【开源】嵌入式Linux（IMX6U）应用层综合项目（4）--音乐播放器APP

1.简介

此文章并不是教程，只能当作笔者的学习分享，只会做一些简单的介绍，其他的各位结合着代码和运行现象自己分析吧，相信通过函数名和注释，基本上是不难看懂代码的，其中涉及到的一些技术栈，也请各位学习到的时候多查阅资料。

本篇的内容为嵌入式Linux应用层的一个综合性比较强的项目，结尾会将源码放在网盘中开源出来，笔者能力有限，只是简单的把功能实现了，代码开源供大家一起交流学习，有什么好的建议，请各位一定不吝赐教！！！

1.1功能介绍

项目包括了四个app：

1.云平台的调试窗口，用于查看订阅主题所下发的数据，另一个为输入Json格式的数据来控制STM32单片机上的外设。

2.智能家居的界面，有4个图片按钮用于控制STM32板子上的LED灯、门（舵机）、蜂鸣器，量计分别为温度、湿度和亮度的值，同样是STM32获取发布到云平台的。

3.通过一个摄像头模块做的一个相机功能，可以拍照、录像，以及查看拍摄的照片，和播放录制视频的回放。

4.简易的音乐播放器：能够切换歌曲，以及暂停播放音乐。

1.2技术栈介绍

虽然项目简单，但是所涉及到的技术栈还是比较杂，我简单在此列出：

1.LVGL库用于绘制UI。

2.MQTT协议，连接阿里云平台与STM32通讯。

3.alsa库用于音频处理。

4.LED、BEEP

5.V4L2 摄像头应用编程

1.3演示视频

【开源】Linux应用综合项目|云平台调试工具+智能家居+相机+音乐播放器_哔哩哔哩_bilibili

1.4硬件介绍

硬件使用的是正点原子的阿尔法开发板，芯片是IMX6U，类似开发板应该都可以运行。

2.软件设计

2.1.asla音频应用编程

此文件初始化了声卡和混音器，创建了一个线程来播放我们所选的音乐，在切换和暂停歌曲时用到了互斥量来保护所要访问的资源，以防切换时出现错误。总共包括了4首歌曲，可以通过左右两个按键来切换上一首和下一首歌曲，可以调节音量和暂停开始播放。

#include "ds_music.h"
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <alsa/asoundlib.h>/************************************宏定义************************************/
#define PCM_PLAYBACK_DEV "hw:0,0"
#define MIXER_DEV "hw:0"
/************************************WAV音频文件解析相关数据结构申明************************************/
typedef struct WAV_RIFF
{char ChunkID[4];     /* "RIFF" */u_int32_t ChunkSize; /* 从下一个地址开始到文件末尾的总字节数 */char Format[4];      /* "WAVE" */
} __attribute__((packed)) RIFF_t;typedef struct WAV_FMT
{char Subchunk1ID[4];     /* "fmt " */u_int32_t Subchunk1Size; /* 16 for PCM */u_int16_t AudioFormat;   /* PCM = 1*/u_int16_t NumChannels;   /* Mono = 1, Stereo = 2, etc. */u_int32_t SampleRate;    /* 8000, 44100, etc. */u_int32_t ByteRate;      /* = SampleRate * NumChannels * BitsPerSample/8 */u_int16_t BlockAlign;    /* = NumChannels * BitsPerSample/8 */u_int16_t BitsPerSample; /* 8bits, 16bits, etc. */
} __attribute__((packed)) FMT_t;
static FMT_t wav_fmt;typedef struct WAV_DATA
{char Subchunk2ID[4];     /* "data" */u_int32_t Subchunk2Size; /* data size */
} __attribute__((packed)) DATA_t;/************************************static静态全局变量定义************************************/
static snd_pcm_t *pcm = NULL;                      // pcm句柄
static snd_mixer_t *mixer = NULL;                  // 混音器句柄
static snd_mixer_elem_t *playback_vol_elem = NULL; // 播放<音量控制>元素
static unsigned int buf_bytes;                     // 应用程序缓冲区的大小（字节为单位）
static void *buf = NULL;                           // 指向应用程序缓冲区的指针
static int fd = -1;                                // 指向WAV音频文件的文件描述符
static snd_pcm_uframes_t period_size = 1024;       // 周期大小（单位: 帧）
static unsigned int periods = 16;                  // 周期数（设备驱动层buffer的大小）
static struct termios old_cfg;                     // 用于保存终端当前的配置参数static pthread_t g_play_music_thread = NULL;
static pthread_t g_mixer_music_thread = NULL;bool is_playing = false;
int music_select = 1;
char *music_name, *music_singer;pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
pthread_mutex_t volume_mutex = PTHREAD_MUTEX_INITIALIZER;static int snd_pcm_init(void)
{snd_pcm_hw_params_t *hwparams = NULL;int ret;/* 打开PCM设备 */ret = snd_pcm_open(&pcm, PCM_PLAYBACK_DEV, SND_PCM_STREAM_PLAYBACK, 0);if (0 > ret){fprintf(stderr, "snd_pcm_open error: %s: %s\n",PCM_PLAYBACK_DEV, snd_strerror(ret));return -1;}/* 实例化hwparams对象 */snd_pcm_hw_params_malloc(&hwparams);/* 获取PCM设备当前硬件配置,对hwparams进行初始化 */ret = snd_pcm_hw_params_any(pcm, hwparams);if (0 > ret){fprintf(stderr, "snd_pcm_hw_params_any error: %s\n", snd_strerror(ret));goto err2;}/**************设置参数***************//* 设置访问类型: 交错模式 */ret = snd_pcm_hw_params_set_access(pcm, hwparams, SND_PCM_ACCESS_RW_INTERLEAVED);if (0 > ret){fprintf(stderr, "snd_pcm_hw_params_set_access error: %s\n", snd_strerror(ret));goto err2;}/* 设置数据格式: 有符号16位、小端模式 */ret = snd_pcm_hw_params_set_format(pcm, hwparams, SND_PCM_FORMAT_S16_LE);if (0 > ret){fprintf(stderr, "snd_pcm_hw_params_set_format error: %s\n", snd_strerror(ret));goto err2;}/* 设置采样率 */ret = snd_pcm_hw_params_set_rate(pcm, hwparams, wav_fmt.SampleRate, 0);if (0 > ret){fprintf(stderr, "snd_pcm_hw_params_set_rate error: %s\n", snd_strerror(ret));goto err2;}/* 设置声道数: 双声道 */ret = snd_pcm_hw_params_set_channels(pcm, hwparams, wav_fmt.NumChannels);if (0 > ret){fprintf(stderr, "snd_pcm_hw_params_set_channels error: %s\n", snd_strerror(ret));goto err2;}/* 设置周期大小: period_size */ret = snd_pcm_hw_params_set_period_size(pcm, hwparams, period_size, 0);if (0 > ret){fprintf(stderr, "snd_pcm_hw_params_set_period_size error: %s\n", snd_strerror(ret));goto err2;}/* 设置周期数（驱动层buffer的大小）: periods */ret = snd_pcm_hw_params_set_periods(pcm, hwparams, periods, 0);if (0 > ret){fprintf(stderr, "snd_pcm_hw_params_set_periods error: %s\n", snd_strerror(ret));goto err2;}/* 使配置生效 */ret = snd_pcm_hw_params(pcm, hwparams);snd_pcm_hw_params_free(hwparams); // 释放hwparams对象占用的内存if (0 > ret){fprintf(stderr, "snd_pcm_hw_params error: %s\n", snd_strerror(ret));goto err1;}buf_bytes = period_size * wav_fmt.BlockAlign; // 变量赋值，一个周期的字节大小return 0;err2:snd_pcm_hw_params_free(hwparams); // 释放内存
err1:snd_pcm_close(pcm); // 关闭pcm设备return -1;
}static int snd_mixer_init(void)
{snd_mixer_elem_t *elem = NULL;const char *elem_name;long minvol, maxvol;int ret;/* 打开混音器 */ret = snd_mixer_open(&mixer, 0);if (0 > ret){fprintf(stderr, "snd_mixer_open error: %s\n", snd_strerror(ret));return -1;}/* 关联一个声卡控制设备 */ret = snd_mixer_attach(mixer, MIXER_DEV);if (0 > ret){fprintf(stderr, "snd_mixer_attach error: %s\n", snd_strerror(ret));goto err;}/* 注册混音器 */ret = snd_mixer_selem_register(mixer, NULL, NULL);if (0 > ret){fprintf(stderr, "snd_mixer_selem_register error: %s\n", snd_strerror(ret));goto err;}/* 加载混音器 */ret = snd_mixer_load(mixer);if (0 > ret){fprintf(stderr, "snd_mixer_load error: %s\n", snd_strerror(ret));goto err;}/* 遍历混音器中的元素 */elem = snd_mixer_first_elem(mixer); // 找到第一个元素while (elem){elem_name = snd_mixer_selem_get_name(elem); // 获取元素的名称/* 针对开发板出厂系统：WM8960声卡设备 */if (!strcmp("Speaker", elem_name) ||   // 耳机音量<对喇叭外音输出有效>!strcmp("Headphone", elem_name) || // 喇叭音量<对耳机输出有效>!strcmp("Playback", elem_name)){ // 播放音量<总的音量控制，对喇叭和耳机输出都有效>if (snd_mixer_selem_has_playback_volume(elem)){                                                                      // 是否是音量控制元素snd_mixer_selem_get_playback_volume_range(elem, &minvol, &maxvol); // 获取音量可设置范围printf("minvol = %d, maxvol = %d\n", minvol, maxvol);snd_mixer_selem_set_playback_volume_all(elem, (maxvol - minvol) * 0.9 + minvol); // 全部设置为90%if (!strcmp("Playback", elem_name))playback_vol_elem = elem;}}elem = snd_mixer_elem_next(elem);}return 0;err:snd_mixer_close(mixer);return -1;
}static int open_wav_file(const char *file)
{RIFF_t wav_riff;DATA_t wav_data;int ret;fd = open(file, O_RDONLY);if (0 > fd){fprintf(stderr, "open error: %s: %s\n", file, strerror(errno));return -1;}/* 读取RIFF chunk */ret = read(fd, &wav_riff, sizeof(RIFF_t));if (sizeof(RIFF_t) != ret){if (0 > ret)perror("read error");elsefprintf(stderr, "check error: %s\n", file);close(fd);return -1;}if (strncmp("RIFF", wav_riff.ChunkID, 4) || // 校验strncmp("WAVE", wav_riff.Format, 4)){fprintf(stderr, "check error: %s\n", file);close(fd);return -1;}/* 读取sub-chunk-fmt */ret = read(fd, &wav_fmt, sizeof(FMT_t));if (sizeof(FMT_t) != ret){if (0 > ret)perror("read error");elsefprintf(stderr, "check error: %s\n", file);close(fd);return -1;}if (strncmp("fmt ", wav_fmt.Subchunk1ID, 4)){ // 校验fprintf(stderr, "check error: %s\n", file);close(fd);return -1;}/* 打印音频文件的信息 */printf("<<<<音频文件格式信息>>>>\n\n");printf("  file name:     %s\n", file);printf("  Subchunk1Size: %u\n", wav_fmt.Subchunk1Size);printf("  AudioFormat:   %u\n", wav_fmt.AudioFormat);printf("  NumChannels:   %u\n", wav_fmt.NumChannels);printf("  SampleRate:    %u\n", wav_fmt.SampleRate);printf("  ByteRate:      %u\n", wav_fmt.ByteRate);printf("  BlockAlign:    %u\n", wav_fmt.BlockAlign);printf("  BitsPerSample: %u\n\n", wav_fmt.BitsPerSample);/* sub-chunk-data */if (0 > lseek(fd, sizeof(RIFF_t) + 8 + wav_fmt.Subchunk1Size,SEEK_SET)){perror("lseek error");close(fd);return -1;}while (sizeof(DATA_t) == read(fd, &wav_data, sizeof(DATA_t))){/* 找到sub-chunk-data */if (!strncmp("data", wav_data.Subchunk2ID, 4)) // 校验return 0;if (0 > lseek(fd, wav_data.Subchunk2Size, SEEK_CUR)){perror("lseek error");close(fd);return -1;}}fprintf(stderr, "check error: %s\n", file);return -1;
}long vol = 229;
void *play_music_thread(void *args)
{int ret;/* 播放 */for (;;){pthread_mutex_lock(&mutex);while (!is_playing){// 在暂停时关闭PCM设备if (pcm != NULL){snd_pcm_close(pcm);pcm = NULL;printf("PCM设备已暂停并关闭\n");}pthread_cond_wait(&cond, &mutex);}// 在恢复播放时重新初始化PCM设备if (pcm != NULL){snd_pcm_close(pcm);pcm = NULL;}if (fd != -1){close(fd);fd = -1;}switch (music_select){case 0:if (open_wav_file("/home/root/wav_music/keximeiruguo.wav"))goto err2;break;case 1:if (open_wav_file("/home/root/wav_music/seeyoulater.wav"))goto err2;break;case 2:if (open_wav_file("/home/root/wav_music/xihuanni.wav"))goto err2;break;case 3:if (open_wav_file("/home/root/wav_music/xiyangwuxianhao.wav"))goto err2;break;default:printf("select music false\n");goto err2;break;}/* 初始化PCM Playback设备 */if (snd_pcm_init())goto err1;/* 初始化混音器 */if (snd_mixer_init())goto err2;/* 申请读缓冲区 */buf = malloc(buf_bytes);if (NULL == buf){perror("malloc error");goto err2;}pthread_mutex_unlock(&mutex);while (is_playing){memset(buf, 0x00, buf_bytes);   // buf清零ret = read(fd, buf, buf_bytes); // 从音频文件中读取数据if (0 >= ret)                   // 如果读取出错或文件读取完毕break;ret = snd_pcm_writei(pcm, buf, period_size);if (0 > ret){fprintf(stderr, "snd_pcm_writei error: %s\n", snd_strerror(ret));break;}else if (ret < period_size){ // 实际写入的帧数小于指定的帧数// 此时我们需要调整下音频文件的读位置// 将读位置向后移动（往回移）(period_size-ret)*frame_bytes个字节// frame_bytes表示一帧的字节大小if (0 > lseek(fd, (ret - period_size) * wav_fmt.BlockAlign, SEEK_CUR)){perror("lseek error");break;}}// 设置音量pthread_mutex_lock(&volume_mutex);long volume;pthread_mutex_unlock(&volume_mutex);snd_mixer_selem_get_playback_volume(playback_vol_elem,SND_MIXER_SCHN_FRONT_LEFT, &volume);printf("volume = %d\n", volume);volume = vol;snd_mixer_selem_set_playback_volume_all(playback_vol_elem, volume);}free(buf);buf = NULL;}
err2:if (buf)free(buf); // 释放内存
err1:if (pcm != NULL){snd_pcm_close(pcm); // 关闭pcm设备pcm = NULL;printf("已关闭pcm设备\r\n");}if (fd != -1){close(fd); // 关闭打开的音频文件fd = -1;printf("音频已被关闭\r\n");}pthread_exit(NULL);
}void *mixer_music_thread(void *args)
{
}void clean_music_file(void)
{// free(buf);          // 释放内存snd_pcm_close(pcm); // 关闭pcm设备printf("已关闭pcm设备\r\n");close(fd); // 关闭打开的音频文件printf("音频已被关闭\r\n");
}void ds_music_init(void)
{int32_t res;res = pthread_create(&g_play_music_thread, NULL, play_music_thread, NULL);if (res < 0){printf("pthread_create play_music_thread failed: %d\n", res);return -1;}printf("play_music_thread created successfully\n");res = pthread_create(&g_mixer_music_thread, NULL, mixer_music_thread, NULL);if (res < 0){printf("pthread_create mixer_music_thread failed: %d\n", res);return -1;}printf("mixer_music_thread created successfully\n");return 0;
}

2.2.音乐播放器UI设计

以下为音乐播放器的UI设计，基本上在前面了解了LVGL控件的设计之后，这部分看起来应该就没有什么难度了。

#include "ui_app_music.h"#define MUSIC_NUM 4
// LV_IMG_DECLARE(disc_img);
LV_IMG_DECLARE(img_next_64);
LV_IMG_DECLARE(img_play_64);
LV_IMG_DECLARE(img_prev_64);
LV_IMG_DECLARE(img_stop_64);
LV_IMG_DECLARE(img_disc_256);
LV_IMG_DECLARE(img_love_48);
LV_IMG_DECLARE(img_love_off_48);
LV_IMG_DECLARE(img_sound_48);static lv_obj_t *disc_img;
static lv_obj_t *prev_btn;
static lv_obj_t *play_pause_btn;
static lv_obj_t *next_btn;
static lv_obj_t *love_btn;
static lv_obj_t *sound_btn;lv_obj_t *bg_click_area;
lv_obj_t *sound_slider;
lv_obj_t *sound_slider_label;
bool slider_visible = false; // 用于记录滑块是否可见extern bool is_playing;
bool is_love;extern char *music_name, *music_singer;
extern pthread_mutex_t mutex;
extern pthread_cond_t cond;
extern int music_select;static void play_pause_event_cb(lv_event_t *e);
static void prev_event_cb(lv_event_t *e);
static void next_event_cb(lv_event_t *e);
static void love_event_cb(lv_event_t *e);
static void sound_event_cb(lv_event_t *e);
static void sound_slider_event_cb(lv_event_t *e);
static void bg_click_event_cb(lv_event_t *e);void show_music_info(const char *name, const char *singer, const lv_font_t *font)
{lv_obj_t *music_name_label = lv_label_create(lv_scr_act());lv_label_set_text(music_name_label, name);static lv_style_t music_name_label_style;lv_style_init(&music_name_label_style);lv_style_set_text_font(&music_name_label_style, font);                    // 设置字体lv_style_set_text_color(&music_name_label_style, lv_color_hex(0x515151)); // 设置字体颜色lv_obj_add_style(music_name_label, &music_name_label_style, LV_PART_MAIN);lv_obj_align(music_name_label, LV_ALIGN_TOP_LEFT, 460, 130);lv_obj_t *music_singer_label = lv_label_create(lv_scr_act());lv_label_set_text(music_singer_label, singer);static lv_style_t music_singer_label_style;lv_style_init(&music_singer_label_style);lv_style_set_text_font(&music_singer_label_style, font);                    // 设置字体lv_style_set_text_color(&music_singer_label_style, lv_color_hex(0xbfbfbf)); // 设置字体颜色lv_obj_add_style(music_singer_label, &music_singer_label_style, LV_PART_MAIN);lv_obj_align(music_singer_label, LV_ALIGN_TOP_LEFT, 460, 160);
}void show_music_info_select(int select)
{clear_area(460, 130, 200, 60, lv_color_hex(MY_UI_COLOR_WHITE));switch (select){case 0:show_music_info("可惜没有如果", "林俊杰", &lv_font_SiYuanHeiTi_Light_28);break;case 1:show_music_info("See you later", "marmixer", &lv_font_montserrat_24);break;case 2:show_music_info("喜欢你", "邓紫棋", &lv_font_SiYuanHeiTi_Light_28);break;case 3:show_music_info("夕阳无限好", "陈奕迅", &lv_font_SiYuanHeiTi_Light_28);break;}
}void create_music_player_ui(void)
{int btn_x = 340, btn_y = 380;music_name = "See you later";music_singer = "marmixer";show_music_info(music_name, music_singer, &lv_font_montserrat_24);disc_img = lv_imgbtn_create(lv_scr_act());lv_obj_set_size(disc_img, 256, 256);lv_obj_add_event_cb(disc_img, prev_event_cb, LV_EVENT_CLICKED, NULL);lv_img_set_src(disc_img, &img_disc_256);lv_obj_align(disc_img, LV_ALIGN_TOP_LEFT, 145, 80);prev_btn = lv_imgbtn_create(lv_scr_act());lv_obj_set_size(prev_btn, 64, 64);lv_obj_add_event_cb(prev_btn, prev_event_cb, LV_EVENT_CLICKED, NULL);lv_img_set_src(prev_btn, &img_prev_64);lv_obj_align(prev_btn, LV_ALIGN_TOP_LEFT, btn_x, btn_y);play_pause_btn = lv_imgbtn_create(lv_scr_act());lv_obj_set_size(play_pause_btn, 64, 64);lv_obj_add_event_cb(play_pause_btn, play_pause_event_cb, LV_EVENT_CLICKED, NULL);lv_img_set_src(play_pause_btn, &img_play_64);lv_obj_align(play_pause_btn, LV_ALIGN_TOP_LEFT, btn_x + 80, btn_y);next_btn = lv_imgbtn_create(lv_scr_act());lv_obj_set_size(next_btn, 64, 64);lv_obj_add_event_cb(next_btn, next_event_cb, LV_EVENT_CLICKED, NULL);lv_img_set_src(next_btn, &img_next_64);lv_obj_align(next_btn, LV_ALIGN_TOP_LEFT, btn_x + 80 * 2, btn_y);love_btn = lv_imgbtn_create(lv_scr_act());lv_obj_set_size(love_btn, 48, 48);lv_obj_add_event_cb(love_btn, love_event_cb, LV_EVENT_CLICKED, NULL);lv_img_set_src(love_btn, &img_love_48);lv_obj_align(love_btn, LV_ALIGN_TOP_LEFT, 460, 260);sound_btn = lv_imgbtn_create(lv_scr_act());lv_obj_set_size(sound_btn, 48, 48);lv_obj_add_event_cb(sound_btn, sound_event_cb, LV_EVENT_CLICKED, NULL);lv_img_set_src(sound_btn, &img_sound_48);lv_obj_align(sound_btn, LV_ALIGN_TOP_LEFT, 680, 260);sound_slider = lv_slider_create(lv_scr_act());lv_bar_set_range(sound_slider, 180, 255);lv_obj_set_size(sound_slider, 10, 120);lv_obj_align(sound_slider, LV_ALIGN_TOP_LEFT, 698, 110);lv_obj_add_event_cb(sound_slider, sound_slider_event_cb, LV_EVENT_VALUE_CHANGED, NULL);lv_obj_add_flag(sound_slider, LV_OBJ_FLAG_HIDDEN);lv_slider_set_value(sound_slider, 229, LV_ANIM_OFF);// 更新标签char buf[8];int percentage = (229 - 180) * 100 / (255 - 180);lv_snprintf(buf, sizeof(buf), "%d%%", percentage);sound_slider_label = lv_label_create(lv_scr_act());lv_label_set_text(sound_slider_label, buf);lv_obj_align_to(sound_slider_label, sound_slider, LV_ALIGN_OUT_TOP_MID, 25, 65);lv_obj_add_flag(sound_slider_label, LV_OBJ_FLAG_HIDDEN);bg_click_area = lv_obj_create(lv_scr_act());lv_obj_set_size(bg_click_area, LV_HOR_RES, LV_VER_RES);lv_obj_add_flag(bg_click_area, LV_OBJ_FLAG_CLICKABLE | LV_OBJ_FLAG_HIDDEN);lv_obj_add_event_cb(bg_click_area, bg_click_event_cb, LV_EVENT_CLICKED, NULL);lv_obj_move_background(bg_click_area);
}static void play_pause_event_cb(lv_event_t *e)
{lv_event_code_t code = lv_event_get_code(e);if (code == LV_EVENT_CLICKED){printf("Button clicked!\n");pthread_mutex_lock(&mutex);is_playing = !is_playing;if (is_playing){lv_img_set_src(play_pause_btn, &img_stop_64); // 切换为暂停图标pthread_cond_signal(&cond);}else{lv_img_set_src(play_pause_btn, &img_play_64); // 切换为播放图标}pthread_mutex_unlock(&mutex);}
}static void prev_event_cb(lv_event_t *e)
{// Handle previous song actionlv_event_code_t code = lv_event_get_code(e);if (code == LV_EVENT_CLICKED){printf("prev_event_cb clicked!\n");pthread_mutex_lock(&mutex);if (!is_playing){music_select--;if (music_select == -1)music_select = MUSIC_NUM - 1;}pthread_cond_signal(&cond);pthread_mutex_unlock(&mutex);printf("music_select = %d\n", music_select);show_music_info_select(music_select);}
}static void next_event_cb(lv_event_t *e)
{// Handle next song actionlv_event_code_t code = lv_event_get_code(e);if (code == LV_EVENT_CLICKED){printf("next_event_cb clicked!\n");pthread_mutex_lock(&mutex);if (!is_playing){music_select++;if (music_select == MUSIC_NUM)music_select = 0;}pthread_cond_signal(&cond);pthread_mutex_unlock(&mutex);printf("music_select = %d\n", music_select);show_music_info_select(music_select);}
}static void love_event_cb(lv_event_t *e)
{lv_event_code_t code = lv_event_get_code(e);if (code == LV_EVENT_CLICKED){printf("love_event_cb clicked!\n");is_love = !is_love;if (is_love){lv_img_set_src(love_btn, &img_love_48); // 切换为暂停图标}else{lv_img_set_src(love_btn, &img_love_off_48); // 切换为播放图标}}
}static void sound_event_cb(lv_event_t *e)
{lv_event_code_t code = lv_event_get_code(e);if (code == LV_EVENT_CLICKED){printf("sound_event_cb clicked!\n");slider_visible = !slider_visible;if (slider_visible){lv_obj_clear_flag(sound_slider, LV_OBJ_FLAG_HIDDEN);       // 显示滑块lv_obj_clear_flag(sound_slider_label, LV_OBJ_FLAG_HIDDEN); // 显示标签lv_obj_clear_flag(bg_click_area, LV_OBJ_FLAG_HIDDEN);      // 显示背景点击区域}else{lv_obj_add_flag(sound_slider, LV_OBJ_FLAG_HIDDEN);       // 隐藏滑块lv_obj_add_flag(sound_slider_label, LV_OBJ_FLAG_HIDDEN); // 隐藏标签lv_obj_add_flag(bg_click_area, LV_OBJ_FLAG_HIDDEN);      // 隐藏背景点击区域}}
}static void bg_click_event_cb(lv_event_t *e)
{if (slider_visible){lv_obj_add_flag(sound_slider, LV_OBJ_FLAG_HIDDEN);       // 隐藏滑块lv_obj_add_flag(sound_slider_label, LV_OBJ_FLAG_HIDDEN); // 隐藏标签lv_obj_add_flag(bg_click_area, LV_OBJ_FLAG_HIDDEN);      // 隐藏背景点击区域slider_visible = false;}
}extern long vol;
extern pthread_mutex_t volume_mutex;
static void sound_slider_event_cb(lv_event_t *e)
{lv_obj_t *slider = lv_event_get_target(e);char buf[8];long volume = (int)lv_slider_get_value(slider);// 将滑条值转换为百分比int percentage = (volume - 180) * 100 / (255 - 180);pthread_mutex_lock(&volume_mutex);vol = volume;pthread_mutex_unlock(&volume_mutex);printf("vol = %d\n", vol);lv_snprintf(buf, sizeof(buf), "%d%%", percentage);lv_label_set_text(sound_slider_label, buf);lv_obj_align_to(sound_slider_label, slider, LV_ALIGN_OUT_TOP_MID, 25, 65);
}void ui_app_music(void)
{clear_area(0, 0, 800, 480, lv_color_hex(MY_UI_COLOR_DEEP_WHITE));ui_left_app_bar(20, 70);lv_obj_t *img = lv_img_create(lv_scr_act());lv_img_set_src(img, &img_music_on);lv_obj_align(img, LV_ALIGN_TOP_LEFT, 32, 360);lv_obj_t *mid_label = lv_label_create(lv_scr_act());lv_label_set_text(mid_label, "Music");static lv_style_t mid_label_style;lv_style_init(&mid_label_style);lv_style_set_text_font(&mid_label_style, &lv_font_montserrat_24);           // 设置字体lv_style_set_text_color(&mid_label_style, lv_color_hex(MY_UI_COLOR_BLACK)); // 设置字体颜色lv_obj_add_style(mid_label, &mid_label_style, LV_PART_MAIN);lv_obj_align(mid_label, LV_ALIGN_TOP_MID, 0, 20);create_split_background(lv_scr_act(), 135, 70, 640, 280, lv_color_hex(0xfefaec), lv_color_hex(MY_UI_COLOR_WHITE));create_music_player_ui();
}

3.结尾（附网盘链接）

链接：百度网盘请输入提取码

提取码：2jia

--来自百度网盘超级会员V5的分享