SDL基础使用04（SDL_image与SDL_mixer扩展库）

SDL_image扩展库使用（显示jpg图片）

基本流程

• 1.初始化SDL 、IMG SDL_Init IMG_Init
• 2.创建窗口 SDL_CreateWindow
• 3.基于窗口创建渲染器 SDL_CreateRenderer
• 4.加载图片到surface IMG_Load
• 5.根据图片surface创建纹理 SDL_CreateTextureFromSurface

• 6.绘制三部曲

      清空渲染器                          SDL\_RenderClear  
      拷贝纹理数据到渲染器        SDL\_RenderCopy  
      刷新渲染器显示                   SDL\_RenderPresent
  

• 7.退出SDL、IMG SDL_Quit IMG_Quit

#include <iostream>
/* SDL_image 扩展库使用 */
extern "C"
{
#include <SDL.h>
#include <SDL_image.h>
}

#pragma comment(lib, "SDL2.lib")
#pragma comment(lib, "x86/SDL2_image.lib")


#undef main
int main()
{
    // 1. 初始化
    int nRet = SDL_Init(SDL_INIT_EVERYTHING);
    if (nRet < 0)
    {
        std::cout << "SDL Error: " << SDL_GetError() << std::endl;
        return -1;
    }

    nRet = IMG_Init(IMG_INIT_JPG | IMG_INIT_PNG);
    if (nRet < 0)
    {
        std::cout << "SDL Error: " << SDL_GetError() << std::endl;
        return -1;
    }

    // 2.  创建窗口
    SDL_Window* pWnd = SDL_CreateWindow("Title",
        SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
        640, 480,
        SDL_WINDOW_SHOWN);
    if (NULL == pWnd)
    {
        std::cout << "SDL Error: " << SDL_GetError() << std::endl;
        return -1;
    }

    // 3. 创建渲染器
    SDL_Renderer* pRender = SDL_CreateRenderer(pWnd, -1, SDL_RENDERER_ACCELERATED);
    if (NULL == pRender)
    {
        SDL_DestroyWindow(pWnd);
        std::cout << "SDL Error: " << SDL_GetError() << std::endl;
        return -1;
    }

    // 4. 加载图片
    SDL_Surface* pSurface = IMG_Load("./longong.jpg");
    if (NULL == pSurface)
    {
        SDL_DestroyRenderer(pRender);
        SDL_DestroyWindow(pWnd);
        std::cout << "SDL Error: " << SDL_GetError() << std::endl;
        return -1;
    }

    // 5. 根据表面创建纹理
    SDL_Texture* pTexture = SDL_CreateTextureFromSurface(pRender, pSurface);
    if (NULL == pTexture)
    {
        SDL_FreeSurface(pSurface);
        SDL_DestroyRenderer(pRender);
        SDL_DestroyWindow(pWnd);
        std::cout << "SDL Error: " << SDL_GetError() << std::endl;
        return -1;
    }

    // 6. 绘制三部曲
    SDL_RenderClear(pRender);            // 清空一下（防止有残留的数据）
    SDL_RenderCopy(pRender, pTexture, NULL, NULL);        // 拷贝纹理数据到渲染器
    SDL_RenderPresent(pRender);                            // 刷新渲染器显示

    SDL_Delay(2000);

    // 7. 释放资源
    if (pSurface)
    {
        SDL_FreeSurface(pSurface);
    }
    if (pTexture)
    {
        SDL_DestroyTexture(pTexture);
    }
    if (pRender)
    {
        SDL_DestroyRenderer(pRender);
    }
    if (pWnd)
    {
        SDL_DestroyWindow(pWnd);
    }
    IMG_Quit();
    SDL_Quit();

    return 0;
}

注意坑

1. 放置dll文件时还需要其它的dll文件 zlib1.dll(解压算法库) SDL2_ttf.dll SDL2_image.dll libpng16-16.dll zlib1.dll等
2. 没有zlib1.dll会导致图像显示不出来

SDL_mixer扩展库使用（播放wav音频文件）

基本流程

• 1.初始化 SDL_Init
• 2.打开音频 Mix_OpenAudio
• 3.加载音频文件 Mix_LoadWAV
• 4.创建窗口 SDL_CreateWindow
• 5.根据窗口获取surface SDL_GetWindowSurface
• 6.播放音频文件 Mix_PlayChannel
• 7.循环将数据喂给声卡播放 Mix_Playing
• 8.释放资源退出 Mix_FreeChunk Mix_CloseAudio SDL_DestroyWindow SDL_Quit

#include <iostream>
/* 使用 SDL_mixer 播放wav格式音频（内部音频为pcm）文件 */
extern "C"
{
#include <SDL.h>
#include <SDL_mixer.h>
}

#pragma comment(lib, "SDL2.lib")
#pragma comment(lib, "x86/SDL2_mixer.lib")


#undef main
int main()
{    
    int channel = -1;

    // 1. 初始化
    int nRet = SDL_Init(SDL_INIT_AUDIO | SDL_INIT_VIDEO);
    if (nRet < 0)
    {
        std::cout << "SDL Error: " << SDL_GetError() << std::endl;
        return -1;
    }

    int audio_rate = 22050;                    // 音视频播放频率
    int audio_format = AUDIO_S16SYS;        // 播放格式
    int audio_channels = 2;                    // 通道数
    int audio_chunkSize = 4096;                // 每次读取数据的大小

    // 2. 打开音频
    nRet = Mix_OpenAudio(audio_rate, audio_format, audio_channels, audio_chunkSize);

    // 3. 加载音频文件
    Mix_Chunk* sound = Mix_LoadWAV("./sound.wav");        // 存储音频文件在内存中
    if (NULL == sound)
    {
        std::cout << "SDL Error: " << SDL_GetError() << std::endl;
        return -1;
    }

    SDL_Window* pWnd = SDL_CreateWindow("Title",
        SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
        640, 480,
        SDL_WINDOW_SHOWN);
    if (NULL == pWnd)
    {
        std::cout << "SDL Error: " << SDL_GetError() << std::endl;
        return -1;
    }

    SDL_Surface* pSurface = SDL_GetWindowSurface(pWnd);
    if (NULL == pSurface)
    {
        std::cout << "SDL Error: " << SDL_GetError() << std::endl;
        return -1;
    }

    // 4. 播放音频文件
    channel = Mix_PlayChannel(-1, sound, 0);        // 返回声道数
    if (-1 == channel)
    {
        std::cout << "SDL Error: " << SDL_GetError() << std::endl;
        return -1;
    }

    while (Mix_Playing(channel) != 0);                // 将音频数据喂给声卡播放

    // 5. 释放资源
    Mix_FreeChunk(sound);
    Mix_CloseAudio();

    if (pWnd)
    {
        SDL_DestroyWindow(pWnd);
    }

    SDL_Quit();

    return 0;
}