c printing more pages with cairo and cups - c

Question

I need, in C in under a linux environment, to print documents with an image as a background.
I found an example which use Cairo vector graphics library to author a PostScript, and then sends it that off to CUPS for printing.
I modified the initial source code to integrate it with a background image (background-img.png) .
The text to be printed is more than one page, I would like to know how can I print on multiple pages keeping the same image as background and changing only the foreground text ?
How can I resize the background image to match the size of an A4 page ?
Here is the code used as a starting point :
// compile with:
// gcc -Wall -o cairo_print_png cairo_print_png.c `pkg-config --cflags --libs cairo` `cups-config --cflags --libs`
#include <stdio.h>
#include <cairo.h>
#include <cairo-ps.h>
#include <cups/cups.h>
// A4 width, height in points, from GhostView manual:
// http://www.gnu.org/software/gv/manual/html_node/Paper-Keywords-and-paper-size-in-points.html
#define WIDTH 595
#define HEIGHT 842
int main(int argc, char** argv) {
int widthPng, heightPng;
if (argc!= 2){
fprintf (stderr, "usage: %s word\n", argv[0]);
return 1;
}
// setup
char* tmpfilename = tempnam(NULL,NULL);
cairo_surface_t* surface = cairo_ps_surface_create(tmpfilename,
WIDTH,
HEIGHT);
cairo_t *context = cairo_create(surface);
// draw some text
cairo_select_font_face(context,
"mono",
CAIRO_FONT_SLANT_NORMAL,
CAIRO_FONT_WEIGHT_NORMAL);
cairo_set_font_size(context, 30);
cairo_move_to(context, WIDTH/2, HEIGHT/2);
cairo_show_text(context, argv[1]); // the text we got as a parameter
// draw a dotted box
const double pattern[] = {15.0, 10.0};
cairo_set_dash(context, pattern, 2, 0);
cairo_set_line_width(context, 5);
cairo_rectangle(context, WIDTH*0.33, HEIGHT*0.33, WIDTH*0.5, WIDTH*0.5);
cairo_stroke(context);
cairo_surface_t* surface_png = cairo_image_surface_create_from_png("background-img.png");
if (surface_png == NULL || cairo_surface_status (surface_png)) {
printf("***** load error *****\n");
}
widthPng = cairo_image_surface_get_width(surface_png);
heightPng = cairo_image_surface_get_height(surface_png);
cairo_surface_set_device_scale (surface_png,
widthPng/WIDTH*1.33,
heightPng/HEIGHT*1.29);
cairo_set_operator(context, CAIRO_OPERATOR_DEST_OVER);
cairo_set_source_surface(context, surface_png, 0, 0);
cairo_paint(context);
/*** second page ***/
{
cairo_t *cr;
cr = cairo_create (surface);
/* Duplicate the last frame onto another page. (This is just a
* way to sneak cairo_copy_page into the test).
*/
cairo_show_page (cr);
//draw text on second page
cairo_select_font_face(cr,
"mono",
CAIRO_FONT_SLANT_NORMAL,
CAIRO_FONT_WEIGHT_NORMAL);
cairo_set_font_size(cr, 30);
cairo_move_to(cr, WIDTH/2, HEIGHT/2);
cairo_show_text(cr, "text over second page");
cairo_set_operator(cr, CAIRO_OPERATOR_DEST_OVER);
cairo_set_source_surface(cr, surface_png, 0, 0);
cairo_paint(cr);
cairo_destroy (cr);
}
// finish up
cairo_show_page(context);
cairo_destroy(context);
cairo_surface_flush(surface);
cairo_surface_destroy(surface);
cairo_surface_flush(surface_png);
cairo_surface_destroy(surface_png);
// print
cupsPrintFile("Cups-PDF", tmpfilename, "cairo PS", 0, NULL);
unlink(tmpfilename);
return 0;
}
Update :
I added the text enclosed in "second page". I can create another page, but I can't resize the background image.
How can I resize the image to fit the A4 size?
Update
I used cairo_surface_set_device_scale to resize the image, and the mono font to use a fixed width font
Update
The problem now is that the code works with cairo-1.15.12-4 while if I try to compile with cairo-1.8.8-3.1 I get undefined reference to cairo_surface_set_device_scale'.
What can I solve the problem? At the moment I cannot update the libraries using rpm as I would have to update the whole operating system.
Can I somehow replace the cairo_surface_set_device_scale with functions that perform the same task?
Update:
In the Cairo Mailing Lists I found the following function that does the job :
cairo_surface_t *scale_to_half(cairo_surface_t *s, int orig_width, int
orig_height, double x_scale, double y_scale)
{
cairo_surface_t *result = cairo_surface_create_similar(s,
cairo_surface_get_content(s), orig_width*x_scale, orig_height*y_scale);
cairo_t *cr = cairo_create(result);
cairo_scale(cr, x_scale, y_scale);
cairo_set_source_surface(cr, s, 0, 0);
cairo_set_operator(cr, CAIRO_OPERATOR_SOURCE);
cairo_paint(cr);
cairo_destroy(cr);
return result;
}
but the quality is very low compared to cairo_surface_set_device_scale.