gvloadimage_webp.c

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/*************************************************************************
 * Copyright (c) 2011 AT&T Intellectual Property 
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors: Details at https://graphviz.org
 *************************************************************************/
 
#include "config.h"
 
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <util/prisize_t.h>
 
#include <gvc/gvplugin_loadimage.h>
#include <gvc/gvio.h>
 
#ifdef HAVE_WEBP
#ifdef HAVE_PANGOCAIRO
#include <cairo.h>
#include <webp/decode.h>
 
static const char* const kStatusMessages[] = {
    "OK", "OUT_OF_MEMORY", "INVALID_PARAM", "BITSTREAM_ERROR",
    "UNSUPPORTED_FEATURE", "SUSPENDED", "USER_ABORT", "NOT_ENOUGH_DATA"
};
 
typedef enum {
    FORMAT_WEBP_CAIRO,
} format_type;
 
static void webp_freeimage(usershape_t *us)
{
    cairo_surface_destroy(us->data);
}
 
static cairo_surface_t* webp_really_loadimage(const char *in_file, FILE* const in)
{
    WebPDecoderConfig config;
    WebPDecBuffer* const output_buffer = &config.output;
    WebPBitstreamFeatures* const bitstream = &config.input;
    VP8StatusCode status = VP8_STATUS_OK;
    cairo_surface_t *surface = NULL; /* source surface */
    int ok;
    void* data = NULL;
 
    if (!WebPInitDecoderConfig(&config)) {
        fprintf(stderr, "Error: WebP library version mismatch!\n");
        return NULL;
    }
 
    fseek(in, 0, SEEK_END);
    long size = ftell(in);
    if (size < 0) {
        fprintf(stderr, "Error: WebP could not determine %s size\n", in_file);
        return NULL;
    }
    size_t data_size = (size_t)size;
    rewind(in);
    data = malloc(data_size);
    ok = data_size == 0 || (data != NULL && fread(data, data_size, 1, in) == 1);
    if (!ok) {
        fprintf(stderr, "Error: WebP could not read %" PRISIZE_T
                " bytes of data from %s\n", data_size, in_file);
        free(data);
        return NULL;
    }
 
    status = WebPGetFeatures(data, data_size, bitstream);
    if (status != VP8_STATUS_OK) {
        goto end;
    }
 
    output_buffer->colorspace = MODE_RGBA;
    status = WebPDecode(data, data_size, &config);
 
    /* FIXME - this is ugly */
    if (! bitstream->has_alpha) {
        int x, y;
        unsigned char *p, t;
 
        for (y = 0; y < output_buffer->height; y++) {
            p = output_buffer->u.RGBA.rgba + output_buffer->u.RGBA.stride * y;
            for (x = 0; x < output_buffer->width; x++) {
                t = p[0];     /* swap red/blue */
                p[0] = p[2];
                p[2] = t;
                p += 4;
            }
        }
    }
 
end:
    free(data);
    ok = status == VP8_STATUS_OK;
    if (!ok) {
        fprintf(stderr, "Error: WebP decoding of %s failed.\n", in_file);
        fprintf(stderr, "Status: %d (%s)\n", status, kStatusMessages[status]);
        return NULL;
    }
 
    surface = cairo_image_surface_create_for_data (
            output_buffer->u.RGBA.rgba,
            CAIRO_FORMAT_ARGB32,
            output_buffer->width,
            output_buffer->height,
            output_buffer->u.RGBA.stride);
 
    return surface;
}
 
/* get image either from cached surface, or from freskly loaded surface */
static cairo_surface_t* webp_loadimage(GVJ_t * job, usershape_t *us)
{
    cairo_surface_t *surface = NULL; /* source surface */
 
    assert(job);
    assert(us);
    assert(us->name);
 
    if (us->data) {
        if (us->datafree == webp_freeimage)
             surface = us->data; /* use cached data */
        else {
             us->datafree(us);        /* free incompatible cache data */
             us->datafree = NULL;
             us->data = NULL;
        }
    }
    if (!surface) { /* read file into cache */
        if (!gvusershape_file_access(us))
            return NULL;
        switch (us->type) {
            case FT_WEBP:
                if ((surface = webp_really_loadimage(us->name, us->f)))
                    cairo_surface_reference(surface);
                break;
            default:
                surface = NULL;
        }
        if (surface) {
            us->data = surface;
            us->datafree = webp_freeimage;
        }
        gvusershape_file_release(us);
    }
    return surface;
}
 
/* paint image into required location in graph */
static void webp_loadimage_cairo(GVJ_t * job, usershape_t *us, boxf b, bool filled)
{
    (void)filled;
 
    cairo_t *cr = job->context; /* target context */
    cairo_surface_t *surface;    /* source surface */
 
    surface = webp_loadimage(job, us);
    if (surface) {
        cairo_save(cr);
        cairo_translate(cr, b.LL.x, -b.UR.y);
        cairo_scale(cr, (b.UR.x - b.LL.x) / us->w, (b.UR.y - b.LL.y) / us->h);
        cairo_set_source_surface (cr, surface, 0, 0);
        cairo_paint (cr);
        cairo_restore(cr);
    }
}
 
static gvloadimage_engine_t engine_webp = {
    webp_loadimage_cairo
};
#endif
#endif
 
gvplugin_installed_t gvloadimage_webp_types[] = {
#ifdef HAVE_WEBP
#ifdef HAVE_PANGOCAIRO
    {FORMAT_WEBP_CAIRO, "webp:cairo", 1, &engine_webp, NULL},
#endif
#endif
    {0, NULL, 0, NULL, NULL}
};