Intro #

How Chapter 6 works? #

1. init()
   1. SDL_Init()
   2. SDL_CreateWindow()
   3. IMG_Init()
   4. SDL_GetWindowSurface()
2. loadMedia()
   1. loadSurface()
      1. load PNG file on intermediate surface with IMG_Load().
      2. optimize loaded intermediate surface into optimized surface with SDL_ConvertSurface().
         • free memory of intermediate surface with SDL_FreeSurface().
3. start loop untill variable quit is true.
   1. start loop that calls SDL_PollEvent() untill it returns 0.
      1. if SDL_Event.type is SDL_QUIT, quit is true( which means first loop will end).
      2. copy screen(Blit) with SDL_BlitSurface() from chosen PNG surface to screen surface.
      3. update window with SDL_UpdateWindowSurface() to refresh and show what we’ve done.
4. close()
   1. SDL_FreeSurface()
   2. SDL_DestroyWindow()
   3. IMG_Quit()
   4. SDL_Quit()

SDL_image.h #

• SDL_image is used in this chapter
• if you’re running on Windows, you need to place dll file inside proper system directory (like Windows/System32)
  • if you have dll error, use where <dll_name.dll> command to find error-able dll’s location
• writer is using IMG_2.0.4 version on SDL_2.0.9 version

Function #

IMG_Init() #

int IMG_Init( int flags );

• param
  • flsgs : bit flag indicates which image format to use while program
• return
  • flags that loaded successfully on both entire, partial success
  • 0 on failure

IMG_isJPG(), IMG_isPNG(), IMG_isTIF() doesn’t requires its initialization.
you can check currently loaded system with calliing this function with 0.

IMG_GetError() #

char* IMG_GetError( void );

• param
  • void
• return
  • char array with recent error information on error
  • empty array on no error happen

IMG version of SDL_GetError()

IMG_Load() #

SLD_Surface* IMG_Load( const char* file );

• param
  • file : image file name string (char array/pointer)
• return
  • image-loaded surface’s address on success
  • NULL on error

this function calls IMG_LoadTyped_RW() inside logic.
since this function returns surface, call SDL_FreeSurface() after use of this surface.

IMG_Quit() #

void IMG_Quit( void );

• param
  • void
• return
  • void

this function called after all IMG jobs are done.
SDL recommend to call this function essentially at end of program if you used IMG subsystem.

Struct #

• nothing new

Term #

IMG_Init() #

• IMG_INIT_PNG
• IMG_INIT_JPG
• IMG_INIT_TIF
• IMG_INIT_*