create-for-stream.c

按照官方的说法：Cairo is a vector graphics library with cross-device output support. 翻译过来

/*
 * Copyright © 2006 Red Hat, Inc.
 *
 * Permission to use, copy, modify, distribute, and sell this software
 * and its documentation for any purpose is hereby granted without
 * fee, provided that the above copyright notice appear in all copies
 * and that both that copyright notice and this permission notice
 * appear in supporting documentation, and that the name of
 * Red Hat, Inc. not be used in advertising or publicity pertaining to
 * distribution of the software without specific, written prior
 * permission. Red Hat, Inc. makes no representations about the
 * suitability of this software for any purpose.  It is provided "as
 * is" without express or implied warranty.
 *
 * RED HAT, INC. DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
 * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS, IN NO EVENT SHALL RED HAT, INC. BE LIABLE FOR ANY SPECIAL,
 * INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
 * RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR
 * IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * Author: Kristian Høgsberg <[e-mail]>
 */

#include <stdio.h>
#include <string.h>
#include <errno.h>

#include <cairo.h>

#if CAIRO_HAS_PS_SURFACE
#include <cairo-ps.h>
#endif

#if CAIRO_HAS_PDF_SURFACE
#include <cairo-pdf.h>
#endif

#if CAIRO_HAS_SVG_SURFACE
#include <cairo-svg.h>
#endif

#include "cairo-test.h"

/* The main test suite doesn't test the *_create_for_stream
 * constructors for the PDF, PS and SVG surface, so we do that here.
 * We draw to an in-memory buffer using the stream constructor and
 * compare the output to the contents of a file writting using the
 * file constructor.
 */

#define MAX_OUTPUT_SIZE 4096

#define WIDTH_IN_INCHES  3
#define HEIGHT_IN_INCHES 3
#define WIDTH_IN_POINTS  (WIDTH_IN_INCHES  * 72.0)
#define HEIGHT_IN_POINTS (HEIGHT_IN_INCHES * 72.0)

static void
draw (cairo_surface_t *surface)
{
    cairo_t *cr;

    /* Just draw a rectangle. */
    cr = cairo_create (surface);

    cairo_rectangle (cr, WIDTH_IN_POINTS / 10, HEIGHT_IN_POINTS /10,
		     WIDTH_IN_POINTS - 2 * WIDTH_IN_POINTS / 10,
		     HEIGHT_IN_POINTS - 2 * HEIGHT_IN_POINTS /10);
    cairo_fill (cr);

    cairo_show_page (cr);

    cairo_destroy (cr);
}

typedef struct _write_closure {
    char buffer[MAX_OUTPUT_SIZE];
    int index;
    cairo_test_status_t status;
} write_closure_t;

static cairo_status_t
test_write (void		*closure,
	    const unsigned char	*data,
	    unsigned int	 length)
{
    write_closure_t *wc = closure;

    if (wc->index + length >= sizeof wc->buffer) {
	cairo_test_log ("Error: out of bounds in write callback\n");
	wc->status = CAIRO_TEST_FAILURE;
	return CAIRO_STATUS_SUCCESS;
    }

    memcpy (&wc->buffer[wc->index], data, length);
    wc->index += length;

    return CAIRO_STATUS_SUCCESS;
}


typedef cairo_surface_t *
(*file_constructor_t) (const char	       *filename,
		       double			width_in_points,
		       double			height_in_points);

typedef cairo_surface_t *
(*stream_constructor_t) (cairo_write_func_t	write_func,
			 void		       *closure,
			 double			width_in_points,
			 double			height_in_points);

static cairo_test_status_t
test_surface (const char		 *filename,
	      file_constructor_t	 file_constructor,
	      stream_constructor_t	 stream_constructor)
{
    cairo_surface_t *surface;
    write_closure_t wc;
    char file_contents[MAX_OUTPUT_SIZE];
    cairo_status_t status;
    FILE *fp;

    wc.status = CAIRO_TEST_SUCCESS;
    wc.index = 0;

    surface = stream_constructor (test_write, &wc,
				  WIDTH_IN_POINTS, HEIGHT_IN_POINTS);

    status = cairo_surface_status (surface);
    if (status) {
	cairo_test_log ("Failed to create surface for stream\n");
	return CAIRO_TEST_FAILURE;
    }

    draw (surface);

    cairo_surface_destroy (surface);

    if (wc.status != CAIRO_TEST_SUCCESS) {
	/* Error already reported. */
	return wc.status;
    }

    surface = file_constructor (filename,
				WIDTH_IN_POINTS, HEIGHT_IN_POINTS);

    status = cairo_surface_status (surface);
    if (status) {
	cairo_test_log ("Failed to create surface for file %s: %s\n",
			filename, cairo_status_to_string (status));
	return CAIRO_TEST_FAILURE;
    }

    draw (surface);

    cairo_surface_destroy (surface);

    fp = fopen (filename, "r");
    if (fp == NULL) {
	cairo_test_log ("Failed to open %s for reading: %s\n",
			filename, strerror (errno));
	return CAIRO_TEST_FAILURE;
    }

    if (fread (file_contents, 1, wc.index, fp) != wc.index) {
	cairo_test_log ("Failed to read %s: %s\n",
			filename, strerror (errno));
	return CAIRO_TEST_FAILURE;
    }

    if (memcmp (file_contents, wc.buffer, wc.index) != 0) {
	cairo_test_log ("Stream based output differ from file output for %s\n",
			filename);
	return CAIRO_TEST_FAILURE;
    }

    fclose (fp);

    return CAIRO_TEST_SUCCESS;
}


int
main (void)
{
    cairo_test_status_t status;

    printf("\n");

#if CAIRO_HAS_PS_SURFACE
    status = test_surface ("create-for-stream.ps",
			   cairo_ps_surface_create,
			   cairo_ps_surface_create_for_stream);
    if (status != CAIRO_TEST_SUCCESS)
	return status;
#endif

#if CAIRO_HAS_PDF_SURFACE
    status = test_surface ("create-for-stream.pdf",
			   cairo_pdf_surface_create,
			   cairo_pdf_surface_create_for_stream);
    if (status != CAIRO_TEST_SUCCESS)
	return status;
#endif

#if CAIRO_HAS_SVG_SURFACE
    status = test_surface ("create-for-stream.svg",
			   cairo_svg_surface_create,
			   cairo_svg_surface_create_for_stream);
    if (status != CAIRO_TEST_SUCCESS)
	return status;
#endif

    return CAIRO_TEST_SUCCESS;
}