The document is a source code for a simple SDL-based graphics application that initializes a window, loads background and sprite images, and animates the sprite moving within the window boundaries. It includes functions for loading images, moving the sprite, and handling user input to quit the program. Main functionalities also involve setting up the display and refreshing the graphics in a loop as long as the program is running.

1. #include
SDL_Surface* Background = NULL;
SDL_Surface* SpriteImage = NULL;
SDL_Surface* Backbuffer = NULL;
SDL_Rect SpritePos;
int xPos;
int yPos;
int width=100;
int height=90;
int xDir;
int yDir;
SDL_Surface* LoadImage(char* fileName);
bool LoadFiles();
void moveBitMap(int& xPosition, int& yPosition, int width, int height, int& xDirection, int&
yDirection);
void FreeFiles();
bool ProgramIsRunning();
int main(int argc, char* args[])
{
if(SDL_Init(SDL_INIT_EVERYTHING) < 0)
{
printf("Failed to initialize SDL! ");
return 0;
}
Backbuffer = SDL_SetVideoMode(800, 600, 32, SDL_SWSURFACE);
SDL_WM_SetCaption("Color Keying", NULL);
if(!LoadFiles())
{
printf("Failed to load files! ");
FreeFiles();
SDL_Quit();
return 0;
}
SpritePos.x = 0;
SpritePos.y = 0;

2. while(ProgramIsRunning())
{
xPos = SpritePos.x; //get the current x position
yPos = SpritePos.y; //get the current y position
moveBitMap( xPos, yPos, width, height, xDir, yDir); //move the bitmap
SpritePos.x=xPos; //update x with new posivoid moveBitMap(int& xPosition, int& yPosition, int
width, int height, int& xDirection, int& yDirection)tion
SpritePos.y=yPos; //update y with new position
SDL_BlitSurface(Background, NULL, Backbuffer, NULL);
SDL_BlitSurface(SpriteImage, NULL, Backbuffer, &SpritePos);
SDL_Delay(20);
SDL_Flip(Backbuffer);
}
FreeFiles();
SDL_Quit();
return 0;
}
SDL_Surface* LoadImage(char* fileName)
{
SDL_Surface* imageLoaded = NULL;
SDL_Surface* processedImage = NULL;
imageLoaded = SDL_LoadBMP(fileName);
if(imageLoaded != NULL)
{
processedImage = SDL_DisplayFormat(imageLoaded);
SDL_FreeSurface(imageLoaded);
if(processedImage != NULL)
{
Uint32 colorKey = SDL_MapRGB(processedImage->format, 0, 0, 0);
SDL_SetColorKey(processedImage, SDL_SRCCOLORKEY, colorKey);
}
}
return processedImage;
}
bool LoadFiles()

3. {
Background = LoadImage("graphics/background.bmp");
if(Background == NULL)
return false;
SpriteImage = LoadImage("graphics/aieplane.bmp");
if(SpriteImage == NULL)
return false;
return true;
}
void FreeFiles()
{
SDL_FreeSurface(Background);
SDL_FreeSurface(SpriteImage);
}
void moveBitMap(int& xPosition, int& yPosition, int width, int height, int& xDirection, int&
yDirection)
{
int x = xPosition;
int y = yPosition;
int dirX = xDirection;
int dirY = yDirection;
x = x + dirX;
//if the bitmap has reached the right side
if(x > 800-width)
{
x = width - 100;
dirX = (-1);
}
if(x= 0)
{
x = 5;
dirX = 1;
}
y = y + dirY;
if(y > 600-height)

4. {
y = height - 90;//void moveBitMap(int& xPosition, int& yPosition, int width, int height, int&
xDirection, int& yDirection)
dirY = (-1);
}
if(y = 0)
y = 5;
dirY = 1;
xPosition = x;
yPosition = y;
xDirection = dirX;
yDirection = dirY;
}
bool ProgramIsRunning()
{
SDL_Event event;
bool running = true;
while(SDL_PollEvent(&event))
{
if(event.type == SDL_QUIT)
running = false;
}
return running;
}
Solution
#include
SDL_Surface* Background = NULL;
SDL_Surface* SpriteImage = NULL;
SDL_Surface* Backbuffer = NULL;
SDL_Rect SpritePos;
int xPos;
int yPos;
int width=100;
int height=90;

5. int xDir;
int yDir;
SDL_Surface* LoadImage(char* fileName);
bool LoadFiles();
void moveBitMap(int& xPosition, int& yPosition, int width, int height, int& xDirection, int&
yDirection);
void FreeFiles();
bool ProgramIsRunning();
int main(int argc, char* args[])
{
if(SDL_Init(SDL_INIT_EVERYTHING) < 0)
{
printf("Failed to initialize SDL! ");
return 0;
}
Backbuffer = SDL_SetVideoMode(800, 600, 32, SDL_SWSURFACE);
SDL_WM_SetCaption("Color Keying", NULL);
if(!LoadFiles())
{
printf("Failed to load files! ");
FreeFiles();
SDL_Quit();
return 0;
}
SpritePos.x = 0;
SpritePos.y = 0;
while(ProgramIsRunning())
{
xPos = SpritePos.x; //get the current x position
yPos = SpritePos.y; //get the current y position
moveBitMap( xPos, yPos, width, height, xDir, yDir); //move the bitmap
SpritePos.x=xPos; //update x with new posivoid moveBitMap(int& xPosition, int& yPosition, int
width, int height, int& xDirection, int& yDirection)tion
SpritePos.y=yPos; //update y with new position
SDL_BlitSurface(Background, NULL, Backbuffer, NULL);
SDL_BlitSurface(SpriteImage, NULL, Backbuffer, &SpritePos);

6. SDL_Delay(20);
SDL_Flip(Backbuffer);
}
FreeFiles();
SDL_Quit();
return 0;
}
SDL_Surface* LoadImage(char* fileName)
{
SDL_Surface* imageLoaded = NULL;
SDL_Surface* processedImage = NULL;
imageLoaded = SDL_LoadBMP(fileName);
if(imageLoaded != NULL)
{
processedImage = SDL_DisplayFormat(imageLoaded);
SDL_FreeSurface(imageLoaded);
if(processedImage != NULL)
{
Uint32 colorKey = SDL_MapRGB(processedImage->format, 0, 0, 0);
SDL_SetColorKey(processedImage, SDL_SRCCOLORKEY, colorKey);
}
}
return processedImage;
}
bool LoadFiles()
{
Background = LoadImage("graphics/background.bmp");
if(Background == NULL)
return false;
SpriteImage = LoadImage("graphics/aieplane.bmp");
if(SpriteImage == NULL)
return false;
return true;
}
void FreeFiles()

7. {
SDL_FreeSurface(Background);
SDL_FreeSurface(SpriteImage);
}
void moveBitMap(int& xPosition, int& yPosition, int width, int height, int& xDirection, int&
yDirection)
{
int x = xPosition;
int y = yPosition;
int dirX = xDirection;
int dirY = yDirection;
x = x + dirX;
//if the bitmap has reached the right side
if(x > 800-width)
{
x = width - 100;
dirX = (-1);
}
if(x= 0)
{
x = 5;
dirX = 1;
}
y = y + dirY;
if(y > 600-height)
{
y = height - 90;//void moveBitMap(int& xPosition, int& yPosition, int width, int height, int&
xDirection, int& yDirection)
dirY = (-1);
}
if(y = 0)
y = 5;
dirY = 1;
xPosition = x;
yPosition = y;

8. xDirection = dirX;
yDirection = dirY;
}
bool ProgramIsRunning()
{
SDL_Event event;
bool running = true;
while(SDL_PollEvent(&event))
{
if(event.type == SDL_QUIT)
running = false;
}
return running;
}