IMG_Load 返回 SDL_image 错误“不支持的图像格式”

Question

当我尝试加载 png 文件时，返回错误“不支持的图像格式”。人们之前已经在 StackOverflow 上发布了关于这个主题的帖子，但似乎没有一个解决方案对我有用。

我在 Linux 机器上工作，用 g++ 编译

这是我的图书馆...

#include <SDL2/SDL.h>
#include <SDL/SDL_image.h>
#include <stdio.h>
#include <string>
#include <zlib.h>
#include <png.h>

当我编译时，我包含了 -lSDL2 和 -lSDL_image 标志。我不使用 SDL2/SDL_image.h，因为它没有安装在我正在使用的机器上。此外，我的 png 文件肯定与我尝试加载它的代码位于同一目录中，我确实调用了 IMG_Init(IMG_INIT_PNG) 和 IMG_INIT_PNG。

这是我的代码，错误发生在 loadSurface 函数中（我相信）。

//Using SDL, SDL_image, standard IO, and strings
#include <SDL2/SDL.h>
//#include <SDL/SDL_version.h>
#include <SDL/SDL_image.h>
#include <stdio.h>
#include <string>
#include <zlib.h>
#include <png.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();

//Loads individual image
SDL_Surface* loadSurface( std::string path );

//The window we'll be rendering to
SDL_Window* gWindow = NULL;

//The surface contained by the window
SDL_Surface* gScreenSurface = NULL;

//Current displayed PNG image
SDL_Surface* gPNGSurface = 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
                {
                        //Initialize PNG loading
                        int imgFlags = IMG_INIT_PNG;
                      if( !( IMG_Init( imgFlags ) & imgFlags ) )
                      {
                              printf( "SDL_image could not initialize! SDL_image Error: %s\n", IMG_GetError() );
                              success = false;
                      }
                      else
                        {
                                //Get window surface
                                gScreenSurface = SDL_GetWindowSurface( gWindow );
                        }
                }
        }

        return success;
}

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

        //Load PNG surface
        gPNGSurface = loadSurface( "loaded.png" );
        if( gPNGSurface == NULL )
        {
                printf( "Failed to load PNG image!\n" );
                success = false;
        }

        return success;
}

void close()
{
        //Free loaded image
        SDL_FreeSurface( gPNGSurface );
        gPNGSurface = NULL;

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

        //Quit SDL subsystems
        IMG_Quit();
        SDL_Quit();
}

SDL_Surface* loadSurface( std::string path )
{
        //The final optimized image
        SDL_Surface* optimizedSurface = NULL;
 //Load image at specified path
        SDL_Surface* loadedSurface = IMG_Load( path.c_str() );
        if( loadedSurface == NULL )
        {
                printf( "1Unable to load image %s! SDL_image Error: %s\n", path.c_str(), IMG_GetError() );
        }
        else
        {
                //Convert surface to screen format
                optimizedSurface = SDL_ConvertSurface( loadedSurface, gScreenSurface->format, NULL );
                if( optimizedSurface == NULL )
                {
                        printf( "2Unable to optimize image %s! SDL Error: %s\n", path.c_str(), SDL_GetError() );
                }

                //Get rid of old loaded surface
                SDL_FreeSurface( loadedSurface );
        }

        return optimizedSurface;
}

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
                {
                       //Main loop flag
                        bool quit = false;

                        //Event handler
                        SDL_Event e;

                        //While application is running
                        while( !quit )
                        {
                                //Handle events on queue
                                while( SDL_PollEvent( &e ) != 0 )
                                {
                                        //User requests quit
                                        if( e.type == SDL_QUIT )
                                        {
                                                quit = true;
                                        }
                                }

                                //Apply the PNG image
                                SDL_BlitSurface( gPNGSurface, NULL, gScreenSurface, NULL );

                                //Update the surface
                                SDL_UpdateWindowSurface( gWindow );
                        }
                }
        }

        //Free resources and close SDL
        close();

        return 0;
}

编译时，我使用 g++、编译器标志 -w 和链接器标志 -lSDL2 -lSDL_image

当我运行时，输出如图所示......

1无法加载图片loaded.png！SDL_image 错误：不支持的图像格式

无法加载 PNG 图片！

无法加载媒体！

Answer 1

编译器标志-lSDL_image应该是-lSDL2_image