#include "stdio.h"
#include "cairo.h"

cairo_status_t write_func(void * closure, const unsigned char *data, unsigned length)
{
    if (closure==NULL) return CAIRO_STATUS_SUCCESS;
    if (length == fwrite(data, 1, length, (FILE*)closure))
        return CAIRO_STATUS_SUCCESS;
    else
        return CAIRO_STATUS_WRITE_ERROR;
}

int main()
{
    /* Vary these input parameters */
    const int offset = 20000; /* How much do we offset our elements in Y direction. */
    const double scale = 1.6; /* How much scaling do we want to apply */

    /* Additional preparation */
    const int viewport_x = 200, viewport_y= 200; /* The size of our viewport in pixels.*/
    char scale_text[1000];
    char fname[1000];
    sprintf(scale_text, "scale: %g, offset: %i", scale, offset);
    sprintf(fname, "test_%i_%i.png", (int)(scale*100), offset);

    /* Record a simple line and text at y position of 'offset'. */
    /* Note that the recorded surface does not depend on scale or
     * offset other than the text output */
    cairo_surface_t *rec = cairo_recording_surface_create(CAIRO_CONTENT_COLOR_ALPHA, NULL);
    cairo_t *cr = cairo_create(rec);
    cairo_move_to(cr, 0, offset);
    cairo_line_to(cr, 100, offset);
    cairo_stroke(cr);
    cairo_move_to(cr, 0, offset);
    cairo_show_text(cr, scale_text);
    cairo_destroy(cr);


    /* Replay the recorded surface to an image scaled by 'scale'.
    * (We only play back a small area of it around our elements to reduce
    * output image size to 'viewport'.)*/
    cairo_surface_t *surf = cairo_image_surface_create(CAIRO_FORMAT_RGB24, viewport_x, viewport_y);
    cr = cairo_create(surf);
    cairo_set_source_rgb(cr, 1, 1, 1);
    cairo_rectangle(cr, 0, 0, viewport_x, viewport_y);
    cairo_fill(cr);
    cairo_scale(cr, scale, scale);
    cairo_set_source_surface(cr, rec, 0, -offset+viewport_y/2/scale);
    cairo_paint(cr);
    cairo_destroy(cr);
    FILE *outFile = fopen(fname, "wb");
    cairo_surface_write_to_png_stream(surf, write_func, outFile);
    fclose(outFile);
    cairo_surface_destroy(surf);
}