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04_key_presses.cpp~
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04_key_presses.cpp~
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/*This source code copyrighted by Lazy Foo' Productions (2004-2015)
and may not be redistributed without written permission.*/
//Using SDL, standard IO, and strings
#include <SDL2/SDL.h>
#include <stdio.h>
#include <string>
//Screen dimension constants
const int SCREEN_WIDTH = 640;
const int SCREEN_HEIGHT = 480;
//Key press surfaces constants
enum KeyPressSurfaces
{
KEY_PRESS_SURFACE_DEFAULT,
KEY_PRESS_SURFACE_UP,
KEY_PRESS_SURFACE_DOWN,
KEY_PRESS_SURFACE_LEFT,
KEY_PRESS_SURFACE_RIGHT,
KEY_PRESS_SURFACE_TOTAL
};
//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;
//The images that correspond to a keypress
SDL_Surface* gKeyPressSurfaces[ KEY_PRESS_SURFACE_TOTAL ];
//Current displayed image
SDL_Surface* gCurrentSurface = 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 default surface
gKeyPressSurfaces[ KEY_PRESS_SURFACE_DEFAULT ] = loadSurface( "gpress.bmp" );
if( gKeyPressSurfaces[ KEY_PRESS_SURFACE_DEFAULT ] == NULL )
{
printf( "Failed to load default image!\n" );
success = false;
}
//Load up surface
gKeyPressSurfaces[ KEY_PRESS_SURFACE_UP ] = loadSurface( "gup.bmp" );
if( gKeyPressSurfaces[ KEY_PRESS_SURFACE_UP ] == NULL )
{
printf( "Failed to load up image!\n" );
success = false;
}
//Load down surface
gKeyPressSurfaces[ KEY_PRESS_SURFACE_DOWN ] = loadSurface( "gdown.bmp" );
if( gKeyPressSurfaces[ KEY_PRESS_SURFACE_DOWN ] == NULL )
{
printf( "Failed to load down image!\n" );
success = false;
}
//Load left surface
gKeyPressSurfaces[ KEY_PRESS_SURFACE_LEFT ] = loadSurface( "gleft.bmp" );
if( gKeyPressSurfaces[ KEY_PRESS_SURFACE_LEFT ] == NULL )
{
printf( "Failed to load left image!\n" );
success = false;
}
//Load right surface
gKeyPressSurfaces[ KEY_PRESS_SURFACE_RIGHT ] = loadSurface( "gright.bmp" );
if( gKeyPressSurfaces[ KEY_PRESS_SURFACE_RIGHT ] == NULL )
{
printf( "Failed to load right image!\n" );
success = false;
}
return success;
}
void close()
{
//Deallocate surfaces
for( int i = 0; i < KEY_PRESS_SURFACE_TOTAL; ++i )
{
SDL_FreeSurface( gKeyPressSurfaces[ i ] );
gKeyPressSurfaces[ i ] = NULL;
}
//Destroy window
SDL_DestroyWindow( gWindow );
gWindow = NULL;
//Quit SDL subsystems
SDL_Quit();
}
SDL_Surface* loadSurface( std::string path )
{
//Load image at specified path
SDL_Surface* loadedSurface = SDL_LoadBMP( path.c_str() );
if( loadedSurface == NULL )
{
printf( "Unable to load image %s! SDL Error: %s\n", path.c_str(), SDL_GetError() );
}
return loadedSurface;
}
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;
//Set default current surface
gCurrentSurface = gKeyPressSurfaces[ KEY_PRESS_SURFACE_DEFAULT ];
//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;
}
//User presses a key
else if( e.type == SDL_KEYDOWN )
{
//Select surfaces based on key press
switch( e.key.keysym.sym )
{
case SDLK_UP:
gCurrentSurface = gKeyPressSurfaces[ KEY_PRESS_SURFACE_UP ];
break;
case SDLK_DOWN:
gCurrentSurface = gKeyPressSurfaces[ KEY_PRESS_SURFACE_DOWN ];
break;
case SDLK_LEFT:
gCurrentSurface = gKeyPressSurfaces[ KEY_PRESS_SURFACE_LEFT ];
break;
case SDLK_RIGHT:
gCurrentSurface = gKeyPressSurfaces[ KEY_PRESS_SURFACE_RIGHT ];
break;
default:
gCurrentSurface = gKeyPressSurfaces[ KEY_PRESS_SURFACE_DEFAULT ];
break;
}
}
}
//Apply the current image
SDL_BlitSurface( gCurrentSurface, NULL, gScreenSurface, NULL );
//Update the surface
SDL_UpdateWindowSurface( gWindow );
}
}
}
//Free resources and close SDL
close();
return 0;
}