QT5:C++实现基于multimedia的音乐播放器（一）
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2022-07-25 14:53:30
上一篇里简略的描述了一下播放器的实现，这一篇开始具体描述一下过程。 环境配置：Qt Creator 打开Qt Creator，创建一个new project，项目名称随你喜欢（我的是MusicPlayer），类名也随你喜欢（我的是Music），基类选择QWidget，不勾选界面UI（你也可以勾选UI ......
上一篇里简略的描述了一下播放器的实现，这一篇开始具体描述一下过程。
环境配置：Qt Creator
打开Qt Creator，创建一个new project，项目名称随你喜欢（我的是MusicPlayer），类名也随你喜欢（我的是Music），基类选择QWidget，不勾选界面UI（你也可以勾选UI，用QT自带的UI设计来创建界面），然后要记住项目保存路径不能有中文。
创建成功后，在MusicPlayer.pro（项目名称.pro）里加上“QT += multimedia”这一句：
1 QT += core gui 2 QT += multimedia 3 greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
然后在头文件music.h（类名.h）里添加要用到的头文件名：
1 #include <QWidget> 2 #include <QMediaPlayer> 3 #include <QPushButton> 4 #include <QSlider> 5 #include <QLabel> 6 #include <QTime> 7 #include <QPaintEvent> 8 #include <QMediaPlaylist> 9 #include <QTimer> 10 #include <QListWidget>
并且在music类里写上要用到的对象成员和函数：
1 class Music : public QWidget
2 {
3 Q_OBJECT
4 public:
5 explicit Music(QWidget *parent = 0);
6 static int z;
7
8 public slots:
9 void addMoremusic();
10 void playMusic();
11 void preMusic();
12 void nextMusic();
13 void meteOpen();
14 void volumChange(int);
15 void positionChange(qint64 position);
16 void showMessage(bool);
17 void seekChange(int position);
18 void posChange();
19 void clearMessage();
20 void musicPlayPattern();
21
22 private:
23 void init_controls();
24 void init_skin();
25
26 QPushButton *BtnClose;
27 QPushButton *BtnMin;
28 QPushButton *BtnPlay;
29 QPushButton *BtnPrev;
30 QPushButton *BtnNext;
31 QPushButton *muteButton;
32 QPushButton *addMore;
33 QPushButton *playPattern;
34 QSlider *volumeControl;
35 QSlider *seekSlider;
36 QLabel *showTime;
37 QLabel *showPro;
38 QLabel *showMge;
39 QLabel *title;
40 QLabel *message;
41 QListWidget *list;
42 bool add;
43 QTimer *timer;
44 QTimer *timer2;
45 int moved;
46 QPoint dragPosition;
47 QMediaPlayer *player;
48 QMediaPlaylist * playList;
49
50 protected:
51 void paintEvent(QPaintEvent *event);
52 void mousePressEvent(QMouseEvent *event);
53 void mouseMoveEvent(QMouseEvent *event);
54 };
还要在源文件music.cpp里加上要用的头文件名：
1 #include "music.h" 2 #include <QPixmap> 3 #include <QFile> 4 #include <QPainter> 5 #include <QFileDialog> 6 #include <QUrl> 7 #include <QDebug> 8 #include <QMediaMetaData> 9 #include <QMessageBox> 10 #include <QFileInfo>
接着添加资源文件，把要用的图标和背景图片都添加到项目里，然后就可以在music.cpp里写播放器的界面了。
1 Music::Music(QWidget *parent) : QWidget(parent)
2 {
3 QPixmap background;
4 background.load(":/image/music_bg.bmp");//加载背景图片
5 this -> resize(background.width(),background.height());//设置窗口和背景图片大小一致
6 this -> setWindowFlags(Qt::FramelessWindowHint);//产生一个无窗口边框的窗口，用户无法改变它的大小也无法移动它
7 add = false;
8 moved = 0;
9 timer = new QTimer(this);
10 timer2 = new QTimer(this);
11
12 player = new QMediaPlayer(this);//QMediaplayer用于解析音频文件和视频文件
13 playList = new QMediaPlaylist;
14
15 init_controls();//创建按钮
16 init_skin();//外部加载qss文件，绘制界面样式
17
18 connect(player, SIGNAL(metaDataAvailableChanged(bool)), this, SLOT(showMessage(bool)));
19 connect(seekSlider,SIGNAL(sliderMoved(int)), this,SLOT(seekChange(int)));
20 }
因为我创建的是一个无法移动的窗体，所以重写鼠标左键函数来让它可以被移动，这样的话，鼠标左键按住时可以拖动窗体了：
//令窗口可以被拖动
void Music::mousePressEvent(QMouseEvent *event){
if(event->buttons()==Qt::LeftButton)
{
dragPosition=event->globalPos()-frameGeometry().topLeft();
event->accept();
}
}
void Music::mouseMoveEvent(QMouseEvent *event)
{
if(event->buttons() & Qt::LeftButton)//event->buttons()==Qt::LeftButton && event ->y() < 50 && event ->x() < 330
{
this ->move(event->globalPos() - dragPosition);
event->accept();
}
}
//绘制背景
void Music::paintEvent(QPaintEvent *event)
{
QPainter paint(this);
QPixmap backgound;
backgound.load(":/image/music_bg.bmp");
paint.drawPixmap(0, 0, backgound.width(), backgound.height(),backgound);
event ->accept();
}
然后写创建按钮的函数以及连接槽函数来响应信号的连接语句：
//创建按钮
void Music::init_controls()
{
BtnClose = new QPushButton(this);
BtnClose -> setObjectName("BtnClose");//如果要对这个对象单独设stylesheet的话一定要设置它的objectName
BtnClose -> setGeometry(365,2,30,30);//窗口左上角为原点（X365，Y2），（宽30，高30）
BtnClose -> setToolTip(tr("退出"));
BtnClose -> setCursor(QCursor(Qt::PointingHandCursor));//鼠标指针形状为手
BtnMin=new QPushButton(this);
BtnMin->setObjectName(tr("BtnMin"));
BtnMin->setGeometry(330,5,25,30);
BtnMin->setToolTip(tr("最小化"));
BtnMin->setCursor(QCursor(Qt::PointingHandCursor));
playPattern=new QPushButton(this);
/*QIcon icon1(":/image/Seq.png");
playPattern->setIcon(icon1);*/
playPattern->setObjectName(tr("playPattern"));
playPattern->setGeometry(20,255,50,50);
playPattern->setToolTip(tr("列表循环"));
playPattern->setCursor(QCursor(Qt::PointingHandCursor));
BtnPlay=new QPushButton(this);
BtnPlay->setObjectName(tr("BtnPlay"));
BtnPlay->setGeometry(160,250,56,56);
BtnPlay->setToolTip(tr("播放"));
BtnPlay->setCursor(QCursor(Qt::PointingHandCursor));
BtnPrev=new QPushButton(this);
BtnPrev->setObjectName(tr("BtnPrev"));
BtnPrev->setGeometry(120,255,45,45);
BtnPrev->setToolTip(tr("上一首"));
BtnPrev->setCursor(QCursor(Qt::PointingHandCursor));
BtnNext=new QPushButton(this);
BtnNext->setObjectName(tr("BtnNext"));
BtnNext->setGeometry(210,255,45,45);
BtnNext->setToolTip(tr("下一首"));
BtnNext->setCursor(QCursor(Qt::PointingHandCursor));
muteButton=new QPushButton(this);
muteButton->setObjectName(tr("muteButton"));
muteButton->setGeometry(370,320,25,25);
muteButton->setToolTip(tr("关闭声音"));
muteButton->setCursor(QCursor(Qt::PointingHandCursor));
volumeControl=new QSlider(Qt::Vertical,this);//QSlider(Qt::Vertical,this)创建一个竖直方向的滑动条QSlider控件
volumeControl->setObjectName(tr("volumeControl"));
volumeControl->setGeometry(375,240,15,80);
volumeControl->setCursor(QCursor(Qt::PointingHandCursor));
volumeControl->setRange(0,100);//设置滑动条控件的最小值和最大值
volumeControl ->setValue(50);//设置初值为50；
seekSlider = new QSlider(Qt::Horizontal,this);//QSlider(Qt::Horizontal,this)创建一个水平方向的滑动条QSlider控件
seekSlider -> setGeometry(100,345,200,15);
seekSlider->setObjectName(tr("seekSlider"));
seekSlider -> setCursor(QCursor(Qt::PointingHandCursor));
addMore = new QPushButton(this);
addMore -> setGeometry(295,2,30,30);
addMore -> setObjectName(tr("addMore"));
addMore->setToolTip(tr("添加歌曲"));
addMore -> setCursor(QCursor(Qt::PointingHandCursor));
showMge = new QLabel(this);
showMge -> setGeometry(34,320,400,20);
showMge -> setFont(QFont("Times",10,QFont::Bold));//字体使用Times,10号字体，加粗
QPalette pac;//创建调色板
pac.setColor(QPalette::WindowText,QColor(70,80,70));
showMge -> setPalette(pac);
list = new QListWidget(this);
list ->setGeometry(20,50,360,180);
list -> setFont(QFont("Times",10,QFont::Bold));
list -> setPalette(pac);
list ->setStyleSheet("background: rgba(0,0,0,0.1);");
message = new QLabel(this);
message -> setGeometry(20,30,140,20);
message -> setFont(QFont("Times",10,QFont::Bold));
message -> setPalette(pac);
showPro = new QLabel(this);
showPro -> setGeometry(35,340,50,20);
showPro -> setFont(QFont("Times",10,QFont::Bold));
showPro -> setPalette(pac);
QTime mov(0,0,0);
showPro ->setText(mov.toString("mm:ss"));
showTime = new QLabel(this);
showTime -> setGeometry(325,340,50,20);
showTime -> setFont(QFont("Times",10,QFont::Bold));
showTime -> setPalette(pac);
QTime mo(0,0,0);//QTime 提供时间函数给用户使用
showTime ->setText(mo.toString("mm:ss"));//显示分：秒
title = new QLabel(this);//设置标题
title -> setGeometry(5,0,200,30);
title ->setFont(QFont("Times",15,QFont::Bold));
QPalette pa;
pa.setColor(QPalette::WindowText,QColor(0,0,0));
title -> setPalette(pa);
title -> setText("MusicPlayer");
//信号与槽
connect(BtnClose, SIGNAL(clicked(bool)), this, SLOT(close()));
connect(BtnMin, SIGNAL(clicked(bool)), this, SLOT(showMinimized()));
connect(addMore, SIGNAL(clicked(bool)), this, SLOT(addMoremusic()));
connect(BtnPlay, SIGNAL(clicked(bool)), this, SLOT(playMusic()));
connect (BtnPrev,SIGNAL(clicked(bool)), this, SLOT(preMusic()));
connect(BtnNext, SIGNAL(clicked(bool)), this, SLOT(nextMusic()));
connect(muteButton, SIGNAL(clicked(bool)), this, SLOT(meteOpen()));
connect(volumeControl, SIGNAL(sliderMoved(int)), this, SLOT(volumChange(int)));
connect(player,SIGNAL(positionChanged(qint64)),this,SLOT( positionChange(qint64)));
connect(playPattern,SIGNAL(clicked(bool)),this,SLOT(musicPlayPattern()));
}
但界面很丑，所以下一步就是加载qss文件，绘制界面样式：
1 //外部加载qss文件，绘制界面样式
2 void Music::init_skin()
3 {
4 QFile file(":/qss/skin.qss");
5 file.open(QFile::ReadOnly);
6 this -> setStyleSheet(QObject::tr(file.readAll()));
7 file.close();
8
9 }
我的qss代码如下（qss和css的语法几乎一模一样）：
1 QPushButton#playPattern:!hover
2 {
3 border-image: url(:/image/Seq.png);
4 }
5 QPushButton#playPattern:hover
6 {
7 border-image: url(:/image/Seq.png);
8 }
9 QPushButton#playPattern:pressed{
10 border-image: url(:/image/Seq.png);
11 }
12 QPushButton#BtnClose:!hover
13 {
14 border-image: url(:/image/close.png);
15 }
16 QPushButton#BtnClose:hover
17 {
18 border-image: url(:/image/close.png);
19 }
20 QPushButton#BtnClose:pressed
21 {
22 border-image: url(:/image/close.png);
23 }
24 QPushButton#BtnClose:focus{padding:-1;}
25
26
27
28 QPushButton#addMore
29 {
30 border-image: url(:/image/addMore.png);
31
32 }
33
34
35 QPushButton#BtnMin:!hover
36 {
37 border-image: url(:/image/min.png);
38 }
39 QPushButton#BtnMin:hover
40 {
41 border-image: url(:/image/min.png);
42 }
43 QPushButton#BtnMin:pressed
44 {
45 border-image: url(:/image/min.png);
46 }
47 QPushButton#BtnMin:focus{padding:-1;}
48
49
50 QPushButton#BtnPlay:!hover
51 {
52 border-image: url(:/image/play_hover.png);
53 }
54 QPushButton#BtnPlay:hover
55 {
56 border-image: url(:/image/play_hover.png);
57 }
58 QPushButton#BtnPlay:pressed
59 {
60 border-image: url(:/image/play_press.png);
61 }
62 QPushButton#BtnPlay:focus
63 {
64 padding:-1;
65 }
66
67 QPushButton#BtnPrev:!hover
68 {
69 border-image: url(:/image/prev_hover.png);
70 }
71 QPushButton#BtnPrev:hover
72 {
73 border-image: url(:/image/prev_hover.png);
74 }
75 QPushButton#BtnPrev:pressed
76 {
77 border-image: url(:/image/prev_press.png);
78 }
79 QPushButton#BtnPrev:focus{padding:-1;}
80
81 QPushButton#BtnNext:!hover
82 {
83 border-image: url(:/image/next_hover.png);
84 }
85 QPushButton#BtnNext:hover
86 {
87 border-image: url(:/image/next_hover.png);
88 }
89 QPushButton#BtnNext:pressed
90 {
91 border-image: url(:/image/next_press.png);
92 }
93 QPushButton#BtnNext:focus{padding:-1;}
94
95
96 QPushButton#muteButton:!hover
97 {
98 border-image: url(:/image/sound.png);
99 }
100 QPushButton#muteButton:hover
101 {
102 border-image: url(:/image/sound.png);
103 }
104 QPushButton#muteButton:pressed
105 {
106 border-image: url(:/image/sound_close.png);
107 }
108 QPushButton#muteButton:focus{padding:-1;}
109
110
111
112 QSlider#volumeControl::groove:Vertical {
113 border: 0px solid #bbb;
114 background: rgba(0,0,0,0.1);
115 width: 4px;
116 border-radius: 1px;
117 }
118
119 QSlider#volumeControl::sub-page:Vertical {
120 background: rgba(0,0,0,0.1);
121 border: 0px solid #777;
122 width: 4px;
123 border-radius: 1px;
124 }
125
126 QSlider#volumeControl::add-page:Vertical {
127 background:url(:/image/progress_sound.bmp);
128 border: 0px solid #777;
129 width: 4px;
130 border-radius: 1px;
131 }
132
133 QSlider#volumeControl::handle:Vertical {
134 border-image:url(:/image/progress_thume.png);
135 border: 0px solid #777;
136 width: 28px;
137 height: 28px;
138 margin-left:-12px;
139 margin-right:-12px;
140 margin-top: -12px;
141 margin-bottom: -12px;
142 border-radius: 4px;
143 }
144
145
146 QSlider#seekSlider::groove:horizontal {
147 border-left:-14px solid;
148 background: rgba(0,0,0,0.1);
149 height: 4px;
150 border-radius: 4px;
151 }
152
153 QSlider#seekSlider::sub-page:horizontal {
154 background:url(:/image/progress.bmp);
155 border: 0px solid #777;
156 height: 4px;
157 border-radius: 4px;
158 }
159
160 QSlider#seekSlider::add-page:horizontal {
161 background: rgba(0,0,0,0.1);
162 border: 0px solid #777;
163 height: 4px;
164 border-radius:4px;
165 }
166
167 QSlider#seekSlider::handle:horizontal {
168 background:url(:/image/progress_thume.png);
169 border: 0px solid #777;
170 width: 28px;
171 height: 28px;
172 border-left:0px;
173 border-right:0px;
174 margin-left:2px;
175 margin-right:-12px;
176 margin-top: -12px;
177 margin-bottom: -12px;
178 border-radius: 4px;
179 }
这样样式就已经基本搞定了，只剩下写槽函数来实现具体功能了。
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