Cairo: Draw an array of pixels - cairo

Question

I'm just starting to explore Cairo, but right now I really want to use it for something very simple.
I have a very low-tech bitmap, i.e., a 3*X*Y array of numbers. I'd like to use Cairo to make this into a bitmap and write to a file. I'm looking through tutorials and I'm not seeing a way to use it for comparatively low-level functions like this.
I don't think I need guidance on how to use the tool once I know what the tool is.

Answer 1

I didn't actually test this, but the following should give you lots of useful hints:
#include <cairo.h>
#include <stdint.h>
#define WIDTH 42
#define HEIGHT 42
uint8_t data[WIDTH][HEIGHT][3];
cairo_surface_t* convert()
{
cairo_surface_t *result;
unsigned char *current_row;
int stride;
result = cairo_image_surface_create(CAIRO_FORMAT_RGB24, WIDTH, HEIGHT);
if (cairo_surface_status(result) != CAIRO_STATUS_SUCCESS)
return result;
cairo_surface_flush(result);
current_row = cairo_image_surface_get_data(result);
stride = cairo_image_surface_get_stride(result);
for (int y = 0; y < HEIGHT; y++) {
uint32_t *row = (void *) current_row;
for (int x = 0; x < WIDTH; x++) {
uint32_t r = data[x][y][0];
uint32_t g = data[x][y][1];
uint32_t b = data[x][y][2];
row[x] = (r << 16) | (g << 8) | b;
}
current_row += stride;
}
cairo_surface_mark_dirty(result);
return result;
}