This is a very simple introduction to a very simple API.  (I love
simple APIs. :) If you want more in-depth documentation, see corona.h.

First, #include <corona.h>

Corona has a C++ API.  All symbols are in the 'corona' namespace.  For
convenience, you may wish to:

#include <corona.h>
using namespace corona;

However, this document assumes you don't want to clutter the global
namespace, and thus will prefix Corona symbols with corona::.

The most basic way to load an image is as follows:


corona::Image* image = corona::OpenImage("image.png");
if (!image) {
  // error
}

int width = image->getWidth();
int height = image->getHeight();
corona::PixelFormat format = image->getFormat();
void* pixels = image->getPixels();
switch (format) {
  case corona::PF_R8G8B8A8:  // process image data
  case corona::PF_R8G8B8:    // process image data
  default:  // can't handle the format?
}

delete image;


However, since I hate manually dealing with the possibility of
multiple pixel formats, I'd like corona to just give me the image in a
single format I can handle.  The second parameter to OpenImage is the
format you want the returned image in.  It defaults to PF_DONTCARE
(i.e., just give me any format you can).  The third parameter is the
file format, which defaults to FF_AUTODETECT.


corona::Image* image = corona::OpenImage("img.png", corona::PF_R8G8B8A8);
if (!image) {
  // error!
}

int width  = image->getWidth();
int height = image->getHeight();
void* pixels = image->getPixels();

// we're guaranteed that the first eight bits of every pixel is red,
// the next eight bits is green, and so on...

typedef unsigned char byte;
byte* p = (byte*)pixels;
for (int i = 0; i < width * height; ++i) {
  byte red   = *p++;
  byte green = *p++;
  byte blue  = *p++;
  byte alpha = *p++;
}