C Library Commands and How to Use Them

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Introduction


This guide will eventually list almost every C Library command in the SDK, and give a detailed explanation on how to use each one.


Graphics Commands

Here you will find all of the graphx library commands


gfx_AllocSprite and gfx_GetSprite


This command is useful to set room aside in the program for new sprites you will create with gfx_GetSprite and/or for sprites to need to decompress.

gfx_MallocSprite() In the graphx.h file:

/**
 * Allocates room on the heap for sprite data of given size
 * Returns NULL upon failure to allocate space, otherwise a pointer to the sprite structure
 * Note that if you use the system malloc routine, it must be used elsewhere in your program
 * otherwise it will not be linked correctly
 */
gfx_image_t *gfx_MallocSprite(uint8_t width, uint8_t height );
  • width - The width of the sprite you want to decompress or create
  • height - The height of the sprite you want to decompress or create

gfx_GetSprite() In the graphx.h file:

/**
 * Quickly grab the background behind a sprite (useful for transparency)
 * sprite_buffer must be pointing to a large enough buffer to hold width*height number of bytes
 * A pointer to sprite_buffer is also returned for ease of use.
 * sprite_buffer is updated with the screen coordinates given.
 */
gfx_image_t *gfx_GetSprite(gfx_image_t *sprite_buffer, int x, int y);
  • sprite_buffer - The name of the sprite you want to create, the one defined with MallocSprite
  • x - The x position on the screen of where to grab the sprite
  • y - The y position on the screen of where to grab the sprite

Ok, so now we're going to show you how to use both commands. Check this example code out, to be explained afterwards.

gfx_image_t *sprite;
malloc( 0 );
sprite = gfx_MallocSprite( 30, 40 );
gfx_GetSprite( sprite, 20, 50 );
  • gfx_image_t sprite; declares a sprite variable
  • malloc( 0 ); makes sure malloc is linked correctly. You only need to do this once.
  • sprite = gfx_MallocSprite( 30, 40 ); sets the width and height of sprite
  • gfx_GetSprite( sprite, 20, 50 ); grabs a sprite at x = 20 and y = 50, and stores it in `sprite` for later use