├── .gitignore
├── LICENSE
├── QtCamera.cpp
├── QtCamera.h
├── QtCamera.pro
├── README.md
├── app.ico
└── main.cpp


/.gitignore:
--------------------------------------------------------------------------------
 1 | # C++ objects and libs
 2 | *.slo
 3 | *.lo
 4 | *.o
 5 | *.a
 6 | *.la
 7 | *.lai
 8 | *.so
 9 | *.dll
10 | *.dylib
11 | 
12 | # Qt-es
13 | object_script.*.Release
14 | object_script.*.Debug
15 | *_plugin_import.cpp
16 | /.qmake.cache
17 | /.qmake.stash
18 | *.pro.user
19 | *.pro.user.*
20 | *.qbs.user
21 | *.qbs.user.*
22 | *.moc
23 | moc_*.cpp
24 | moc_*.h
25 | qrc_*.cpp
26 | ui_*.h
27 | *.qmlc
28 | *.jsc
29 | Makefile*
30 | *build-*
31 | 
32 | # Qt unit tests
33 | target_wrapper.*
34 | 
35 | # QtCreator
36 | *.autosave
37 | 
38 | # QtCreator Qml
39 | *.qmlproject.user
40 | *.qmlproject.user.*
41 | 
42 | # QtCreator CMake
43 | CMakeLists.txt.user*
44 | 


--------------------------------------------------------------------------------
/LICENSE:
--------------------------------------------------------------------------------
 1 | MIT License
 2 | 
 3 | Copyright (c) 2019 aeagean
 4 | 
 5 | Permission is hereby granted, free of charge, to any person obtaining a copy
 6 | of this software and associated documentation files (the "Software"), to deal
 7 | in the Software without restriction, including without limitation the rights
 8 | to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 9 | copies of the Software, and to permit persons to whom the Software is
10 | furnished to do so, subject to the following conditions:
11 | 
12 | The above copyright notice and this permission notice shall be included in all
13 | copies or substantial portions of the Software.
14 | 
15 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 | IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 | FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
18 | AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 | LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 | OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
21 | SOFTWARE.
22 | 


--------------------------------------------------------------------------------
/QtCamera.cpp:
--------------------------------------------------------------------------------
  1 | /**********************************************************
  2 | Author: Qt君
  3 | 微信公众号: Qt君(首发)
  4 | QQ群: 732271126
  5 | Email: 2088201923@qq.com
  6 | LICENSE: MIT
  7 | **********************************************************/
  8 | #include "QtCamera.h"
  9 | #include "QtCamera.h"
 10 | #include <QDebug>
 11 | 
 12 | QtCamera::QtCamera(QVideoWidget *widget) :
 13 |     m_videoWidget(widget),
 14 |     m_isStarted(false),
 15 |     m_camera(NULL)
 16 | {
 17 |     selectDevice(QCameraInfo::defaultCamera());
 18 |     start();
 19 | 
 20 |     connect(&m_checkDeviceListTimer, SIGNAL(timeout()), this, SLOT(checkDeviceList()));
 21 |     connect(this, SIGNAL(deviceListChanged()), this, SLOT(autoRestore()));
 22 |     connect(this, SIGNAL(deviceListChanged()), this, SLOT(autoSelectDevice()));
 23 | 
 24 |     m_checkDeviceListTimer.start(3000);
 25 | 
 26 |     QList<QCameraInfo> curCameraInfoList = QCameraInfo::availableCameras();
 27 |     for (int i = 0; i < curCameraInfoList.count(); i++) {
 28 |         qDebug() << curCameraInfoList.at(i).deviceName();
 29 |     }
 30 | }
 31 | 
 32 | QtCamera::~QtCamera()
 33 | {
 34 | 
 35 | }
 36 | 
 37 | bool QtCamera::start()
 38 | {
 39 |     if (! m_isStarted) {
 40 |         m_isStarted = true;
 41 | 
 42 |         m_camera->start();
 43 |     }
 44 | 
 45 |     return true;
 46 | }
 47 | 
 48 | bool QtCamera::stop()
 49 | {
 50 |     if (m_isStarted) {
 51 |         m_isStarted = false;
 52 | 
 53 |         m_camera->stop();
 54 |     }
 55 | 
 56 |     return true;
 57 | }
 58 | 
 59 | bool QtCamera::isStarted()
 60 | {
 61 |     return m_isStarted;
 62 | }
 63 | 
 64 | bool QtCamera::selectDevice(const QCameraInfo &cameraInfo)
 65 | {
 66 |     bool restart = isStarted();
 67 |     if (isStarted()) {
 68 |         stop();
 69 |     }
 70 | 
 71 |     if (m_camera) {
 72 |         delete m_camera;
 73 |     }
 74 | 
 75 |     m_curCameraInfo = cameraInfo;
 76 |     m_camera = new QCamera(m_curCameraInfo);
 77 |     m_camera->setViewfinder(m_videoWidget);
 78 | 
 79 |     if (restart)
 80 |         start();
 81 | }
 82 | 
 83 | void QtCamera::autoRestore()
 84 | {
 85 |     if (! m_isStarted) {
 86 |         return;
 87 |     }
 88 | 
 89 |     if (deviceExist(m_curCameraInfo)) {
 90 |         if (m_camera->status() != QCamera::ActiveStatus) {
 91 |             QTimer::singleShot(500, m_camera, SLOT(start()));
 92 |         }
 93 |     }
 94 |     else {
 95 |         if (m_camera->status() == QCamera::ActiveStatus) {
 96 |             m_camera->stop();
 97 |             m_camera->unload();
 98 |         }
 99 |     }
100 | }
101 | 
102 | void QtCamera::autoSelectDevice()
103 | {
104 |     QList<QCameraInfo> curCameraInfoList = QCameraInfo::availableCameras();
105 |     if (curCameraInfoList.isEmpty())
106 |         return;
107 | 
108 |     if (curCameraInfoList.contains(m_curCameraInfo)) {
109 |         selectDevice(m_curCameraInfo);
110 |         return;
111 |     }
112 | 
113 |     selectDevice(curCameraInfoList.first());
114 | }
115 | 
116 | void QtCamera::checkDeviceList()
117 | {
118 |     QList<QCameraInfo> curCameraInfoList = QCameraInfo::availableCameras();
119 |     if ( m_preCameraInfoList.count() != curCameraInfoList.count() ) {
120 |         emit deviceListChanged();
121 |     }
122 | 
123 |     m_preCameraInfoList = curCameraInfoList;
124 | }
125 | 
126 | bool QtCamera::deviceExist(const QCameraInfo &cameraInfo) const
127 | {
128 |     QList<QCameraInfo> cameraInfoList = QCameraInfo::availableCameras();
129 |     for (int i = 0; i < cameraInfoList.count(); i++) {
130 |         if (cameraInfo.deviceName() == cameraInfoList.at(i).deviceName())
131 |             return true;
132 |     }
133 | 
134 |     return false;
135 | }
136 | 


--------------------------------------------------------------------------------
/QtCamera.h:
--------------------------------------------------------------------------------
 1 | /**********************************************************
 2 | Author: Qt君
 3 | 微信公众号: Qt君(首发)
 4 | QQ群: 732271126
 5 | Email: 2088201923@qq.com
 6 | LICENSE: MIT
 7 | **********************************************************/
 8 | #ifndef QT_CAMERA_H
 9 | #define QT_CAMERA_H
10 | 
11 | #include <QCamera>
12 | #include <QCameraInfo>
13 | #include <QVideoWidget>
14 | #include <QTimer>
15 | 
16 | class QtCamera : public QObject
17 | {
18 |     Q_OBJECT
19 | public:
20 |     QtCamera(QVideoWidget *widget);
21 |     ~QtCamera();
22 | 
23 |     bool start();
24 |     bool stop();
25 |     bool isStarted();
26 | 
27 |     bool selectDevice(const QCameraInfo &cameraInfo);
28 | 
29 | signals:
30 |     void deviceListChanged();
31 |     void deviceStatusChanged();
32 | 
33 | private slots:
34 |     void autoRestore();
35 |     void autoSelectDevice();
36 |     void checkDeviceList();
37 | 
38 | private:
39 |     bool deviceExist(const QCameraInfo &cameraInfo) const;
40 | 
41 | private:
42 |     bool               m_isStarted;
43 |     QTimer             m_checkDeviceListTimer;
44 | 
45 |     QVideoWidget      *m_videoWidget;
46 |     QCamera           *m_camera;
47 |     QCameraInfo        m_curCameraInfo;
48 |     QList<QCameraInfo> m_curCameraInfoList;
49 |     QList<QCameraInfo> m_preCameraInfoList;
50 | };
51 | 
52 | #endif // QT_CAMERA_H
53 | 


--------------------------------------------------------------------------------
/QtCamera.pro:
--------------------------------------------------------------------------------
 1 | #**********************************************************
 2 | #Author: Qt君
 3 | #微信公众号: Qt君
 4 | #QQ群: 732271126
 5 | #Email: 2088201923@qq.com
 6 | #LICENSE: MIT
 7 | #**********************************************************
 8 | 
 9 | QT       += core gui
10 | QT       += multimedia multimediawidgets
11 | 
12 | greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
13 | 
14 | TARGET = QtCamera
15 | TEMPLATE = app
16 | 
17 | win32: RC_ICONS += app.ico
18 | 
19 | # The following define makes your compiler emit warnings if you use
20 | # any feature of Qt which has been marked as deprecated (the exact warnings
21 | # depend on your compiler). Please consult the documentation of the
22 | # deprecated API in order to know how to port your code away from it.
23 | DEFINES += QT_DEPRECATED_WARNINGS
24 | 
25 | # You can also make your code fail to compile if you use deprecated APIs.
26 | # In order to do so, uncomment the following line.
27 | # You can also select to disable deprecated APIs only up to a certain version of Qt.
28 | #DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0
29 | 
30 | CONFIG += c++11
31 | 
32 | SOURCES += \
33 |         main.cpp \
34 |         QtCamera.cpp
35 | 
36 | HEADERS += \
37 |     QtCamera.h
38 | 
39 | # Default rules for deployment.
40 | qnx: target.path = /tmp/$${TARGET}/bin
41 | else: unix:!android: target.path = /opt/$${TARGET}/bin
42 | !isEmpty(target.path): INSTALLS += target
43 | 


--------------------------------------------------------------------------------
/README.md:
--------------------------------------------------------------------------------
 1 | <!-- ---
 2 | title: Qt摄像头热插拔实现
 3 | date: 2019-08-07 22:41:222
 4 | tags: Qt
 5 | comments: true
 6 | --- -->
 7 | 
 8 | > 基于Qt的Camera模块实现摄像头的热插拔。当只有一个摄像头时，被拔开后再插入能自动恢复相机状态。当有多个摄像头时，拔开当前摄像头会自动设置另外一个摄像头。
 9 | 
10 | ## 基于定时查询的方法
11 | * **定时查询**设备列表变化；
12 | ```cpp
13 | connect(&m_checkDeviceListTimer, SIGNAL(timeout()), 
14 |          this, SLOT(checkDeviceList()));
15 | ```
16 | * 如果当前设备列表**对比**上一次缓存的设备列表有变化则**发送**设备列表变化**事件**(信号)`deviceListChanged()`；
17 | ```cpp
18 | void QtCamera::checkDeviceList()
19 | {
20 |     QList<QCameraInfo> curCameraInfoList = QCameraInfo::availableCameras();
21 |     if ( m_preCameraInfoList.count() != curCameraInfoList.count() ) {
22 |         emit deviceListChanged();
23 |     }
24 | 
25 |     m_preCameraInfoList = curCameraInfoList;
26 | }
27 | ```
28 | 
29 | ## 单设备重连机制
30 | * 先前`autoRestore()`槽函数**绑定**设备列表变化信号。
31 | ```cpp
32 | connect(this, SIGNAL(deviceListChanged()), this, SLOT(autoRestore()));
33 | ```
34 | * 触发自动重连机制。
35 | &emsp;&emsp;当设备**存在**则会重新启动`start()`;  
36 | &emsp;&emsp;当设备**不存**在则关闭该设备。  
37 | ```cpp
38 | void QtCamera::autoRestore()
39 | {
40 |     if (! m_isStarted) {
41 |         return;
42 |     }
43 | 
44 |     if (deviceExist(m_curCameraInfo)) {
45 |         if (m_camera->status() != QCamera::ActiveStatus) {
46 |             QTimer::singleShot(500, m_camera, SLOT(start()));
47 |         }
48 |     }
49 |     else {
50 |         if (m_camera->status() == QCamera::ActiveStatus) {
51 |             m_camera->stop();
52 |             m_camera->unload();
53 |         }
54 |     }
55 | }
56 | ```
57 | 
58 | ## 多设备自动切换
59 | * `autoSelectDevice()`槽函数连接设备列表变化信号。
60 | ```cpp
61 | connect(this, SIGNAL(deviceListChanged()), this, SLOT(autoSelectDevice()));
62 | ```
63 | 
64 | * 当设备已存在再次刷新**当前的**设备；
65 | * 当设备被**断开**，自动切换到第一个设备。
66 | ```cpp
67 | void QtCamera::autoSelectDevice()
68 | {
69 |     QList<QCameraInfo> curCameraInfoList = QCameraInfo::availableCameras();
70 |     if (curCameraInfoList.isEmpty())
71 |         return;
72 | 
73 |     if (curCameraInfoList.contains(m_curCameraInfo)) {
74 |         selectDevice(m_curCameraInfo);
75 |         return;
76 |     }
77 | 
78 |     selectDevice(curCameraInfoList.first());
79 | }
80 | ```
81 | 
82 | ## 关于更多
83 | * 源码地址：
84 | ```
85 | https://github.com/aeagean/QtCamera
86 | ```
87 | * 文章首发公众号：**Qt君**  
88 | <p align="center">
89 |   <img src="http://www.qtbig.com/about/index/my_qrcode.jpg" alt="微信公众号:Qt君">
90 |   <p align="center"><em>Qt君</em></p>
91 | </p>
92 | 
93 | * **后续**更新摄像头参数选择算法(自动匹配用户设置摄像头参数，**分辨率**，**帧率**，**格式**)。
94 | 


--------------------------------------------------------------------------------
/app.ico:
--------------------------------------------------------------------------------
https://raw.githubusercontent.com/aeagean/QtCamera/31039f1fcd3fd6e36a6ec79a8d9b60f550832ba0/app.ico


--------------------------------------------------------------------------------
/main.cpp:
--------------------------------------------------------------------------------
 1 | /**********************************************************
 2 | Author: Qt君
 3 | 微信公众号: Qt君(首发)
 4 | QQ群: 732271126
 5 | Email: 2088201923@qq.com
 6 | LICENSE: MIT
 7 | **********************************************************/
 8 | #include "QtCamera.h"
 9 | 
10 | #include <QApplication>
11 | 
12 | int main(int argc, char *argv[])
13 | {
14 |     QApplication a(argc, argv);
15 | 
16 |     QVideoWidget widget;
17 |     QtCamera camera(&widget);
18 |     widget.show();
19 |     return a.exec();
20 | }
21 | 


--------------------------------------------------------------------------------