Question

我试图让这个代码在不同的类上运行，它出现了一个空的窗口，然后立即关闭。

的main.cpp

//The Headers
#include "SDL_SCREEN.h"
#include "SDL/SDL.h"
#include "SDL/SDL_image.h"

//The event structure
SDL_Event event;

int main (int argc, char* args[]){

    printf( "START" );    
    //The quit flag
    bool quit = false;

    //The Surface to be displayed
    SDL_Surface* dis = NULL;

    //The Screen Surface
    SDL_Surface* screen = NULL;
    //The screen
    SDL_SCREEN screen_sdl;



    if ( screen_sdl.init( "TEST", screen ) == false )
    {
            return 1;
    }

    dis = screen_sdl.load_image( "a.png" );

    screen_sdl.apply_surface( 0, 0, dis, screen, NULL );

    if ( SDL_Flip ( screen ) == -1 )
    {
            return 1;
    }
    while ( quit == false )
    {
            //While there are events to handle
            while ( SDL_PollEvent( &event ) )
            {
                    //if the user has xed out the window
                    if ( event.type == SDL_QUIT )
                    {
                            //Quit the program
                            quit = true;
                    }
            }
    }

    screen_sdl.clean_up( dis, screen );
    SDL_Quit();
}

SDL_SCREEN.h

#include "SDL/SDL.h"
#include "SDL/SDL_image.h"

class SDL_SCREEN{    
        public:
            SDL_Surface *load_image( char* );
            void apply_surface( int, int, SDL_Surface*, SDL_Surface*, SDL_Rect* );
            bool init(char*, SDL_Surface*);
            void clean_up(SDL_Surface*, SDL_Surface*);
            void flip_screen (SDL_Surface* screen){
                    if ( SDL_Flip ( screen ) == -1)
                    {
                            printf( "BLAH" );
                    }
            }
};

SDL_SCREEN.cc

//The Headers
#include "SDL/SDL.h"
#include "SDL/SDL_image.h"
#include "SDL_SCREEN.h"
#include <stdio.h>
//Screen atrabutes
const int SCREEN_WIDTH = 640;
const int SCREEN_HEIGHT = 480;
const int SCREEN_BPP = 32;

SDL_Surface *SDL_SCREEN::load_image ( char *filename )
{
        printf( "LOADING" );
    //the image thats loaded
    SDL_Surface* loadedImage = NULL;

    //The optimized image
    SDL_Surface* optimizedImage = NULL;

    //Load the image
    loadedImage = IMG_Load( filename );

    if ( loadedImage != NULL )
    {
            printf("Loaded");
            //Create the optimized image
            optimizedImage = SDL_DisplayFormat( loadedImage );

            //Free the old surface
            SDL_FreeSurface( loadedImage );

            //If the surface was optimized
            if ( optimizedImage != NULL )
            {
                    printf( " OPTIMIZED" );
                    //Color key the surface
                    SDL_SetColorKey( optimizedImage, SDL_SRCCOLORKEY, SDL_MapRGB( optimizedImage->format, 0, 0xFF, 0xFF ) );
            }


    }

    //return the optimized image
    return optimizedImage;
}

void SDL_SCREEN::apply_surface( int x, int y, SDL_Surface* source, SDL_Surface* destination, SDL_Rect* clip = NULL )
{

    //holds offsets
    SDL_Rect offset;

    //get offsets
    offset.x = x;
    offset.y = y;

    //blit
    SDL_BlitSurface( source, clip, destination, &offset );
}

void SDL_SCREEN::clean_up( SDL_Surface* to_clean, SDL_Surface* screen  )
{
    //Free the surfaces
    SDL_FreeSurface( to_clean );
    SDL_FreeSurface( screen );

}

bool SDL_SCREEN::init (char *Caption, SDL_Surface *screen)
{

    //Initialize all SDL subsystems
    if ( SDL_Init( SDL_INIT_EVERYTHING == -1 ) )
    {
            return false;
    }

    //set ut the screen
    screen = SDL_SetVideoMode( SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_BPP, SDL_SWSURFACE );

    //if there was an error setting up the screen
    if( screen == NULL )
    {
            return false;
    }

    //set up the window caption
    SDL_WM_SetCaption( Caption, NULL );

    return true;
}

Answer 1

您的init仅修改screen参数，而不修改main中的变量当你到达apply_surface时，它仍然是NULL （你可以使用调试器在几秒钟内找到它。）

您的SDL_Init来电也有错位的括号 - 您使用SDL_INIT_EVERYTHING == -1调用它而不是检查其返回值。

请改为：

SDL_Surface* SDL_SCREEN::init (char *Caption)
{
    if (SDL_Init(SDL_INIT_EVERYTHING) == -1)
    {
        return NULL;
    }   
    SDL_Surface* screen = SDL_SetVideoMode( SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_BPP, SDL_SWSURFACE );
    if (screen != NULL)
    {
        SDL_WM_SetCaption( Caption, NULL );
    }
    return screen;
}

（旁注：由于SDL_SCREEN没有任何状态，因此将它作为一个类是没有意义的。）

Answer 2

尝试在SDL_Quit();之前使用断点，并尝试在调试模式下运行它。或者使用getch（）强制程序在关闭之前显示输出。

试图让代码在类上运行

2 个答案: