoxAnimationOnView:(UIView *)view point:(CGPoint)point {
view.center = point;
view.hidden = NO;
[UIView animateWithDuration:0.15f
delay:0.0f
options:UIViewAnimationOptionCurveEaseInOut
animations:^{
view.layer.transform = CATransform3DMakeScale(0.5, 0.5, 1.0);
}
completion:^(BOOL complete) {
double delayInSeconds = 0.5f;
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(delayInSeconds * NSEC_PER_SEC));
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
view.hidden = YES;
view.transform = CGAffineTransformIdentity;
});
}];
}
- (void)runResetAnimation {
if (!self.tapToFocusEnabled && !self.tapToExposeEnabled) {
return;
}
AVCaptureVideoPreviewLayer *previewLayer = (AVCaptureVideoPreviewLayer *)self.layer;
CGPoint centerPoint = [previewLayer pointForCaptureDevicePointOfInterest:CGPointMake(0.5f, 0.5f)];
self.focusBox.center = centerPoint;
self.exposureBox.center = centerPoint;
self.exposureBox.transform = CGAffineTransformMakeScale(1.2f, 1.2f);
self.focusBox.hidden = NO;
self.exposureBox.hidden = NO;
[UIView animateWithDuration:0.15f
delay:0.0f
options:UIViewAnimationOptionCurveEaseInOut
animations:^{
self.focusBox.layer.transform = CATransform3DMakeScale(0.5, 0.5, 1.0);
self.exposureBox.layer.transform = CATransform3DMakeScale(0.7, 0.7, 1.0);
}
completion:^(BOOL complete) {
double delayInSeconds = 0.5f;
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(delayInSeconds * NSEC_PER_SEC));
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
self.focusBox.hidden = YES;
self.exposureBox.hidden = YES;
self.focusBox.transform = CGAffineTransformIdentity;
self.exposureBox.transform = CGAffineTransformIdentity;
});
}];
}
- (void)setTapToFocusEnabled:(BOOL)enabled {
_tapToFocusEnabled = enabled;
self.singleTapRecognizer.enabled = enabled;
}
- (void)setTapToExposeEnabled:(BOOL)enabled {
_tapToExposeEnabled = enabled;
self.doubleTapRecognizer.enabled = enabled;
}
- (UIView *)viewWithColor:(UIColor *)color {
UIView *view = [[UIView alloc] initWithFrame:BOX_BOUNDS];
view.backgroundColor = [UIColor clearColor];
view.layer.borderColor = color.CGColor;
view.layer.borderWidth = 5.0f;
view.hidden = YES;
return view;
}
設(shè)置捕捉會話丧慈、輸入和輸出
????捕捉會話的代碼會放置在一個相機(jī)控制器的類 CameraController 里面。這個類用于配置和管理不同的捕捉設(shè)備簇搅，同時也對捕捉的輸出進(jìn)行控制和交互馍资。首先編寫一個設(shè)置會話的方法 - (BOOL)setupSession:(NSError **)error：
包括與主捕獲會話相關(guān)的輸入設(shè)備和捕獲輸出
- 創(chuàng)建
AVCaptureSession實例 - 并添加攝像頭和麥克風(fēng)輸入，
AVMediaTypeVideo和AVMediaTypeAudio類型的捕捉設(shè)備建钥，并將它們封裝成AVCaptureDeviceInput對象熊经。 - 最后添加捕捉靜態(tài)圖片
AVCaptureStillImageOutput和 QuickTime 視頻AVCaptureMovieFileOutput的輸出實例
- (BOOL)setupSession:(NSError **)error {
//創(chuàng)建捕捉會話镐依。AVCaptureSession 是捕捉場景的中心樞紐
self.captureSession = [[AVCaptureSession alloc]init];
/*
AVCaptureSessionPresetHigh
AVCaptureSessionPresetMedium
AVCaptureSessionPresetLow
AVCaptureSessionPreset640x480
AVCaptureSessionPreset1280x720
AVCaptureSessionPresetPhoto
*/
//設(shè)置圖像的分辨率
self.captureSession.sessionPreset = AVCaptureSessionPresetHigh;
//拿到默認(rèn)視頻捕捉設(shè)備 iOS系統(tǒng)返回后置攝像頭
AVCaptureDevice *videoDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
//將捕捉設(shè)備封裝成AVCaptureDeviceInput
//注意：為會話添加捕捉設(shè)備槐壳，必須將設(shè)備封裝成AVCaptureDeviceInput對象
AVCaptureDeviceInput *videoInput = [AVCaptureDeviceInput deviceInputWithDevice:videoDevice error:error];
//判斷videoInput是否有效
if (videoInput)
{
//canAddInput：測試是否能被添加到會話中
if ([self.captureSession canAddInput:videoInput])
{
//將videoInput 添加到 captureSession中
[self.captureSession addInput:videoInput];
self.activeVideoInput = videoInput;
}
}else
{
return NO;
}
//選擇默認(rèn)音頻捕捉設(shè)備 即返回一個內(nèi)置麥克風(fēng)
AVCaptureDevice *audioDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeAudio];
//為這個設(shè)備創(chuàng)建一個捕捉設(shè)備輸入
AVCaptureDeviceInput *audioInput = [AVCaptureDeviceInput deviceInputWithDevice:audioDevice error:error];
//判斷audioInput是否有效
if (audioInput) {
//canAddInput：測試是否能被添加到會話中
if ([self.captureSession canAddInput:audioInput])
{
//將audioInput 添加到 captureSession中
[self.captureSession addInput:audioInput];
}
}else
{
return NO;
}
//AVCaptureStillImageOutput 實例 從攝像頭捕捉靜態(tài)圖片
self.imageOutput = [[AVCaptureStillImageOutput alloc]init];
//配置字典：希望捕捉到JPEG格式的圖片
self.imageOutput.outputSettings = @{AVVideoCodecKey:AVVideoCodecJPEG};
//輸出連接 判斷是否可用，可用則添加到輸出連接中去
if ([self.captureSession canAddOutput:self.imageOutput])
{
[self.captureSession addOutput:self.imageOutput];
}
//創(chuàng)建一個AVCaptureMovieFileOutput 實例枫笛，用于將Quick Time 電影錄制到文件系統(tǒng)
self.movieOutput = [[AVCaptureMovieFileOutput alloc]init];
//輸出連接 判斷是否可用刑巧，可用則添加到輸出連接中去
if ([self.captureSession canAddOutput:self.movieOutput])
{
[self.captureSession addOutput:self.movieOutput];
}
self.videoQueue = dispatch_queue_create("example.VideoQueue", NULL);
return YES;
}
啟動和停止會話
????捕捉會話的對象圖會通過調(diào)用 setupSession：方法被妥善處置啊楚，不過在使用捕捉會話前特幔，首先要啟動會話蚯斯。有啟動會話當(dāng)初就會有啟動會話拍嵌，這里定義兩個相應(yīng)的方法：startSession 和 stopSession 方法供外界調(diào)用：
- (void)startSession {
//檢查是否處于運(yùn)行狀態(tài)
if (![self.captureSession isRunning])
{
//使用同步調(diào)用會損耗一定的時間横辆，則用異步的方式處理
dispatch_async(self.videoQueue, ^{
[self.captureSession startRunning];
});
}
}
- (void)stopSession {
//檢查是否處于運(yùn)行狀態(tài)
if ([self.captureSession isRunning])
{
//使用異步方式狈蚤，停止運(yùn)行
dispatch_async(self.videoQueue, ^{
[self.captureSession stopRunning];
});
}
}
切換攝像頭
????基本上所有的 iOS 設(shè)備都具有前置和后置兩個攝像頭脆侮。首先要開發(fā)的功能就是讓用戶能夠在攝像頭之間進(jìn)行切換：
-
cameraWithPosition:方法根據(jù)攝像頭的position從數(shù)組中查找相應(yīng)的攝像頭并返回靖避； -
activeCamera方法返回當(dāng)前捕捉會話對應(yīng)的攝像頭; -
inactivceCamera方法返回當(dāng)前激活攝像頭的反向攝像頭幻捏； -
canSwitchCameras方法返回一個 BOOL 值用于表示是否有超過一個攝像頭可用篡九； -
cameraCount方法返回可用視頻捕捉設(shè)備的數(shù)量 - 最后
switchCameras方法實現(xiàn)切換未激活攝像頭功能瓮下。
#pragma mark - Device Configuration 配置攝像頭支持的方法
- (AVCaptureDevice *)cameraWithPosition:(AVCaptureDevicePosition)position {
//獲取可用視頻設(shè)備
NSArray *devicess = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
//遍歷可用的視頻設(shè)備 并返回position 參數(shù)值
for (AVCaptureDevice *device in devicess)
{
if (device.position == position) {
return device;
}
}
return nil;
}
- (AVCaptureDevice *)activeCamera {
//返回當(dāng)前捕捉會話對應(yīng)的攝像頭的device 屬性
return self.activeVideoInput.device;
}
//返回當(dāng)前未激活的攝像頭
- (AVCaptureDevice *)inactiveCamera {
//通過查找當(dāng)前激活攝像頭的反向攝像頭獲得讽坏，如果設(shè)備只有1個攝像頭路呜，則返回nil
AVCaptureDevice *device = nil;
if (self.cameraCount > 1)
{
if ([self activeCamera].position == AVCaptureDevicePositionBack) {
device = [self cameraWithPosition:AVCaptureDevicePositionFront];
}else
{
device = [self cameraWithPosition:AVCaptureDevicePositionBack];
}
}
return device;
}
//判斷是否有超過1個攝像頭可用
- (BOOL)canSwitchCameras {
return self.cameraCount > 1;
}
//可用視頻捕捉設(shè)備的數(shù)量
- (NSUInteger)cameraCount {
return [[AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo] count];
}
//切換攝像頭
- (BOOL)switchCameras {
//判斷是否有多個攝像頭
if (![self canSwitchCameras])
{
return NO;
}
//獲取當(dāng)前設(shè)備的反向設(shè)備
NSError *error;
AVCaptureDevice *videoDevice = [self inactiveCamera];
//將輸入設(shè)備封裝成AVCaptureDeviceInput
AVCaptureDeviceInput *videoInput = [AVCaptureDeviceInput deviceInputWithDevice:videoDevice error:&error];
//判斷videoInput 是否為nil
if (videoInput)
{
//標(biāo)注原配置變化開始
[self.captureSession beginConfiguration];
//將捕捉會話中，原本的捕捉輸入設(shè)備移除
[self.captureSession removeInput:self.activeVideoInput];
//判斷新的設(shè)備是否能加入
if ([self.captureSession canAddInput:videoInput])
{
//能加入成功抵屿，則將videoInput 作為新的視頻捕捉設(shè)備
[self.captureSession addInput:videoInput];
//將獲得設(shè)備 改為 videoInput
self.activeVideoInput = videoInput;
}else
{
//如果新設(shè)備轧葛，無法加入尿扯。則將原本的視頻捕捉設(shè)備重新加入到捕捉會話中
[self.captureSession addInput:self.activeVideoInput];
}
//配置完成后衷笋， AVCaptureSession commitConfiguration 會分批的將所有變更整合在一起辟宗。
[self.captureSession commitConfiguration];
}else
{
//創(chuàng)建AVCaptureDeviceInput 出現(xiàn)錯誤泊脐，則通知委托來處理該錯誤
[self.delegate deviceConfigurationFailedWithError:error];
return NO;
}
return YES;
}
配置捕捉設(shè)備
配置聚焦
-
cameraSupportsTapToFocus判斷是否支持聚焦 -
focusAtPoint：設(shè)置聚焦點(diǎn)
#pragma mark - Focus Methods 點(diǎn)擊聚焦方法的實現(xiàn)
- (BOOL)cameraSupportsTapToFocus {
//詢問激活中的攝像頭是否支持興趣點(diǎn)對焦
return [[self activeCamera]isFocusPointOfInterestSupported];
}
- (void)focusAtPoint:(CGPoint)point {
AVCaptureDevice *device = [self activeCamera];
//是否支持興趣點(diǎn)對焦 & 是否自動對焦模式
if (device.isFocusPointOfInterestSupported && [device isFocusModeSupported:AVCaptureFocusModeAutoFocus]) {
NSError *error;
//鎖定設(shè)備準(zhǔn)備配置晨抡，如果獲得了鎖
if ([device lockForConfiguration:&error]) {
//將focusPointOfInterest屬性設(shè)置CGPoint
device.focusPointOfInterest = point;
//focusMode 設(shè)置為AVCaptureFocusModeAutoFocus
device.focusMode = AVCaptureFocusModeAutoFocus;
//釋放該鎖定
[device unlockForConfiguration];
}else{
//錯誤時耘柱，則返回給錯誤處理代理
[self.delegate deviceConfigurationFailedWithError:error];
}
}
}
配置曝光
-
cameraSupportsTapToExpose判斷是否支持曝光 -
exposeAtPoint:設(shè)置曝光點(diǎn) - 監(jiān)聽
adjustingExposure屬性调煎，在曝光完成后士袄，鎖定曝光娄柳，并移除通知
#pragma mark - Exposure Methods 點(diǎn)擊曝光的方法實現(xiàn)
- (BOOL)cameraSupportsTapToExpose {
//詢問設(shè)備是否支持對一個興趣點(diǎn)進(jìn)行曝光
return [[self activeCamera] isExposurePointOfInterestSupported];
}
static const NSString *THCameraAdjustingExposureContext;
- (void)exposeAtPoint:(CGPoint)point {
AVCaptureDevice *device = [self activeCamera];
AVCaptureExposureMode exposureMode =AVCaptureExposureModeContinuousAutoExposure;
//判斷是否支持 AVCaptureExposureModeContinuousAutoExposure 模式
if (device.isExposurePointOfInterestSupported && [device isExposureModeSupported:exposureMode]) {
[device isExposureModeSupported:exposureMode];
NSError *error;
//鎖定設(shè)備準(zhǔn)備配置
if ([device lockForConfiguration:&error])
{
//配置期望值
device.exposurePointOfInterest = point;
device.exposureMode = exposureMode;
//判斷設(shè)備是否支持鎖定曝光的模式秫筏。
if ([device isExposureModeSupported:AVCaptureExposureModeLocked]) {
//支持这敬，則使用kvo確定設(shè)備的adjustingExposure屬性的狀態(tài)崔涂。
[device addObserver:self forKeyPath:@"adjustingExposure" options:NSKeyValueObservingOptionNew context:&THCameraAdjustingExposureContext];
}
//釋放該鎖定
[device unlockForConfiguration];
}else
{
[self.delegate deviceConfigurationFailedWithError:error];
}
}
}
- (void)observeValueForKeyPath:(NSString *)keyPath
ofObject:(id)object
change:(NSDictionary *)change
context:(void *)context {
//判斷context（上下文）是否為THCameraAdjustingExposureContext
if (context == &THCameraAdjustingExposureContext) {
//獲取device
AVCaptureDevice *device = (AVCaptureDevice *)object;
//判斷設(shè)備是否不再調(diào)整曝光等級缭保，確認(rèn)設(shè)備的exposureMode是否可以設(shè)置為AVCaptureExposureModeLocked
if(!device.isAdjustingExposure && [device isExposureModeSupported:AVCaptureExposureModeLocked])
{
//移除作為adjustingExposure 的self涮俄，就不會得到后續(xù)變更的通知
[object removeObserver:self forKeyPath:@"adjustingExposure" context:&THCameraAdjustingExposureContext];
//異步方式調(diào)回主隊列彻亲，
dispatch_async(dispatch_get_main_queue(), ^{
NSError *error;
if ([device lockForConfiguration:&error]) {
//修改exposureMode
device.exposureMode = AVCaptureExposureModeLocked;
//釋放該鎖定
[device unlockForConfiguration];
}else
{
[self.delegate deviceConfigurationFailedWithError:error];
}
});
}
}else
{
[super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
}
}
重置對焦和曝光
//重新設(shè)置對焦&曝光
- (void)resetFocusAndExposureModes {
AVCaptureDevice *device = [self activeCamera];
AVCaptureFocusMode focusMode = AVCaptureFocusModeContinuousAutoFocus;
//獲取對焦興趣點(diǎn) 和 連續(xù)自動對焦模式 是否被支持
BOOL canResetFocus = [device isFocusPointOfInterestSupported]&& [device isFocusModeSupported:focusMode];
AVCaptureExposureMode exposureMode = AVCaptureExposureModeContinuousAutoExposure;
//確認(rèn)曝光度可以被重設(shè)
BOOL canResetExposure = [device isFocusPointOfInterestSupported] && [device isExposureModeSupported:exposureMode];
//回顧一下，捕捉設(shè)備空間左上角（0宙址，0）调卑，右下角（1，1） 中心點(diǎn)則（0.5注益，0.5）
CGPoint centPoint = CGPointMake(0.5f, 0.5f);
NSError *error;
//鎖定設(shè)備丑搔，準(zhǔn)備配置
if ([device lockForConfiguration:&error]) {
//焦點(diǎn)可設(shè)啤月，則修改
if (canResetFocus) {
device.focusMode = focusMode;
device.focusPointOfInterest = centPoint;
}
//曝光度可設(shè)谎仲，則設(shè)置為期望的曝光模式
if (canResetExposure) {
device.exposureMode = exposureMode;
device.exposurePointOfInterest = centPoint;
}
//釋放鎖定
[device unlockForConfiguration];
}else
{
[self.delegate deviceConfigurationFailedWithError:error];
}
}
配置閃光燈和手電筒
#pragma mark - Flash and Torch Modes 閃光燈 & 手電筒
//判斷是否有閃光燈
- (BOOL)cameraHasFlash {
return [[self activeCamera]hasFlash];
}
//閃光燈模式
- (AVCaptureFlashMode)flashMode {
return [[self activeCamera]flashMode];
}
//設(shè)置閃光燈
- (void)setFlashMode:(AVCaptureFlashMode)flashMode {
//獲取會話
AVCaptureDevice *device = [self activeCamera];
//判斷是否支持閃光燈模式
if ([device isFlashModeSupported:flashMode]) {
//如果支持，則鎖定設(shè)備
NSError *error;
if ([device lockForConfiguration:&error]) {
//修改閃光燈模式
device.flashMode = flashMode;
//修改完成，解鎖釋放設(shè)備
[device unlockForConfiguration];
}else
{
[self.delegate deviceConfigurationFailedWithError:error];
}
}
}
//是否支持手電筒
- (BOOL)cameraHasTorch {
return [[self activeCamera]hasTorch];
}
//手電筒模式
- (AVCaptureTorchMode)torchMode {
return [[self activeCamera]torchMode];
}
//設(shè)置是否打開手電筒
- (void)setTorchMode:(AVCaptureTorchMode)torchMode {
AVCaptureDevice *device = [self activeCamera];
if ([device isTorchModeSupported:torchMode]) {
NSError *error;
if ([device lockForConfiguration:&error]) {
device.torchMode = torchMode;
[device unlockForConfiguration];
}else
{
[self.delegate deviceConfigurationFailedWithError:error];
}
}
}
配置視頻縮放
- 首先是
cameraSupportsZoom:方法的實現(xiàn)，通過當(dāng)前選中的AVCaptureDevice獲取它的活動AVCaptureDeviceFormat十拣，如果格式的videoMaxZoomFactor值大于 1.0夭问，則設(shè)備支持縮放功能缰趋； -
maxZoomFactor方法要確定最大允許縮放因子 -
setZoomValue:方法提供改變縮放等級 -
rampZoomToValue:方法支持在一段時間內(nèi)從當(dāng)前值到zoomValue的縮放 - 取消縮放
- 監(jiān)聽
videoZoomFactor和rampingVideoZoom用于頁面更新
- (BOOL)cameraSupportsZoom {
return self.activeCamera.activeFormat.videoMaxZoomFactor > 1.0f; // 1
}
- (CGFloat)maxZoomFactor {
return MIN(self.activeCamera.activeFormat.videoMaxZoomFactor, 4.0f); // 2
}
- (void)setZoomValue:(CGFloat)zoomValue { // 3
if (!self.activeCamera.isRampingVideoZoom) {
NSError *error;
if ([self.activeCamera lockForConfiguration:&error]) { // 4
// Provide linear feel to zoom slider
CGFloat zoomFactor = pow([self maxZoomFactor], zoomValue); // 5
self.activeCamera.videoZoomFactor = zoomFactor;
[self.activeCamera unlockForConfiguration]; // 6
} else {
[self.delegate deviceConfigurationFailedWithError:error];
}
}
}
- (void)rampZoomToValue:(CGFloat)zoomValue { // 1
CGFloat zoomFactor = pow([self maxZoomFactor], zoomValue);
NSError *error;
if ([self.activeCamera lockForConfiguration:&error]) {
[self.activeCamera rampToVideoZoomFactor:zoomFactor // 2
withRate:THZoomRate];
[self.activeCamera unlockForConfiguration];
} else {
[self.delegate deviceConfigurationFailedWithError:error];
}
}
- (void)cancelZoom { // 3
NSError *error;
if ([self.activeCamera lockForConfiguration:&error]) {
[self.activeCamera cancelVideoZoomRamp]; // 4
[self.activeCamera unlockForConfiguration];
} else {
[self.delegate deviceConfigurationFailedWithError:error];
}
}
- (void)addVideoZoomFactorObserver{
[self.activeCamera addObserver:self // 2
forKeyPath:@"videoZoomFactor"
options:0
context:NULL];
[self.activeCamera addObserver:self // 3
forKeyPath:@"rampingVideoZoom"
options:0
context:NULL];
}
- (void)observeValueForKeyPath:(NSString *)keyPath
ofObject:(id)object
change:(NSDictionary *)change
context:(void *)context {
if ([keyPath isEqualToString: @"videoZoomFactor"]) {
[self updateZoomingDelegate]; // 4
} else if ([keyPath isEqualToString: @"rampingVideoZoom"]) {
if (self.activeCamera.isRampingVideoZoom) {
[self updateZoomingDelegate]; // 5
}
} else {
[super observeValueForKeyPath:keyPath
ofObject:object
change:change
context:context];
}
}
- (void)updateZoomingDelegate {
CGFloat curZoomFactor = self.activeCamera.videoZoomFactor;
CGFloat maxZoomFactor = [self maxZoomFactor];
CGFloat value = log(curZoomFactor) / log(maxZoomFactor); // 6
[self.zoomingDelegate rampedZoomToValue:value]; // 7
}
拍攝靜態(tài)圖片
????AVCaptureStillImageOutput 類定義了 captureStillImageAsynchronouslyFromConnection:completionHandler: 方法來執(zhí)行實際的拍攝，定義一個 captureStillImage 方法用于拍照按鈕執(zhí)行：
- 通過
connectionWithMediaType:獲取AVCaptureConnection指針 - 設(shè)置連接
connection的視頻方向videoOrientation; - 定義一個
completition handler塊仔涩，在內(nèi)部接收一個有效的CMSampleBuffer熔脂，調(diào)用AVCaptureStillImageOutput類的jpegStillImageNSDataRepresentation:獲取表示圖片字節(jié)的NSData霞揉，并轉(zhuǎn)換為UIImage實例
#pragma mark - Image Capture Methods 拍攝靜態(tài)圖片
//獲取方向值
- (AVCaptureVideoOrientation)currentVideoOrientation {
AVCaptureVideoOrientation orientation;
//獲取UIDevice 的 orientation
switch ([UIDevice currentDevice].orientation) {
case UIDeviceOrientationPortrait:
orientation = AVCaptureVideoOrientationPortrait;
break;
case UIDeviceOrientationLandscapeRight:
orientation = AVCaptureVideoOrientationLandscapeLeft;
break;
case UIDeviceOrientationPortraitUpsideDown:
orientation = AVCaptureVideoOrientationPortraitUpsideDown;
break;
default:
orientation = AVCaptureVideoOrientationLandscapeRight;
break;
}
return orientation;
return 0;
}
/*
AVCaptureStillImageOutput 是AVCaptureOutput的子類。用于捕捉圖片
*/
- (void)captureStillImage {
//獲取連接
AVCaptureConnection *connection = [self.imageOutput connectionWithMediaType:AVMediaTypeVideo];
//程序只支持縱向隶症，但是如果用戶橫向拍照時蚂会，需要調(diào)整結(jié)果照片的方向
//判斷是否支持設(shè)置視頻方向
if (connection.isVideoOrientationSupported) {
//獲取方向值
connection.videoOrientation = [self currentVideoOrientation];
}
//定義一個handler 塊胁住，會返回1個圖片的NSData數(shù)據(jù)
id handler = ^(CMSampleBufferRef sampleBuffer,NSError *error)
{
if (sampleBuffer != NULL) {
NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:sampleBuffer];
UIImage *image = [[UIImage alloc]initWithData:imageData];
//捕捉圖片成功后彪见，寫入圖片
}else
{
NSLog(@"NULL sampleBuffer:%@",[error localizedDescription]);
}
};
//捕捉靜態(tài)圖片
[self.imageOutput captureStillImageAsynchronouslyFromConnection:connection completionHandler:handler];
}
視頻捕捉
????AVCaptureMovieFileOutput 類大多數(shù)核心功能繼承于父類 AVCaptureFileOutput余指，AVCaptureFileOutput 類定義了許多實用功能酵镜。比如錄制到最長時限或錄制到特定文件大小時為止淮韭。還可以配置成保留最小可用的磁盤空間靠粪。這一點(diǎn)在存儲空間有限的移動設(shè)備上錄制視頻時非常重要庇配。
????通常當(dāng) QuickTime影片準(zhǔn)備發(fā)布時捞慌，影片頭的元數(shù)據(jù)處于文件的開始位置啸澡。這樣可以讓視頻播放器快速讀取頭包含信息嗅虏，來確定文件的內(nèi)容皮服、結(jié)構(gòu)和其包含的多個樣本的位置龄广。不過，當(dāng)錄制一個 QuickTime 影片時择同，直到所有的樣片都完成捕捉后才能創(chuàng)建信息頭裹纳。當(dāng)錄制結(jié)束時剃氧，創(chuàng)建頭數(shù)據(jù)并將它附在文件結(jié)尾處她我。
????將創(chuàng)建頭的過程放在所有影片樣本完成捕捉之后存在一個問題番舆，尤其是在移動設(shè)備的情況下恨狈。如果遇到崩潰或其他中斷呛讲，比如有電話撥入贝搁，則影片頭就不會被正確寫入雷逆，會在磁盤生成一個不可讀的影片文件膀哲。 AVCaptureMovieFileOutput 提供一個核心功能就是分段捕捉 QuickTime 影片仿村。
????當(dāng)錄制開始時蔼囊，在文件最前面寫入一個最小化的頭信息衣迷，隨著錄制的進(jìn)行畏鼓，片段按照一定的周期寫入，創(chuàng)建完整的頭信息蘑险。默認(rèn)狀態(tài)下滴肿，每10秒寫入一個片段，不過這個時間的間隔可以通過修改捕捉設(shè)備輸出的 movieFragentInterval 屬性來改變佃迄。
isRecording判斷是否在錄制狀態(tài)startRecording方法中獲取處理當(dāng)前視頻捕捉連接的信息泼差，設(shè)置enablesVideoStabilizationWhenAvailable提搞視頻穩(wěn)定性，設(shè)置攝像頭平滑對焦模式smoothAutoFocusEnabled降低對焦操作的速率堆缘，根據(jù)指定文件路徑調(diào)用startRecordingToOutputFileURL:recordingDelegate:開始錄制stopRecording停止錄制-
實現(xiàn)
AVCaptureFileOutputRecordingDelegate協(xié)議中的captureOutput:didFinishRecordingToOutputFileAtURL:fromConnections: error:方法，接收返回信息進(jìn)行處理視頻錄制的委托回調(diào)時間線
#pragma mark - Video Capture Methods 捕捉視頻
//判斷是否錄制狀態(tài)
- (BOOL)isRecording {
return self.movieOutput.isRecording;
}
//開始錄制
- (void)startRecording {
if (![self isRecording]) {
//獲取當(dāng)前視頻捕捉連接信息普碎，用于捕捉視頻數(shù)據(jù)配置一些核心屬性
AVCaptureConnection * videoConnection = [self.movieOutput connectionWithMediaType:AVMediaTypeVideo];
//判斷是否支持設(shè)置videoOrientation 屬性吼肥。
if([videoConnection isVideoOrientationSupported])
{
//支持則修改當(dāng)前視頻的方向
videoConnection.videoOrientation = [self currentVideoOrientation];
}
//判斷是否支持視頻穩(wěn)定 可以顯著提高視頻的質(zhì)量。只會在錄制視頻文件涉及
if([videoConnection isVideoStabilizationSupported])
{
videoConnection.enablesVideoStabilizationWhenAvailable = YES;
}
AVCaptureDevice *device = [self activeCamera];
//攝像頭可以進(jìn)行平滑對焦模式操作。即減慢攝像頭鏡頭對焦速度缀皱。當(dāng)用戶移動拍攝時攝像頭會嘗試快速自動對焦斗这。
if (device.isSmoothAutoFocusEnabled) {
NSError *error;
if ([device lockForConfiguration:&error]) {
device.smoothAutoFocusEnabled = YES;
[device unlockForConfiguration];
}else
{
[self.delegate deviceConfigurationFailedWithError:error];
}
}
//查找寫入捕捉視頻的唯一文件系統(tǒng)URL.
self.outputURL = [self uniqueURL];
//在捕捉輸出上調(diào)用方法 參數(shù)1:錄制保存路徑 參數(shù)2:代理
[self.movieOutput startRecordingToOutputFileURL:self.outputURL recordingDelegate:self];
}
}
- (CMTime)recordedDuration {
return self.movieOutput.recordedDuration;
}
//寫入視頻唯一文件系統(tǒng)URL
- (NSURL *)uniqueURL {
NSFileManager *fileManager = [NSFileManager defaultManager];
//temporaryDirectoryWithTemplateString 可以將文件寫入的目的創(chuàng)建一個唯一命名的目錄；
NSString *dirPath = [fileManager temporaryDirectoryWithTemplateString:@"kamera.XXXXXX"];
if (dirPath) {
NSString *filePath = [dirPath stringByAppendingPathComponent:@"kamera_movie.mov"];
return [NSURL fileURLWithPath:filePath];
}
return nil;
}
//停止錄制
- (void)stopRecording {
//是否正在錄制
if ([self isRecording]) {
[self.movieOutput stopRecording];
}
}
#pragma mark - AVCaptureFileOutputRecordingDelegate
- (void)captureOutput:(AVCaptureFileOutput *)captureOutput
didFinishRecordingToOutputFileAtURL:(NSURL *)outputFileURL
fromConnections:(NSArray *)connections
error:(NSError *)error {
//錯誤
if (error) {
[self.delegate mediaCaptureFailedWithError:error];
}else
{
//寫入圖片
}
self.outputURL = nil;
}
