SDL2 程序在 Ubuntu 22.04.2 上编译，但是当我运行它们时没有出现

Question

我最近一直在努力学习SDL2，我按照这里显示的说明安装了它：https://github.com/libsdl-org/SDL/blob/main/docs/README-linux.md。 在 VS Code 中，我设法正确包含 SDL2 库，以便代码可以编译。但是，无论我编译什么源代码（我正在遵循 Lazy Foo 的教程），当我实际运行该程序时，该窗口永远不会出现。该程序似乎运行，看着终端，但没有任何反应。

给你一个想法，这是我尝试编译的 Lazy Foo 的教程代码，当我运行它时没有任何反应。我没有收到任何错误消息。

/*This source code copyrighted by Lazy Foo' Productions (2004-2022)
and may not be redistributed without written permission.*/

//Using SDL and standard IO
#include <SDL2/SDL.h>
#include <stdio.h>

//Screen dimension constants
const int SCREEN_WIDTH = 640;
const int SCREEN_HEIGHT = 480;

//Starts up SDL and creates window
bool init();

//Loads media
bool loadMedia();

//Frees media and shuts down SDL
void close();

//The window we'll be rendering to
SDL_Window* gWindow = NULL;
    
//The surface contained by the window
SDL_Surface* gScreenSurface = NULL;

//The image we will load and show on the screen
SDL_Surface* gHelloWorld = NULL;

bool init()
{
    //Initialization flag
    bool success = true;

    //Initialize SDL
    if( SDL_Init( SDL_INIT_VIDEO ) < 0 )
    {
        printf( "SDL could not initialize! SDL_Error: %s\n", SDL_GetError() );
        success = false;
    }
    else
    {
        //Create window
        gWindow = SDL_CreateWindow( "SDL Tutorial", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, SCREEN_WIDTH, SCREEN_HEIGHT, SDL_WINDOW_SHOWN );
        if( gWindow == NULL )
        {
            printf( "Window could not be created! SDL_Error: %s\n", SDL_GetError() );
            success = false;
        }
        else
        {
            //Get window surface
            gScreenSurface = SDL_GetWindowSurface( gWindow );
        }
    }

    return success;
}

bool loadMedia()
{
    //Loading success flag
    bool success = true;

    //Load splash image
    gHelloWorld = SDL_LoadBMP( "hello_world.bmp" );
    if( gHelloWorld == NULL )
    {
        printf( "Unable to load image %s! SDL Error: %s\n", "02_getting_an_image_on_the_screen/hello_world.bmp", SDL_GetError() );
        success = false;
    }

    return success;
}

void close()
{
    //Deallocate surface
    SDL_FreeSurface( gHelloWorld );
    gHelloWorld = NULL;

    //Destroy window
    SDL_DestroyWindow( gWindow );
    gWindow = NULL;

    //Quit SDL subsystems
    SDL_Quit();
}

int main( int argc, char* args[] )
{
    //Start up SDL and create window
    if( !init() )
    {
        printf( "Failed to initialize!\n" );
    }
    else
    {
        //Load media
        if( !loadMedia() )
        {
            printf( "Failed to load media!\n" );
        }
        else
        {
            //Apply the image
            SDL_BlitSurface( gHelloWorld, NULL, gScreenSurface, NULL );
            
            //Update the surface
            SDL_UpdateWindowSurface( gWindow );

            //Hack to get window to stay up
            SDL_Event e; bool quit = false; while( quit == false ){ while( SDL_PollEvent( &e ) ){ if( e.type == SDL_QUIT ) quit = true; } }
        }
    }

    //Free resources and close SDL
    close();

    return 0;
}

TLDR；我可以编译这个 SDL2 代码，但是当我运行这个程序时，没有窗口出现。 无论我写什么代码，或者为了测试而借用，似乎都是这种情况。 我没有收到任何错误消息。

Answer 1

您的程序找不到

hello_world.bmp

文件，它会导致它在不显示窗口的情况下过早退出。

修复方法如下：首先检查

hello_world.bmp

是否在正确的位置，然后在

close()

函数中的

main()

之前添加一个 get_char() 调用，这将暂停程序并让您看到如果有错误。

int main( int argc, char* args[] )
{
    // Start up SDL and create window
    if( !init() )
    {
        printf( "Failed to initialize!\n" );
    }
    else
    {
        // Load media
        if( !loadMedia() )
        {
            printf( "Failed to load media!\n" );
        }
        else
        {
            // Apply the image
            SDL_BlitSurface( gHelloWorld, NULL, gScreenSurface, NULL );
            
            // Update the surface
            SDL_UpdateWindowSurface( gWindow );

            // Hack to get window to stay up
            SDL_Event e; bool quit = false; while( quit == false ){ while( SDL_PollEvent( &e ) ){ if( e.type == SDL_QUIT ) quit = true; } }
        }
    }

    // Add this line to pause the program before closing
    getchar();

    // Free resources and close SDL
    close();

    return 0;
}