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最近公司的项目中用到了相机，由于不用系统的相机，ui给的相机切图，必须自定义才可以。就花时间简单研究了一下相机的自定义。
相机属于系统硬件，这就需要我们来手动调用iphone的相机硬件，分为以下步骤：
1、首先声明以下对象
#import <avfoundation/avfoundation.h> //捕获设备，通常是前置摄像头，后置摄像头，麦克风（音频输入） @property (nonatomic, strong) avcapturedevice *device; //avcapturedeviceinput 代表输入设备，他使用avcapturedevice 来初始化 @property (nonatomic, strong) avcapturedeviceinput *input; //输出图片 @property (nonatomic ,strong) avcapturestillimageoutput *imageoutput; //session：由他把输入输出结合在一起，并开始启动捕获设备（摄像头） @property (nonatomic, strong) avcapturesession *session; //图像预览层，实时显示捕获的图像 @property (nonatomic ,strong) avcapturevideopreviewlayer *previewlayer;
2、初始化各个对象
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- (void)cameradistrict
{
// avcapturedevicepositionback 后置摄像头
// avcapturedevicepositionfront 前置摄像头
self.device = [self camerawithposition:avcapturedevicepositionfront];
self.input = [[avcapturedeviceinput alloc] initwithdevice:self.device error:nil];
self.imageoutput = [[avcapturestillimageoutput alloc] init];
self.session = [[avcapturesession alloc] init];
// 拿到的图像的大小可以自行设定
// avcapturesessionpreset320x240
// avcapturesessionpreset352x288
// avcapturesessionpreset640x480
// avcapturesessionpreset960x540
// avcapturesessionpreset1280x720
// avcapturesessionpreset1920x1080
// avcapturesessionpreset3840x2160
self.session.sessionpreset = avcapturesessionpreset640x480;
//输入输出设备结合
if ([self.session canaddinput:self.input]) {
[self.session addinput:self.input];
}
if ([self.session canaddoutput:self.imageoutput]) {
[self.session addoutput:self.imageoutput];
}
//预览层的生成
self.previewlayer = [[avcapturevideopreviewlayer alloc] initwithsession:self.session];
self.previewlayer.frame = cgrectmake(0, 64, screen_width, screen_height-64);
self.previewlayer.videogravity = avlayervideogravityresizeaspectfill;
[self.view.layer addsublayer:self.previewlayer];
//设备取景开始
[self.session startrunning];
if ([_device lockforconfiguration:nil]) {
//自动闪光灯，
if ([_device isflashmodesupported:avcaptureflashmodeauto]) {
[_device setflashmode:avcaptureflashmodeauto];
}
//自动白平衡,但是好像一直都进不去
if ([_device iswhitebalancemodesupported:avcapturewhitebalancemodeautowhitebalance]) {
[_device setwhitebalancemode:avcapturewhitebalancemodeautowhitebalance];
}
[_device unlockforconfiguration];
}
}
根据前后置位置拿到相应的摄像头：
- (avcapturedevice *)camerawithposition:(avcapturedeviceposition)position{
nsarray *devices = [avcapturedevice deviceswithmediatype:avmediatypevideo];
for ( avcapturedevice *device in devices )
if ( device.position == position ){
return device;
}
return nil;
}
3、拍照拿到相应图片：
- (void)photobtndidclick
{
avcaptureconnection *conntion = [self.imageoutput connectionwithmediatype:avmediatypevideo];
if (!conntion) {
nslog(@"拍照失败!");
return;
}
[self.imageoutput capturestillimageasynchronouslyfromconnection:conntion completionhandler:^(cmsamplebufferref imagedatasamplebuffer, nserror *error) {
if (imagedatasamplebuffer == nil) {
return ;
}
nsdata *imagedata = [avcapturestillimageoutput jpegstillimagensdatarepresentation:imagedatasamplebuffer];
self.image = [uiimage imagewithdata:imagedata];
[self.session stoprunning];
[self.view addsubview:self.cameraimageview];
}
4、保存照片到相册：
#pragma - 保存至相册
- (void)saveimagetophotoalbum:(uiimage*)savedimage
{
uiimagewritetosavedphotosalbum(savedimage, self, @selector(image:didfinishsavingwitherror:contextinfo:), null);
}
// 指定回调方法
- (void)image: (uiimage *) image didfinishsavingwitherror: (nserror *) error contextinfo: (void *) contextinfo
{
nsstring *msg = nil ;
if(error != null){
msg = @"保存图片失败" ;
}else{
msg = @"保存图片成功" ;
}
uialertview *alert = [[uialertview alloc] initwithtitle:@"保存图片结果提示"
message:msg
delegate:self
cancelbuttontitle:@"确定"
otherbuttontitles:nil];
[alert show];
}
5、前后置摄像头的切换
- (void)changecamera{
nsuinteger cameracount = [[avcapturedevice deviceswithmediatype:avmediatypevideo] count];
if (cameracount > 1) {
nserror *error;
//给摄像头的切换添加翻转动画
catransition *animation = [catransition animation]；
animation.duration = .5f；
animation.timingfunction = [camediatimingfunction functionwithname:kcamediatimingfunctioneaseineaseout];
animation.type = @"oglflip";
avcapturedevice *newcamera = nil;
avcapturedeviceinput *newinput = nil;
//拿到另外一个摄像头位置
avcapturedeviceposition position = [[_input device] position];
if (position == avcapturedevicepositionfront){
newcamera = [self camerawithposition:avcapturedevicepositionback];
animation.subtype = kcatransitionfromleft;//动画翻转方向
}
else {
newcamera = [self camerawithposition:avcapturedevicepositionfront];
animation.subtype = kcatransitionfromright;//动画翻转方向
}
//生成新的输入
newinput = [avcapturedeviceinput deviceinputwithdevice:newcamera error:nil];
[self.previewlayer addanimation:animation forkey:nil];
if (newinput != nil) {
[self.session beginconfiguration];
[self.session removeinput:self.input];
if ([self.session canaddinput:newinput]) {
[self.session addinput:newinput];
self.input = newinput;
} else {
[self.session addinput:self.input];
}
[self.session commitconfiguration];
} else if (error) {
nslog(@"toggle carema failed, error = %@", error);
}
}
}
6、相机的其它参数设置
//avcaptureflashmode 闪光灯
//avcapturefocusmode 对焦
//avcaptureexposuremode 曝光
//avcapturewhitebalancemode 白平衡
//闪光灯和白平衡可以在生成相机时候设置
//曝光要根据对焦点的光线状况而决定,所以和对焦一块写
//point为点击的位置
- (void)focusatpoint:(cgpoint)point{
cgsize size = self.view.bounds.size;
cgpoint focuspoint = cgpointmake( point.y /size.height ,1-point.x/size.width );
nserror *error;
if ([self.device lockforconfiguration:&error]) {
//对焦模式和对焦点
if ([self.device isfocusmodesupported:avcapturefocusmodeautofocus]) {
[self.device setfocuspointofinterest:focuspoint];
[self.device setfocusmode:avcapturefocusmodeautofocus];
}
//曝光模式和曝光点
if ([self.device isexposuremodesupported:avcaptureexposuremodeautoexpose ]) {
[self.device setexposurepointofinterest:focuspoint];
[self.device setexposuremode:avcaptureexposuremodeautoexpose];
}
[self.device unlockforconfiguration];
//设置对焦动画
_focusview.center = point;
_focusview.hidden = no;
[uiview animatewithduration:0.3 animations:^{
_focusview.transform = cgaffinetransformmakescale(1.25, 1.25);
}completion:^(bool finished) {
[uiview animatewithduration:0.5 animations:^{
_focusview.transform = cgaffinetransformidentity;
} completion:^(bool finished) {
_focusview.hidden = yes;
}];
}];
}
}
7、遇到的一些坑和解决办法
1) 前后置摄像头的切换
前后值不能切换，各种尝试找了半天没找到有原因。后来发现我在设置图片尺寸的时候设置为1080p [self.session cansetsessionpreset: avcapturesessionpreset1920x1080] ，前置摄像头并不支持这么大的尺寸，所以就不能切换前置摄像头。我验证了下 前置摄像头最高支持720p,720p以内可自由切换。
当然也可以在前后置摄像头切换的时候，根据前后摄像头来设置不同的尺寸，这里不在赘述。
2）焦点位置
cgpoint focuspoint = cgpointmake( point.y /size.height ,1-point.x/size.width );
setexposurepointofinterest：focuspoint 函数后面point取值范围是取景框左上角（0，0）到取景框右下角（1，1）之间。官方是这么写的：
the value of this property is a cgpoint that determines the receiver's focus point of interest, if it has one. a value of (0,0) indicates that the camera should focus on the top left corner of the image, while a value of (1,1) indicates that it should focus on the bottom right. the default value is (0.5,0.5).
我也试了按这个来但位置就是不对，只能按上面的写法才可以。前面是点击位置的y/previewlayer的高度，后面是1-点击位置的x/previewlayer的宽度
3）对焦和曝光
我在设置对焦是 先设置了模式setfocusmode，后设置对焦位置，就会导致很奇怪的现象，对焦位置是你上次点击的位置。所以一定要先设置位置，再设置对焦模式。
曝光同上
8、写在最后
附上demo：photographdemo
常用到的基本就这么多，写的并不完善，有什么不对的，欢迎大家批评指正，共同学习。
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